Optimization of Orthodontics Elastics. m. Manglade

MICHEL LANGLADED. C. D. - D. S. O. - D. U. O.

OPTIMIZATION oforthodontic ELASTICS

Edited by GAC International

MICHEL LANGLADE

D. C. D. - D. S. O. - D. U. O.

OPTIMIZATION of orthodontic ELASTICS

224 pages - 159 pictures

Edited by GAC International Inc.185 Oval Drive

Central Islip. N. Y. 11722 - 1402 Fax: (516) 582 57 04

January 2000

From the same author:

CEPHALOMETRIE ORTHODONTIQUEPréface Carl F. GUGINO

281 Pages - 202 Photos - 1978.

DIAGNOSTIC ORTHODONTIQUEPréface Ruel W. BENCH

768 Pages - 552 Photos - 1981.

THERAPEUTIQUE ORTHODONTIQUEPréface Robert M. RICKETTS

3rd Edition - 1986

OPTIMISATION DES CHOIX ORTHODONTIQUESAide à la décision

347 Pages - 146 Photos - 1994

OPTIMISATION TRANSVERSALEDES OCCLUSIONS CROISEES UNILATERALES POSTERIEURE

Préface Rudolf SLAVICEK384 Pages - 349 Photos - 1996

French editor: MALOINE27, rue de l’Ecole de Médecine75006 Paris FRANCETél.: (33) 01.43.25.60.45Fax: (33) 01.46.34.05.89

Italian editor: S. T. D. EDIZIONI INTERNAZIONALIVia Capecelatro 7520 148 Milano ITALIATél.: (39) 02 - 404.43.21Fax: (39) 03 - 036.15 27

Brazilian editor: SANTOS EDITORIA701 rua Dona Brigida04111 081 Sao Paulo S. P. BRAZILTél.: (5511) 574 - 1200Fax: (5511) 573 - 8774 And soon on the Web...

CHAPTER I: Definitions.............................................................. p 1• Definitions• Presentation of orthodontic elastics• Elastics force use

CHAPTER II: History of Elastics Forces...................................... p 5

CHAPTER III: Classification of Orthodontic Elastic Forces........ p 7• Classification • Clinical statement• Force delivery• Classification of forces• Basis for prescribed pressures• Anchorage

CHAPTER IV: Elastics Wearing Motivation................................ p 20• Patient compliance with elastics• Motivation of elastics wearers• Motivation card• Appointment interval of elastics wearers• Headgear instruction card• Motivation scoring card

CHAPTER V: Class I Elastic Forces......................................….. p 32• Definition• Disposition• Biomechanics of Class I elastic• Class I elastics effects with continuous archwires• Class I elastics indications• Clinical application of Class I elastics• Elastomeric chains • Clinical problems with Class I elastics• The O shape occlusal elastic

TABLE OF CONTENTS

CHAPTER VI: Class II Elastics Forces........................................ p 53• Definition• Disposition• Biomechanics of Class II elastics• Class II elastics effects with continuous archwires• Class II elastics indications• Clinical applications of Class II elastics• Clinical problems with Class II elastics• TMD and Class II elastics• Pain and Class II elastics• Orthognatics and Class II elastics• Influence of the archwire and hooked point• Bioprogressive torque Class II elastics• The Class II molar extrusion elastic• How to diminish the extrusion component force• The split positioner

CHAPTER VII: Class III Elastics Forces...................................... p 83• Definition• Disposition• Biomechanics of Class III elastics• Class III elastics effects on continuous archwires• Indication of Class III elastics• Clinical applications of Class III elastics• Clinical problems with Class III elastics• TMD and Class III elastics• Pain and Class III elastics• Orthognatics and Class III elastics

CHAPTER VIII: Particular Intermaxillary Elastics....................... p 97 • The Rectangular elastic• The U shape elastic• The Delta elastic• The V shape elastic• The M or W shape elastics• The Accordion elastics• The Class II Triangular elastic• The Class III Triangular elastic• Squeeze elastics• The cross bite elastics

- Cross bite classification- Homolateral crossbite elastic- Controlateral crossbite elastic

• Elastics and dental asymmetries- Canted anterior occlusal plane- Unilateral posterior cross bite- Midline shift deviation- Asymmetric arch form

• Elastics in condylar fractures

CHAPTER IX: Elastics and Extra Oral Forces.............................. p 128• The twenty commandments of E. O. F.• The Class I elastic headgear• The Class II elastic headgear• The Class III elastic headgear• The whiskers headgear• Postero anterior elastics

- The PHILIPPE’s Circummandibular Arch- The Facial Mask of:

DELAIRE-VERDONPETITGRUMMONS NANDA

- The J. HICKHAM’s Chin Cup- The M. LANGLADE’s Reciprocal Mini Chin Cup- Orthopedic Class III Chin Cup

CHAPTER X: Rationale for Elastics Prescription......................... p 159• Before using intra oral elastics• How to prescribe elastics• Clinical example• Quiz of clinical situations

CONCLUSION............................................................................ p 178

BIBLIOGRAPHY........................................................................ p 180

CHAPITER I

Definitions

1

CHAPTER I: Definitions

DEFINITIONS

• ELASTICITY:

It is the property of a material to return to its original form.

• ELASTIC MATERIAL:

Presents usually 3 properties:

1 - a distorsion not going beyond its limit of elasticity2 - physically homogeneous3 - isotrop, giving the same force in any direction ( see Fig I. 1 ).

Fig I. 1: A 3 ounce elastic in different clinical situations.

• LIMIT OF ELASTICITY:

It is the amount of forced distorsion without deterioration and loss of elasticity .

• CLAPEYRON’S THEOREM OF RECIPROCITY

When an elastic force is applied to two identical solids ( for instance two central incisors ) themoving force is identical and reciprocal.

• ELASTOMERS

General term encompassing materials returning to their original dimensions immediately aftersubstantial distorsion. Under this term are:

- natural rubber or latex coming from hevea trees

- synthetic rubber polymers such as styren butadien rubber, butyl, polyisopren,polybutadien, ethylpropylen, teflons, hypalon, silicons.

2


PRESENTATION OF ORTHODONTIC ELASTICS

For a long time rubber elastics have been offered to the Orthodontic community in:- different sizes- different shape forces giving a precise applied force.

They are presented in a plastic bag decorated with various symbols to help patientsrecognize which elastic was received for the last prescription.

All elastics are sold in packages of 100 with a rapid zip and forces are indicated with:

colour coding countries fruitfirst name animals toys

sports plants objects

Some Ortho manufacturers have even proposed mint flavoured elastics in order to improvepatient compliance in elastic wear.

Orthodontic elastics can be designated as:- intraoral- extraoral

Usually,the prescribed force is obtained when the elastic is stretched out three times its diameter.

To check the elastic forces, the orthodontist can use CORREX or DONTRIX gauges ( see Fig I.3 ).

ADVANTAGE OF ELASTICS:

• placed and removed by the patient• discarded after worn out• no activation required by the orthodontist• effect increased by mandibular movements ( mastication, phonation )• can be changed upon prescription one, two, three times a day or even worn at night.

DISADVANTAGE OF ELASTICS:

The orthodontist must be aware of:

• deterioration and loss of elasticity:Any elastic worn in mouth is affected by:

PH of oral environmentsaliva➩➩

3


dental plaquetimefoods and drinks.

• moisture absorption makes the elastic swollen and odoriferous.• non odor free when worn after 24 hours.• unpredictably variable forces exerted if the prescription is not well explained and

controlled.• the exerted force is not constant and depends on patient compliance• elastics can be placed incorrectly, upsetting biomechanic effects of the appliance.• patient motivation.

The more the rubber elastic is worn, the less the elasticity memory stays, as E. HIXON 4 et. al.have demonstrated ( see Fig I.2 ).

After 2 hours in the mouth,the module elastic force decreases about 30%, and after 3 hours about 40%.

It means that in clinical uses, elastics must be changed regularly according to the orthodonti-st’s prescription.

Fig I.2: Percentage of elastic force lost in mouth from E. HIXON 5 et. al.A. J. O. Vol 57 N° 5. p 481 1970.

➩➩➩

4


ELASTICS FORCE USE

Keep in mind:1 - Components forces2 - Anchorage3 - Hooked point of force application4 - Clinical objectives5 - Biomechanic systems used6 - Elastic types7 - Patient cooperation

FACTORS IN ANCHORAGE LOSSin extraction cases treated with continuous archwires

1 - Friction2 - Anterior torque3 - Poor canine root control4 - Excessive pressure5 - Cooperation

Fig I.3: To check the elastic forces the Orthodontist can use CORREX or DONTRIX gauges.

CHAPITER II

History of Elastics Forces

5

CHAPTER II: History of Elastics Forces

The first known elastic was the natual rubber used by INCAN and MAYAN civilizationsextracted from Hevea trees.

☛ 1728: Pierre FAUCHARD in his book “ Le Chirurgien Dentiste ou Traité desDents ” proposed to close anterior diastema with silk ligature.

☛ 1756: P. BOURDET used a “ bandeau ” with golden or silk ligatures to moveteeth, prefiguring the straightwire era.

☛ 1803: F. CELLIER introduced for the first time the “ Chin Cup Fround ” withrubber bandages.

☛ 1839: Charles GOODYEAR discovered vulcanization.

☛ 1841: J. M. A. SCHANGE, in his “ Précis sur le redressement des dents ”published in Paris, used elastic threads to move teeth.

☛ 1892: Calvin CASE was the first to use intermaxillary elastic forces to cor-rect malocclusions.

☛ 1904: H. BAKER published in the International Dental Journal an articleentitled “ Treatment of protruding and receding jaws by the use ofintermaxillary elastics ”.

☛ 1907: Edward H. ANGLE in his book “ Treatment of malocclusion of teeth ”proposed a classification of malocclusions and the use of correspon-ding elastic forces: Class I ; Class II ; Class III.

☛ 1948: Charles TWEED initiated the Class III elastic use to reinforce theanchorage preparation of Class II malocclusion before using Class IIelastics.

☛ 1958: Fred SHUDY recommended short Class II elastics coming from theupper first molar and in association with a high pull anterior extraoralforce in order to control the vertical sense.

☛ 1963: J. JARABAK and FIZZEL in their book “ Technique and treatmentwith the light wire appliance ” page 70 to 82 from Mosby were descri-bing the biomechanics of Class II elastics for the first time.

6

CHAPTER II: History of Elastics Forces

☛ 1965: R. BEGG in his book “ Begg orthodontic theory and technique ” usedClass II elastics which were changed every five days.

☛ 1964-1970: Robert M. RICKETTS originated the Bioprogressive segmented lightsquare wire technique advising the closing elastics conduct in openbite cases.

☛ 1972: Ron ROTH recommended short Class II intermaxillary elastics to helpthe curve of SPEE leveling associated with high pull headgear to con-trol the vertical sense.

☛ 1973-1996: Michel LANGLADE developed the clinical applications of elastic for-ces in different situations such as occlusal elastics or controlateralcrossbite elastics, proposing biomechanics comparison in clinicaluses.

Intraoral ElasticsOnly pure, natural latex is used in producing GAC elastics. Precise wall thickness and predictable forcesare consistent characteristics of our full line of elastics. Our Travel Pack recognition system makes it funand easy for patients to remember the correct size and force. In addition to size and force designation,each smudge-proof bag has a landmark, symbol, or activity associated with a specific country. Each pack ofGAC intraoral elastics contains a bright white placer to help patients properly and easily use their elastics.

Inside Light Medium Heavy Super Heavy XH XXHDiameter Red /1.8oz Green/2.7oz Blue/4oz Black/6oz Brown/6oz Black/8oz

3mm 11-100-03 11-101-03 11-102-03(1/8Ó) Australia Germany India4mm 11-100-04 11-101-04 11-102-04 11-103-04 11-105-04(3/16Ó) Holland Mexico Switzerland Thailand Africa 6mm 11-100-06 11-101-06 11-102-06 11-103-06 11-105-06(1/4Ó) China USA Japan Korea Kenya8mm 11-100-08 11-101-08 11-102-08 11-103-08 11-104-08 11-105-08(5/16Ó) Canada Italy Scandinavia So. America Greece Argentina10mm 11-100-10 11-101-10 11-102-10 11-104-10 11-105-10(3/8Ó) England Spain France Greece Peru12mm 11-104-12(1/2Ó) Greece14mm 11-104-14(9/16Ó) Greece16mm 11-100-16 11-104-16(5/8Ó) Ireland Greece18mm 11-104-18(11/16Ó) Greece

Light, Medium, Heavy, and SH are packaged in boxes of 50 zip lock bags of 100 elastics. XH and XXH arepackaged in boxes of 25 zip lock bags of 50 elastics.

ELF Ð Latex Free ElasticsEliminate rashes, irritation, and other allergic reactions with GAC's Latex Free Elastics. ELF Elastics aremade from a surgical material that is hypoallergenic and exerts a more consistent force at up to 500% elon-gation. Available in a variety of sizes, in boxes of 50 bags of 100 ELF Elastics in each bag. Get the per-formance you want without the risk of allergic reaction.

INTRAORAL EXTRAORAL

Light Medium Heavy Super HeavyRed/1.8oz. Green/2.7oz. Blue/4oz. Black/6oz.

1/8" 11-201-03 / Panama 11-202-03 / Columbia

3/16" 11-201-04 / Belgium 11-202-04 / Brazil 11-203-04 / So. Africa1/4" 11-200-06 / Philippines 11-201-06 / Russia 11-202-06 / Chile 11-203-06 / Saudi Arabia5/16" 11-200-08 / Singapore 11-201-08 / Indonesia 11-202-08 / Luxembourg 11-203-08 / Hungary3/8" 11-200-10 / Malaysia 11-201-10 / Finland5/8" 11-200-16 / Guatemala

Elastomers

CHAPITER III

Elastics Forces Classification

7

CH

APT

ER

III: Classification of O

rthodontic Elastic Forces

ELASTICDISPOSITION

ELASTICCLASSIFICATION

MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Class I

Monomaxillary

Monomandibular

Contraction

• horizontal• vertical• transversal

• Space closure• Distal movement• Mesial movement• Tipping• Extrusion• Intrusion

NO

Class II

Regular

Distal max

Mesial mandible

Extrusion

Dental and

Skeletal

Class II

Class III and

Class II skeletal open bite

Closing

Class II

Distal max

Mesial mandible

Close the bite

Open bite

Class II

Class III and

Class II deep bite

→

→

→

→

→

8

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Class III

Regular

Mesial max

Distal mandible

Extrusion Ø

Dental and

Skeletal

Class III

( normal vertically )

Class II and

Skeletal open bite

Closing

Class III

Mesial max

Distal mandible

Extrusion

Dental

Deep bite

Class III

Class II and

Skeletal open bite

Short closing

Class III

Mesial max canine

Distal mandible

Close the bite

Open bite

Class III

Class II and

deep bite

→→

→

→

→→

→

→

9

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Class II

and

Class III

Oblique pull

extrusion

Midline correction

canine relationship

Skeletal

open bite

Anterior

Diagonal

Oblique

Oblique pull

extrusion

Midline

shift correction

Anterior

Triangular

Oblique pull

extrusion

of one side

Canted occlusal plane

with

midline shift

Deep bite ?

10

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Posterior

triangular

Class II

Distal max

Mesial mandible

Extrusion

Dental

deep bite

Class II

Open bite

Anterior

U shape

Extrusive

force

Dental

open bite

Deep bite

Anterior

rectangular

Contraction

and

extrusion

Dental

open bite

Deep bite

→ →

→

→

11

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Intermaxillary

vertical elastic

Extrusive

force

Vertical

extrusion

Open bite

Delta

elastic

Extrusive force

+

light contraction

Vertical

extrusion

Open bite

W and M

elastic

Extrusive

force

Vertical extrusion

to

squeeze the bite

Skeletal

open bite

12

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Accordion

elastic

Contraction+ + + +

Extrusion+ + + +

Open bite

with

spaces to close

Skeletal

open bite

Posterior

triangular

Class III

Mesial max

Distal mandible

Extrusion

Deep bite

dental

Class III

Skeletal

open bite

Homolateral

cross bite

elastic

Transversal force +

Extrusion + + +

Edge to edge

cross bite

degree 1

Skeletal

open bite

→→→

→

→

13

CH

APT

ER



ELASTICDISPOSITION


MOVEMENTFORCE

INDICATIONCOUNTER

INDICATION

Controlateral

cross bite

elastic

Horizontal transversalforce

+ + + +

Extrusion

Degree 2 to 3

cross bite

Skeletal

open bite

O shape

occlusal elastic

Tranversal

contraction

Too buccal

ectopic tooth

position

Combined

elastics

Class I + Class II

Class I + Cross bite

Class II + Cross bite

Etc.......( see chapters ).

See and check

CR

▼

Individual clinicalObjective

14

CHAPTER III: Classification of Orthodontic Elastic Forces

CLINICAL STATEMENT

Name: N°: Date:

A / TRANSVERSAL:

RIGHT Crossbite NORMAL Crossbite LEFT

Maxillary Maxillary

Mandible Mandible

Grade by a figure 1, 2, 3 the malposed teeth

B / VERTICAL:

3SD 2SD 1SD 3SD 2SD 1SD

Class : Deep bite Normal Open bite

Skeletal

Dental

Grade by 1 SD, 2 SD, 3 SD . Use an arrow for tendency

C / SAGITTAL:

Right Maxilla LeftA yes yes yes yes yes yes yes yes AN R no no no no no no no no N RC A Loose Mini Mean Maxi Maxi Mean Mini Loose C AH G yes yes yes yes yes yes yes yes H GO E no no no no no no no no O E

Right Mandible Left

15


Sunburstª ElasticsGACÕs Sunburst Elastics are made from the finest quality latex. They are clean-cut, durable, hygienic, and made with regulation coloring. Available in a wide range of sizes andforce values, Sunburst provides the precise degree ofrequired control with a continuous force. Like our regular intra-oral elastics, Sunburst is packaged with a bright white placerin each bag for easier use and greater patient cooperation.Colors are randomly assorted and are not available in specificcolors. Sold in boxes of 50 zip bags, 100 elastics per bag.

Catalog NumberDescription 3/16" 1/4" 5/16" 2.7 oz. 11-001-04 11-001-06 11-001-084.0 oz. 11-002-04 11-002-06 11-002-086.0 oz. 11-003-04 11-003-06 11-003-08

Elastics RacksOur aluminum anodized elastics rack is durable, light weight,and has holes for mounting on a wall. Holds four boxes of GACelastics.

Aluminum Elastics Rack 97-300-30

FORCE DELIVERY

Force application plays a strategic influence on orthodontic movement by means ofwires and elastic rubber bands.

Histologicaly optimum orthodontic movement had been related to an intact vascular supply.An optimum force should not exceed the capillary blood pressure ( 20 to 25 gm/cm2 ).

If forces are above this level, clinical observations demonstrate possible ligament strangula-tion and sometimes root resorption.

Many authors had concluded that one of the major factors, if not the principal, gover-ning bone resorption during tooth movement is the presence of an intact vascular system.

Z. DAVIDOVITCH 3 had proposed intermittent forces as more suitable because their durationwould not be sufficient to produce anoxic destruction of the ligament.

According to this author, osteoclasts, which were stimulated to function by the force applica-tion, would continue to resorb bone for a brief period of time mobilizing the necessary boneremoving cells.

16


CLASSIFICATION OF FORCES

OUNCES GRAMS FORCE

0.5 14.17 veryO 1 28.35 light O

R 2 56.6 R

T 3 84.9 light T

H 4 113.2 H

O 5 141.5 O

D 6 169.8 D

O 7 198.1 O

N 8 226.4 medium N

T 9 254.7 T

I 10 283.0 I

C 11 311.3 C

12 339.6O 13 367.9 heavy O

R P 14 396.2 R P

T E 15 424.5 T E

H D 16 453.6 very H D

O I 32 907.2 heavy O I

C 48 1360.8 C

Table III.1

17


BASIS FOR PRESCRIBED PRESSURES

According to the Brian LEE theory, the value of 200 g. per square centimeter of enfa-ce root surface could be an average of sagittal malocclusion.R. M. RICKETTS 2 had advocated a lighter force at 150 g./ cm2 for biological efficiency ( seeTable III.2 ).

Root rating scale in transversal movements:

Root surface 1.20 .55 .75 .75 .40 .50 Total4.15 cm2

Necessaryforce 180 85 110 115 60 75 Total

635 g.

Necessary Totalforce 175 90 90 115 40 40 635 g.

TotalRoot surface 1.10 .60 .60 .75 .25 .25 3.55 g.

Table III.2: Root ratings with a 150 grams use / cm2.

The size of enface root surface exposed to sagittal movement is measured in square centime-ters. Every tooth can be evaluated as to the necessary force based on its root surface involved.

That means, on average, a force of:➩ 635 g. in maxilla➩ 550 g. in mandibleto move all of the teeth.

With friction, continuous archwires used with ceramic bracketts, it’s easy to understand thatheavy forces may be needed to move teeth.In order to use lighter forces, a frictionless biomechanic system may be advised with segmen-ted archwires.Doing so, orthodontic movement with elastic forces should be faster and more efficient.

Root rating scale in transversal movements:

1.05 1.35 .50 .50 .70 .65 .70

Maxilla 155 205 75 75 105 100 105forces 105 135 50 50 70 65 70Mandible 95 105 60 60 70 50 50forces 140 155 90 90 105 75 75

.95 1.05 .60 .60 .70 .50 .50

Table III.3

Root rating scale in vertical movements:

.70 .80 .30 .30 .45 .30 .40

Maxilla 105 120 45 45 65 45 60forces 70 80 30 30 45 30 40Mandible 95 105 60 60 70 50 50forces 140 155 90 90 105 75 75

.95 1.05 .60 .60 .70 .50 .50

Table III.4

18


19


Table III.5

>

STATIC

FIXED

RIGID

MEASURABLE

ABSOLUTECOOPERATION

WITH ORWITHOUT

COOPERATION

NON MEASURABLE

DIFFERENTIAL

MOBILE

DYNAMIC

LIGHT FORCESHEAVYFORCES

WITHFRICTION

CONTINUOUSARCHWIRES

SEGMENTEDARCHWIRES

FRICTIONLESS

MECHANIC BIOLOGIC

ANCHORAGE

CHAPITER IV

Elastics Wearing Motivation

20

CHAPTER IV: Elastics Wearing Motivation

PATIENT COMPLIANCE WITH ELASTICS

As a clinical statement patient compliance is difficult to evaluate before the treatment.However as a useful predictor evaluation, some factors must be taken in account:

- Girls are usually more cooperative than boys.Of 10 studies relating gender to various aspects of compliance, 5 reported that girls weremore cooperative, but 5 found no sex difference.

- Children under age of 10 years are more cooperative than older children.

- Socio-economic status may be a predicting factor.Less cooperation is experience with patients from lower socio-economic status; but thatdoes not mean that high class patients are more concerned.

- Personality is a better factor to consider for uncooperative patients, characterized asbeing concerned with appearance, having conflicts with a mother, a father, or both, andneeding the presence of authority to enforce ethical behaviour.

- Cooperation is not related to severity of the malocclusion.

- Embarrassment may be given as an excuse, forgetfulness, nuisance for low motivation,or apathy.

- Pain is sometimes underestimated in the clinical setting of elastics bearers.Its importance should not be dismissed since pain is one of the most frequent reasons fornot wearing intra oral or extra oral rubber bands. Some patients will require more com-munication regarding the amount of discomfort and progressive elastic forces to getaccustomed with.

In conclusion, communication is essential.

So, three rules to keep in mind:

1 Explain

2 Explain

3 Explain

21


MOTIVATION OF ELASTICS WEARERS

During some phases of orthodontic treatment, elastics or rubber bands are used to moveteeth or jaws or sometimes both.Sometimes elastics are absolutely necessary to keep anchorage in order to move the goodtooth.

Patient compliance is essential:

➩ to maximize cooperation

➩ to avoid headgear use, if possible

➩ to avoid mechanic problems

➩ to avoid relapse.

Remember that the Motivation key is to dramatize any little problem:

Fig IV.I

22


Elastics prescription needs:

1 - a written prescription on a motivation card to reinforce the message .

2 - to explain why, when, and how to wear elastics (see Fig IV.3 ).

3 - to check that the patient understands well the message and is able to place properly the prescribed elastics (see Fig IV.4 ).

4 - to keep an eye on motivation, ask to the patient to put on his elastics in front of you.

5 - to evaluate patient cooperation with:

∑ weakness of progress correction

∑ improvement of motivation means

∑ threats of complications:

➨ increased treatment time

➨ possibilities of extractions

➨ possibilities of surgery

➨ increased fees ...

“ Please follow your elastics prescription exactly as we askedyou: you’ll get faster and better results ”.

“ Change them and wear them as indicated. Stay with your ela-stics even if you have some discomfort particularly during the firsttwo days ( as with a new pair of shoes ) ”.

“ Remember that well worn elastics mean you are speeding yourtreatment time ”.

“ Bring back your worn out elastics at each visit ”, said R. BEGG 27, as a good way to educa-te a recalcitrant patient.

23


FRONT of Motivation card

Dr. STRAIGHT1057 Paradise Av.

L. A.CALIFORNIA

INSTRUCTIONS FOR ELASTICS WEARING

Now you have elastics to wear to help us tostraighten your teeth. They are used to exert light for-ces to move dental arches.The different elastics sizes and prescription corre-spond to various tractions that will be used in succes-sion of the correction of your teeth.At the beginning of elastic wearing, you may havesome light tenderness during one or two days. Don’tbe afraid, go on wearing them, you’ll be accustomedto them very quickly !

• Wear your elastics EXACTLY as has prescribedon the back.

• If you have any difficulties in placing them,please come back to our office. We will help.

• In order to brush your teeth and your gums cor-rectly, remove the elastics and put them back onimmediately after brushing.

• Always have some extra elastics in your pocketto use in the event of breakage.

PLACE ON your elastics IN FRONT of a MIRROR.

Wear them: Change them:❏ day and night ______ time(s) a day❏ only at night.

If you need elastics, please call our office immediately.

FAILURE to follow instructions may result in biomechanic complications and POSTPONE the FINAL RESULT.

BACK of Motivation card

FOLLOWING INSTRUCTION and GOOD COOPERATION MAKE YOUR TREATMENT FASTER.

24


Fig IV. 2: Example of an elastic worn around two upper incisors with initial diastema. Theelastic went up in the gingiva with periodontal damage.

Fig IV.3: Clinical example of an exaggerated movement given by Class II elastics changing aClass II in Class III.

25


Fig IV.4: Example of a misunderstood prescription of elastics. To correct the Class II caninewe need a closing Class II elastic.

Fig IV.5: A supply of elastics on the watch of a well motivated patient. During school hours,elastics can be changed.

26


APPOINTMENT INTERVAL OF ELASTICSWEARERS

It is always difficult to give a rule, because any patient at any visit during treatmenttime presents a clinical situation to which the orthodontist has to offer an appropriate and indi-vidual therapeutic solution.

During the course of a treatment the practitioner has to ask himself the following questions:

- What is the actual clinical situation ? > Use the chart in chapter 10 to lay down the problem.

- What are the objectives to reach for the next visit ?- How do I meet those objectives ?- With what kind of biomechanic systems can we reach those objectives ?- Which elastics should the patient wear to accomplish good results ?

On a general basis, an appointment visit is subject to different factors:

1- Importance of movement to obtain

The appointment interval may be regulated according to the gravity of the malocclu-sion. The more the sagittal Class II canine relationship is important the longer the intervals ofthe first visits.Generally, when starting the Class II discrepancy, the interval of the first two or three visitsmay be every 8 weeks. Then in succession of interarch correction the interval may be 6 or even4 weeks, according to the clinical exams. There is no absolute rule because the orthodontistmay slow down elastics wearing in prescribing them full time at the beginning and duringnight time only at the end of correction (see Table IV.1 ).

APPOINTMENT INTERVAL OF ELASTICS BEARERS

Skeletal Class II Skeletal Class I

every 8 wks ➝➝➝➝➝➝➝ 8 wks ➝➝➝➝➝➝➝ 6 wks/ 4 wks ➝➝➝➝➝➝➝ 2 wks ➨Elastics changes:

X3 per day ➝➝➝➝➝➝➝ X2 per day ➝➝➝➝➝➝➝ X1 per night

Dental Class II Dental Class I

every 6wks ➝➝➝➝➝➝➝ 4 wks ➝➝➝➝➝➝➝➝➝ 2 wks ➝➝➝➝➝➝➝➝➝➝➝➝ ➨Elastics changes:

X2 per day ➝➝➝➝➝➝➝➝➝➝➝➝ X1 per night

Table IV.1

27


2- The clinical goal to reach

The Orthodontist may advise the patient to schedule his next visit only when the goalwill be reached.For instance, if the patient has to wear a delta elastic to bring down an upper ectopic canine,you can ask him or her to wear elastics until the canine contact with antagonists, and then callfor a new visit.

FRICTIONLESS LIGHT FORCES+

SEGMENTATION=

Minimum EFFORT for a MAXIMUM EFFECT

3- In exaggerate correction risks

Some clinical cases have to be watched. Particulary some Class II discrepancies, whoare used to well wear their elastics, are sometimes able to go in an excessive Class III and evenwith the caution of the Orthodontist.Explain to the patient about the danger of undesirable movement.Do not hesitate to reduce the interval of clinical visits or to reduce elastics wearing in an alter-nate way-night time only or every other night for exemple.

Visit intervals and elastics wearing depend on:➤ anchorage used➤ importance of movement➤ patient typology➤ patient motivation➤ biomechanic archwires technique used➤ patient growth➤ parodontal situation.

Be carefull:Badly or incorrectly hooked elastics may change

biomechanics effects and complicate the treatment.

Risks of excessive elastics wear:

• an excessive correction ( a Class II becoming a Class III as shown in fig IV.3 ).• an exaggerate tipping of lower or upper incisors ( backward / forward ).• anchorage lost.• undesirable extrusion / overbite.

28


• exaggerate rotation.• parodontal problem, such as Class II worn too much, may give lower incisors

dehyscence.

Be carefull: To dual biteClass II elastics wearing for a long time may

simulate a corrected malocclusion.The patient may exhibit a misleading convenience bite ( dual bite ).

So, check centric relation at any appointment before any elasticsprescription.

CENTRIC RELATION OUTLINE

1 - CR is a necessary treatment.2 - Patient must be seated at 90°.3 - In absence of pathology, CR is not static but a dynamic relationship.4 - With muscle pathology, CR does not exist !5 - 85 % of TMD’s are muscular problems.6 - CO - CR discrepancies are the result of muscle pathology or internal derangement.7 - Sliding CO - CR may change.8 - When healthy, TMJ are flexible, adaptable and have the capacity to compensate.9 - Think chronologicaly:

1 - muscles2 - TMJ3 - occlusion4 - MRI5 - articulators.

10 - Use deprogrammation splint, if pain exists.11 - Use sagittal range of motion to detect dual bite.12 - Screen TMD:

pain ( dynamic vs static )functional restrictionnoise ? ?dyskinesiamuscle tenderness.

13 - Choose pain reduction first ( ultrasounds, Tens, stress management, pharmacology).14 - Instruct the patient.15 - Patient’s eyes closed.16 - Sting the soft palate with a probe.17 - Ask the patient to swallow with the tongue placed on the soft palate sting.18 - Stop the closing mouth at the first interdental contact.19 - Check the CR occlusion.20 - Use a Moyco wax bite to register CR.

➩➩➩➩➩

29


LIMITATIONS AND WARNING SIGNAL OF ELASTICS WEARING

1 - Muscular fatigue ? ➝ myalgia.

2 - TMJ arthralgia ➝ pain.

3 - Functional mandible limitation.

4 - Mandibular dyskinesia.

5 - Increased noise: - clicking- ligament laxity- crepitus.

6 - Excessive dental tipping:- molar anchorage- forward / backward incisors.

7 - Teeth interferences:- mobility- dental pain- parodontal problems.

8 - Condylar loading signals with:- Class III elastics- chin cup/facial mask- excessive molar extrusion.

9 - Improper incisor guidance:- open bite- overbite.

10 - Insufficient arch coordination ( 3 D ) transverse first!

11 - Multiple root resorption ( extrusion / intrusion ).

12 - Chronic tongue interposition ( thumb sucker ).

13 - Chronic respiratory problems ( apnea or sleep disorders ).

14 - Excessive growth.

15 - Insufficient growth.

30


HEADGEAR INSTRUCTION CARD

Headgear therapy is ordinarily used when the upper jaw has out grown the lower jaw.This easy correction is going to modify the skeletal maxilla and your appearence, in slowingthe upper growth and allowing the lower jaw to catch up:

1 - Handle everything carefully, especially when removing or inserting the inner bow.

2 - Never try to pull the headgear off without first unhooking elastics or the strap whichis attached to the outer bow.

3 - If a molar band becomes loose, come immediately to our office as an emergencyappointment.

4 - Wear your appliance from:

❒ 12 to 14 hours ❒ 16 to 20 hours

5 - Discomfort is temporary; wear your appliance faithfully.

6 - Use your score card to keep record of the number of hours you are wearing yourappliance night and day.

7 - Recording the wearing hours allows your orthodontist to determine needed forces forproper correction.

8 - To put on your headgear is quite simple in front of a mirror, or have someone helpyou.

9 - Don’t twist or distort your inner or outer bow by playing with it.

10 - Please don’t wear your headgear during rough play, sports, cycling.... This couldresult in injury to you.

Very important:

Remember to bring your appliance to any appointmentto give us a chance to properly adjust it.

31


MOTIVATION SCORING CARD

HOURS S M T W Th F Sat S M T W Th F Sat ...242322212019181716151413121110

Please score how many hours you have worn your headgear per 24 hours

Name:

Adress:

Don’t forget to bring this card to each appointment.

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Description Catalog NumberElastics Placers 11-999-99

CHAPITER V

Class I Elastics Forces

32

CHAPTER V: Class I Elastics Forces

1 - Definition

The Class I elastic can be a chain, a rubber band, a ring or a thread placed on a singlearch and having a vertical or a horizontal force movement.The Class I elastic has a reciprocical biomechanic action in a straight line

2 - Disposition

The Class I elastic can be placed:

• one tooth to another tooth

• one tooth in opposite way as a couple of forces

• one tooth to an archwire, a loop

• one point to another point of the archwire

• one tooth to an auxilary appliance such as Quad Helix, a palatal bar, a biteplate etc...

The Class I elastic is a monomaxillary or monomandibular elastic which can be used withother elastics in the same time.

3 - Biomechanics of a Class I elastic

Whatever it is a chain, a ring or a thread, the Class I elastic has reciprocal action instraight line.The force exerted depends on clinical objectives, considering the STABLE force or anchora-ge used and the MOBILE force to move the teeth, we must always have:

STABLE force > MOBILE force

That means, for example, that if you have, as in Fig V.8, to move distally a 41 and to close adiastema, an elastic thread ligature around 42 and 41 will move both equally in the space. Tomove distally the 41 you should placed the thread elastic on two or more teeth or thru the uti-lity helix to keep the stable force higher than the mobile one.

Be careful: Elastics not well hang on or worn by the patient cancomplicate treatment objectives.

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Fig V. 1: Different Class I elastics uses.

34


Fig V.2:Buccal upper incisor tipping foradult in typical Class II.2.The elastic thread is tied on a .045wire.

Fig V.3: Intrusion of a molar or cuspid witha thread elastic, tied on utility arch.

Fig V.4: Intrusion of lower incisors in adult,with a thread elastic, on a R.BENCH lower arch.

35


Fig V.5: Class I elastic ligature used to rotate and bring forward the left lateral incisor in theopened space by the M utility.

Fig V.6: Class I elastic to slide backward the right lower lateral incisor. The elastic is chan-ged 3 times a day.

36


Fig V.7: Example of elastic ligatures tied to rotate the 24 with an opposing force couple.

Fig V.8: Example of a Class I elastic ligature thru an utility Helix to close a lower incisor diastema in moving distally the 41.

37


Fig V.9: Example of Class I elastic chain and ligature to rotate a canine and an upper firstpremolar with a force couple.

Fig V.10: Example of Class I elastics on a bite plate to correct a midline deviation and closediastemas.

38


Fig V.11: Example of a tongue thruster who had reopened a diastema after a treatment. ClassI elastic is placed on a bite plate.

Fig V.12: Detail of the Class I cross elastic to close diastemas.

39


Fig V.13: Class I elastic ligature tied on the 4T4 to close the lower diastema. The patientwas already in retention.

Fig V.14: Result obtained with the Class I cross elastic and lower elastic ligature. Permanentretention with Ribbond was made.

40


Fig V.15: Example of space reopened after treatment. The patient does not want to have bra-ces any more.

Fig V.16: A bonded hook is made distal to the upper lateral incisor.

41


Fig V.17: An upper bite plate with an “ O ” occlusal elastic is worn to close the diastema.

Fig V.18: Detail of the “ O ” occlusal elastic used to close the diastema.

42


Fig V.19: Frontal view showing the diastema closure with the “ O ” elastic.

Fig V.20: The bonded hook is removed and the upper incisors are splinted with a ribbondwire.

43


Fig V.21: Class I elastics used on a crossway on a bite plate ( intraoral view ) for space clo-sing.

Fig V.22: Class I elastics used on a crossway on a bite plate for space closing.

44


4 - Class I elastics effects with continuous archwires

Most of Class I elastics can have a contraction movement effect which may be hori-zontal, vertical, or transversal.The effects may include:

• space closure• distal movement ( retraction )• mesial movement ( advancement )• tipping• extrusion• intrusion.

Again, the Class I elastic may be used in association with other elastics to reinforce a move-ment or anchorage ( see Fig V.23 and 24 ).

5 - Class I elastics indications

According to most practioners, utilization of elastic thread has proven to be one of the simplestand most efficient way to methods:

➨ to rotate of a single tooth or reciprocal teeth ( see Fig V.1 and 9 )

➨ to achieve space closure

➨ to use force couple maintaining the centroïd axis of a tooth during rotation control

➨ to move a tooth which is difficult to tie in the archwire

➨ to intrude a tooth or a group of teeth ( cuspid intrusion )

➨ to extrude a tooth which is impacted or in ectopic position.

In finishing and detailing occlusion, an elastic thread can be helpful to get an overcorrectionof a canine, a molar, etc.

6 - Clinical applications of Class I elastics

Clinical applications are numerous:1 - SPACE CLOSING as diastema, the Class I is used as a contraction system ( see Fig

V.11 - 14 ).

2 - DENTAL MOVEMENT for retraction of a tooth or a forward advancement of aposterior segment ( see Fig V.23 and 24 ).

3 - EXTRUSION of a single tooth in ectopic position ( buccally or palatally ).

4 - INTRUSION of incisors ( the elastic is placed on from a reciprocal 0.45 arch ).

5 - TIPPING CORRECTION of a tooth axis.

45


Influence of elastic association used - in extraction cases - on continuous archwires

Fig V.23: A: A Class I elastic on maxillary arch to retract the upper canine can certainly moveit backward, but a slight forward movement of the upper molar can be seen if M1is not anchored by an auxilary such as a palatal bar, a headgear...

B: A Class I elastic on maxillary arch anchored on the second molar is a betteranchorage than can achieve a retraction of the upper canine.

C: A Class I elastic used simultaneously on maxilla and mandible moves forwardthe upper molar with the lower during the retraction of the upper canine.

46


Fig V.24: D: The association of a maxillary Class I with a Class II elastic moves forwardslightly the maxillary molar when the lower goes forward

E: The association of a bimaxillary Class I elastic with a Class II one moves themolar forward and the upper canine backward.

F: The association of a maxillary Class I with a short Class II allows retraction ofthe upper canine without moving the upper molar. Then the lower molar can bebrought forward without losing maxillary anchorage.

47


6 - ROTATION with one Class I or with force couple of two opposed Class I ( see FigV.9 ).

7 - STRENGTHENING FORCE such as to increase:• the loosening anchorage, a Class I can be added to a Class II or III according

to the clinical objectives.• the maximum anchorage, a Class I can be also added for differential forces

to increase the stable force.• the midline shift correction.

7 - Elastomeric chains

Polyurethane chain elastics are commonly used in daily orthodontics as Class I elastics.They are made by Ortho manufacturers in:

- long filament chain- short filament chain- closed loop chain.

Elastomeric chains are mainly used for intra arch tooth movement and for spaces closing,because placement and removal requires little chairtime and no patient cooperation.

More than 50 studies had been done on elastomeric chains; a consensus of clinicians may besummarized as follow:

• a permanent deformation may result after extension of plastic module

• the degradation of force is increased over time

• the force exerted is unpredictable and inconstant

• the configuration of chain affects the behaviour of the force

• after 3 weeks, the residual force is generally about 5 %.

• oral environment ( such as PH, light, saliva, drinks, foods, dental plaque ) has beenassociated with degradation of the polyurethane elastomer

• extension or prestretching has been advocated before inserting the chains

• the elastomeric chains must be kept in a container and protected from light.

The elastomeric chains must be changed at least every 3 weeks.

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Fig V.25: Configuration of elastomeric chains:A - long filament chainB - short filament chainC - closed loop chain.

The longer the chain’s filament, the lower the initial force

8 - Clinical problems with Class I elastics

Clinical problems are very rare. The most important one is that usually the force decreases rap-idly. So the thread or chain must be changed at least every 3 weeks.

As with any system in Orthodontics, Class I elastics may give complications such as:

- abnormal tipping- exaggerated rotation- exaggerated extrusion- anchorage lost- minor or insufficient displacement...

Since more and more practitioners are using straight wires, some of them have undesirableeffects in using a continuous elastic chain on too light archwire < 0.016.

49


Undesirable effects of continuous elastic chain

1 Mesial molar rotation with too light wires

2 Light wires do not sustain the chain force

3 Posterior expansion of archwire

4 Wilson’s curve is threatened ( molar crossbite )

5 Undesirable root tipping

6 Increased Class II elastic forces

7 Risk of weakening anchorage

8 Molar tipping ➩ interferences

9 Incisors extrusion ➩ Torque lost

10 Lateral pterygoïd tenderness

11 Lower incisor retroversion with mandibular arch contraction

12 Increased overbite.

9 The « O » shape occlusal elastic

The “ O ” shape occlusal elastic had been introduced by M. LANGLADE in 1975 tocorrect dental transverse malposition, which is most of the time unitarian.

This elastic is placed occlusally on the maxillary or mandibular arch in order to correct:

• a buccal tooth position which is in buccal cross bite degree 1 or 2 (see Chapter VIII Table VIII.1 ). Sometimes it may be a second molar.

• an arch asymmetry• spaces or diastemas• a lack of canine contact in maxillary arch ( see Fig V.26 ).

Biomechanically, the “ O ” shape elastic moves one tooth or a limited group of teethtransversaly. That could be a canine, a premolar, or a molar. Usually, it can be worn on a sim-ple way or in criss cross according the clinical objectives ( see Fig V.29 ).

The “ O ” shape occlusal elastic:

➨ must be worn during night only

➨ must be worn during a short time because of its efficiency

➨ must be controlled every week.

50


Fig V.26: Occlusal elastic placed on upper canine to correct a retarded occlusal contact func-tion. The light contraction is usually obtained in a week.

Fig V.27: Correction of a too buccal position of first upper bicuspids with an occlusal elastic.

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51


Fig V.28: Clinical example of the application of an occlusal elastic worn on the lower molarwhich became too buccal.This kind of “ O ” elastic is worn during night only and for a short time ( 2 to 3 weeks ) tocorrect the lower buccal cross bite degree 2 (see text ).

With a mandibular reverse arch curve,don’t use a continuous elastomeric chain...

Prefer a segmented chain to allow a buccal tipping of retruded incisors !

Chain segmentation:[R Molar - R canine] [incisors] [L canine - L Molar]

52


Fig V.29: Clinical example of bilateral buccal upper canine corrected with cross “ O ” shapeelastics.

CHAPITER VI

Class II Elastics Forces

53

CHAPTER VI: Class II Elastics Forces

1 - Definition

Class II elastics are intermaxillary elastics placed on the maxilla anteriorly, and on themandible posteriorly.

2 - Disposition

Class II elastics may be placed differently on:

➨ the mandibular arch posteriorly buccally, lingually or simultaneously from:

• different teeth M2, M1, Pm2, Pm1• distal to a molar tube• a hook• a loop• a JARABAK or KAYABASHI ligature tie• a buccal hook coming from a lingual arch• a bite plate with a distal hook.

➨ the maxillary arch anteriorly from:

• a sectional archwire• a Class II utility arch• a continuous archwire with anterior loop• a sliding hook• a JARABAK or KAYABASHI ligature tie• a bracket hook• a Jig• a Class II headgear• a reciprocal archwire 0.45 with hooks• a reciprocal Mini Chin Cup.

3 - Biomechanics of a Class II elastic

Let us take an example of a Class II elastic _ inch, heavy placed on the distal buccalpart of the lower archwire and on an anterior loop in front of the upper canine.

In occlusion, if this elastic makes a 20 degree angle with the upper continuous archwire and a100 g force, the elastic effect has:

➩ a horizontal component force of: 100 X cos 20° = 93.90 g.

➩ a vertical component force of: 100 X sin 20° = 34.20 g.

54


Centric occlusion

Opening 10 mm

Opening 25 mm

Fig VI.1: Biomechanic influence of mouth opening on Class II elastic force ( see text ).

55


• With a mouth open 10 m/m at the incisors level, the force varies with different angulationof the Class II elastic and has different effects upon:

- the maxillary arch

➩ The vertical component of extrusion is: 160 X sin 29° = 77.60 g.because the elastic has now a 29° angulation with the upper arch ( see Fig VI.1 ).➩ The horizontal component of distalization is: 160 X cos 29° = 139.90 g.

- on the mandible

The elastic has a 35 degree angulation with the lower archwire. So we have:

➩ A forward component force of: 160 X cos 35° = 131 g.➩ A vertical component of extrusion force which is: 160 X sin 35° = 91.8 g.

• With a mouth open 25 m/m, which can happen when the patient is speaking, smiling or yaw-ning, the elastic force can be again increased to 190 grams. But this force cannot be constantand is going to decrease with time, in the saliva.This maximum force occasionally exerted has again different effects upon:

- the maxillary arch

➩ The vertical component of extrusion force is: 190 X sin 38.5° = 118.3 g.➩ The horizontal distalizing force is: 190 X cos 38.5° = 148.7 g.

- the mandibular arch

➩ The horizontal forward force is: 190 X cos 52.5° = 115.7 g.➩ The vertical component of extrusion force is: 190 X sin 52.5° = 150.7 g.

From those figures, it is now easy to notice that by opening of the mouth from 10 to 25m/m, the forward mandibular force drops down from 131 to 115.7 g.That means it decreasedabout 10% despite the patient opened his mouth more. Notice also that the extrusive mandi-bular force went from 91.8 to 150.7 g. That means it increased 64% !

From this biomechanic explanation, the clinician must understand that the use of Class II inter-maxillary elastics has to take into account the facial type in order to avoid a facial patternaggravation.

During day:Intermaxillary elastics have a vertical component of extrusion that is

much more significant than the horizontal component.During night

Intermaxillary elastics have an equivalentvertical and horizontal component.

56


Fig VI.2: Facial type influence with Class II elastic use and consequences on the anterosuperior occlusal plane when using continuous archwires. ( See text ).

57


Fig VI.3:Ch. TWEED’s Class II elastics areworn on continuous arches (with tipback) and headgear.

Fig VI.4:F. SHUDY’s Class II elastics areplaced on three points in a closingway with High Pull Headgear tocontrol anterior occlusal plane andreinforce maxillary anchorage.

Fig VI.5:R. ROTH’s Class II elastics areshort and used with headgear accor-ding to the facial type.

58


Fig VI.6:The R. RICKETTS’s bioprogressivetechnique. Class II elastic on sectio-nal maxillary archwire.

Fig VI.7:R. RICKETTS’s utility arch withClass II hook for maximum ancho-rage.

Fig VI.8:J. PHILIPPE’s circummandibulararch to protract the mandibulararch. Unfortunately, when thepatient opens his mouth, the Class Ielastic becomes a Class II withextrusion consequences.

59


4 - Class II elastics effects with continuous archwires

The Class II elastics have different effects.

➨ Effects upon the maxillary arch

• backward movement of the upper arch• extrusion and downward movement of anterior occlusal plane

( see FigVI.2 )• upper incisors are more vertical• all teeth are distallized.

➨ Effects upon the mandibular arch

• entire mandibular arch is brought forward• the lower molar can be extruded• buccal tipping of lower incisors.

➨ Effects upon occlusal plane

• sagittal correction of Class II relationship• downward tilting of the anterior occlusal plane.

➨ Effects upon facial pattern

• the mandible is brought forward with a posterior rotation• chin goes forward• the lower facial height is increased according to the amount of elastic

force used and wearing time.

5 - Class II elastics indications

Class II elastics may be used for main or secondary objectives according to the indivi-dual clinical case such as:

• skeletal and/or dental Class II malocclusions• anchorage reinforcement• backward movement of the upper incisors• mandibular arch advancement• bite opening• buccal tipping of retruded lower incisors• midline deviation correction• dual bite correction.

60


Fig VI.9: Example of a Class II elastic placed on a sliding hook to compress a spring for minordistalization.

Fig VI.10: Example of a Class II elastic placed on a sliding Jig to correct a molar relationship.

61


Fig VI.11: Example of a Class II elastic placed on a Class II utility arch to correct a midlineshift.

Fig VI.12: Example of a Class II elastic placed on a contraction utility arch to correct an upperincisor protrusion and close anterior spaces.

62


Fig VI.13: Example of a Class II elastic placed on a continuous archwires.This kind of inter-maxillary elastic has an extrusion component on the occlusal plane ( see text ).

Fig VI.14: Clinical case of one Class II elastic placed on the upper sectional to settle the cani-ne relationship and one other Class II elastic placed on the contraction utility archwire to helpthe incisor retraction and torque.

63


Fig VI.15: Clinical example of a Class II canine relationship associated with a Class I molarrelationship before treatment.

Fig VI.16: After treatment of a Class II elastic placed on a sectional maxillary arch.

64


Fig VI.17: Example of clinical dental Class II 1 deep bite before treatment. Notice the canineClass II relationship.

Fig VI.18: After 3 months the canine relationship had been corrected with a Class II elasticworn on a reciprocal maxillary arch.

65


In incisor overclosure, the use of Class II elastics isrecommended only after:

➩ the correction of the vertical sense ( overbite )➩ the segmentation of the maxillary archwire.

6 - Clinical applications of Class II elastics

➨ In dental Class II malocclusions

Any kind of elastics can be used whatever they are Class I postero anterior, regularClass II or combined with different ones.In case of dental open bite, closing Class II elastics are recommended to close the bite (see Fig 24 ).

➨ In skeletal Class II patterns

We must differentiate:• vertically normal: where the Class II elastic has a light effect of posterior man-dibular rotation.• deep bite: the extrusion component of Class II can be used with the combinationof triangular Class II.

Remember:➩ correct the overbite before the overjet➩ level the curve of Spee before using the Class II elastic

➩ segment the maxillary arch.

In some cases, the bite plate can help to open the bite when using intermaxillary elastics.

• open bite: in those cases the use of Class II elastics must be avoided becausetheir effects increase the mandibular rotation even when using closing Class II.It’s better to use Class I elastics associated with judicious extraction strategiesand/or surgery.

The vertical component of Class II elastics extrusion depends on:➤ the facial type➤ the occlusal plane orientation➤ the curve of Spee➤ cases with or without extraction➤ the mandibular anchorage posterior point of the elastic( M2, M1, Pm2, Pm1 )➤ the force exerted ( day and/or night ).

66


7 - Clinical problems with Class II elastics

Many clinical problems may be observed even with careful clinical watching on:• insufficient wearing• excessive wearing• parodontal problems such as:

- lower incisors dehyscence- abnormal rotation and fenestration, etc...

• biomechanic complication such as:- space opening- space closing- anchorage lost- abnormal tipping- exaggerated rotation- exaggerated extrusion.

Be aware of the DUAL BITE !The Class II elastic wearing can simulate a corrected malocclusion and

disappoint someone’s hopes.

Some patients have worn Class II elastics for so long that they can develop a convenience biteand cheat their Class II correction.

Before stopping Class II elastics check the centric relationship and look at the patientocclusion.

8 - T. M. D. and Class II elastics

Some clinical cases are true temporomandibular disorders and some have only a pre-disposition or a dysfunctional recurrence of TMD. Most of the time they can have separatelyor all together:

a premature contact giving a mandibular shifta muscular hyperactivity resulting from stressed lifean instability of the collateral condylar ligament with a disc interference. In this kind of

patient it’s better to tripod the mandible.

The Class II elastics with mandibular tripod must consider:• to segment the maxillary arch• segmented tripod to keep posterior wedges• to distalize lateral segments, try to obtain overcorrection• to intrude incisors• to advance the lower arch.

➩➩➩

67


9 - Pain and Class II elastics

Some dysfunctional patients have difficulties tolerating intermaxillary elastics, becau-se wearing may increase the tenderness and pain. For this kind of patient a splint must berecommended to control muscular or articular pain resulting from the muscular hyperactivitycoming from the elastics use.Tripodization of the mandible can be a helpful solution as noted by D. GRUMMONS 29.

For example, some Class II Div. 1 clinical patients may develop excessive buccal lower inci-sors tipping and going on with Class II elastics, particularly in those with deep overbite, awa-king the sleeping cat - PAIN- because the incisor contact with exaggerate use of Class II ela-stics may give again a condylar compression.

In those kinds of clinical cases the mandibular tripod is very useful and allows intrusion oflower incisors and/or upper incisors.Then the segmentation of the splint may help the segmentation of archwires and may go onwith intermaxillary elastics.

Extrusion of lateral segments must be done with a parodontal approach in order toavoid bone lose by elongating teeth. Usually, this elongation must not go beyond 2 mm foreach arch, according to D. GRUMMONS 29.

Not every patient should have their vertical dimension of occlusion increased.

Some skeletal Class II micrognatia patients may have vertical deficiencies due to over-closure in jaw position in closed mouth. A modest increase does not appear to be detrimental,and addresses:

- molar tipping or rotation- forwarding incisors- intruding incisors- advancing lower arch- surgery.

Remember that an excessive thickness of the tripod beyond the freeway space or mandibularpostural position can lead to detrimental intrusion of the posterior teeth.

The orthodontic management of cases with lack of posterior support involves:1 - reestablishment of the vertical support2 - elimination of the anterior excessive contacts due to overbite.

This can be done by:• uprighting posterior teeth• extruding posterior teeth• intruding incisors and/or?• buccal tipping of incisors to correct incisal angulation and overbite• surgery.

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10 - Orthognatics and Class II elastics

Surgerised orthognathics cases may need some Class II elastics for different reasons:

to maintain a good skeletal relationship during healing and consolidating phaseto overcorrect dental relationshipto correct midline deviationto seat the canine occlusal relationship.

The practitioner must consider the patient on an individual basis and the kind of surgery under-taken.

The Class II elastics should be used:

• to avoid bone mobilization, even in rigid fixation cases• to segment the surgerised arch to its opposing arch, if possible• to prefer short closing Class II elastics• to use segmented archwires instead of continuous ones, with frictionless forces.• to keep posterior wedges and avoid posterior mandibular rotation.

In orthognatics cases, the control of the vertical sense is fundamentalin maintaining the advantages of sagittal correction.

11 - Influence of the archwire and hooked point

To make more comprehensive this notion, let us see the Fig VI.19 where we have adental Class II malocclusion with a locked second premolar.

Different biomechanic systems could be used:

➨ WITH FRICTION

In using a continuous archwire with an opened coil spring for Pm2 space, we can placethe Class II elastics as follows:

1 - behind the lower molar, which is going to be extruded and advanced with the whole man-dibular arch without opening the Pm2 space.

2 - on the mesial hook of the lower molar which is going to be advanced without extrusion,but without opening the Pm2 space.

3 - distal to Pm1 on a KOBAYASHI tied ligature. The Class II elastic is going to advance themesial part of the mandibular arch before the Pm2, with a friction system which is better thanFig.VI.19 n° 1 or 2, but less efficient than Fig.VI.19 n° 6.

➩➩➩➩

69


➨ FRICTIONLESS

Using an archwire with an activated M loop with tip back, we can place the Class IIelastic:

4 - behind the lower molar to advance the whole mandibular arch with less extrusion than inFig. n° 1.

5 - on the mesial hook of the lower molar to help the activation of the M loop and open thePm2 space and advance the mandibular arch with more efficiency than in Fig. n° 2.

6 - distal to Pm 1 on a KOBAYASHI tied ligature, the Class II elastic is going to help the Mloop to give a reciprocal effect in opening quickly the Pm2 space and advancing the mandi-bular arch in a very efficient way.

There are other biomechanic systems that could be used such as segmented arches with utilityarch etc; but the principle remains mainly the same.

In LINGUAL TECHNIQUES all biomechanic principles remainthe same, except that elastics are placed on lingual side.

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WITH FRICTION FRICTIONLESS

Fig VI.19: Influence of biomechanic archwires systems and the hooked point of the Class IIelastics ( see text ).

1

2

3

4

5

6

71


12 - Bioprogressive torque Class II elastics

Class II elastic placed on the anterior part of a contraction utility arch has an effect ofincreasing the TORQUE during the incisor backward movement ( see Fig VI.20 ).

In fact, the Class II elastic pulls downward and backward the anterior loop which raises theanterior segment of the arch and increases the anterior torque progressively with the contrac-tion. This is a big difference between a continuous contraction arch and the RICKETTS’s seg-mented technique.

Remember that when a continuous contraction arch is activated, the anterior occlusal planegoes downward during the contraction. If you need to control it, you have to use a high pullanterior headgear with good patient compliance.This bioprogressive torque, in using Class II elastics, is a very innovative biomechanic system.

Fig VI.20: Biomechanics of Progressive Torque with the RICKETTS’s utility arch.The Class II elastic pulls downward and backward the anterior loop which raises the anteriorsegment of the arch increasing progressively the torque with the contraction. A bodily move-ment of the upper incisors is the result. See text.

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Fig VI.21: Clinical example of Class II elastics placed on a Class II utility maxillary archwireand a sectional to correct Class II molar and canine relationship on one side.

Fig VI.22: Clinical example of Class II elastic on right side to correct a midline deviation andhelp to close the space between upper canine and lateral incisor.

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Fig VI.23: Clinical example of U shape anterior elastic to close the bite. Notice the controla-teral crossbite elastic to move the first bicuspid palatally.

Fig VI.24: Clinical example of closing Class II elastics to help closing the bite. Notice theextrusion Class I elastic placed from right to left hook of the lateral maxillary sectional arch-wires.

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13 - The Class II molar extrusion elastic

This Class II elastic is hooked over the cinched distal end of the upper archwire, both strandsare hooked under the cinched distal end of the lower end of the archwire, and the other is hoo-ked mesial to the upper canine ( see Fig VI.25 ).This kind of elastic had been dubbed by R. HOCEVAR 22 “ The check elastic ” according toits upside down V shape.Its clinical indication is mainly:

• skeletal and/or dental deep bite• expansion which must be used in conjunction with thoses elastics... or may

be hooked palatally on the maxillary molar.

The vertical component on the lower molar is between three to four times greater with thecheck elastic according to R. HOCEVAR.

14 - How to diminish the extrusion component forcewith the Class II elastics use

According to many authors, about 15% of Class II Div.1 malocclusions have a poten-tially vertical excess dimension. Some of those cases are usually treated with extraction ofbicuspids that results, when using Class II elastics, in an increased extrusion component force ( see Fig VI.28 ).

There are different means to diminish the extrusion force such as:

• wearing elastics only during sleeping hours

• more horizontal elastics with hooked point more posterior in the mandible and moreanterior for the maxilla.

In using:➩ molar M2 banding➩ Class II headgear➩ .045 reciprocal arch➩ reciprocal mini chin cup.

Before RETRACTION,

the more vertical the upper incisors are, the more TORQUE is needed.

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Fig VI.25: The R. HOCEVAR“ Check elastic ” is a Class II molarextrusion.

Fig VI.26:Class II molar extrusion elastic indi-cated in deep bite cases.

Fig VI.27: Triangular Class II ela-stic with a double component ofClass II and extrusion for deep bitetendency cases.

76


Fig VI.28: Influence of the hooked point of the Class II elastic:A - In extraction case.B - In non extraction case from M1.C - In non extraction case from M2.

Notice the difference of the vertical component of extrusion.

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A

Fig VI.29:A, B, C,Class II 1malocclusionbeforetreatment.

B

C

78


D

Fig VI.30:D, E, F,Aftercorrectionwith Class IIelastics placedon an . 045upperreciprocalarch.

E

F

79


Fig VI.31: Example of oblique and Class II elastics to correct midline shift with a segmentedfrictionless mechanism.

80


Fig VI.32: Example of a Class II elastic headgear with anterior welded hooks opened ante-riorly.

Fig VI.33: Intraoral example of unilateral Class II elastic headgear for midline shift and Class II correction.

81


Fig VI.34:M. LANGLADE’s reciprocalmaxillary arch used with a Class IIelastic on a .016 X .022 lower utilityarch.

Fig VI.35:With a maxillary sectional arch anda LANGLADE’s reciprocal arch thepatient can wear two Class II ela-stics on each side.

Fig VI.36:With the same system we can add aLANGLADE’s reciprocal mini chincup to reinforce the Class II effectaccording the degree of difficulty ofthe clinical case (3 X 100 g. force oneach side → mandibular protractioneffect ).See Chapter IX.

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15 - The Split elastic positioner

The Split elastic positioner was developed by G. and B. KAPRELIAN 25 to improveresults when compared to the traditional one piece tooth positioner ( see Fig VI.37 ).This appliance, as its name indicates, is a two piece positioner occlusally flat, with buccalhooks for Class II elastics.

The advised force ranges from 100 to 150 g. depending on the prescription and the finalgrowth potential of the child.

The benefits of the Split elastic positioner are:• improvement of occlusion• elimination of breathing problems• sleep disorders assistance• no adjustment needed• good patient acceptance• can be worn independently• clinching prevention• stops deep bite return• long term retainer.

Fig VI.37: KAPRELIAN “ K 2 P ”. A split elastic positioner, worn with Class II elastics, duringhome hours and sleeping.

CHAPITER VII

Class III Elastics Forces

83

CHAPTER VII: Class III Elastics Forces

1 - Definition

Class III elastics are intermaxillary elastics placed posteriorly on the maxillary archand anteriorly on mandibular arch.

2 - Disposition

According to the clinical problem, Class III elastics may be placed:

Posteriorly• buccally• palatally ➩ to help expansion• buccally and palatally ➩ to increase the force• from the distal part of the archwire ( Fig VII.4 )• from a molar hook ( Fig VII.5 )• before the maxillary molar, even from Pm2 or Pm1• from a Class III headgear• from a bite plate distal upper hook.

Anteriorly

• a loop on archwire• a JARABAK or KOBAYASHI ligature• from a Class III bite plate with anterior hooks and inclined plane to

help to jump the bite ( see Fig VII.6 ).

3 - Biomechanic of Class III elastics

Let us take an exemple of a 100 g. Class III elastic put on continuous arches (see Fig VII.1 ).

In occlusion, the elastic having a 20 degree angle with horizontal plane is developing:➩ a vertical component force of 100 X sin 20° = 34.20 g.➩ a horizontal component force which can be written 100 X cos 20° = 93.90 g.

In a mouth open 25 mm, the elastic force becomes 190 g. with a reciprocal action:

- on maxilla:vertical component of 136.67 g.horizontal component of 131.98 g.

- on the mandible:horizontal component of 92.11 g.vertical component of 166.17 g.

With those figures, it is easy to understand the effect of incisors elongation anteriorally and toappreciate the vertical effect of such an elastic!

84


Centricocclusion

Opening10 mm

Opening25 mm

Fig VII.1: Class III elastics biomechanics. See text.

85


Fig VII.2: Influence of conventional Class III elastics on the occlusal plane tilting whenusing continuous archwires ( see text ).

86


Fig VII.3: Influence of conventional Class III elastic forces with facial type and consequenceson the vertical component of extrusion, when using continuous archwires. See text.

87


Influence of Class III elastics on occlusal plane tilting with continuous archwire:

When a regular Class III is placed distally to the upper molar and mesially to the lowercanine with continuous arches, the resulting force depends on the tilting of the occlusal plane-in other words on the facial type:

- in a normal vertical dimension the resultant is a 50% forward movement of the maxilla ofapplied Class III elastic ( see Fig VII.3A ) with an extrusion on upper molar and an extrusionwith lingual tipping of the lower incisors.

- the more the vertical dimension is increased ( see Fig VII.3B and C ), the less the mesialmovement of the upper molar from 33% to 25% with an increased extrusion worsening theopen bite.

So, it is very important to keep the posterior wedge in a patient with a potential borderlineopen bite. Segment the arch behind the first upper premolar and use short closing Class IIIelastics.

The vertical component of extrusion of Class III elastics depends on:• the curve of Spee• the cases with or without extractions• the point where the elastic is placed• the facial type: the more the open bite, the greater the extrusion component

4 - Class III elastics effects on continuous archwires

The use of Class III elastic has different effects:

Effects upon maxillary arch➩ forward mesial tipping and extrusion of the first molar➩ light maxillary advancement➩ buccal tipping of upper incisors.

Effects upon mandibular arch➩ lower incisors extrusion ( see Fig VII.2 )➩ lower lingual tipping of lower incisors➩ lower arch distalization.

Effects upon occlusal plane➩ sagittal correction of occlusal relationship➩ upward tilting of lower anterior occlusal plane ( see Fig VII.3 ).

Effects upon facial type➩ backward rotation of the mandible➩ the chin goes downward and backward➩ the lower facial height is increased.

Class III elastics have a counterclockwise effect on theocclusal plane anteriorly and posteriorly.

88


5 - Indications of Class III elastics

Before using Class III elastics, the Long Range Growth Forecast is recommended forpredicting the mandibular dimension and position in the face in the growing patient.Knowing the final mandibular position during the Class III elastic use, it is possible to get aposterior mandibular rotation in cases with deep bite skeletal pattern with:

- dental overbite

- closed labio nose angle

- collapsed labial esthetics

In such a way camouflage becomes possible.

In normal vertical cases, it becomes dangerous to open the bite with an extrude ful-cruming maxillary molar which may increase T. M. J. tenderness.Regular Class III elastics may increase patient mandibular growth ( see Chapter IX ).For normal vertical Class III cases, it’s better to keep posterior wedges, if you want to treatyour patient orthodontically.

Evidently, for open bite skeletal Class III patterns, treatment should include surgery.Finally the Class III elastics indications may include:

• dental Class III occlusal relationship with deep bite skeletal pattern

• anterior crossbite going edge to edge in centric relation

• retromaxilla deep bite with

• incisor overbite Class III allowing a possibility of camouflage by posteriormandibular rotation

• mandibular incisors protrusion in which you need closing and retraction space

• maximum mandibular anchorage with monomandibular extraction of the firstpremolars

• midline deviation correction.

Camouflage with posterior mandibular rotation in Class III squeletal pattern depends on:

➩ growth potential (use Long Range growth Forecast )

➩ dental overbite

➩ collapsed labial esthetics ( see Table VII.1 )

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CHILDREN

GROWTHPOTENTIAL

NOGROWTH

ADULTS

LONGRANGE

FORECAST

CANINEFUNCTION

T.M.J.

KEEP POSTERIOR WEDGE

DENTALOVERBITE

NOSELABIALANGLE

LABIALESTHETICS

VERTICALDIMENSION

LONGRANGE

FORECAST

limited by POSTERIORROTATION

Class III Mandibular• Dimension

• Position

90


Fig VII.4: Conventional Class III elastic placed behind the upper molar. A high componentof extrusion exists on the occlusal plane.

Fig VII.5: Regular Class III elastic placed on maxillary mesial molar hook. The extrusioncomponent force still exists.

91


Fig VII.6: Example of Class III elastics placed on behind the maxillary molar posteriorly andon anterior hook of a lower inclined bite plate in order to bring forward the upper arch andjump the bite.

Fig VII.7: Example of a Class III elastic to correct a midline shift.

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Fig VII.8: In this Class III, almost edge to edge incisor relationship, the vertical sense is cri-tical and must not be opened. The posterior wedge must be kept.

Fig VII.9: Notice that the arch is segmented behind the 14th, and the patient is wearing a clo-sing short Class III elastic to jump the bite.

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6 - Clinical applications of Class III elastics

In order to recognize the risky prognathic true Class III, remember to use the longrange growth forecast.

In deep bite cases it is useful to:

• protract the maxillary arch• procline maxillary incisors: bond them upside down to advance Point A• use inclined 45° bite plate with Class III elastics• use utility M loop to advance upper arch• use brackets with buccal crown torque on lower incisors to resist the extrusion

and lingual tipping elastic force ( to avoid gingiva dehyscence ).

In borderline or open bite cases it is useful to:

• segment the maxillary archwire behind the first upper premolar• keep the posterior wedges• avoid increasing the vertical sense• use short closing anterior Class III elastics ( see Fig VII.9 )• check and watch T. M. J.

The deeper the overbite, the better the prognosis in Class III malocclusions.

7 - Clinical problems with Class III elastics

Many clinical problems may be observed even with careful clinical management such as:

• insufficient wearing

• excessive wearing

• parodontal problems such as lower incisors dehyscence

• biomechanics problems like lingual tipping or excessive extrusion of lowerincisors.

The distal lower tipping of the mandibular canine may increase the retroversion oflower incisors, when using Class III elastics with light memory archwires.

For example, when a Class III elastic is placed on an 0.016 X 0.016 lower Niti or TMA, thelower canine can be distally tipped, inducing an increased extrusion of lower incisors alreadysubject to the vertical component of extrusion of the Class III elastic.

94


8 - T. M. D. and Class III elastics

Some clinical cases are true temporomandibular disorders but are very rare in this kindof malocclusion.The excessive use of Class III elastics may bring a recurrence of T. M. D. problems by acondylar compression.

According to the clinical problem, the treatment can be done:

➨ without mandibular tripod:

• watch lower incisors extrusion• fight against lingual tipping of lower incisors ( use buccal crown torque

brackets )• use segmented maxillary archwires• keep posterior wedges• don’t open the bite anteriorly.

➨ with mandibular tripod:

• optimize condyle disc relationship• use mandibular tripod• keep posterior wedges• segment maxillary archwire behind the upper canine or the first premolar• grind the tripod progressively to control the occlusal situation three

dimensionaly• use short anterior closing Class III elastics.

9 - Pain and Class III elastics

Some dysfunctional patients have difficulties tolerating intermaxillary elastics. Thewearing may increase the tenderness and even become painful due to the condylar compres-sion loading.

For these patients, a splint may be recommended for control of the muscular hyperactivitycoming from the elastics use.

Tripodization of the mandible can be a helpful solution as noted by D. GRUMMONS 29.

Class III elastics forces can be associated with postero anterior elastics in order to advance theretruded maxilla.

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10 - Orthognatics and Class III elastics

Surgerised Class III cases may need some Class III elastics for different reasons:

to maintain a good skeletal relationship healing and consolidating phaseto overcorrect dental relationshipsto correct midline deviationto seat the canine occlusal relationship.

Most of the time the orthodontist has to consider the patient on an individual basis without for-getting the kind of surgery undertaken.

Class III elastics should be used:

• to avoid bone mobilization, even in rigid fixation cases, using light forces

• to segment the antagonist arch to the surgerised one, if possible

• to prefer short closing Class III elastics

• to keep posterior wedges

• to control vertical dimension

• to use segmented archwires instead of continuous ones with frictionless forces.

In orthognatics cases:Extrude teeth on an unitarianly way in order to avoid moving bone fragments.

In some OPEN BITE cases with

TONGUE INTERPOSITION,

vertical intermaxillary elastics can be

LINGUALLY placed on

cleat lugs, bonded buttons,

to provide an

ANTI-TONGUE SCREEN.

➩➩➩➩

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Centric occlusion

Opening 10 mm

Opening 25 mm

Fig VII.10: Triangular Class III biomechanics with a _, light elastic in 10 cm opened mouth.We have:

• at the maxilla: an extrusion force of 119.1 g.a forward force of 32 g.

• at the mandible: an extrusion force of 115.1 g.a backward force of 44.3 g.

CHAPITER VIII

ParticularIntermaxillary Elastics

97

CHAPTER VIII: Particular Intermaxillary Elastics

Many intermaxillary elastics may be used for a specific extrusion component associa-ted in conjunction with others such as contraction, in a horizontal or vertical way.Among them let us see:

1 - THE RECTANGULAR ELASTIC

This elastic has a rectangular shape adding a contraction and extrusion force movement( see Fig VIII.10 ). It is well indicated for closing spaces and extruding a segment of the den-tal arch. So it can be placed:

- posteriorly- anteriorly

in order to close the bite and to close remaining spaces at both arches.

2 - THE U SHAPE ELASTIC

The U shape elastic has a contraction and extrusion effect on only one arch. So it canbe used with a segmented arch to the antagonist arch and can be used in U shape or upsidedown ( see Fig VIII.1 ).Most of the time, this elastic is used anteriorly, but it can also be used posteriorly.

3 - THE DELTA ELASTIC

This elastic has a delta shape, a short triangle using a vertical component of extrusionfor a single ectopic tooth, most of the time an upper canine ( see Fig VIII.7 ).

4 - THE V SHAPE ELASTIC

This elastic has a vertical component of extrusion without a light contraction. It can beworn to bring a tooth on the occlusal plane in a V shape or upside down according to the cli-nical need.

5 - THE M OR W SHAPE ELASTICS

These elastics are used for extruding a group of teeth in order to squeeze the bite in aneffective closing way. Heavy elastic up to 300 g. may be used ( see Fig VIII.3 and 4 ).

6 - THE ACCORDION ELASTICS

They have the same purpose as the M or W ones, but they add a contraction compo-nent that could be interesting for closing spaces when extruding a group of teeth ( see FigVIII.3 and 4 ).

7 - THE CLASS II TRIANGULAR ELASTIC

This elastic has a triangular shape with a Class II orientation, indicated for its verticalcomponent of extrusion of deep bite Class II clinical cases.

98


Fig VIII.1: Example of the U shape vertical closure elastic on segmented arch.

99


ELASTICS CONDUCT IN OPEN BITE CASES

Fig VIII.2: From R. M. RICKETTS and al. Bioprogressive Therapy. RMO Editor. 1979

100


Fig VIII.3: Example of M and W elastics to close the bite faster than locking up the maxil-lary teeth in a straight wire.

Fig VIII.4: Two weeks later, the bite is closed with the M and W vertical elastics.

101


Fig VIII.5: Clinical example of a squeeze of the bite with M and W shape elastics ( see text ).

Fig VIII.6: Post surgery TMJ patient wearing a splint with lateral rectangular elastics toextrude lower molar and first bicuspid.

102


Fig VIII.7: Example of an upside down V elastic to bring down a right upper canine instead oflocking it up with a straight wire.

8 - THE CLASS III TRIANGULAR ELASTIC

This kind of elastic has also a triangular shape used for its vertical component of extru-sion of the posterior part of the maxillary arch as Class III sagittal correction of occlusion ( seeChapter VII. Fig VII.10 ).

9 - SQUEEZE ELASTICS

In some borderline surgery open bite cases, R. M. RICKETTS 2 had advocated heavyelastics forces ranging from 800 to 1500 g. to close the bite (see Fig VIII.5 ).Those elastics are worn 24 hours a day, and changed three times during two weeks, to obtainthe bite closure.

10 - THE CROSS BITE ELASTICS

They must be differentiated in:

A - homolateral cross bite

B - controlateral cross bite

But, before seeing their clinical application, we must look at a new international classification.

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CROSS BITE CLASSIFICATION

Most authors have identified the unilateral posterior cross bite occlusion only in termsof transversal relationship of the maxillary molar.The term “ cross bite ” means an abnormal labio lingual, edge to edge or bucco lingual rela-tionship of the antagonist teeth. This incomplete definition has caused some confusion sinceapparent tooth relationships can hide underlying skeletal discrepancies sagittally and/or trans-versely.

The reality of clinical and functional exams of patients, presenting a unilateral poste-rior cross bite occlusion with three dimensional cephalometric analysis, axiography and studymodels, has shown to M. LANGLADE that the lower molar can be affected in 19.36 % ofthose cases in a sample of 280 orthodontic patients.Since 1988, the author has used an international classification based on the responsible molar( upper or lower ) with a figure 1, 2 or 3, expressing the transversal unwedging by degree ofdifficulty:

- normal is 0- 1 is edge to edge- 2 is a one cusp unwedging- 3 is the complete jump of the bite

Doing so, it is possible to establish the true pathologic situation which opens concre-tely on the appropriate therapeutic solution.For instance, all third degree cross bites must be corrected with a bite plate on the antagonistarch.

See Table VIII.1

MAXILLA:UB3 = upper buccal 3 cross biteUB2 = upper buccal 2 cross biteUEE1 = upper edge to edge 1UL2 = upper lingual 2 cross biteUL3 = upper lingual 3 cross bite

MANDIBLE:LB3 = lower buccal 3 cross biteLB2 = lower buccal 2 cross biteLEE1 = lower edge to edge 1LL2 = lower lingual 2 cross biteLL3 = lower lingual 3 cross bite

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Buccal Edge to edge Lingual

Table VIII.1

International Classification ofposterior unilateral cross bite:Grade the pathologic situation according to the unwedging cusp:1 - for edge to edge2 - for one cusp3 - for the jump of the bite

Buccal Edge to edge Lingual

→→→→→→→→→→→→→→→→→→→→→→

→→→→→→→→→→→→→→→→→→→→→→

105


Fig VIII.8: Differential posterior cross bite occlusion diagnosis must distinguishA - a dental malocclusionB - a narrow maxillaC - a mandibular latero deviation ( functional shift ).

106


A / HOMOLATERAL CROSS BITE ELASTIC

Definition:The homolateral cross bite elastic is usually used to jump the bite of a tooth or a groupof teeth. It is placed opposing teeth, for instance a palatal cleat lug of an upper molar inlingual cross bite degree two, to the buccal hook of the lower molar of the same side (or contrary ).This kind of intermaxillary cross bite elastic can be used on any kind of tooth from thepalatal side to the buccal side or conversely.

Biomechanism:The Biomechanism of a homolateral cross bite elastic may explain a clinical example ofsuch an elastic developing a 90 g. horizontal force in occlusion.This elastic, as in Fig VIII. 9, gives a rotation moment written:

M = 90 X 16 = 1440 g.If the distance of elastic insertion to the center of resistance is 16mm:

➩ the upper molar undergoes a palato buccal rotation➩ the lower molar undergoes a bucco lingual rotation.

When the patient opens his mouth to 30 mm, the 90 g. force becomes a 180 g. If wesuppose that each molar has an 8 mm width and the jump of the bite is 4 mm, the elastic isobliquely stretched exerting a force of rotation on each molar, which is decomposable in avertical and a horizontal force.We have now a triangle with two known sides:

a = 30 mmb = ( 8 + 4 ) = 12 mm

According to the Pythagorian theorem, the hypotenuse is:c2 = a2 + b2

or c = √( 30 )2 + ( 12 )2 = 39.8 mm

So, the exerted force in the mouth is dependent on:- a horizontal force ➩ Fh = 180 X (12/39.8) = 54.3 g.- a vertical force ➩ Fv = 180 X (30/39.8) = 171.7 g.

This oblique force exerted on each molar in inverted sense has moments which can be writ-ten:

- for the horizontal force ➩ Mh = 54.3 X 16 = 868.8 g.mm- for the vertical force ➩ Mv = 171.7 X 8 = 1573.6 g.mm

It is clear now that an intermaxillary homolateral cross bite elastic in an open mouth gives anextrusive force three times greater than the original horizontal force.This biomechanic demonstration shows that such elastics are to be avoided in open bitecases.

Intermaxillary homolateral cross bite elastic can be used:• in normal or deep bite skeletal cases• in deep bite cases where expansion is desired.

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Occlusion

Open 30 mm

Fig VIII.9: Biomechanics of homolateral cross bite elastics ( see text ).

In maxilla

In mandible

In maxilla

In mandible

108


B / CONTROLATERAL CROSS BITE ELASTIC

Definition:The controlateral cross bite elastic is an intermaxillary elastic placed on opposite sidesof dental arches; for example from a left upper molar buccally to a right lower molar, orvice versa.

Biomechanics:We can, for instance, use the same demonstration with a 130g. elastic force in a closedmouth ( see Table VIII.2 ). If the patient opens his mouth again to 30 mm:

➩ the transversal force is 273 g.➩ the vertical force is 115.38 g.

Now, we have a new situation with a horizontal force which is three times the extrusive one.That means that the controlateral cross bite elastic is much more effective transversaly thanany other.

TABLE VIII.2

HOMO

LATERAL

CONTRO

LATERAL

In closedmouth

occlusionF = 90 g.

In closedmouth

occlusionF = 120 g.

In open mouth 30 m/m

Fh transversal:54.3 g.

Fv extrusion:171.7 g.

In open mouth 30 m/m

Fh transversal:273.3 g.

Fv extrusion:115.38 g.

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Fig VIII.10: Posterior rectangularelastic ( see text ).

Fig VIII.11:Short vertical elastics have a ten-dency to narrow the transversaldimension

Fig VIII.12:GRUMMONS double cross biteused for molar extrusion in TMDpatients to unload the condyle.

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Clinical applications:The clinical application of this kind of controlateral cross bite elastic suggests it ishelpful in various transverse corrections, more especially in posterior unilateralcrossbite situations.

In 1990, M. LANGLADE 39 did a comparative study on cross bite correction of unilateral pala-tal upper molar in two degree cross bite wearing a Quadhelix with or without the help of a con-trolateral cross bite elastic (see Table VIII.3 ).

The treatment time was shortened from approximately 270 to 60 days with the controlateralelastic !

Unilateral expansion Quadhelix

Maxillary lingual degree 2 cross bite

Without any elastics With controlateral elastics

8 Male N12 N12 6 Male4 Female 6 Female

Average age: 12.4 years Average age: 10.9 years

Transverse unwedging Transverse unwedging4.91 mm 5.58 mm

Range from 3 to 6 mm Range from 3 to 7 mm

Treatment time Treatment time267.25 days 60.33 days

Table VIII.3: Comparison of Unilateral posterior cross bite correction from M. LANGLADE. Foundation forOrthodontic Research 1990.

The intermaxillary controlateral cross bite elastic is very helpful in correctingunilateral posterior cross bite.

Clincal indications of the controlateral cross bite can be summarized as:

• mandibular functional side shift

• posterior unilateral cross bite:

1 - for helping an expansion2 - for helping a contraction3 - for helping an expansion and a contraction4 - for helping a contraction and an extrusion.

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Fig VIII.13: Use of a controlateral cross bite elastic to correct a right maxillary buccal degree2 with a unilateral contraction Quadhelix. The elastic is reinforcing the stable force andhelping to increase the moving force.

Fig VIII.14: The controlateral cross bite elastic has a double action on the unilateral move-ment of the Quadhelix by:

1 - increasing the molar anchorage on the right side2 - increasing the expansion force of the Quadhelix with a transversal elastic helping to

jump the left molar bite ( mobile force ).

112


Fig VIII.15: Controlateral cross bite elastic used to correct a lingual maxillary molar degree2 with a unilateral expansion Quadhelix.

In DISTRACTION OSTEOGENESIS,the practitioner can use all biomechanic principlesin order to correct maxillo mandibular anomalies using intermaxillary elastics such as:

U ● vertical rectangular, M, W etc

N BI ● diagonal, oblique etc IL LA ● controlateral cross bite AT TE ● homolateral cross bite ER RA ● Class I, Class II, Class III AL L

● combination

113


Fig VIII.16: Example of buccally ectopic canines with anterior open bite.

Fig VIII.17: A cross controlateral elastic is going to palatally move each canine in a week.

114


Fig VIII.18: One week later the bite is closed and the upper canines are settled transversallyand vertically ( see Fig VIII.16 and 17 ).

Fig VIII.19: Example of a controlateral elastic helping the correction of a cross bite degreetwo with a unilateral Quadhelix force.

115


Fig VIII.20: The palatal ramp unilateraly on a bite plate can be used to guide the mandible infunctional shifts:

A - without occlusal plateB - with bilateral bite plateC - with unilateral bite plate.

Controlateral or intermaxillary elastics can be placed to help the midline shift correction.

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11 - ELASTICS AND DENTAL ASYMMETRIES

Many dental asymmetries exist and can be divided into:

1 - CANTED ANTERIOR OCCLUSAL PLANE

With a tilting in the frontal plane associated with:➩ unilateral divergent➩ unilateral convergent➩ inclined divergent➩ inclined convergent

The association of segmented biomechanic archwires with oblique or anterior triangular ela-stics could help to correct the anterior occlusal plane (see Fig VIII.22 and 23).

2 - UNILATERAL POSTERIOR CROSS BITE

It can be corrected with a Quadhelix developing unilateral force movement associated with anhomolateral or a controlateral cross bite elastic, according to the degree of difficulty (see FigVIII.13 to 15).

3 - MIDLINE SHIFT DEVIATION

It is usually corrected by three means:

A / Different module force elastics:

For example, you can have on one side a Class II changed one time a day and on the other sidea closing short Class II changed three times a day that means you have double force on that side.

B / Different elastic disposition:

Such as a Class II on right side and a Class III on left side. But you may have also a cross biteand Class II elastics on the same side in an opposite one ( see Fig VIII.22 ).

C / Segmented arch form:

It is very helpful to correct the dental midline deviation using frictionless forces associatedwith intermaxillary elastics.But one can also use a different arch form of the archwires in using the transversal loop.

Continuous archwires don’t workin a dental asymmetric arch or with facial asymmetry.

Mandibular functional shifts can be corrected with the help of a guiding bite plate (see FigVIII.20) and controlateral cross bite or associated intermaxillary elastics.Usually the cross bite elastic is placed in opposition to the side of mandibular shift (see Fig VIII.22)

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4 - ASYMMETRIC ARCH FORM:

It may exist in different planes:

• vertically• horizontally• transversely• sagittally.

Some practitioners are not well aware of the straight wire limitations to correcting such asym-metric dental arch form.

Most of the time, the segmentation of archwires and/or the different arch form givenby a transversal loop associated with combined elastic forces may be the therapeutic solutionfor those difficult clinical cases.

Midline shift diagnosis summary

✸ Check Mdb centric relation.✸ Set the Mid sagittal plane of reference.✸ What has caused the Midline deviation ?✸ How does the deviation affect the occlusion ?✸ Is it necessary to correct it ? and how ?✸ Do 4 D dental arches analysis.

Midline treatment summary

➩ Mandibular reposition with:● functional appliance● palatal Ramp ( Fig VIII. 20 )● surgery ?

➩ Dental arch coordination:● particular extraction (controlateral ? unilateral ? )● reproximation / stripping● segmented archwires● asymmetric mechanics ( transversal loop )● special intermaxillary elastics

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N: Normal:Check CR

A: Opposed midline deviation: • oblique elastics• Class II / III elastics• cross bite elastics• cross stripping ?

B: Unilateral bimaxillary midlinedeviation ( Right ):• left extractions ?• left Class II elastics• right Class III elastics• unilateral stripping ?

C: Unilateral maxillary midlinedeviation ( Left ):• right max extraction ?• right Class II elastics• left Class III elastics ?• unilateral Mx stripping ?

D: Mandibular midline deviation• check CR ?• bite plate with ramp ?• Class III left elastics ? +• cross bite elastics• unilateral Mdb stripping ?

Fig VIII.21: Elastics use and possibilities of correction. Check:- Fronto facial / profile esthetics- Frontal cephalometric analysis- CR occlusal relationships.

DENTAL MIDLINE DEVIATION

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MANDIBULAR SHIFT and MIDLINE DEVIATION

1) Choose Mandibular Reposition with: ● functional appliance● bite plate ramp● surgery ?

Then reconsider midline deviation and chooseclinical options:

A:2) Use Class III elastic on opposite side to the

Mdb shift ?3) Unilateral Mdb maximum anchorage on

opposite side Mdb shift.4) Unilateral Mdb stripping opposite to Mdb

shift ?5) Combination ?

B:2) Mx extraction on opposite to midline

deviation, and also3) Maxi anchorage.4) Class I elastic on opposite side to midline

deviation.5) Unilateral Mx stripping on opposite midline

deviation.

C:2) Mx extraction on opposite midline deviation.3) Unilateral arch advance on side of midline

deviation.4) Class III elastic on opposite to Mdb shift

(anterior diagonal + vertical).5) Cross stripping ?

D:2) Mx and Mdb unilateral extractions on side of

Mdb shift.3) Class II elastics on Mdb deviation side.4) Unilateral stripping on opposite midline

deviation.

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MANDIBULAR SHIFT and MIDLINE DEVIATION

1) Choose Mandibular Reposition with: ● functional appliance● bite plate ramp● surgery ?

Then reconsider midline deviation and chooseclinical options:

E:2) Mdb extraction on Mdb side shift ?3) Class III elastic on opposite side of Mdb

shift.4) Unilateral Mdb arch maximum anchorage.5) Stripping and/or combination of above.

F:2) Unilateral Mx and Mdb extraction on side

of Mdle shift.3) Class II elastic ( anterior or diagonal ) on

Mdb side shift.4) Unilateral Mx maximum anchorage opposite

to Mx midline deviation.5) Stripping and/or combination.

G:2) Cross extractions 14 / 34.3) Cross maximum anchorage.4) Anterior diagonal elastic and/or Class II

elastic on opposite side of Mdb shift.5) Stripping and/or combination.

H:2) Mx unilateral extraction on opposite side

of Mdb shift.3) Latero vertical and/or Class I elastics.4) Unilateral stripping on opposite side Mdb

shift.5) Stripping

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Fig VIII.22: Midline shift correction

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A: Inclined divergent:• segmentation of archwires• triangular anterior elastics

B: Unilateral divergent openbite:• segmentation of archwires• unilateral M and W elastics

C: Maxillary anterior open bite:• U shape elastics• segmentation of archwires• anterior squeeze elastics• rectangular anterior elastic

Fig VIII.23:CLASSIFICATION OF VERTICAL ASYMMETRY

OF ANTERIOR OCCLUSAL PLANE

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D: Inclined convergent:• bite plate• segmentation of archwires• unilateral triangular elastics• Class II / III elastics

E: Unilateral convergent:• unilateral bite plate• unilateral rectangular elastics

F: Deep anterior overbite:• anterior bite plate• utility intrusion archwires• segmentation• Class II elastics and/or• postero rectangular elastics

Fig VIII.23:Elastics use and possibilities of correction

Check::- Fronto facial / profile esthetics- Frontal cephalometric analysis- CR occlusal relationships.

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A: Anterior and left closing Class IIelastics with unilateral left segmentedmaxillary archwire.Objectives: to correct left Class II to closethe bite and correct maxillary midline.

B: Triangular anterior elastic and anteriorsegmented maxillary archwire.Objectives: to close the bite and to closelower incisors spaces.

C: Oblique and left Class II elastics withmaxillary segmented archwire.Objectives: to correct midline deviationsand close the bite.

D: Triangular anterior elastic andsegmented utility Class II in a left maxianchorage.Objectives: to correct left Class II, to closethe bite and correct maxillary midline.

Fig VIII. 24: Elastic use in canted anterior occlusal plane:1 - check sagittal plane of reference2 - determine midline deviation3 - look at vertical dimension4 - prefer maxillary archwire segmentation5 - use elastics combination.

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12 - ELASTICS IN CONDYLAR FRACTURES

Sports and automobile accidents frequently involve condylar fractures.

In the growing patient, treatment for the fractured condylar, either unilateral or bilateral, isusually a conventional functional appliance.

In the adult case, elastics may be a part of an orthodontic treatment such as:

A / IN UNILATERAL CONDYLAR FRACTURE

where the condylar neck is anteromedialy displaced with an opening deflexion on the affectedside ( see Fig VIII. 25 ). The treatment should be:

● a unilateral bite plate on the controlateral fractured side, to help condylar distraction.

● segmented archwires on affected side with

● rectangular vertical elastics.

B / IN BILATERAL CONDYLAR FRACTURE

the mandible is rapidly rotating posteriorly with an anterior open bite and limited mouth ope-ning ( see Fig VIII. 26 ). The treatment should be:

● a bilateral posterior bite plate to help the condylar distraction for healing.

● anterior segmented archwires with

● anterior vertical elastics.

In any case, the elastics are worn for two to three months and progress can be checked withXrays.

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Fig VIII. 25: ELASTICS AND UNICONDYLAR FRACTURES ( see text ).

● a unilateral bite plate on controlateral fractured side, to help distraction.

● segmented archwires on affected side with

● rectangular vertical elastics.

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Fig VIII. 26: ELASTICS AND BILATERAL CONDYLAR FRACTURES ( see text ).

● bilateral posterior bite plate to help the condylar distraction for healing.

● anterior segmented archwires with

● anterior vertical elastics.

CHAPITER IX

Elastics and ExtraOral Forces

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CHAPTER IX: Elastics and ExtraOral Forces

The Twenty Commandments of E. O. F.

1 - The E. O. F.is a biologic orthopedic appliance

2 - Don’t use it with an occlusal 0.45 molar tube ( extrusion / tipping )

3 - Use an expansion of the inner face bow

4 - Use the natural muscular effect of cheecks

5 - Control the molar rotation

6 - Expand maxillary arch to avoid buccal eruption of M2

7 - Keep away archwires when using E. O. F.

8 - Don’t use any maxillary bite plate with E. O. F.

9 - Ask for 15 hours daily wear

10 - Don’t use excessive forces

11 - Don’t limit the treatment to E. O. F. only

12 - Don’t use E. O. F. in maxillary incisor overbite

13 - Don’t use E. O. F. in every Class II. With Long Range Growth Forecast, you may choose to use:

- extractions- activators- surgery

14 - Don’t stop the E. O. F. abruptly.

15 - Do overcorrect

16 - Time is needed to obtain growth correction

17 - Don’t use E. O. F. on a patient who is still thumbsucking ?

18 - Encourage patient motivation

19 - Don’t stop treatment after the orthopedic correction

20 - Don’t underestimate the simplicity of E. O. F.

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Extra Oral Force Delivery

➩ Juvenile preventive phase: 350 g.

➩ Interceptive phase: 400 - 500 g.

➩ Adolescent corrective phase: 750 g.• in vertical excess tendencies: 1000 g.• in true vertical excess E. O. F. is not advisable.

The convexity reduction decreases with age;after 12 years the reduction in point A is about 1 mm only.

In high convexity cases with a protrusive maxilla,it’s advisable to begin E. O. F. before 8 years old.

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Fig IX. 1: The same malocclusion can be seen in different facial types. A different extra oralpull must be appropriate to it.

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Long Medium Short

High

Horizontal

Low

Fig IX. 2: Biomechanical diagram of LOW pull.( From M. LANGLADE in “ Therapeutique Orthodontique ” 3rd edition. Maloine. PARIS 1986 ).

Low traction

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Long Medium Short

High

Low

Fig IX. 3: Biomechanical diagram of HORIZONTAL pull.( From M. LANGLADE in “ Therapeutique Orthodontique ” 3rd edition. Maloine. PARIS 1986 ).

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Long Mediu Short

High

Horiz.

Low

Fig IX. 4: Biomechanical diagram of HIGH pull.( From M. LANGLADE in “ Therapeutique Orthodontique ” 3rd edition. Maloine. PARIS 1986 ).

High traction

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Fig IX. 5: Recommended geometric configuration of power-arm unilateral face bow.The long arm should be placed on the favored side to receive the greater distal force and shouldterminate posteriorly near the first molar. It should extend laterally so that it clears the cheekby two inches when in an activated state. The short arm is placed on the other side and termi-nates near the canine tooth. It should extend laterally just enough to allow its tip to gentlytouch the soft tissue of the cheek, allowing the traction strap on that side to approximatelyparallel the midsagittal plane of the patient.

( From H. G. HERSHEY et. al. A. J. O. Vol 79 N° 3 page 230-249. 1981 ).

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DIFFERENTIAL FORCE DELIVERY SYSTEMS

From R.M. RICKETTS et. al. Bioprogressive Therapy. Book 1. R.M. 1979.

2 - Cervical headgearand 2 X 4 lower

3 - Combinationheadgear

4 - Combination and2 X 4 upper

1 - Cervical headgear

FORCESYSTEM

Mesofacialthrough

brachyfacial

Mesofacialthrough

dolichofacial

Mesofacialthrough

dolichofacial

Mesofacialthrough

brachyfacial

GENERALRANGE OF

FACIAL TYPE

12 - 14Long term

12 - 14Long term

20 +Short term

12 - 14Long term

TIMEINCREMENTS

IN HOURS

400 +

1000 +

1000 +

400 +

FORCE DELIVEREDIN GRAMS

Hold or close facial axisMaxillary responseMandibular setbackExpansion

Hold facial axisMaxillary responseNo mandibular responseExpansion

Hold facial axisMaxillary responseNo mandibular responseHold arch form

Open facial axisMaxillary responseUpright lower molarsExpansion

GENERALIZEDRESPONSE

Elastics RacksOur aluminum anodized elastics rack is durable, light weight,and has holes for mounting on a wall. Holds four boxes of GACelastics.

Aluminum Elastics Rack 97-300-30

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THE CLASS I ELASTIC HEADGEAR

This is an appliance for upper incisor protrusion correction.This headgear has an inner face bow with two welded hooks distal to the canine area, openedbackward for placing a Class I elastic from the right to the left hook to push backward themaxillary incisors having protrusion with spaces to close ( see Fig IX. 6 ).

In an incisors diastema condition, it is indicated to using this appliance, which allows to pushback and to close spaces ( see Fig IX. 7 ).

This appliance is able to correct a minor clinical problem of Class II canine relationshipwithout bonding the full arch, using only two molars bands.

Fig IX. 6: Class I elastic Headgear ( see text ).

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Fig IX. 7: Clinical example of a Class II malocclusion corrected with only a Class I head-gear elastic. Correction of canine relationship and incisor protrusion had been obtained at thesame time (see text ).

138


THE CLASS II ELASTIC HEADGEAR

This headgear has an inner bow with two welded hooks at the distal point of the maxil-lary lateral incisors.Those hooks are opened forward in order to place Class II elastics coming from the mandibu-lar molars ( see Fig VI. 32 and 33 ).

This appliance has a backward effect on the maxillary arch and a forward effect on the man-dibular arch.

Usely, the Class II elastic headgear is worn at home during homework and sleeping hours.

Class II elastics are reinforcing the headgear effect on the maxilla and at the same time pro-tracting the mandible.

THE CLASS III ELASTIC HEADGEAR

This is a very useful appliance in cases needing simultaneously maximum anchoragein the maxilla and in the mandible.

This headgear has an inner bow with a welded hook, opened posteriorly, mesial to the molarbayonet, allowing to place a Class III elastic ( see Fig IX. 8 and 9 ).

This welded hook avoids placing the elastic behind the upper molar, and abstaining from anextrusion and a forward movement of the maxilla molar, as it is usually noticed with the regu-lar Class III elastic wearing. The elastics are worn only when the headgear is worn.

The Class III elastic headgear is very effective in:

• Non extraction biprotrusion where bite and space closure is obtained with a maximum anchorage system using closing Class III elastic headgear.

• Biprotrusion with extraction where the closure of the bite must be done without moving forward the maxillary molar.

• Bimaxillary maximum anchorage in cases treated with extractions of the first premolars on both arches.

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Fig IX. 8: Example of a Class III elastic headgear. Notice the welded hook mesial to theupper molar, on which the closing Class III elastic is placed ( see text ).

Fig IX. 9: Typical Class III elastic headgear. The Class III elastic force has no influence onposterior occlusal plane ( see text ).

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THE WHISKERS HEADGEAR

This arch was born from problems with the patient needing help placing elastics onSTEINER’s arch bow or the SHUDY’s J hook.

M. LANGLADE 33 proposed in 1973 the Whiskers headgear which is an extra oral bow in .045round wire with two hooks coming under the maxillary archwire, between the central and thelateral incisors ( see Fig IX.10 to 12).

This appliance may be used with 100 to 150 g. elastic force placed on helmet.

Indications for the Whiskers head gear:

• palatal root torque

• upper incisors intrusion ( gummy smile )

• anterior occlusal plane rising upwards.

Fig IX.10: LANGLADE’s whiskers headgear.

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Fig IX.11

The Whiskers headgear isuseful for gummy smilecorrection.

Fig IX.12

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POSTERO ANTERIOR ELASTICS

The purpose of this kind of elastic is to bring forward the maxilla or the mandible.

If the posterior support is always the first or the second molar, at the anterior level the sup-port may be variable upon:

1 - the PHILIPPE’s circummandibular arch 26.

2 - the Facial Mask:

• of DELAIRE - VERDON 62

• of H. PETIT

• of D. GRUMMONS 29

• of R. NANDA 51.

3 - the J. HICKHAM’s Chin Cup 53.

4 - the M. LANGLADE’s Reciprocical Mini Chin Cup 35.

5 - Orthopedic Class III Chin Cup

As we are going to see, some of those appliances have an excessive extrusion component thatlimits their clinical use.

1 - THE PHILIPPE’s CIRCUMMANDIBULAR ARCH

It’s a .045 round wire thru the upper first molar which comes down in the lower buc-cal part all around the mandibular arch; two welded hooks are at the canine level, opened ante-riorly for postero anterior elastics from the first or second lower molar ( see Fig VI.8 ).

Unfortunately, when the patient opens the mouth, the Class I postero anterior elastic becomesa Class II elastic force with a high clockwise movement of the maxillary molar.

It seems that this circummandibular arch should be recommended rather for retention of theretruded lower incisor patients, especially those who have a strong mentalis muscle.

Night wearing seems better for adolescents and adult patients.

2 - THE FACIAL MASK

Proposed in 1904 by Victor Hugo JACKSON with metallic lamella framework for pro-tracting the maxilla, then made fashionable by J. DELAIRE, the facial mask is a precious anduseful auxilary; but its indication is very limited.

Too many orthodontists, faced with an anterior cross bite, quickly choose the facial mask use,thinking “ If it’s not good, it would not be bad for the profile concavity ”.

143


The action of the facial mask which supplies a vertical counter clockwise rotation of the uppermolar and palatal plane, what ever, high, horizontale, is known as the postero anterior pull.

Any sagittal movement goes with a vertical one,from which it’s impossible to escape

Disposition:This appliance is used to protract forward the retruded maxilla from:

➩ a welded buccal hook on a labio lingual wire cemented on the first premolars andfirst molars.

➩ the distal maxillary archwire.

The advised force:According to different clinicians, heavy elastics can range from 1000 to 2000 g.Whatever the protraction force is, it should be:

• parallel to the occlusal plane• 20° upward as DELAIRE and VERDON suggested, or• 20° downward as T. ITOH and S. J. CHACONAS 49 et. al. proposed.

The resulting effect ( see Fig IX.13 to15 ) is an extrusion of the posterior palatal plane,a counter clockwise rotation of the occlusal plane, and a backward mandibular rotation.

The effect:The facial mask effect is accompanied by:

➩ at the maxillary level:

• a limited advancement of point A from 1 to 3 mm maximum, with a downward descent

• a downward and forward movement of posterior palatal spine ( see Fig IX.15 ).For every forward millimeter of the point A, the posterior palatal plane goesdownward 4 mm.

• an upper molar extrusion of 5 mm for 1 mm of point A advancement.

➩ at the mandibular level with a postero anterior traction with a chin support it gives:

• a posterior condylar compression more or less tolerated which creates analleviation attempt by the digastric muscle with

• a posterior rotation of the mandible• an aggravation of prognathic growth tendencies of the mandible in the growing

patient.

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➩ at the dental level:

• a downward movement of the antero superior occlusal plane• an opening of the bite with an aggravation of the anterior incisal open bite and,

sometimes, a tongue interposition as concluded the P. H. BUSCHANG et. al.studies.

The use:The facial mask use shows that the more the point A goes forward, the more the anterioropen bite increases. This alleviation tongue interposition reflex phenomenon is aresponse of the muscular chains to the posterior condylar compression.The TMJ by its numerous receptors is the regulation mechanism of the mandibulargrowth.By those facts, the facial mask use is much more limited than some authors haddeclared.

Instead of a choice in uncertain future, the orthodontist must use a RICKETTS’s LongRange Growth Forecast “ to begin with the end in mind ”.

If you have a 7 year old patient with anterior cross bite, how can you make a decision at pres-ent time, if you ignore the final growth pattern of this patient ? Are you going to treat himimmediately with a facial mask ? By orthopedics or with Class III elastics ? And run for a use-less jump of the bite during many years to finally use surgery to treat him ?

In orthodontics, profits and winnings, as losses and relapses, are not given by the dia-gnosis only, but also by the prognosis.After your decision, you may suffer the consequences of your treatment, if you have no imageof the final growth pattern ( see Table IX. 1 ).

In using the long range growth forecast, you can predict:

• the convexity• the mandibular corpus length• the mandible in the face• the esthetic profile

with the three prognosis key factors:

1 - Long Range Growth Forecast

2 - anterior overbite

3 - collapsed lower facial height.

You may use dental compensation or dental camouflage in some Class III cases, as D.WOODSIDE 59 or P. TURLEY 60 had shown ( see Table VII. 1 ).

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Fig IX. 13: The facial mask use has a triple chain reaction:A - a lowering down of posterior palatal plane with a DOWNWARD and forward

maxillary dental arch advancement.B - a posterior condylar loading which unlatch by reflex track.C - a posterior mandibular rotation allowing a sagittal increase of prognathic growth.

Please remember that it is the vertical sense in TMJ that gives opportunity to the mandible togrow SAGITTALLY.

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Fig IX. 14: According to R. M. RICKETTS 2, the maxillary growth is much more verticalposterior than anterior. This natural phenomenon must be taken into account in the facial maskuse.

Fig IX. 15: Any kind of facial mask pull always involves a downward movement of theposterior palatal plane, increasing the vertical sense with consequences on mandibularovergrowth.

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SKELETAL SKELETAL SKELETALCLASS I CLASS I CLASS III

Pseudo Class III True Class III

1SD 2SD 3SD 4SD

DENTAL Functional shift dental skeletal

CLASS III Borderline

Elastics correction Post mandible rotation Extractions Surgery

USE LONG RANGE GROWTH FORECAST

Table IX. 1

“ The face mask produces orthodontic instead of orthopedic effect in most of the cases.Dental and skeletal relapse will happen due to continued mandibular growth ”.

JONG HIN 58 et. al. 1993.

In deep overbite Class III cross bite:

• Use anterior bite 45° inclined plate, with Class III elastics.

• Bond maxillary incisors upside down to advance point A.

• Procline maxillary incisors ( use M loops ).

• Retrocline mandibular incisors➩ close diastema➩ use stripping of distal 33T43➩ extractions of 34T44 ? ? ( surgery )

• Extrude posterior maxillary teeth.

In Class III, the deeper the overbite, the better the prognosis.

→→→ →→→→ → →→

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● H. PETIT’s Face Mask

This appliance is a little modification of DELAIRE - VERDON facial mask, with anapparent simplified wire frame work.

● D. GRUMMONS’s Face Mask 29

This is a modified face mask having a support from the forehead and cheeks instead ofthe chin, allowing the maxilla or the mandible arch or both to be brought forward.The author recommends a 12 hours wearing with 400 g. intra oral elastics on each side.

Because this face mask has no support on the mandible, there is no impact on the T. M. J.

Fig IX.16: D. GRUMMONS 29 face mask. See text.

● NANDA’s Reverse Headgear 41

This appliance, according to his author, is recommended for maxilla retrusion.It goes posteriorly to the maxilla molar tube and is worn with the extra oral elastics placed ona HICKHAM 53 Chin Cup with postero anterior elastic forces in order to bring forward themaxilla ( see Fig IX.17 to 19 ).

With a hook welded in front of the molar, an intra oral Class III elastic can be added to increasethe maxilla protraction with:

- intra oral forces = 150g.- extra oral forces = 500g.

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Fig IX. 17: R. NANDA reverse headgear with a mesial molar hook for a Class III elastic toreinforce postero anterior maxilla protraction.

Fig IX. 18: R. NANDA reverse headgear worn in mouth with complementary Class III elasticson a lower Class III hooked bite plate.

150


Fig IX. 19: A

Fig IX. 19 B: The NANDA postero anterior headgear is worn with a HICKHAM Chin Cup tobring forward the maxilla.

151


Fig IX. 20: The HICKHAM chin cup for maxillary protraction.

Fig IX. 21: The HICKHAM chin cup for maxillary protraction is worn with postero anteriorintra and extra oral elastics placed on a head cup.

152


3 - THE HICKHAM’S CHIN CUP 53

This chin cup has two vertical labial hooks for postero anterior elastics to protract themaxilla or the dental mandibular arch ( see Fig IX.20 and 21 )

Unfortunately, this appliance must be worn with a headgear that is difficult to keep on thehead, even during sleeping hours.

4 - THE LANGLADE’S RECIPROCICAL MINI CHIN CUP 35

This new appliance was invented by Dr M. LANGLADE in 1978 for the treatment ofdental Class II malocclusions.

This appliance consists of two parts:• a reciprocal maxillary arch• a mini chin cup ( see Fig IX.22 to 24 )

● THE RECIPROCAL MAXILLARY ARCH

Similar to an inner face bow, it is an .045 round wire inserted into maxillary molartubes. A vertical step goes under the upper lip, and two welded anterior hooks are used toattach intermaxillary Class II elastics.

The arch can be worn 24 hours a day, and because it has a lip bumper and headgear effect,along with Class II elastics, it can replace headgear during school hours and sometimes alto-gether.

● THE MINI CHIN CUP

For a more severe malocclusion, the mini chin cup can be inserted in a welded .045tube to the buccal sections of the reciprocal maxillary arch.

The chin cup has anterior hooks at the level of the labial commissure for attachment of poste-ro anterior elastics from the mandibular molars.It should be worn during homework and sleeping hours to increase the mandibular protractioneffect of the elastic force.

This mini chin cup is highly recommended for:

• Class II dental relationships in Class I skeletal patterns ( even with no growth potential)• mandibular dental retrusion• tipped back mandibular canines with or without mesial spacing• borderline surgery cases• microdontia with deep bite and spacing• missing mandibular teeth that may cause a deepening of the bite.

When spaces must be closed in those two last indications, to correct the Class II dental rela-tionship, some contradictory biomechanical movements come into play, with any techniquewithout a force coming from outside of the mouth.

153


Fig IX. 22: The reciprocal mini chin cup with:1 - a reciprocal maxillary arch worn full time with Class II elastics2 - a mini chin cup, worn at home and during sleeping hours with postero anterior

elastics.

154


This appliance is not cumbersome and may help to bring forward the retruded mandibular archand open the bite despite the spaces closing.

The reciprocal mini chin cup advantages are:

• appliance is prefabricated

• quickly adjusted ( only 5 minutes )

• does not require special bands

• no lab assistance needed

• easily inserted and removed

• well tolerated by children and adults

• invisible, not cumbersome

• easily worn 24 hours a day

• reinforces Class II elastics effects

• may avoid headgear use.

Actions of this appliance:

• block / move back upper molar

• control palatal plane

• advance lower incisors during space closing

• advance lower arch even in non extraction cases ( reciprocal effect )

• appliance of choice for rough cases with missing teeth, agenesia, or anodontia in mandibular arch

• supplemental chance for conservative treatment plan in borderline extraction/surgical cases.

This appliance is most effective for its reciprocal effect allowing use two, three, or even fourintermaxillary Class II elastics.Usually the reciprocal mini chin cup is worn during a short time ( from two to five months ),even in adults cases.

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Fig IX. 23: The LANGLADE’s prefabricated maxillary reciprocal arch which is worn 24hours a day with Class II elastics using a bumper effect. See text.

Fig IX. 24: The LANGLADE’s prefabricated reciprocal mini chin cup which goes in the late-ral tubes of the maxillary reciprocal arch which can be used with two to three Class II elasticsand a postero anterior Class I elastic.This appliance is very effective and easily worn by adults.

156


Fig IX.25: Clinical example of dental Class II malocclusion with a retruded mandibular archcorrected in three months with a Reciprocal Mini Chin Cup. Notice the sagittal and verticalovercorrection ( before and after ).

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5 - ORTHOPEDIC CLASS III CHIN CUP

This appliance provides a retruding extra oral force used to posteriorly rotate themandible.

Indications:It first requires a long range growth forecast to diagnose the risky true prognathic case,in order to determine treatment effectiveness (see Table IX.1 ).

Use:This appliance can be used:

• for functional pseudo Class III• for moderate Class III skeletal borderline cases• in primary or deciduous dentition only• with CR Æ near edge to edge incisor relationship• in very early age 2.5 - 4 years• with short vertical facial height• with normal or protrusive lower incisors• with or without an inclined bite plane• with or without Class III intra oral elastics• when the extra oral force used is between 120 to 300 g., 24 hours a day

during 6 to 8 months according to W. DOYLE 61.

P. D. WENDELL, R. NANDA 56 et. al. found a reduced mandibular length by 60 to 68% advocating the chin cup as a viable mode of three years treatment for younger mode-rate prognathic patients.

Effects:The wearing effects of orthopedic Class III chin cup are:

• backward and downward mandibular rotation• increased VDO• backward tilting of lower incisors• clockwise maxilla rotation• decreased gonial angle• “ restricted ” vertical condylar growth

According to L. GRABER 47, who treated 30 Class III malocclusions in patients between 5 to8 years during a three year period, his study provided strong support for the use of orthopedicforce mini chin cup appliance in the clinical management of young patients with moderate ske-letal mandibular prognathism.

The deeper the overbite,the better the prognosis in Class III malocclusions.

158


Fig IX.26 : The two piece corrector from G. EGANHOUSE 57 is constructed with a slidingguide and worn with closing Class III elastics and Chin Cup.From J. C. O. Vol. XXXI. N° 4. pages 246 - 250. 1997.

CHAPITER X

Rationale forElastics Prescription

159

CHAPTER X: Rationale for Elastics Prescrition

Even with the knowledge of all elastic possibilities, it is sometimes difficult for the cli-nician to decide on the best elastic treatment.

Separate the different clinical objectives:

- take notice of primary objective

- accept or refuse, for a while, the secondary objectives.

The primary objective:

It may be:• to open the bite or,

• to close the bite.

The vertical dimension of skeletal pattern is the main factor to consider clinically. Rememberthat all intermaxillary elastics have a tendency to increase the vertical dimension.

The secondary objectives:

They may be numerous choices for reaching selective secondary objectives.

For instance, a Class II molar relationship can exist with an edge to edge that could be cor-rected by placing the intermaxillary elastic buccally or palatally according to the transverseproblem.

160


BEFORE USING INTRA ORAL ELASTICS

1 - Consider the vertical dimension first:

• How is the skeletal pattern ? Normal ? Open bite tendancy ? True open bite ? Deep bite tendancy ? Or true deep bite tendancy ?

• What is the dental problem ?= Do we have to close the bite ?= Do we have to open the bite ?

• What kind of biomechanics are need to reach our goals ?= continuous archwires ?= segmented archwires ?

• Are we allowed to use intermaxillary elastics forces ? Or do we have to use Class I or closing elastic forces ?

Refer to the skeletal pattern and to the Long Range Growth Forecast.Look at the occlusal bite. If you have an edge to edge incisor relationship yourpriority will be to close the bite absolutely; so in that case you must use closingelastics and/or eventually extractions.

2 - Observe the transversal sense afterwards:

Look at the centric occlusion:• Is it a normal occlusion relationship ?• How are the median lines ? Is there a midline shift ? Which one must be

corrected ?• Do you have a cross bite ? If yes, what is the degree of the cross bite 1, 2, or

degree 3 ?• Do you need an expansion on one side ?• Do you need a contraction on one side ?• Do you need cross bite elastics ? Closing elastics ?• Do you need a bite plate to jump the bite ?

For example, a lingual crossbite relationship of a maxillary canine may be corrected in placingon the Class II elastic palatally to correct in the same time the transversal and sagittal sense.

A midline shift clinical case can suggest increasing the Class II elastic force on one side by:➩ changing three times the elastic on one side and only one time per day the other side or,➩ using a closing elastic force on one side and a regular one on the other side or,➩ using a heavy elastic on one side and a lighter on the other.

3 - Correct sagittal relationship at last:

In good order:1 - molar relationship2 - canine relationship3 - incisor relationship.

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HOW TO PRESCRIBE ELASTICS

A: Observe the malocclusion ( see next page ).

B: Write down the occlusal chart.

C: Lay down the problem !

Come up with objectives to reach: use arrows

- Consider the vertical sense first:Observe the open bite tendency, more important on the left side of thepatient’s mouth, and the edge to edge incisors relationship. This reportmeans that we will probably need closing elastics in order to close the bitewhile correcting sagittal problems.

- Note the midline shift of the mandible on the left side.- Notice the half cusp Class II canine relationship on the left side and the

Class III canine and molar relationship on the right side.

D: Draw the needed biomechanic archwires:

1 - Determine the needed anchorage:

2 - Archwire with friction + Extra Oral forces:

❏ yes ❑ yes❑ no ❑ no

3 - Frictionless segmented archwires:

❑ yes ❑ no ❑ asymmetric...

4 - Needed cooperation:

❑ maximum ❑ mean ❑ minimum

In using arrows on the chart and after determining the needed anchorage on each side of themaxilla, the archwires may be chosen with the elastics forces which must be used to reachclinical goals.

Right Maxilla LeftA yes yes yes yes yes yes yes yes AN R no no no no no no no no N RC A Loose Mini Mean Maxi Maxi Mean Mini Loose C AH G yes yes yes yes yes yes yes yes H GO E no no no no no no no no O E

Right Mandible Left

162


A: Observe the malocclusion:

B: Write down the occlusal chart:

C: Lay down the problem ! Come up with the objectives to reach. Use arrows:

D: Draw the needed biomechanic archwires:

E: Draw elastic forces necessary to reach clinical goal:

163


CLINICAL EXAMPLE

A - Observe this dysfunctional patient with a painful left TMJ ( Fig X. 1A ):

- on right side she has a Class II lingual degree 2 cross bite and a Class II canine relationship.

- a midline shift of 3 mm with an edge to edge incisor relationship.

- on left side she has an open bite with a Class III canine relationship.

B - Let us write down the problem:

C - Solution ( Fig X. 1B ):

• on right side, a triangular Class II cross bite elastic is going to correct the Class II and jump the bite.

• anteriorly a closing Class III elastic is going to correct the midline shift, bring forward the left upper canine, and close the bite !

• on left side, we are keeping the posterior wedge so we don’t need any elastic.

D - After 8 weeks ( Fig X. 1C ):

The correct prescription of elastics corrected the majority of the malocclusion and the patientis pain free.

164


A

Fig X. 1

B

C

165


TEST your clinical SKILL

Answear the following QUIZ:

● QA -

● QB -

● QC -

● QD -

Remember to follow the rationale for elastic prescription:

1 - Observe the problem.

2 - Establish the clinical statement of each case.

3 - Write down the occlusal chart on a paper.

4 - Lay down the problem

5 - Draw the needed biomechanical archwires, and your elastic prescription.

6 - After your answer, go to the solution; you’ll be rewarded.

166


QUIZ A

A - Observe Fig X. 2A, 2B, 2C ):

John has three missing teeth: 12 - 22 and 23.

- on right side notice the Class II canine relationship: we’ll have to open the lateral upper incisor space for a future implant.

- anteriorly we have an open bite tendency edge to edge with a 2 mm maxillary midline shift.

- on left side 22 and 23 are missing and we have a Class II edge to edge position of the first bicuspid, we would like to use for canine function. We also need to keep a space for the upper left incisor implant.


C - Solution ( Fig X. 3A, 3B, 3C ):

• on right side, we need a maximum Class II anchorage with two Class II elastics, one on the sectional arch, the other on the Class II utility arch.

• to correct the midline shift, we can add an oblique elastic worn during night.

• to bring forward the first left bicuspid, we need a Class III elastic which is also going to help the midline shift correction.

To increase elastics efficiency, we could also use closing elastics in this case... but we don’tneed too much overbite with future implants.

167


A

Fig X. 2

B

C

QUIZ A

168


A

Fig X. 3

B

C

SOLUTION A

169


QUIZ B

A - Observe ( Fig X. 4A, 4B, 4C ):

Jerome’s clinical problem:

- on right side we have a 2 mm Class II canine relationship.

- anteriorly, the mandibular midline shift is off 2 mm on the left.

- on left side we are in Class II canine and premolar relationship.


We need a maximum anchorage on left side.


Evidently segmentation may use:

• on right side, a sectional with a Class II elastic placed the canine worn only at night.

• on left side, we’ll use a double Class II elastic worn 24 hours a day and changed three times.

Notice that one elastic is placed the utility Class II and the other on the left sectional, sowe have a maximum anchorage on that side, which is also going to correct the mandibularmidline !

170


A

Fig X. 4

B

C

QUIZ B

171


A

Fig X. 5

B

C

SOLUTION B

172


QUIZ C


Look at Sophie’s clinical problem:

- on right side, we are in Class I molar and premolar, but with a mesial space in front of the first bicuspid, the right upper canine is in total Class II relationship.

- anteriorly, there is a distal diastema to the upper right lateral incisor; a maxillary midline deviation of 4 mm.

- on left side, we have a maxillary ectopic canine, however in Class I, because the upper left incisor is edge to edge with the lower left canine.


We need a maximum anchorage on the right side.


• on right side, a sectionnal retractor with a Class II elastic and a Class II utility arch withagain a Class II elastic, worn 24 hours a day and changed three times.

• notice that the utility arch is cut behind the left central for placing on oblique elasticduring sleeping hours.

• on left side, a sectional retractor with a Class II elastic worn 24 hours a day and chan-ged three times is going to bring downward and backward the left upper canine.

173


A

Fig X. 6

B

C

QUIZ C

174


A

Fig X. 7

B

C

SOLUTION C

175


QUIZ D


Sylvain’s clinical problem:

- on right side, the upper right canine is missing, and we would like to use the first bicuspid for canine function.

- anteriorly, we have a light open bite, with a light midline maxillary deviation of 2 mm and an upper incisor protrusion.

- on left side, we have a Class II canine tendency.



With straight wires we may use closing elastics; but with the frictionless segmented techni-que we can use:

• on right side, an M loop to bring forward the first bicuspid; and a closing loop behindthe upper lateral incisor to contract the incisor protrusion.

• on left side, we can have a contraction utility arch wire to close the bite and to contractthe incisor protrusion with the help of a double Class II elastic, the second one placed onthe canine in order to correct the Class II tendency and close the distal diastema.

176


A

Fig X. 8

B

C

QUIZ D

177


A

Fig X. 9

B

C

SOLUTION D

CONCLUSION

178

1) In treating your patient, use a whole philosophy rather than a technique.

2) Evaluate all patient’s functions: respiration - swallowing - occlusion -mastication - phonation - growth - ... - and personality.

3) Individualize the patient by a 4 D diagnosis including growth potential withthe long range forecast: “ Begin with the END in mind ”.

4) Do an early diagnosis of the risky patient to postpone orthodontics untilafter surgery.

5) Set a long range visualization of treatment objectives (the short range VTOis not enough ! ).

6) Progressive banding or bonding makes scheduling easier and reduces stresson both the patient and the doctor.

7) Take advantage of pretorqued, preangulated brackets. The double buccaltubes on the lower molars and the triple buccal tubes on the upper molarprovide archwire combinations and flexibility.

8) Unlock the malocclusion in a progressive sequence and establish more nor-mal function and growth.

9) Use expansion first, before sagittal correction.

10) Choose FRICTIONLESS biomechanics with light forces:

Resistance to sliding mechanics such as friction and binding reducesthe efficiency of a fixed appliance; resist the urge to increase the FORCE

which will result in excessive pain and lost anchorage along with unwanted tooth movement.

Your patient tells you: “ Please use frictionless and light mechanicsto increase efficiency and comfort ”.

179

11) Treat the overbite before the overjet.

12) Prefer Progressive Torque control throughtout the treatment.

13) Increase the ease and efficiency of tooth movement with segmented arch-wires.

14) Diminish anchorage problems with the use of utility archwires which alsoallow more cases to be treated on a non-extraction basis in recovering theLee way.

15) Use elastics forces carefully to get a mobile force without threateninganchorage.

16) In the mixed dentition malocclusion, to get early canine function, useprovocation of sequences of teeth eruption ( E the first, D the second and Cthe last ).

17) Use the ideal patient arch form according to the facial type.

18) Recognize the benefit of the segmented technique to get intraoral adjust-ments and optimize elastic forces.

19) Overtreat the malocclusion.

20) Use selective retention devices to maintain treatment results until thepatient reaches maturity.

BIBLIOGRAPHY

180

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The BEST COOK BOOK on ELASTICS

more than 100 ways to use them!

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Optimization of Orthodontics Elastics. m. Manglade

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