Basic Removable Appliances Design

7/22/2019 Basic Removable Appliances Design

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C O N T E N T S H i s t o r y

S c o p e o f R e m o v a b l e A p p l i a n c e s

C l a s s i f i c a t i o n

I n d i c a t i o n s

A d v a n t a g e s

D i s a d v a n t a g e s

L i m i t a t i o n s

D e s i g n C o m p o n e n t s P a t i e n t i n s t r u c t i o n s a n d A p p l i a n c e

C a r e

C o n c l u s i o n


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HISTORY

Victor Hugo Jackson Chief proponent of removable

appliances in the US

Charles Hawley Introduced Hawleys appliance in

1908

Martin Schwartz In mid 20th century developed a

variety of split plate appliances


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Philip Adams

Modified arrowhead clasp into Adams Crib

Became the basis for English removable appliances

Still the most effective clasp for orthodontic purpose

George Crozat

In early 1900s developed a removable applianceentirely in precious metal

Heavy gold wires as framework Lighter gold finger springs for desired tooth

movement


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Norman W. Kingsley (1879)

Described his p la te for Jumping the

b i te P ioneer in or thodont ic therapy for the

forward pos i t ion ing of the mandib le.

Monobloc by Pierre Robin(1902)Passive posi t ioning device

Modif ied from bi te jumpingvulcani te maxi l lary guide planesdesigned by Norman Kingsley

Indica ted in pa t ien ts wi th severe


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S cope of removable appliances The quality of outcome is not as high as with

fixed appliances

Higher chances of discontinuation of treatment

associated with the use of removable

appliances


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The use of removable appl iances s t i l l

var ies widely between c l in ic ians, buti t

i s p o s s i b l e t o a c h i e v e a d e q u a t e

o c c l u s a l i m p r o v e m e n t w i t h t h e s e

a p p l i a n c e s , p r o v i d e d s u i t a b l e c a s e s

a r e c h o s e n .

I t i s v i ta l to emphas ize that casessui tab le for removable appl iancet reatment are those that requi re s implet ipp ing movements on ly, andsurpr is ingly few malocc lus ions wi l l fa l lin to th is category.


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Definition:

REMOVABLE ORTHODONTIC APPLIANCE:

An appliance which can be removed forcleaning by the patient or for adjustment bythe orthodontist.


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Classification

Given by Graber for removable appliance

Group A :- tooth supported appliances

E.G.- Catlans appliance, inclined planes, etc.

Group B :-tooth/tissue supported

E.G.-Activator, bionator, twin block, etc

Group C :-vestibular positioned applianceswith isolated support from tooth/tissue

Frankel appliance, lip bumper,etc


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At present removable appliances are indicatedfor three major uses

Growth modification

Limited (Tipping) tooth movements

Retention

Indications


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Majority of malocclusions which require

simple tipping of teeth can besatisfactorily treated with removable

appliance

Can be incorporated with bite platforms to

eliminate occlusal interference and

displacement

Manufactured in the laboratory and

adjustments takes less chair side time.

Advantages


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Can be removed by the patient for

cleaning both teeth and appliance.

Damaged appliances that applyundesirable forces can be removed.

They are aesthetically better

accepted than fixed appliance.

They can also be used as a muscle

exerciser.

They are Inexpensive

removable

fixed


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Disadvantages PATIENT COMPLIANCE

Uncooperative patient may sometimes leaveout the appliance which prolongs the treatmentand uncontrolled drifting of teeth occurs.

Rotation of one or two upper incisors canbe dealt but multiple rotations cannotreadily be treated.

Lower removable appliances are not welltolerated due to encroachment on tongue

space and retention problems.


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If the appliance is not adjusted carefully it

brings about uncontrolled tipping of teeth.

Patients may have have excessive

salivation initially


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LIMITATIONS

Removable Appliances permit only

TIPPING movements

Patient will have difficulty in speech

initially

Appliance can be easily damaged if

care is not taken


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Components of removable appliances

Retentive Components Baseplate

Active components


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Retentive

Components


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IDEAL REQUIREMENTS

Should not impinge

Close contact to the tooth

Usable in both deciduous and permanent

dentition.

Adequate retention

No active force on the anchor tooth

Should be rigid

Easy to fabricate and also replace if needed

Not interfere with the growth of jaws and

eru tion of teeth


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Circum ferent ial Clasp

Fabricated using wire 0.8 mm

-Also known as C clasp or Three Quarter Clasp

Simple clasp used to engage buccocervical undercut Adequate retention.

Easy to fabricate.

Easy to replace.


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Disadvantages

Cannot be used in partially erupted teeth

Decalcification of cervical margin.

Gingival irritation. Plaque accumulation enhanced.

Can easily distort.

J k Cl


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Jacksons Clasp

- Fabricated using 0.8 mm wire

- Also known as Full clasp or U clasp

- Engages both bucco-cervical and proximal undercuts

Offers adequate retention

X Inadequate retention in partially erupted teeth

X Difficult to adjust

C


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Triangu lar Clasp

Fabricated using 0.6mm wire

Used between adjacent posterior

teeth Indicated for additional retention

Elastics can be engaged

Not usefull if adjacent tooth is


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ADAMS CLASPAlso known as Liverpool Clasp,

Universal Clasp,

Modified Arrowhead Clasp

Parts

Bridge

Arrowhead

Retentive arms


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CHARACTERISTICS

The bridge is 2/3rd the mesio dital width of thetooth, or slightly less then the distance betweenmesiobuccal and distobuccal undercuts, or length

should be equal to the intercuspal distance.

Is 1-2mm away from the buccal surface of the

tooth.

Angulated at 45o to the long axis of the tooth.

Bridge


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Arrowheads

They should lie in the disto- andmesio buccal undercuts.

Shaped according to the curveof the gum margins into theinterdental papilla.

Long enough to keep the brideat a proper distance.

Should not touch the adjacentteeth


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ADVANTAGES

Small, neat, occupies minimum space

Rigid, offers excellent retention

Used on any tooth in the arch

If broken can be repaired by soldering

Permits modifications in design


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DISADVANTAGES

Extensive wire bending incorporates

stresses in the wire

Unwanted palatal tipping if it getsactivated.

Can be repaired only if fractured

through the arrowheads.

Cannot be given on proclined

anteriors.


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Modifications

Adams clasp with single

arrowhead

Adams clasp with J hook

Adams clasp with helix


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Adams clasp with additional

arrowhead

Adams clasp with soldered

buccal tube

Adams clasp with distal

extensionDouble clasp on maxillary central incisors


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Schwarz Clasp

Designed by C. M. Schwarz

One of the oldest clasps and is considered as the

predecessor of the Adams Clasp

Can be used in deciduous or permanent teeth

Skill to fabricate

Eyelet Clasp


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Eyelet Clasp

Similar to triangular clasp

Used as single eyelet or multiple eyelet clasp

Eyelets placed in embrasures

On single tooth does not have firm grip so

multiple eyelet clasp is preferred


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Southend Clasp

Spans two adjacent margins of anterior

teeth

Esthetically more pleasing


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Bal lend Clasp

Wire having a knob or ball like structure

on one end

utilizes interdental undercuts

Indicated when additional retention

required


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Crozat c lasp

It resembles a full clasp but

has a additional piece of

wire soldered which engagesinto the mesial and distal

proximal undercut

Offers better retention than

full clasp


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Baseplate


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Greatest portion of removable

appliance and is1-2mm thick

It serves 3 main purposes

1. Act as vehicle to carry all parts

of the appliance

2. Serve as anchorage

3. Become an active part of

appliance itself


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Anter ior bi teplane

Platform behind upper incisorteeth with a 60degree inclination

Height enough to separate

posterior teeth by 1.5-2mm

Reduces overbite of anterior teeth

and causes

opening of the bite


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Sved B iteplane

Introduced by Sved in 1944

Covers incisal edges of upper anteriors

Pressure transmitted axially

Provides reinforces anchorage


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Pos ter ior B itep lane

Can be used for treating

Posterior crossbites

Anterior crossbitesAnterior openbite

after correction appliance acts as a retainer

Lower Inc l ined Plane


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Lower Inc l ined Plane

Introduced by Catlan more than200 yrs ago

Used for treating Anterior crossbite

Inclined at 45 degrees to the

occlusal plane

If used for more than 6wks-

anterior open bite results


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Activecomponents


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LABIAL BOWs

SPRINGS

ELASTICS

SCREWS


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LAB IAL BOWS

Parts of labial bow

1. Incisor segment

2. Vertical loops

3. Cross over section

4. Retentive arm

May have 2 functions

1) Serve as active element for movement of teeth2) Hold the plate in place & retain the teeth

Incisor segment


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Incisor segmentUsual ly in the junct ion o f middle th ird

and incisal th i rd .

Right angle bend a t the dis ta l th i rd of la te ra l inc isors or mesia l th i rd of canine

Contacts only the most prominent teeth

Vertical loopsConsis t s of para l le l ver t ica l legs jo ined

by a smooth curve.

I t i s usual ly 9-12 mm in length ,extending 2-3 mm.

At the gingival level the loop is 1-

1.5mm above the gin gival margin


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The various types of labial

bows are Short labial bow

Long labial bow

Split labial bow Reverse labial bow

Roberts retractor

Mills retractor

High labial bow with apron springs

Fitted labial bow

Beggs retention bow

Short Labial Bow


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Short Labial Bow

Fabricated with a 0.7 mm wire

Flexibility depends on vertical height of U

loops

Used when only minor overjet reduction or

incisor alignment required

Retentive arm distal to canine.


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Adjustment : Compressing of U loop

so that the incisor component is displaced

palatally by only 1mm


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Long Labial Bow

Used to close space between canine and

premolar

Provides better control over the positionof the canine

Used for retention purposes

S


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Spl i t Labial Bow

The flexibility of the wire is increased

Used for incisor retraction and Closure ofdiastemas

Adjustment : at the U loop 1-2 mm at a time.

L bi l B i h R L


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Labial Bow w ith Reverse Loop

Prevents buccal drifting of

canine

Mil ls Bow /Extended Labial Bow


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Mil ls Bow /Extended Labial Bow

Made of 0.7mm wire

Extensive loops- flexibility greatly increased

Indications -Reducing large overjets

-Alignment of irregular incisors

Lighter forces, longer range of action

Due to extensive loops less comfortable

Hi h L bi l B i th A S i


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High Labial Bow w i th Ap ron Spr ing

Used mainly for carrying Apron Springs Heavy base arch made of 0.9-1 mm wire

Apron spring are made of 0.3-0.4mm wire


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Used for retraction of teeth with

severe proclination

Lighter forces

Longer range of action

Not well tolerated by the patient

Time consuming to fabricate

Cannot be used in patients with

shallow sulcus


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Roberts Retracto r

Flexible bow constructed of 0.5mm wire

Steel tubing in the form a buccal sleeve to

give support


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Fit ted Labial Bow

Fabricated with a 0.7 mm wire Adapted closely to labial surface of anterior

teeth

Used for retention


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Beggs Retent ion Bow

0.7mm wire extends till last erupted

molar

U loops made between I & II premolars

Allows better settling of occlusion

Oth M difi ti


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Other Modifications

The labial bow with

retractive canine loop

The modified labial bow

Funct ion : Engagement of

elast ics and so lder ing of

spr ings

The labial bow with

vertical M-loop

Funct ion: Al ignment of the

can ine, if it is labial ly


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SPRINGSThese are the most commonly used

active elements.

Requirements: springs should deliver optimum force

should possess high degree of

elasticity

should have long range of action and

apply light forces.


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0.5mm or 0.6mm wires are used to

move single teeth or groups of

teeth

Constructed in 18/8 austenitic

stainless steel

The more wire incorporated, the

greater the range of the spring

and the li hter the force


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Classification of Springs

I. Based on d irect ion of tooth movement1. Springs for mesio-distal tooth movement

2. Spring for labio-lingual tooth movement

3. Springs for expansion of archesII. Based on nature of suppo rt

1. Self supported springs

2.Guided springs

3. Auxiliary springs

III. Based on presence of loop o r helix

Sing le Can t i lever Spring


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Sing le Can t i lever Spring

active arm

Parts coilretentive arm

Fabricated with a 0.5-0.6mm wire

coil with internal diameter of 3mm

used to move teeth labio-lingually or mesio-

diatally

Double Cant i lever Spr ing / Z spr ing


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Double Cant i lever Spr ing / Z spr ing

Constructed using 0.5 or 0.6 mm wire Spring perpendicular to palatal surface of

tooth

Indicated where incisors are to be proclinedActivation: Done by opening both coils

If not perpendicular to palatal surface of teeth,

it tends to intrude teeth.

T Spring


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T Spring

Constructed using 0.5 mm wire Used for buccal movement of premolars

and molars

C ff i S i


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Coff in Spring

Described by Walter.H.Coffin in 1881

Made of 1.25 mm wire Can be used for slow dentoalveolar

transverse arch expansion


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Canine Retractors

used to move canine in distal direction

CLASSIFICATION

I. Based on location -buccal

-palatal

II. Based on presence of helix or loop

III. Based on mode of action -push type

-pull type

Buccal Sel f Sup po rted Canine Retracto r


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Buccal Self Suppo rted Canine Retracto r

Fabricated with a 0.7 mm wire

Used when buccally placed canine is to

be moved palatally and distally coil just distal to long axis of tooth

U Loop Buccal Canine Retractor


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U Loop Buccal Canine Retractor

Can be used in shallow sulcus

Requires frequent adjustment

Palatal Canine Retracto r


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Palatal Canine Retracto r

-Used for canine placed palatally

requiring distal movement

S


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Screws

Types of screws

The 2 types of expansion screws are

Skeletal expansion screw

Dental expansion screw

PITCH OF THE SCREW


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PITCH OF THE SCREW

When the expansion screw is given one

complete turn, i.e., four one-quarter turns, thetwo halves of the removable orthodontic

appliance advance a distance equal to the

space between the neighbouring lines oftencalled as threads. The distance moved is called

the pitch of the screw.

Act ivat ion


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Act ivat ion

Whenever the screw is turned 90

degrees itwill drive the parts of the plate apart by

0.2 mm which

narrows periodontal ligament by 0.1

mm on each side.

In the case of adult patient 1 quarterturn/week 0.2mm approx which is less than

width of periodontal ligament fibre

U


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Uses :Baseplate divided into sections driven

apart by one or more screws

1) Split along midlineFor correcting Bilateralcrossbites


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2) Split into a larger and a smaller part


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Y-PlatesFor saggital and lateral

expansion

El ti


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Elastics Resembles rubber band Made of latex rubber

Available in various diameters forceapplied depends on their diameter

Colour coded for easy identification

Uses :

For movement of singe teeth and groups ofteeth

For intermaxillary traction

Molar intrusion with removable a appliance


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Molar intrusion with removable a appliance


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Intermaxillary elasticswith removable

plates can be used

for the treatment ofClass II and Class III

Instuctions to the


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patients and Appliance

Care

Appliance should be worn all

the time.

Remove the appliance using

the clasps only.Remove the appliance only

during brushing and for


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Never wrap the appliance in napkin

or in pocketThe patient should avoid playing

with the appliance using the

tongue.

Initial problems faced by patientlike discomfort, pain ,excessivesalivation ,plastic taste anddifficulty in speech.

Storing the appliance in a proper


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PROBLEM 1: UPPER INCISOR INSIDE BITE


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RETENTION: Adams cribs 6/6 and 4/4


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Active component: Z-spring to 1/


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BITE OPENING: Posterior bite capping to654 / 456 (more comfortable

for patient)


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BASEPLATE: to connect everything together, alsosome anchorage


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ACTIVATE THE Z-SPRING....


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PROBLEM 2: All four incisors inside bite, with

deep reverse overbite


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RETENTION: Adams cribs 6/6 and 4/4


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ANTERIOR RETENTION: Southend clasp 1/1


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ACTIVE COMPONENT: Expansion screw tosection 21/12


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BITE OPENING: occlusal capping posteriorly


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Screw is opened by one quarter turn twice a weekand pushes upper incisors forward over the bite


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PROBLEM 3: Increased overjet, proclined incisors


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Extract 4/4 to allow overjet reduction


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RETENTION: Adams cribs on 6/6 ,Southend clasp 1/1


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ACTIVE COMPONENTS: Palatal finger springs 3/3

with wire guards for

stability


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BITE OPENING: flat anterior bite plane

Trim acrylic


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3/3 at end of canine retraction


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Canines retracted. Now the incisorsmust be retracted


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RETENTION: Adams cribs 6/6 with arrowheadextensions to 5/5


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Metal stops mesial to 3/3 to prevent theseteeth from moving forward


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ACTIVE COMPONENT: Labial bow in 0.7 mm wirewith large U-loops to allo

activation


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BITE OPENING: flat anterior bite plane


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Labial bow activated 1-2 mm at each visit bysqueezing vertical legs of U-loops together.

Palatal acrylic must be trimmed away by the

same amount.


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End of incisor retraction


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Where canines are bucally placed, use buccalcanine retractors, made in either 0.7mm wire

or 0.5mm wire supported by 0.5mm internal

diameter tubing where it emerges from the acrylic


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Canines can be pushed palatally into theline of the arch as they move distally


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The labial segment can be retracted also with a

0.5mm labial bow with tubing support.


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ACTIVATION OF LABIAL BOW: Press thevertical leg towards the tubing


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PROBLEM 4: /5 deflected palatally,

/6 has drifted mesially


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RETENTION: Adams cribs 6 / 46 ,

southend clasp 1/1


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ACTIVE COMPONENT: Screw section to /6 ,

Z-spring to /5


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PROBLEM 5: Buccally placed canine /3


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Retention: Adams cribs 6/6 and 4/4


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ANCHORAGE REINFORCEMENT:

Headgear tubes on 6/6


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ACTIVE COMPONENT: Screw section to distalis

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ANCHORAGE REINFORCEMENT:

headgear to tubes on 6/6


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Problem 6: Class II div 1, and both upper first permanent

molars are carious


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Adams cribs on 73/37, finger springs 5/5 and

4/4, fitted labial bow 21/12


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Extract 6/6


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Retract 5/5 (with or without headgear support)


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Retract 4/4


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Adams cribs 74/47, finger springs 3/3,

Southend clasp 1/1


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Upper 3/3 retracted


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URA with labial bow to retract 21/12


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Conclus ionRemovable and fixed appliances are the two facets of the


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Removable and fixed appliances are the two facets of the

orthodontic world.

The science and art of designing and constructing

removable orthodontic appliances forms the basis for

managing most of the orthodontic patients

Sound theoretical knowledge of orthodontics helps us in

designing a removable orthodontic appliance where as

the construction of removable appliance is more of

an art which has to be learned meticulously followingthe procedure and by repeated practice.

References


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Orthodontic treatment with removableappliances- W. W.J.B. Houston, K.G. Issacson

The Design, construction and use or

Removable Orthodontic Appliances C. Philip

Adams Removable Orthodontic Appliances- T.M.

Graber, Bedrich Neumann

Orthodontics Principles and Practice- T.M.

Graber

Contemporary Orthodontics- Proffit


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Basic Removable Appliances Design

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