Asymmetry (dental and skeletal) for orthodontists by Almuzian

Management of facial & dental asymmetry

Personal note

Mohammed Almuzian

.

Table of Contents

Definition .....................................................................................................................................................4

Prevalence ...................................................................................................................................................4

Aetiology and classification..........................................................................................................................6

The local factors of asymmetry can also be divided into..............................................................................9

Diagnosis......................................................................................................................................................9

Class II and Class III Subdivisions................................................................................................................15

Types of Class II Subdivisions......................................................................................................................15

Early intervention.......................................................................................................................................16

Types of Class III Subdivisions.....................................................................................................................16

Treatment of asymmetry ...........................................................................................................................16

Treatment of asymmetry............................................................................................................................17

Treatment of dental asymmetries..............................................................................................................18

Treatment mechanics.................................................................................................................................20

I.Upper incorrect to facial midline......................................................................................................20

II.Lower incorrect, without mandibular shift and without skeletal asymmetry..................................20

III.Lower incorrect, without mandibular shift but with skeletal asymmetry.......................................20

IV.Lower incorrect, with mandibular shift. ........................................................................................20

V.Bimaxillary to the same side............................................................................................................20

VI.Bimaxillary to opposite sides..........................................................................................................21

Functional asymmetry................................................................................................................................21

Skeletal asymmetry....................................................................................................................................21

Indication..............................................................................................................................................23

Advantages...........................................................................................................................................23

Soft tissue asymmetry................................................................................................................................25

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Mandibular asymmetry (Obwegeser classification)...................................................................................25

A.Hemimandibualr elongation...................................................................................................................25

B.Hemimandibualr hypertrophy ................................................................................................................27

C.Hybrid (Mixed) forms of HH and HE........................................................................................................29

OTHER FORMS OF FACIAL ASYMMTERYIES ...............................................................................................29

A.Hemifacial Hypertrophy..........................................................................................................................29

B.Condylar hypoplasia................................................................................................................................29

Similar to hemimandibualr hyperatrophy but with significant antigonial notch........................................29

C.Condylar ankylosis...................................................................................................................................29

D.Limited mouth opening (Trismus) ..........................................................................................................30

Presentation of Ankylosis...........................................................................................................................31

Diagnosis of for ankylosed TMJ .................................................................................................................31

Treatment Choices ....................................................................................................................................32

Surgical Approach and preparation ...........................................................................................................33

Complications ............................................................................................................................................33

Summary of the evidences.........................................................................................................................34

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Facial & dental asymmetry

Definition

Symmetry defined as equality in form of parts distributed around a centre or an axis (Stedman’s

medical Dictionary) while asymmetry defined as dissimilarity of parts on either side of a straight

line or plane, or about a centre or axis.

Prevalence

In general population

• Most people have an asymmetry in the face and dentition, but it is usually mild. (Shah and Joshi,

1978)

• Vig & Hewitt (1975) showed an overall asymmetry present in most of the 36% of children in

their study, with the left side being larger.

• No significant gender difference found (Melnik, 1991).

• Here was a 90% chance that the deviation was to the left

• The mandible and the dentoalveolar region exhibited the greatest degree of symmetry this is

because the growth of the mandible takes the longest period of growth.

• History of trauma was found in only 14% of patients with asymmetry.

• Burden 1999 showed that 56% of the lay person and 83% of the orthodontist can recognize 2mm

ML discrepancy.

• For skeletal asymmetry, anything below 5mm considered irrelevant and not significant clinically

• A recent systematic review (Jason 2011) of smile attractiveness concluded that a limit of 2.2 mm

of midline deviation is considered acceptable.

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• Kokich (1993) has suggested that if the line that forms the contact between the two central

incisors is perpendicular to the incisal plane and parallel to the long axis of the individual’s face,

then the midline discrepancy seems to be camouflaged. When the midline is being corrected, a

cant or skew of the arch could result, or the anterior teeth may tilt. So how far can the midline tilt

before it is considered unacceptable? Orthodontists are generally more discerning than

laypersons, with roughly 70% of orthodontists and 40% of laypersons finding a 10-degree tilt

unacceptable (Thomas 2008)

• Sheats 1998 (US) 12% facial asymmetry and 21% non-coincidence of dental midlines. Among

orthodontic patients, the most common asymmetry trait was mandibular midline deviation from

the facial midline. This occurred in 62% of patients, followed, in descending order of frequency,

by lack of dental midline coincidence (46%, maxillary midline deviation from the facial midline

(39%), molar classification asymmetry (22%), maxillary occlusal asymmetry (20%), mandibular

occlusal asymmetry (18%), facial asymmetry (6%), chin deviation (4%), and nose deviation

(3%).

In orthognathic patients: (Sarver and Proffit 1996)

• 25% of class II have asymmetry

• 40% of class III have asymmetry.

• 26% of orthognathic cases have facial asymmetry (Proffit, 1996) and 60% of them with

asymmetry in the lower face and 80% of them have chin deviation. The midface (primarily the

nose) also was affected in about 30% of the asymmetric patients

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Aetiology and classification

It can be classified according to the structures involved:

1. Skeletal

2. Dental

3. Muscular

4. Functional

5. Combination

Another classification from Bishara 1994 et al and Chai et al 2008

I. Skeletal factors

II. Functional mandibular deviations

III. Muscular factors

IV. Local dental factors

V. Combinations

In details

A. Skeletal factors

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B. Functional mandibular deviations

1. In occlusion:

Constricted maxillary arch or malposed tooth causes premature contact in CR leading to

deviation into CO

2. In opening

• Due to anterior disc derangement that result in mandibular deviation when the condyle

translate from hinge to translation movement

• Eagle mouth syndrome (long styloid process)

C. Muscular

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1. Torticollis

2. Decreased muscle tone after CVA or cerebral palsy

3. Massetric hypertrophy

D. Local dental factors

(Holmes 1989)

1. Number of teeth:

• Premature loss of primary teeth like C or D but not the E

• Traumatic loss of permenant teeth

• Hypodontia

• Supernumerary teeth

2. Size of teeth

• Macrodontia

• Microdontia

3. Position of teeth

• Ectopic eruption of teeth causing asymmetric crowding

• Localization of crowding

4. Habit like digit sucking habit

5. Pathology like caries and loss of tooth contact

6. Iatrogenic due to uncontrolled space closure in orthodontic treatment

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The local factors of asymmetry can also be divided into

(Lunstrom, 1961)

1. Qualitative – different size teeth/location in the arch/position of arch in head

2. Quantitative – differences in no. of teeth/presence of CLP

Diagnosis

i. History (trauma, family history, syndrome, previous radiation therapy)

ii. Clinical examination

A. Extraoral examination

• Profile

• Frontal

• Transverse

B. Intraoral features

• Vertical

• Transverse

• Anteroposterior

• Intraarch feature

• Functional assessment

iii. Supplemental records

1. Lateral Ceph

2. OPG

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3. PA Ceph

• Anatomic approach,

• Bisection approach

• Triangulation approach

4. Technesium isotope scan

5. SPECT (single photo emission computer tomography)

6. Medical CT Scan

7. CBCT

8. MRI Scans

9. Study models

10. Facebow record

11. Photograph

12. Sterophotogrammetry

13. Laser scanning

14. Combinations

In details

I. History (trauma, family history, syndrome, previous radiation therapy)

II. Clinical examination

1. Extraoral examination

Profile assessment

• Class III skeletal pattern which is the first sign of Hemimandibualr hypertrophy problem

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• Class II skeletal pattern indicates Hemimandibualr atrophy

Frontal assessment

To assess the symmetry of the face a midline need to be constructed

I. Dropping a perpendicular line from glabella

• to supraorbital bridge

• to interpupilliary line

• to inter-auricular line

II. Dropping a line pass through nasion and philitrum and tip of the nose

III. By using the rule of fifths

Bird and worm view

Transverse assessment

• Chin cant

• Occlusal cant

2. Intraoral features

a) Vertical occlusal evaluation

• Canted occlusal plane (tongue blade/interpupillary line).

b) Transverse

A. X-bites (skeletal, dental or functional), may need to de-programme with occlusal splint for

definitive diagnosis.

B. Evaluation of dental midlines, when the mouth

• Open,

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• Initial contact

• CR,

• CO

c) Anteroposterior occlusal evaluations

• Molar and canine relationship in both sides

• Overjet

• Overbite

d) Intraarch feature

• Local dental factors (early loss etc.)

• Overall arch shape (max/mand). Lundstrom, 1961 used the maxillary raphe as a reference

line.

e) Functional assessment

• Displacements.

3. Supplemental records

1) Lateral Ceph

Sometime a rough idea can be extracted when the right and left sides are superimposed

2) OPG

• Useful to survey dental and bony structures of the maxilla and mandible.

• Shape of condyles and ramus

But geometric distortions exist due to focal tough, positional problem, magnification problem.

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3) PA Ceph

• Valuable to compare right and left sides as located at relatively equal distances form the

film and X-ray source.

• It provides qualitative and quantitative evaluation.

• Taken in occlusion and mouth open.

• Bishara 1993 describe the methods of using PA radiograph

a) Anatomic approach, by Harvold 1964

• Horizontal line through ZF suture

• Vertical line perpendicular to this from crista galli.

• Nasion and ANS tend to fall on or very near ~ 90% of the time

b) Bisection approach

• Bilateral landmarks are located and bisected

• Reference line through as many of their midpoints as possible

c) Triangulation approach

• Vig and Hewitt,1979

• Identification of bilateral structures and midline

• Triangles are constructed that divide the face into various components

• Right and left triangles compared for symmetry

4) Technesium isotope scan, Proffit 2005

• Bone seeking Tc99m can be used to distinguish an active growing condyle

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• It is injected and then it can be detected in the body by medical equipment (gamma

cameras).

• False +ve is very common.

• Dose equivalent = 20 chest X-rays.

5) SPECT (single photo emission computer tomography) is a nuclear medicine

tomographic[1] imaging technique using gamma rays

6) Medical CT Scan

Accurate but high radiation

7) CBCT

8) MRI Scans

Useful for soft tissue asymmetries.

9) Study models

Demonstrate arch asymmetries

10) Facebow record

Using study casts, demonstrates the relationship of the jaws in all three planes

11) Photograph

12) Sterophotogrammetry Hajeer et al 2004

13) Laser scanning of the face by Toma 2011, Alqattan 2013

14) Combinations

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Class II and Class III Subdivisions

The subdivision always refers to the Class II side for Class II subdivisions and the Class III side

for Class III subdivisions. It is true dental asymmetry not related to localised crowding

Types of Class II Subdivisions

Janson et al 2003 described two basic types

1. A Type 1 Class II subdivision malocclusion demonstrates coincidence of the maxillary dental

midline with the facial midline and deviation of the mandibular midline.

• Any treatment in these Type 1 cases should therefore be aimed at the mandibular arch. This also

maintains symmetry in the maxillary arch, where it is most visible to the patient.

A. For cases with moderate to severe crowding, incisor protrusion, and/or the absence of a passive

lip seal, an extraction approach is ideal. But should three or four premolars be extracted? To

answer this question, Janson 2003 retrospectively evaluated 51 patients with Class II subdivision

malocclusions. Twenty-eight of the patients had four symmetric premolars removed, while the

remaining 23 patients had three premolars removed, two in the maxillary arch and one in the

mandibular arch on the Class I side. The results showed no real difference for most of the

variables assessed. However, the three premolar extraction group had a greater improvement of

the initial interdental midline deviation.

B. Cases with mild crowding are treated with single unit extraction in the lower arch or molar

distalisation

2. A Type 2 Class II subdivision malocclusion has the opposite characteristics, demonstrating

coincidence of the mandibular dental midline with the facial midline and deviation of the

maxillary midline.

• If extraction is indicated in these cases, then one maxillary premolar may be removed

• Care must be taken to avoid tilting the teeth, skewing the arch, or overcorrecting the midline of

the highly visible maxillary anterior dentition.

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• The amount of crowding and midline discrepancy also influence the decision to extract a first or

second premolar.

3. Combination Class II subdivision treatment: The remaining 20% of cases show traits of both

Type 1 and Type 2 Class II subdivision malocclusion, with some discrepancy present in both

arches. The goal is therefore to aim correction at both arches, so interarch mechanics such as

elastics or a spring Class II corrector seem most appropriate

Early intervention

• Some asymmetries may develop because of the early loss of teeth, and this could simply involve

space maintenance therapy to regain space or symmetry followed by space maintenance.

• Another possible cause is a single-or multiple-tooth crossbite, which results in a slide shift upon

occluding. Treatment entails correction of the cross-bite to remove the occlusal interference that

causes the slide shift upon closure

Types of Class III Subdivisions

• Although studies similar to those for Class II subdivisions have not been conducted in dental

Class III subdivision cases, Janson 2009 has suggested that an analogous rationale in diagnosis

and treatment planning can be applied in these patients.

• Another option that could be considered in Class III subdivision cases is the extraction of a

mandibular incisor

Treatment of asymmetry

Treatment depends on:

1. Age

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2. Growth remains

3. Patient concern

4. Compliance

5. Severity

6. Aetiology (skeletal, dental, st, functionl),

7. Location

8. Progressivity.

9. Is there a cant to the maxillary plane

Treatment of asymmetry

A. Treatment of dental asymmetries

1. Stop habits and eliminate mandibular displacements (early in Tx)

2. Space management to correct asymmetry

3. Asymmetric differential mechanics

• Extraoral mechanics

• Inter-arch mechanics

• Intra-arch mechanics

B. Functional asymmetry

C. Skeletal asymmetry

1. Preventive treatment

2. Treatment of asymmetry

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i. Mild cases

ii. Moderate to severe

• Camouflage treatment

• Orthopaedic management

• Orthognathic surgery, Early intervention or Late intervention

D. Soft tissue asymmetry

In details

Treatment of dental asymmetries

Treatment is often orthodontically.

I. Stop habits and eliminate mandibular displacements (early in Tx)

II. Space management to correct asymmetry (space maintainer or balanced extraction)

1. Asymmetric and or Unilateral extraction (Rebellato, 1998)

2. Unilateral distalization by (URA with finger spring on one side supported by HG, asymmetric

HG, non-compliance molar distalizer like Jone Jigs or pendulum appliance, sliding jigs supported

by HG)

3. Space opening in one side and composite build ups of the microdontic teeth.

4. IPS of the macrodontic teeth.

III. Asymmetric differential mechanics

Holmes 1989 divided them into:

1. Extraoral mechanics

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• J hook (either on J hook or even two J hook cab be applied to the U and L simultaneously to

correct ML deviation in opposite direction).

• Asymmetric HG with Class III elastic to correct U & L ML that deviated to one side.

2. Inter-arch mechanics

• Differential II/III elastics,

• Oblique or diagonal elastic anteriorly (if too long can cant the occlusal plane).

3. Intra-arch mechanics

1) Bracket set up: Reverse the lower canine brackets on one side (the side at which the LML shifted)

or using tip edge bracket on one side allowing less tipping to correct the ML.

2) Alignment stage

• Unilateral LB,

• Unilateral cinch back

3) Anchorage

• Differential anchorage or increasing the number of anchor teeth

• TADs

4) Space closure stage:

• Push-pull mechanics

• Asymmetric torque that allow the space closure of the side with less torque of the posterior teeth

to happen thus aims in correcting the ML.

• Unilateral thinning of the AW

• Differential force during space closure

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• Unilateral closing loop,

• Elastomeric modules to increase the friction at one side to allow asymmetric space closure

Treatment mechanics

I. Upper incorrect to facial midline.

• asymmetric extraction

• lace-back canine or cinch back on non-shift side only

• open coil spring on shift side

II. Lower incorrect, without mandibular shift and without skeletal asymmetry.

• apply measures described above

• class III elastics to the non-shift side early in treatment, supported by upper headgear

III. Lower incorrect, without mandibular shift but with skeletal asymmetry.

• in mild cases, apply measures described above

• unilateral extraction in moderate cases where dento-alveolar compensation is to be maximised

• orthognathic surgery in severe cases, or acceptance of the condition

IV. Lower incorrect, with mandibular shift.

Where the centreline shift is due entirely to a mandibular displacement, the discrepancy will

correct once the displacement has been eliminated. Where other causes are also present, apply the

measures described above for types 1 and 2

V. Bimaxillary to the same side.

• The choice of extractions is most important. Removal of first premolars on the non-shift side and

second premolars on the shift side gives the most favourable anchorage balance for correction,

provided extractions are warranted.

• In uncrowded (skeletal asymmetry) cases, unilateral extractions may be considered if dentition is

generally protrusive, or accept the condition.

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VI. Bimaxillary to opposite sides

• Early in treatment, apply measures described as for type 1.

• Later in treatment, diagonal anterior elastic will provide the ideal vector without any demand on

anchorage.

• Class II & class III elastics also gives reciprocal anchorage.

• for resistant shifts in the later stages, "J" hook headgear applied to the canines in the non-shift

sides (eg upper left and lower right quadrants)

Functional asymmetry

1. Habit breaker if the functional displacement is due to cross bite caused by habit.

2. Mild deviations due to functional shifts can be done with minor occlusal adjustments (grinding

C’s, or extraction).

3. Occlusal splints may be needed for deprogramming

4. Expansion of the constricted arch (RME, Q helix, URA, AW or SARPE)

Skeletal asymmetry

Preventive treatment

Fortunately, most jaw fractures in preadolescent children can be treated with little or no surgical

manipulation of the segments and little immobilization of the jaws because the bony segments are

self-retentive and the healing process is rapid. Treatment should involve

• Open reduction of the fracture should be avoided.

• Short fixation times (usually maintained with intraoral intermaxillary elastics) and rapid

return to function.

• A functional appliance during the post-injury period can be used to minimize any growth

restriction. The appliance is a conventional activator or bionator-type appliance that

symmetrically advances the mandible to nearly an edge-to-edge incisor position. Using this

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appliance, the patient is forced to translate the mandible, and any remodelling can occur with the

mandible in the unloaded and forward position.

Treatment of skeletal asymmetry

A. Mild cases, accept or orthodontic camouflage after monitoring the progressivity of the

case.

B. Moderate to severe: after monitoring the progressivity of the case

1. Camouflage treatment by orthodontic alone

2. Orthopaedic management of occlusal canting in growing patients using hybrid functional by Vig

and Vig 1986. It consists of acrylic block at the side of overgrowth and no block at the

undergrowth site to allow eruption of the teeth at the underdeveloped site. There is a buccal

shield same like the one use in Frankle appliance to allow arch expansion.

Construction bite

• Bring Md forward towards vertical & transverse symmetry

• -Wax soft on unaffected side & hard on affected side to torque the ramus downward on

the shorter side.

Design

• Impede tooth eruption on the unaffected side.

• Bite block on the normal side impede further vertical development, eruption

• Lingual pad to posture md to normal side

• On the affected side buccal (expansion) and lingual shields to prevent the tongue getting

in between the teeth where vertical development is desired.

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3. Orthognathic surgery

A. Early intervention

It is better to avoid early maxillary surgery to avoid scar interference with maxillary growth.

Sometime high condylar shaving or condylotomy is prescribed.

Indication

I. Ankylosis: treated by growth centre transplant using costrocondal rib in sever class II

II. HFM usually treated early 5 years by inverted L osteotomies or distraction (Davis and

Sandy1998)

III. Sever class III or class II with social impact

Advantages

I. To avoid consequence of disturbed or secondary unfavourable growth in the craniofacial

structure

II. Psychological benefit.

III. Breathing

B. Late intervention

The surgeries might be:

1. Lefort I osteotomy to reposition the maxilla

2. Sometime, mandibular asymmetry can cause some secondary maxillary asymmetry which might

be treated by:

• Maxillary segmental surgery,

• Surgically assisted RME.

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3. Sagittal split osteotomies of the mandibular ramus to advance or shorten one side more than the

other

4. Other mandibular surgery are:

• Genioplasty

• VSS

• Inverted L

• Condylar excision,

• Condylar shave

• Lower mandibular border plasty (e.g Hemimandibualr hypertrophy)

• Distraction osteogenesis appears to offer the possibility of augmenting the amount of both bone

and soft tissue in the mandibular anterior area.

• Then consider – externalisation of the nerve and a lower border shave or build up of the

unaffected side with implants to improve the ST bulk or Coleman fat

•

Stability after orthognathic surgery

Proffit and Severt 1997 found that

1. Genioplasty to correct asymmetry was stable

2. Maxillary surgery to correct cant was stable

3. Ramus surgery 1/3 of the result is lost

4. Bimax is more stable than mandibular surgery alone

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Soft tissue asymmetry

It can be treated either by:

• Augmentations include the use of bone grafts, collagen filler, Botox and implants to

recontour the desired areas of the face

• Soft tissue reduction surgery.

Mandibular asymmetry (Obwegeser classification)

A. Hemimandibualr elongation

1. Mechanism not understood,

2. Appears early teens (most frequent in girls)

3. Transverse displacement of the chin point

4. Lower dental ML deviation in relation to UML but correct to midpoint of the chin

5. ID canal NOT bowed on affected side,

6. Normal height of ramus of mandible

7. Obtuse angle of mandibular at side effected

8. Long mandibular body at side effected

9. No open bite or occlusal cant

10. Cross bite at the non-affected side and scissor bite on the contralateral.

11. There is no cant to the rima oris, but the lower lip

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B. Hemimandibualr hypertrophy

1. Mechanism not understood

2. Appears late teens (may be earlier, most frequent in girls)

3. Three dimensional enlargement of one side of the mandible including condyle, condylar neck,

ramus and body of the mandible

4. Big condyle

5. ID canal bowed on affected side,

6. Body of mandible bows downwards on affected side,

7. Angle of mandible rounded

8. Increase mandibular ramus height

9. Cant of occlusion at effected side

10. Lower dental ML deviation in relation to midpoint of the chin in order to compensate by increase

in the incisor angulation.

11. Treatment involves ramus osteotomy, condylectomy or condylar shave.

12. There may be a lateral open bite on the affected side depending on whether the extent of

maxillary dentoalveolar compensation on the affected side has kept up with the increased vertical

ramal growth, and whether or not the tongue has found a resting position between the posterior

dental occlusion.

13. The unilateral increase in lower face height gives rise to a sloping rima oris, the oral commissure

on the affected side is displaced inferiorly but not laterally

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C. Hybrid (Mixed) forms of HH and HE.

OTHER FORMS OF FACIAL ASYMMTERYIES

A. Hemifacial Hypertrophy

• Rare

• Overgrowth of ST and HT on one side of the face

• Cause – asymmetric distribution of the NCC

• Problem: You cannot simply debulk the whole mandible due to ID nerve, can place implant on unaffected side to even things out

B. Condylar hypoplasia

Similar to hemimandibualr hyperatrophy but with significant antigonial notch

C. Condylar ankylosis

True condylar ankylosis

• I caused by pathology or trauma or infection

• X ray reveals pure bony union

• Very sever restricted mouth opening

• The best treatment of condylar fracture is early mobilization to avoid ankylosis

False condylar ankylosis

• Transient Limited mouth opening (Trismus)

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• Due to extra-articular abnormality, the result is limited mouth opening

D. Limited mouth opening (Trismus)

There are many causes of limited mouth opening which may be classified as follows.

1. Intra-articular (intracapsular)

• Functional: Anterior displacement of the meniscus without reduction.

• Trauma: Osseous or fibro-osseous ankylosis, secondary to trauma

• Inflammatory: Ankylosing spondylitis, juvenile rheumatoid arthritis.

• Infection in the joint.

• Tumour of the joint structures.

2. Extra-articular (extracapsular)

• Muscle trismus.

• Disuse muscle atrophy, contractures secondary to intra-articular ankylosis or psychogenic

trismus.

• Post-radiotherapy and thermal scarring.

• Post-traumatic scarring.

• Oral submucous fibrosis.

• Infection or inflammation of the masticatory muscle

• Anatomical like Eagle syndrome.

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Presentation of Ankylosis

If developed at early age:

• Ankylosis in children produces impaired mandibular growth with bilateral deformity in all

dimensions.

• This deformity is asymmetrical in unilateral cases with a straight small hemi-mandible on the

ankylosed side, and a marked contralateral bowing deformity.

• Retrognathia and retrogenia become more apparent with age.

• This produces an occlusal cant down to the normal side.

• In rare bilateral cases the mandible is short but symmetrical.

• In all cases the inter-incisal opening can be up to 10 mm even with total bony fusion reflecting

the bone elasticity within the masticatory system.

Diagnosis of for ankylosed TMJ

• History and clinical examination

• Imaging techniques including:

1. OPG.

2. True lateral skull.

3. PA

4. CT scan with 3D reconstruction.

5. Standard orthognathic photographic series.

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Treatment Choices

Resection of the ankylosis should be carried out as early as possible to enable normal growth and

avoid secondary deformity.

There are many treatment strategies depending on the age of the patient the duration of the

deformity and degree of secondary deformity.

A. Ankylosis presenting in childhood or Ankylosis presenting during or post adolescence

1. Excision of the condyle

2. Insertion of an interpositional temporalis myofascial peninsular flap

3. Bilateral coronoidectomies (coronoidotomies) to free temporalis contractures

4. Costochondral growth centre to restore function and ramus growth with or without Distraction

osteogenesis.

NB: The anteroposterior deficiency and asymmetry in childhood is usually self-corrected with

catch-up growth.

B. Ankylosis presenting after the completion of facial growth.

1. Excision of the condyle

2. Insertion of an interpositional temporalis myofascial peninsular flap

3. Bilateral coronoidectomies (coronoidotomies) to free temporalis contractures

4. Reconstruction of the condyle with or without distraction osteogenesis.

5. In addition to one of these:

• Genioplasty

• BSS or inverted L osteotomy.

• The maxillary procedure can be done to correct secondary problems

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C. Very late ankylosis in adults with no interference with facial growth.

Exactly as B but in addition to 7-day pre- and 2-month postoperative course of bisphosphonate,

which is currently alendronic acid 10 mg a day in the morning to avoid the localised

fibrodysplasia ossificans .

Surgical Approach and preparation

The preoperative preparation differs from the standard orthognathic workup in several respects.

1. The anaesthetist must be skilled in fibre optic intubation and tracheostomy or submental

approach.

2. The temporal area must be shaved and cleaned before the patient is taken into theatre.

Complications

1. Scar

2. Damage to the orbital and frontal branches of the facial nerve.

3. Frey’s syndrome

4. Damage to parotid salivary gland

5. Limited opening due to

• Inadequate bone removal

• Failure to do a bilateral coronoidectomies.

• Postoperative fibrodysplasia ossificans

• Fusion of the graft with re-ankylosis

6. Failure of the costochondral graft to grow.

7. Excess growth of the graft

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8. Pneumothorax.

Summary of the evidences

• Vig & Hewitt (1975) showed an overall asymmetry present in most of the 36% of

children in their study, with the left side being larger.

• 26% of orthognathic cases have facial asymmetry (Proffit, 1996) and 60% of them with

asymmetry in the lower face and 80% of them have chin deviation. The midface (primarily the

nose) also was affected in about 30% of the asymmetric patients

• Another classification from Bishara 1994 et al and Chai et al 2008

• Condylar hyperplasia which is subdivided by Obowegeser and Mekek 1986 into:

• Local dental factors , (Holmes 1989)

• Bishara 1993 describe the methods of using PA radiograph

• Technesium isotope scan, Proffit 2005

• Sterophotogrammetry Hajeer et al 2004

• Laser scanning of the face by Toma 2011

• Treatment of dental asymmetries, Space management to correct asymmetry, Asymmetric

XLA’s (Rebellato, 1998)

• Asymmetric differential mechanics , Holmes 1989

• Stability after orthognathic surgery, Proffit and Severt 1997

• Hemifacial microsomia

1. Prevalence

Mohammed Almuzian

2. 1/5000 births but varies

3. Autosomal dominant

4. Affect male than female m:f = 3:2

5. A condition that affects aural, oral and mandibular development. It caused by disturbance

in the number, activity and migration of NCC (especially in the lower face area, the NCC migrate

for long distance)

• Second way of treatment distraction osteogenesis (DO).It is a method of increasing bone

length & originally described by Ilizarov (1988).

Mohammed Almuzian

Asymmetry (dental and skeletal) for orthodontists by Almuzian

Health & Medicine

Transcript of Asymmetry (dental and skeletal) for orthodontists by Almuzian