class 3 malocclusion by almuzian

UNIVERSITY OF GLASGOW

Class III Malocclusion

Personal notes

Mohammed Almuzian

2/20/2013

……………………………………….

Table of Contents

Definition.................................................................................................................1

Incidence.................................................................................................................1

Classification...........................................................................................................2

Aetiology.................................................................................................................2

Features of Class III................................................................................................3

A. Skeletal features...............................................................................................3

B. Soft tissues features..........................................................................................4

C. Dental features.................................................................................................4

D. Displacements..................................................................................................4

E. Facial growth...................................................................................................4

IOTN and class III...................................................................................................8

Crossbite (2.c, 3.c, 4.c)............................................................................................8

Growth status assessment for class III patients.......................................................9

Monitoring the growth of mandible........................................................................9

Differentiation between mandibular prognathism & maxillary deficiency...........10

Treatment options for class III malocclusion........................................................12Mohammed Almuzian, University of Glasgow, 2013 1

Factors influencing treatment options...................................................................12

Summary about treatment strategies according to dental age...............................13

Reasons for early treatment of class 3 malocclusions...........................................16

Orthopaedic treatment option................................................................................17

Effect of orthopaedic appliance in class III maloculsion......................................17

Positive factors for orthopaedic treatment.............................................................17

Types of orthopaedic treatment in class III malocclusion.....................................18

1. Protraction HG...............................................................................................18

Definition...............................................................................................................18

History...................................................................................................................18

Indications.............................................................................................................19

Timing...................................................................................................................20

Effects....................................................................................................................20

Protraction face mask system................................................................................21

Evidence based short term effectiveness of PH....................................................25

Evidence based long term effectiveness of PH.....................................................26

2. Chin caps........................................................................................................26

Types: occipital pull, used for patients with mandibular prognathism or

vertical pull, used for patients with increased anterior face height.......................27

Mohammed Almuzian, University of Glasgow, 2013 2

Best patient for Chin cup therapy..........................................................................27

Ko et al (2004).......................................................................................................27

The effects of chincup therapy..............................................................................27

(Thilander 1963)....................................................................................................27

3. Reverse chin cup therapy...............................................................................28

4. Bone anchored orthopaedic appliance (Bollard miniplates, PFH supported

with miniplates).....................................................................................................28

5. Shapiro and Kokich 1984 used the same idea by inducing artificial ankylosis

and use the ankylosed teeth as anchor...................................................................29

6. Functional appliances.....................................................................................29

Camouflage (dental compensation for mild cases)...............................................31

Indications.............................................................................................................31

Techniques of camoflagable treatments................................................................32

1. Non extraction................................................................................................32

2. Extraction:......................................................................................................32

Orthognathic surgery options................................................................................35

The types of surgery most frequently used are the following...............................35

Intraoperative complications of the mandibular ramus surgery............................36


What Factors need to be taken into Account When Planning a surgical treatment

for class III cases...................................................................................................37

1. Planning the type of surgery..........................................................................37

2. The Pre-Surgical Orthodontics in Class III?..................................................37

What Are the Aims of the Pre-Surgical Orthodontics?.........................................37

Borderline Camouflage/ Orthognathic Surgery Patients.......................................38

Summary of the evidences....................................................................................39


Class III malocclusion

Definition

BSI 1982 defined class III incisor relationship as ‘’the lower incisal edge lies

anterior to the cingulum plateau of the the upper incisors, British Standards

Institute, 1983

The term ‘pseudo-class III’ has been coined for this situation where an

anterior displacement masking what is in fact an underlying skeletal class I base

relationship.

Incidence

1.Class III prevalence in white populations

3% UK (Foster & Day, 1974)

5% (Jones & Oliver, 2000)

5% UK (Todd and Dodd 1975)

2.Class III prevalence in Asian populations

4-14% in Asian (Lew 1993)

3.Dental anterior crossbite

Anterior crossbite in 10% of children (1993 Child Dental Health Survey)


Classification

Lin (2007) divides class 3 malocclusion into three categories according to the

following definitions:

1. True class 3, anterior crossbite cases with bilateral buccal occlusions in class

III.

2. Class 3 subdivision, anterior crossbite cases with one of the bilateral buccal

occlusions in class 1 and the other in class 3.

3. Pseudo class 3, bilateral class 1 buccal occlusions and majority of teeth in

anterior crossbite. The pseudo class 3 malocclusion is often due to collapse of the

arch perimeter resulted from:

Caries in some Eastern societies (caries collapse)

TSD or small, missing or impacted or palatal positioning of the upper teeth

(perimeter-collapse).

Aetiology

1. Skeletal :

A. Environmental

Airway problems like enlarged tonsils & nasal blockage,

Scaring from CLP as a result of surgical repair

Hormonal like in acromegaly.

Some syndromes caused by environmental as well as genetic reasons such as

Crouzons, Aperts, and Cleidocranial dysostosis.


B. Genetic (Litton et al 1970). 1/3 of patients with severe class III have a

parent with class III problems but there is no detected autosomal dominant or

recessive method of transmission.

2. Soft tissue : the ST indeed my act to reduce the severity of CLIII, Lower

incisor retroclination is adaptive due to soft tissue forces and tongue might

procline ULS. Exception in high angle case when there is tongue to lower lip seal

and macroglosia that worsen the CLIII.

3. Dental factors :

Rarely ULS retroclination and LLS proclination.

Hypodontia or microdontia in the upper arch

Impacted upper teeth

4. Habits : tongue to lower lip seal and macroglosia that worsen the CLIII.

Features of Class III

A. Skeletal features

Cranial base features

AP relationship

Vertical relationship

Transverse relationship

Cephalometric skeletal values


B. Soft tissues features

C. Dental features

D. Displacements

E. Facial growth

In details

F. Skeletal features

1. Cranial base features:

Short cranial base length.

Decrease cranial base angle resulting in forwards position of mandible.

2. AP relationship

Mainly skeletal class 3 base relationships but it could be Class I or even class II

skeletal base.

Guyer, Ellis, Behrents and McNamara (1986) 55% of class 3 malocclusions

had maxillary deficiency as one of the components of the malocclusion.

Mandibular prognathsim in 45% of cases.

3. Vertical relationship

Guyer, Ellis, Behrents and McNamara (1986), 59% of class 3 malocclusions had

reduced or neutral lower facial heights and that 41% had increased lower facial

heights.

4. Transverse relationship


The maxillary skeletal base widths were (statistically) significantly smaller in the

class 3 than in the class 1group (Chen et al 2008)

Skeletal asymmetries, particularly in conjunction with mandibular prognathsim,

are also relatively common in class III malocclusions (Severt and Proffit, 1997).

5. Cephalometric skeletal values

Reduced cranial base angle

Increased saddle angle

Obtuse gonial angle

Reduced ANB

Normal or increase MMP angle and lower face height

Increased mand length

Reduced maxillary length

G. Soft tissues features

ST not involved in aetiology but encourage dentoalveolar compensation.

However there are some features which could be found in class III case

depending in the aetiology of the problem:

1. Orbital rim hypoplasia

2. Increase scleral show

3. Check bone flattening

4. Malar hypoplasia in midface deficiency


5. Paranasal hallowing

6. Obtuse NLA

7. Reduced incisor show at smile

8. Increase buccal corridor dark space

9. Upper lip looks thin with reduced vermilion border show while lower lip

may be full and pendulous

10. Obtuse LMA

11. Prominent chin

12. Concave or straight profile with anterior divergence.

13. Increased throat length

H. Dental features

1. Class III incisor relationship

2. Mostly CI III molar relationship could be I or even II. The same applied for

canine relationship.

3. Tendency to or full reverse OJ,

4. Reduced OB, AOB may exist

5. Max probably crowded, mandible unlikely to be so but usually spaced.

6. Incisors compensate for Skeletal base, i.e. Proclined maxillary, retroclined

mandibular incisors


7. Transverse discrepancy expressed in a form of tendency to posterior cross

bite. It could be unilateral with or without displacement or could be bilateral

mainly without displacement and to lesser extent with displacement

I. Displacements

The displacement could be in an anterior or lateral direction or combination.

It is due to:

Unsatisfactory edge-to-edge incisor

Unsatisfactory transverse buccal segment relationship

J.Facial growth

Tends to be unfavourable i.e. backwards growth rotation.

NB: Bacceti 2007, found that the pubertal peak of mandibular growth in AP and

vertical direction occurred between stages CS3 and CS4 in (corresponding with

the eruption of canines and premolars) and CS4-CS6 late developmental stages

(corresponding with the complete eruption of second and third molars) but 2 time

more in male than female.

IOTN and class III

A reverse overjet

It is recorded when ALL four incisors are in lingual occlusion.

If the reverse overjet is greater than 1 mm it is important to investigate whether the

individual has masticatory or speech (M&S) difficulties.


There are several methods of investigation but a simple approach is to ask the

individual to count from 60-70 noting any difficulty in pronunciation. In addition,

any signs and symptoms of mandibular dysfunction should be checked.

Crossbite (2.c, 3.c, 4.c)

An anterior crossbite is when 1, 2 or 3 incisors (but not all of them) are in lingual

occlusion.

A posterior crossbite is recorded when the posterior tooth or teeth are cusp to

cusp or in full crossbite in a buccal or lingual perspective.

The grade recorded depends on the severity of discrepancy between retruded

contact position (RCP) and intercuspal position (IP) (Table 3.4).

The greater the discrepancy between RCP an IP, the higher the grade

Growth status assessment for class III patients

Mandibular skeletal maturity can be assessed by means of a series of biologic

indicators:


1. History (is the patient changing shoes)

2. Growth chart like an increase in body height (Nanda, 1955; Hunter, 1966)

3. Biological parameters like:

Skeletal maturation of the hand and wrist (Bjork, 1967) or cervical vertebral

maturation (CVM) method. Franchi 2000, Beccteti 2002 & 2005 (please

read the summary about ‘’The Cervical Vertebral Maturation’’)

Dental development and eruption (Bjork, 1967)

Chronological age

Secondary sexual features like Menarche, breast, and voice changes (Tanner

1962)

Monitoring the growth of mandible

1.Serial Clinical measurements like OJ

2.Serial Study models

3.Serial Photograph or 3D stereo photogrammetry

4.Serial Ceph (not justified)

5.Growth Treatment Response Vector (GTRV) analysis

Ngan (2005) has described this as a method of determining whether a class 3

malocclusion can be treated by camouflage or if surgical treatment will be

required at a later date.

It is calculated from two serial cephalometric radiographs at least one year apart.


The lines AO and BO are constructed in the same way as for the Wits analysis on

the first radiograph;

The first radiograph is then superimposed on the second using the stable structures

of the cranial base.

New AO and BO are then constructed using the occlusal plane of the first

radiograph.

Horizontal growth change of maxilla is second AO-first AO

Horizontal growth change of mandible is second BO-first BO

The GTRV is then given by the following formula:

GTRV = horizontal growth change of maxilla / horizontal growth change of

mandible

The normal GTRV of patients is 0.77 – ie: normally, mandibular growth usually

exceeds maxillary growth by 23% between the ages of 8 and 16 years.

Differentiation between mandibular prognathsim & maxillary deficiency

Maxillary deficiency Mandibular

prognathism

Frontal Tendency to show sclera Normal show of sclera

Sallow paranasal form Normal paranasal

form


Narrow alar base width Normal alar base

width

Tendency of upper lip to be

thin

Normal upper lip

Normal chin projection Prominent chin

Normal to decreased lower

facial height (LFH)

Normal, increased or

decreased lower facial

height (LFH)

Profile Nasolabial line-Subnasale:

subnasale-tip of nose ,usually

not 1:1 ratio

Normal

Nasal tip down Normal

Obtuse nasolabial angle Normal nasolabial

angle

Smiling

assessment

Less incisor visible Good

Cephalometric

assessment

Normal to decreased total facial

height

Increased total facial

height

Short Pty-ANS normal

Facial concave Anterior divergent


Normal ramus width Narrow

Gonial angle normal obtuse

Occlusal

Assessment

Tendency toward crowding and

missing teeth in the upper

Spacing in lower arch

Transverse deficiencies

noticeable in maxillary arch

Normal

Treatment options for class III malocclusion

McIntyre 2004

1. Accept

2. Interceptive treatment

3. Growth modification

4. Orthodontic camouflage

5. Orthodontic decompensation and orthognathic surgery

6. Compromised orthodontic treatment

Factors influencing treatment options

1. Patient concern (dental or facial concern)

2. Patient age

3. Growth


4. Medical condition

5. Patient compliance

6. Family history of class III

7. Severity of skeletal problem in AP, V & T direction

8. Clinical condition of the teeth and oral tissues.

9. Amount of the OJ &OB

10. Degree of crowding

11. Degree of compensation

12. Presence of displacement

Summary about treatment strategies according to dental age a. In primary dentition

There is no evidence to suggest that orthodontic intervention during the primary

dentition avoids, or reduces, the complexity of later orthodontic treatment.

b. In early mixed dentition

1. Incisor crossbites due to retained primary incisors: Treatment extract

retained primary teeth

2. Premature contact and mandibular displacement or incisors erupted in cross

bite relationship, then

Extract or grind cusp tips (usually primary canines)


Posterior onlay to overcome the posterior crossbite that caused

displacement.

Procline maxillary permanent incisor(s) using an upper removable appliance

(URA) or a fixed appliance (4 x 2 appliance which is well tolerated less

dependent on compliance (Sandler, 2001) Offer three-dimensional control

Anterior cross elastics, Reynolds method 1978

Expand by URA or Q helix…..

c. Mid-Late mixed dentition

Class III incisors with deep overbite and mild/moderate skeletal Class III:

Protraction headgear and rapid maxillary expansion

Proclined lower incisors: URA incorporating inverted labial bow or URA to

procline ULS.

d. Early permanent dentition

1. Mild/moderate skeletal discrepancy

with no concern about facial appearance or growth , Procline maxillary

permanent incisors using URA/fixed appliance or Camouflage skeletal pattern

using fixed appliances with or without extraction.

With concern about facial appearance or growth

A. Postpone treatment decision until skeletal growth completed.


B. sometime, Align maxillary arch with fixed appliance and relieve crowding,

accepting Class III incisor relationship will require orthognathic surgery in

adulthood

2. Severe skeletal discrepancy or a concern about facial appearance

Accept malocclusion will require combined orthodontic

treatment/orthognathic surgery in adulthood

Align maxillary arch with fixed appliance and relieve crowding, accepting

Class III incisor relationship will require orthognathic surgery in adulthood

e. Adult treatment

1. Mild/moderate skeletal discrepancy

A. no concern about facial appearance

Procline maxillary permanent incisors using URA/fixed appliance

Camouflage skeletal pattern using fixed appliances

B. Mild/moderate skeletal discrepancy –concern about facial appearance

Compromised treatment by aligning the UA with or without extraction and if

possible align lower arch on non-extraction base to keep the cop of

decompensation if the Combined orthodontic treatment/orthognathic surgery

decided later

2. Severe skeletal discrepancy with no concern about facial appearance

Compromised treatment by aligning the UA with or without extraction and if

possible align lower arch on non-extraction base to keep the cop of


decompensation if the Combined orthodontic treatment/orthognathic surgery

decided later

3. Severe skeletal discrepancy with a concern about facial appearance

Combined orthodontic treatment/orthognathic surgery

Reasons for early treatment of class 3 malocclusions

Hägg et al (2004) and Ngan (2005) cite the reasons for early treatment as:

a. To eliminate CR-CO discrepancies which may cause

periodontal damage

occlusal wear

TMJ problems

b. To provide a more favourable environment for growth and

development of the maxilla and mandible with a reduction in dental

compensation because remodelling may occur in the joint as the postured position

which will act as functional appliance and making correction of the crossbite

more difficult at a later date

c. To provide space for the eruption of the buccal segments as a result of

proclination of the upper incisor so the canines and premolars can be guided into

a class 1 relationship

d. Psychological benefits resulting from improved dental and facial

appearance


Orthopaedic treatment option

Effect of orthopaedic appliance in class III maloculsion

Dermaut and Aelbers (1996) have reviewed the possible effects of orthopaedic

treatment in class 3 malocclusions.

1. 50% of the studies showed stimulation of maxillary growth

2. 90% showed an inhibition of mandibular projection

In general orthopaedic appliances are more effective if cl3 is due to maxilla

retrusion than mand prognathism.

However, most of the effects are dentoalveolar in nature with maxillary incisor

proclination and mandibular retroclination.

Positive factors for orthopaedic treatment

1. Patient’s factors

good co-operation

No familial prognathism

2. Growth

Young growing patient

3. Soft tissue

Acceptable facial aesthetics

4. Skeletal

Mild skeletal discrepancy (ANB < -20 )


Normal MMPA

No asymmetries (Symmetrical condylar growth)

5. Dental

-2mm reverse OJ or edge to edge relationship

Minimal dental compensation

6. Displacement

Functional shift

Types of orthopaedic treatment in class III malocclusion

1. Protraction HG

Definition

Means of applying anterior directed forces to teeth and/or skeletal structures from

an extra-oral source

History

The technique of maxillary protraction is based on work by Nanda (1978), with

rhesus monkeys in which he showed that a force of approximately 500g could

produce anterior displacement of the maxilla

It is appropriate to refer to this type of treatment as facemask therapy.

Indications

A. Treatment of maxillary retrusion. An ideal case would be;


1. Patient’s factors

good co-operation

No familial prognathism

7. Growth

Young growing patient

8. Soft tissue

Acceptable facial aesthetics

9. Skeletal

Mild skeletal discrepancy (ANB < -20 )

Normal MMPA

No asymmetries (Symmetrical condylar growth)

10. Dental

-2mm reverse OJ or edge to edge relationship

Retroclined ULS

Proclined LLS

11. Displacement

Functional shift

B. Reinforcement of anterior anchorage and dental protraction allowing closure of

space from behind in patients suffering from hypodontia


C. Stabilization following maxillary osteotomy/distraction osteogenisis

D. Rotate arch segments in cleft palate patients

E. Remove hyper-anterior contact in TMJ internal derangement cases,

Timing

1. Dental age: McNamara (1987) suggested that the optimal time for treatment is in

the early late mixed dentition, coincident with the eruption of the upper

permanent incisors.

2. Skeletal age: Baccetti et al (1998) showed that the early treatment group CVM2

showed effective forward displacement of the maxillary structures whereas the

late treatment group CVM3 showed no change compared with controls

3. Chronological age: Other investigators have suggested that for optimal

orthopaedic effects, treatment should be initiated before the patient is 9 years old

(Proffit, 2000). Mandal 2010, 2012 used it at age of 8.5-10 year.

Kim et al., 1999, meta-analysis of effectiveness of protraction HG concluded it

was less effective on patients >10yrs

Effects

1. Correction of a centric occlusion-centric relation discrepancy. This correction

happens relatively rapidly in patients with an edge to edge relationship and

associated displacement

2. Maxillary skeletal protraction, with up to 3mm of forward movement of the

maxilla possible , Mandal 2010 and 2012, showed that these effect are stable after

3 years follow-up

3. Proclination and forward movement of the maxillary dentition


4. Lingual tipping of the lower incisors

5. Redirection of mandibular growth in a downward and backward direction,

resulting in an increase in lower anterior facial height

Protraction face mask system

A. Types Extraoral part

1. Protraction Headgear (Hickham)

2. Facial Mask (Delaire)

3. Suborbital Protraction Appliance (Grummons)

Advantages: frame more rigid, no force on TMJ, no LLS

retroclination, easy to adjust and wear during sleep

Disadvantages: not esthetic due to midfacial support

4. 4. Nola protraction appliance

5. Petit style face mask

The Petit style with a single central vertical bar is also well

tolerated and recent price changes have made it

economically much more attractive.


B. Intraoral part:

1. In order to maximize the amount of skeletal change in young children, a

removable full coverage acrylic splint is used with a protraction headgear (Proffit

1986).

2. McNamara (1987) has described the use of a Biocryl and wire splint that is

bonded in the mouth. The splint material should be at least 3 mm thick with a

0.045" stainless steel wire framework. The two halves of the splint are joined by

an expansion screw. Traction hooks to receive the elastics from the headgear are

placed in the first premolar region.

3. RME with hook can be used

4. Fixed appliance

5. Some recommend using an intraoral bone plate to support the PHG force.

Systematic review to compare the dentally anchored face mask with skeletally

anchored one by Major (2012) in Canada, he found Approximately 3 mm of

horizontal A-point movement is predictably attainable with the skeletal one in

comparison to dental one..

C. Rapid maxillary expansion

Advantages (Haas 1973).

1. Sutural loosening

2. Correct transverse discrepancy that commonly associated with class III

malocclusion


3. Displace the maxillary complex anteriorly. This is due to butterfly effect of

expansion at the Midpalatal suture and because of the anterior sloping of the

facial sutures

Evidences 1. Many clinicians use protraction with a facemask following or simultaneously

with palatal expansion, because some evidence suggests that the expansion makes

antero-posterior skeletal change more likely. Kim et al (1999)

2. There is other evidence that the expansion is optional and should be dictated by

the maxillary arch width related to the lower arch width, Vaughan 2001 and 2005.

D. Techniques

First step is to fabricate and bond/cement the rapid maxillary expansion appliance

Appliance is activated once per day until the desired increase in maxillary width

has been obtained.

If patients do not need an increase in maxillary width, the appliance is still

activated for 7-10 days to disrupt the maxillary sutural system and promote

maxillary protraction (Haas, 1965)

After the patient activated the maxillary appliance for 7-10 days protraction

headgear is fitted.

E. Force level

1. Moving maxillary anterior teeth forward: 400g per side, 12-14h/day

2. Maxillary protraction : 800g per side, 14h/day

3. Overcorrect to compensate for mandibular growth


4. Active treatment should be limited to 9-12 months because of the risk of

decalcification of the dentition

F. Force direction:

1. To avoid bite opening, place protraction elastics near maxillary bicuspids,

2. Force vector should be 15-30 degree below the horizontal

3. To avoid irritation to the lip, use crossed elastic,

4. Pay special attention to airway and tongue posture

5. Ishii et al (1987) describe the effects of providing the protraction force from the

first molars or the premolar region. Protraction from the first molars results in

more anterior movement and a forward and upward rotation of the maxilla;

protraction from the premolars results in less forward movement but fewer

tendencies to upward and forward rotation.

G. Transitional period

After treatment objectives have been achieved, the patient can be retained with a

number of appliances:

The facemask,

FR-3 appliance

Acrylic maxillary retainer with reverse lower labial bow

Chin cup (seldom used).

H. Post protraction treatment consideration

1. As mandibular growth exceeds maxillary growth during adolescence, early Class

III correction may be lost during the teenage period. The patients and parents

should again be warned of the possibility of orthognathic treatment if growth is

unfavourable


2. Upper labial root torque during fixed appliance stage: Most class 3 patients

demonstrate considerable proclination of the upper labial segment at the end of

treatment. Catania et al (1990) recommend in his case report to use inverted U

incisor bracket to counteract the effect of proclination.

Evidence based short term effectiveness of PH

Mandall, 2010 (similar to study of Ngan 1998)

Early Class III orthopaedic treatment with protraction face mask in patients

less than 10 years of age is skeletally and dentally effective in the short term 15

months. (After 15 months of treatment, children undergoing early facemask

therapy had 1.3 degrees more forward movement of SNA, almost 2degrees less

forward movement of SNB and an overall ANB improvement of around 2.6

degrees when compared to the control group. In addition, the overjet improved by

more than 4 mm and the relative PAR score by more than 40% in the facemask

compared to the control group. Thus, early class III protraction facemask

treatment in patients under 10 years of age would seem to be skeletally and

dentally effective in the short-term)

70% of patients had successful treatment, defined as achieving a positive

overjet.

Early treatment does not seem to confer a clinically significant psychosocial

benefit.

No TMJ problem


Evidence based long term effectiveness of PH

Mandal 2012: Early Class III orthopaedic treatment with protraction face

mask in patients less than 10 years of age is skeletally and dentally effective after

3 years of treatment.

Masucci 2011: RME/FM therapy led to successful outcomes in about 73%

of the patients. Significantly improved sagittal dentoskeletal relationships. These

favourable changes were mainly due to significant improvements in the sagittal

position of the mandible, but the maxillary changes reverted completely in the

long term. This treatment not induces a tendency of bite opening or increased

vertical relationship.

A Cochrane review by Watkinson in 2013. This review looked at the use of

four different types of orthodontic treatment for correcting prominent lower front

teeth in children.-Facemask-Chin cup-Mandibular -Tandem traction bow

appliance. This review found some evidence that the use of a facemask appliance

can help to correct prominent lower front teeth on a short-term basis. There was

no evidence available to show whether or not these short-term changes will still

be maintained until the child is fully grown. There was not enough evidence to

support any other types of treatment for prominent lower front teeth.

2. Tandem traction bow appliance:

attachments are fixed to the top and bottom teeth. In

the top attachment there is a hook on each side. A

metal bar is placed in the lower attachment, which


http://summaries.cochrane.org/lexicon/9#review

http://summaries.cochrane.org/lexicon/9#review

sits in front of the lower teeth. An elastic band can then be placed on each side to

pull the top jaw forward and bottom jaw backwards, to correct the prominent

lower teeth

3. Chin caps

The idea of this appliance is that because the condyle is a growth site, the

growth impeded by extra-oral force (Graber, 1977).

Despite success in animal experiments, most human studies have found little

difference in mandibular dimensions between treated and untreated subjects

(Sugawara et al, 1990).

Chincup appliances greatly improve the skeletal profile in the short term

such changes are however rarely maintained during the pubertal growth spurt

Force 500g per side 12-14 h/day for 4-5 years. Once the anterior crossbite

was corrected, the patient was instructed to wear the chin cup at least 10 hours per

day until slight Class II canine and molar relationships were established.

The best age is before canine and premolar erupt (CS2-CS3 maturity) this is

the first growth spurt of mandible, the second one when 7 and 8 erupt CS4-CS6

(Bacceti, 2005).

Types: occipital pull, used for patients with mandibular prognathsim or

vertical pull, used for patients with increased anterior face height

Best patient for Chin cup therapy

Ko et al (2004)

1.Mild Skeletal III, ability to achieve edge to edge incisors


2.Short vertical facial height (.Chincup cause clockwise rotation of the mandible.

3.Proclined or upright LLS (Chincup cause lingual tipping of the lower incisors

(Thilander 1963)

4.Absence of severe facial and dental asymmetry

The effects of chincup therapy

(Thilander 1963)

Retardation of mandibular growth. Effective at reducing mandibular

prognathism before puberty but this is then lost with continual growth, Sugawara

et al., 1990

Remodelling of the condyle and glenoid fossa

Backward rotation of the mandible

Closure of the gonial angle

Result in lingual tipping of LLS,

4. Reverse chin cup therapy

Developed in Germany in 2012 by Rahman 2012 show similar result when

the reverse chin cup therapy compared to face mask therapy in RCT involving 42

samples at age of 8-9 years.


Reverse chin cup therapy is able to produce forward movement of the

maxilla in the growing child associated with lingual tipping of the lower incisors

and labial tipping of the uppers.

The point of application of protraction elastics from the upper removable

appliances was similar for both groups. All patients received the same protraction

force of 500 g per side with a 30 degree downwards pull.

The proposed advantages of the new reverse chin cup design were that it

was smaller and less bulky than other protraction appliances, therefore

encouraging children to wear it.

5. Bone anchored orthopaedic appliance (Bollard miniplates, PFH

supported with miniplates)

Plate comes in different size and form. It should

be adapted to the bone surface and fixed with 2.5mm

width and 5mm length screw.

Heavy Class 3 elastic used

Age of 9-13

Force about 150gm 24h per day. Loading start 3 weeks after plate insertion.

The major problem with this technique is the low rigidity of bone for young

patient which affect stability of bone plate and the presence of teeth follicle which

might cause problem with implant insertion. Also plate removal is problematic

bec it needs surgery and sometime the bone grow over the screw.

Success rate 92% with 3mm improvement of maxilla position and zygoma.

(Nguyen 2011) (De Clerck 2011)


This approach has two advantages:

1. it is clearly more effective than a facemask to a maxillary splint and also

appears to produce more skeletal change than has been reported with

facemasks to anterior miniplates

2. wearing an Extraoral appliance is not necessary and nearly full-time

application of the force can be obtained.

6. Shapiro and Kokich 1984 used the same idea by inducing artificial

ankylosis and use the ankylosed teeth as anchor.

7. Functional appliances

Reverse twin block

a.The design included

Cantilever springs behind the upper incisors,

A midline expansion screw,

A lower labial bow

Intersecting blocks at 70 degrees with a vertical height of 7 mm.

Block on U4s,5s and L5s,6s

b.The patient was instructed to wear the appliance on a full-time basis initially,

activating the midline expansion screw twice a week.

c.Effects:


There is no sustained effect on growth of either the maxilla or mandible.

Reverse TB for mandibular prognatisim (Ucem 2004 claim that it produce dental

effect only) Although there is a reduction in SNB and an increase in ANB due to

the backwards and downwards rotation of the mandible and an increase in lower

face height. Therefore, this type of treatment is inappropriate for high angle cases

with an already increased FMPA.

Seehra 2012, compare the effectiveness of Reverse Twin-Block therapy

(RTB) and protraction face mask treatment (PFM) with respect to an untreated

control in the correction of developing Class III malocclusion. Both appliances

are capable of correction of Class III dental relationships; however, the relative

skeletal and dental contributions differ. Skeletal effects, chiefly anterior maxillary

translation, predominated with PFM therapy. The RTB appliance induced Class

III correction,

Primarily as a result of dentoalveolar effects and by clockwise rotation of the

mandible.

The FR 3

They are designed to rotate the mandible downward and backward, and to

guide the eruption of the teeth so that the upper posterior teeth erupt down and

forward whilst eruption of the lower teeth is restrained. This rotates the occlusal

plane in the direction that favours correction of a class III molar relationship.


These appliances also tip the mandibular incisors lingually and the maxillary

incisors labially, introducing an element of dental camouflage for the skeletal

discrepancy.

In theory, the lip pads stretch the periosteum in a way that stimulates

forward growth of the maxilla. .

Camouflage (dental compensation for mild cases)

Indications

1. Growth

Patient past peak growth

Non-progressive worsening of the Class III.

2. Skeletal

Class I or mild class III skeletal base relationship;

Average or reduced lower face height;

3. Dental

Average or increased overbite;

Minimal reverse OJ or edge-edge relationship

Proclined lower incisors;

Upright or retroclined upper incisors;

Molar relationship less than half unit Cl Ill


4. Soft tissues features

1. Patient not concern about the profile

2. Favourable soft tissue features

5. Displacement

Anterior displacement on closing from RCP into ICP.

Techniques of camoflagable treatments

1. Non extraction

Expansion in upper arch to relieve crowding, eliminate crossbites and

mandibular displacements

Procline upper incisors, retrocline lower incisors (it is unwise to procline the

upper incisors beyond 120 degrees to the maxillary plane or retrocline the lower

incisors beyond 80 degrees to the mandibular plane.)

2. Extraction:

Aims of extraction

To relieve crowding or ML,

Correct incisor inclination

Correction of class III

To achieving a positive overjet

To achieving a positive overbite


To constrict the lower arch in order to correct any transverse problems

Options of extraction:

Extraction upper 5`s to maintain U lip support+ lower 4`s to allow LLS

retroclination.

Extraction of 4x4.

Extraction of a single lower incisor: If the upper arch is well-aligned but

space is required to align and retrocline the lower incisors, extraction of a single

lower incisor can be an option (Zachrisson 1999) but it may leave some black

triangle and gingival recession. This decision depend on the presence of (large IC

distance, minor crowding, TSD in LLS, square shape L incisors not triangular). A

better approach to camouflage in patients of European descent with a moderately

severe Class III problem is extraction of one lower incisor, which prevents major

retraction of the lower teeth, while the maxillary incisors are moved facially with

some tipping allowed. The combination of upright mandibular incisors and

proclined maxillary incisors often leads to good dental occlusion rather than the

expected tooth-size problem, but a wax setup always should be done when one

lower incisor extraction is considered to verify the probably occlusal outcome.

Proffit 2013, For Asian (or rarely, other) Class III patients with major

protrusion of the lower incisors, using skeletal anchorage to move the whole

lower arch posteriorly can be quite helpful in correcting the problem. Extraction

of third molars usually is needed in order to move the mandibular dental arch

back. If second molars are extracted to facilitate distal movement, third molars


may erupt as satisfactory replacements, but this is not as likely as in the maxillary

arch and therefore is not recommended as a routine procedure.

Bracket setup

To get further proclination of ULS, use MBT in the ULS

Lingual crown torque on LLS

Contra-lateral canine brackets (to avoid LLS proclination)

Mechanics

Lacebacks in LA (to avoid LLS proclination)

Cinch back in LA (to avoid LLS proclination)

Banding 7`s to increase posterior anchorage to retract lower dentition

Closing space on a round wire in the lower arch will facilitate

retroclination of the lower incisors.

CIII elastics (better to use short class III elastic to avoid posterior teeth

overeruption)

Avoid distal headgear forces on maxilla in C3 patients

NB: do not extract in lower arch if surgery is anticipated

Transverse problem can be addresses by:

1. URA

2. Q helix


3. RME

4. If more than 8mm, Surgically assisted RME

5. Constriction of the LA

6. AW expansion of the UA

7. Auxillary AW in the UA

Orthognathic surgery options

The types of surgery most frequently used are the following.

1. Sagittal split ramus osteotomy (SSRO) or bilateral sagittal split osteotomy

(BSSO) to set the mandible backward

2. Intraoral vertical ramus osteotomy (IVRO) or vertical subsigmoid osteotomy

(VSSO) or vertical or oblique subcondylar osteotomy (VSO) is different names

for the same technique using an intraoral approach. This type of surgery is used to

reduce the size of the mandible (Cheung 2002). Contraindicated in predisposed

toward developing obstructive sleep apnea syndrome (OSAS) (Turnbull 2000;

Chen 2005).

3. Mandibular step osteotomy (MSO). This is a surgical technique on the

mandible that is performed in the anterior region of the mental foramen. It is

indicated for correcting the size of the mandible by using the space resulting from

the extraction of a posterior tooth or for closing spaces caused by lost posterior

teeth. MSO enables vertical and transversal modifications to the dental arches:

closure of an anterior open bite and correction of the reverse curve of Spee. This

type of osteotomy presents stepwise sectioning, which allows the bone segments


to be brought together as much as possible, thereby ensuring their stability. The

fixation is accomplished with a miniplates on each side (Cheung 2002).

4. Surgically assisted rapid palatal expansion (SARPE) to correct the combined

transverse problems

5. Le Fort I (total maxillary osteotomy), the combination of Le Fort I and Le

Fort III, or Le Fort II in one operation or different operations.

Sugaya 2012 Cochrane review two randomized controlled trials were included in

this review. There are different types of surgery for this type of malocclusion but

only trials of mandible reduction surgery were identified. One trial compared

intraoral vertical ramus osteotomy (IVRO) with sagittal split ramus osteotomy

(SSRO) and the other trial compared vertical ramus osteotomy (VRO) with and

without osteosynthesis. Neither trial found any difference between the two

treatments. The trials did not provide adequate data for assessing effectiveness of

the techniques described

Complications of the mandibular ramus surgery

1. Fractures of the osteotomised segments,

2. Incomplete sectioning (Van Merkesteyn 1987),


3. Infection, necroses, persistent paresthesia,

4. Reduced mouth opening, nausea, airway disturbance (Yamada 2008),

5. Reduced mandibular movement range (Yazdani 2010).

6. Trauma to the inferior alveolar nerve,

What Factors need to be taken into Account When Planning a surgical

treatment for class III cases

1. Planning the type of surgery

The required surgery is planned around the aetiology of the skeletal discrepancy

taking into account facial aesthetics, stability of the result, TMJ and airway, little

morbidity. Allows the decision to make regarding whether the maxilla is to be

advanced or the mandible set back, or a combination of these.

2. The Pre-Surgical Orthodontics in Class III?

The pre-surgical orthodontics is planned around the surgery required to achieve

optimal aesthetics with the best achievable occlusion. Three important points

need to be considered;

1. Expansion: Assessment of arch co-ordination using the pre-treatment models

in a class I position will identify the extent of any required expansion of the

maxillary arch. If minimal expansion is required, this can be achieved using the

orthodontic archwires during pre-surgical orthodontics.

2. Reverse Target overjet: The planned surgical moves for optimal aesthetics

dictate the reverse overjet required pre-surgically.


3. Inclination of the ULS which is determined by the degree of maxillary

impaction while the inclination of LLS would be determined by the amount of

autorotation.

What Are the Aims of the Pre-Surgical Orthodontics?

1. Alignment

2. Levelling and alignment of the arches.

3. Arch co-ordination.

4. Decompensation: In this case, decompensation of the upper and lower

arches was required to produce an appropriate reverse overjet pre-surgically and

allow the desired surgical movements to be carried out to promote the desired

facial change.

5. Maintenance of the centre line with the mid-point of the chin in Lower teeth

and philtrum in the upper teeth.

Borderline Camouflage/ Orthognathic Surgery PatientsThe decision will depend on

1. Growth where there is any doubt about further skeletal growth (principally

mandibular), orthodontic camouflage should be deferred, possibly until the

remaining skeletal growth has been expressed. In class III cases with a significant

skeletal component, the mandible will tend to grow more and later than in class I

individuals (Baccetti et al, 2007).

2. Any concerns about facial appearance.


3. Medical and family history

4. Severity of the underlying skeletal problem

5. Presence or absence of functional displacement

6. Degree dentoalveolar compensation

7. Amount of crowding, OJ, OB

8. Vertical height

9. Cephalometric Yardsticks

A. Kerr et al 1992 in Glasgow showed that surgery is indicated for patients with

ANB <-4°

Maxillary mandibular ratio = 0.84

Lower incisor inclination (LI/MP <= 83°)

Soft tissue profile Holdaway angle > = 3.5° (Holdaway angle means soft

tissue nasion-soft tissue pogonion labrale superius)

Interestingly, vertical dimension had little influence on treatment decision.

B. Stellzig-Eisenhauer et al (2002) surgery indicated when Wits analysis value

of –12.2 ± 4.3 mm or more while camouflage indicated when Wits value is -4.6 ±

1.7 mm or less.

Summary of the evidences BSI 1982 defined class III incisor relationship as ‘’the lower incisal edge lies

anterior to the cingulum plateau of the upper incisors, British Standards Institute,


1983

3% UK (Foster & Day, 1974)

Anterior crossbite in 10% of children (1993 Child Dental Health Survey)

Lin (2007) divides class 3 malocclusion into three categories

Guyer, Ellis, Behrents and McNamara (1986) 55% of class 3 malocclusions had

maxillary deficiency as one of the components of the malocclusion. Mandibular

prognathism in 45% of cases.

Guyer, Ellis, Behrents and McNamara (1986), 59% of class 3 malocclusions had

reduced or neutral lower facial heights and that 41% had increased lower facial

heights.

The maxillary skeletal base widths were (statistically) significantly smaller in the

class 3 than in the class 1group. (Chen et al 2008)

Skeletal asymmetries, particularly in conjunction with mandibular prognathism,

are also relatively common in class III malocclusions (Severt and Proffit, 1997).

Growth status assessment for class III patients

1.Mandibular skeletal maturity can be assessed by means of a series of biologic

indicators:

2.Increase in body height (Nanda, 1955; Hunter, 1966)

3.Skeletal maturation of the hand and wrist (Bjork, 1967)

4.Dental development and eruption (Bjork, 1967)

5.Menarche, breast, and voice changes (Tanner 1962)

6.Cervical vertebral maturation (CVM) method. Franchi 2000, Beccteti 2002 & 2005

(please read the summary about ‘’The Cervical Vertebral Maturation’’)

Growth Treatment Response Vector (GTRV) analysis, Ngan (2005) has described

this as a method of determining whether a class 3 malocclusion can be treated by


camouflage or if surgical treatment will be required at a later date.

Treatment options for class III malocclusion, McIntyre 2004

Procline maxillary permanent incisor(s) using an upper removable appliance

(URA) or a fixed appliance (4 x 2 appliance which is well tolerated less

dependent on compliance (Sandler, 2001) Offer three-dimensional control

Reasons for early treatment of class 3 malocclusions, Hägg et al (2004) and Ngan

(2005) cite the reasons for early treatment

The technique of maxillary protraction is based on work by Nanda (1978), with

rhesus monkeys in which he showed that a force of approximately 500g could

produce anterior displacement of the maxilla

Timing, Dental age:

1.McNamara (1987) suggested that the optimal time for treatment is in the early late

mixed dentition, coincident with the eruption of the upper permanent incisors.

2.Skeletal age: Baccetti et al (1998) showed that the early treatment group CVM2

showed effective forward displacement of the maxillary structures whereas the

late treatment group CVM3 showed no change compared with controls

3.Chronological age: Other investigators have suggested that for optimal orthopaedic

effects, treatment should be initiated before the patient is 9 years old ( Proffit,

2000).

4.Kim et al., 1999, meta-analysis of effectiveness of protraction HG concluded it was

less effective on patients >10yrs

Maxillary skeletal protraction, with up to 3mm of forward movement of the

maxilla possible , Mandal 2010 and 2012, showed that these effect are stable after

3 years follow-up

McNamara (1987) has described the use of a Biocryl and wire splint

Some recommend using an intraoral bone plate to support the PHG force.


Systematic review to compare the dentally anchored face mask with skeletally

anchored one by Major (2012) in Canada, he found Approximately 3 mm of

horizontal A-point movement is predictably attainable with the skeletal one in

comparison to dental one..

Many clinicians use protraction with a facemask following or simultaneously with

palatal expansion, because some evidence suggests that the expansion makes

antero-posterior skeletal change more likely. Kim et al (1999)

There is other evidence that the expansion is optional and should be dictated by the

maxillary arch width related to the lower arch width, Vaughan 2005.

Ishii et al (1987) describe the effects of providing the protraction force from the

first molars or the premolar region. Protraction from the first molars results in

more anterior movement and a forward and upward rotation of the maxilla;

protraction from the premolars results in less forward movement but less

tendency to upward and forward rotation.

Chin caps, The idea of this appliance is that because the condyle is a growth site,

the growth impeded by extra-oral force (Graber, 1977).

Despite success in animal experiments, most human studies have found little

difference in mandibular dimensions between treated and untreated subjects

(Sugawara et al, 1990).

The effects of chincup therapy , (Thilander 1963)

Reverse chin cup therapy, Developed in Germany in 2012 by Rahman 2012 show

similar result when the reverse chin cup therapy compared to face mask therapy

in RCT involving 42 samples at age of 8-9 years.

Bone anchored orthopaedic appliance (Bollard miniplates, PFH supported with

miniplates) , Success rate 92% with 3mm improvement of maxilla position and


zygoma. (Nguyen 2011) (De Clerck 2011)

Shapiro and Kokich 1984 used the same idea by inducing artificial ankylosis and

use the ankylosed teeth as anchor.

Reverse twin block, There is no sustained effect on growth of either the maxilla or

mandible. Reverse TB for mandibular prognatisim (Ucem 2004 claim that it

produce dental effect only)

Extraction of a single lower incisor: If the upper arch is well-aligned but space is

required to align and retrocline the lower incisors, extraction of a single lower

incisor can be an option (Zachrisson 1999) but it may leave some black triangle

and gingival recession. This decision depend on the presence of (large IC

distance, minor crowding, TSD in LLS, square shape L incisors not triangular).

Sugaya 2012 Cochrane review Two randomized controlled trials were included in

this review. There are different types of surgery for this type of malocclusion but

only trials of mandible reduction surgery were identified. One trial compared

intraoral vertical ramus osteotomy (IVRO) with sagittal split ramus osteotomy

(SSRO) and the other trial compared vertical ramus osteotomy (VRO) with and

without osteosynthesis. Neither trial found any difference between the two

treatments. The trials did not provide adequate data for assessing effectiveness of

the techniques described

Cephalometric Yardsticks, Kerr et al 1992 , Stellzig-Eisenhauer et al (2002)


class 3 malocclusion by almuzian

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