DEPARTMENT OF ORTHODONTICS

MANAGEMENT OF CLASS III MALOCCLUSION

Prepared By: Under the Guidance of:Priyanka Vadhera Dr. Rahul PaulBatch-2012 Dr. Vineet GolchaRoll No. 6083059 Dr. Deepti

Dr. Siddhant Taneja Dr. Ankita Jhalani

CONTENTS Introduction Definition Features Of Class III Malocclusion Skeletal Features Of Class III Malocclusion Etiology Diagnosis Treatment

I. Interception During GrowthII. Treatment Using Fixed ApplianceIII. Treatment of Anterior CrossbiteIV. Treatment Of Posterior CrossbiteV. Role Of ExtractionsVI. Treatment Of Severe Class III After

GrowthVII. Treatment Of Pseudo Class III

INTRODUCTION

Class III malocclusion is very easy to identify but

difficult to treat.

It represents a pre-normalcy where the mandible

is in a mesial relation to the upper arch.

This kind of malocclusion finds highest incidence

in Japan & Korea.

DEFINITION According to Edward H. Angle, Class

III malocclusion can be defined as:“A condition where the mesiobuccal cusp of the upper first molar occludes between the mandibular first and second molars.”

FEATURES OF CLASS III MALOCCLUSION

– The patient has a Class III molar relationship.

– An edge-to-edge relationship or an anterior cross-bite may occur.

– Upper arch is narrow & short while the lower arch is broad.

– Posterior cross-bites are common.

– Upper teeth are crowded due to a narrow upper arch while the lower teeth have a spaced dentition due to a broader lower arch.

– Patient has a concave profile due to the presence of a prominent chin.

– Vertical growers exhibit an increased inter-maxillary height may have an anterior open-bite. In some patients a deep bite may develop.

– A type of Class III malocclusion referred as PSEUDO CLASS III MALOCCLUSION is characterized by the presence of occlusal prematurities resulting in a habitual forward positioning of the mandible. These patients may exhibit a forward path of closure.

The following are the features of a Class III malocclusion:

Anterior Cross-bite Posterior Cross-bite Concave Profile

SKELETAL FEATURES OF CLASS III MALOCCLUSION

Most Class III malocclusions are associated with underlying skeletal malrelationships. Commonly seen skeletal features are:

1. A short or retrognathic

maxilla.

2. A long or prognathic mandible.

3. A combination of a retrognathic maxilla & a prognathic mandible.

ETIOLOGY True Class III malocclusion that exhibits

underlying skeletal imbalance is usually

inherited.

Environmental factors such as:

Postural habits

Mouth breathing

Other cause: Habitual forward positioning of

the mandible due to occlusal prematurities or

enlarged adenoids.

Severe Class III malocclusions are believed to

be caused due to genetic factors that have

been made worse by environmental factors.

DIAGNOSIS The diagnostic procedure should help in the

determination the type of Class III malocclusion i.e, dental or skeletal, true or pseudo.– Clinical examination should include

observation of path of closure.– Study models & radiographs should also be

taken– A lateral cephalogram offers a valuable

information on the skeletal nature of the malocclusion.

Lateral Cephalogram Study Models Orthopantomogram

DIAGNOSIS

– The patients with Class III malocclusion often have a family history of other people having an anterior cross-bite or Class III malocclusion.

– Dental Class III malocclusion are characterized by lack of sagittal skeletal discrepancy.• The ANB angle is normal.• The dental problem is caused by labial tipping of the

mandibular incisors & a lingual tipping of maxillary incisors.

– Skeletal Class III malocclusion patients exhibit:• A smaller than normal SNA & a larger SNB angle.• A negative ANB angle.• Maxillary incisors proclination & retroclination of the

mandibular incisors.– In patients with Pseudo Class III malocclusion, a

functional shift is seen. They show a CO-CR shift as a result of abnormal tooth contacts causing a forward shift of the mandible on closure of the mandible.

TREATMENTClass III malocclusion should be

recognized & treated early due to the following reasons:– Early interception reduces the

severity of the developing malocclusion.

– Class III malocclusion characterized by anterior cross-bite often result in retarded maxillary growth due to locking of maxilla within the mandible.

– The occlusal forces on the mandibular incisors exerted by the maxillary incisors in cross-bites encourage the continued forward growth of mandible further worsening the pre-normalcy.

Class III Malocclusion

Growing Patient

Skeletal Class III

Maxillary retrognathism

Face mask to protract maxilla

Mandibular prognathism & maxillary retrognathism

Face mask followed by chin cap/ myofuntional appliances for Class III

Mandibular prognathism

Chin cup therapy to restrict maxillary growth

Dental Class III

Orthodontic treatment as

needed

Non-growing Patient

Dental Class III

Orthodontic treatment as

needed

Skeletal Class III

Mild to

moderate class

III

Orthodontic

camouflage

by extraction of some teeth

Severe

class III

Maxillary retrognathism

Surgical maxillary advancement

Mandibular prognathism

Surgical mandibular setback

Treatment Of Class III Malocclusion

I. Interception During Growth Class III malocclusion with an underlying skeletal

malrelationship require early interception to prevent skeletal malocclussion.

AIM: To improve the skeletal discrepancy thereby providing a more favourable environment for future growth.

It also helps to eliminate or reduce the chances of orthognathic surgeries in future.

INDICATIONS:Good facial estheticsPresence of antero-posterior functional shiftMild skeletal problemAbsence of familial prognathismConvergent facial typeSymmetric condylar growthPatients with growth still presentPatient cooperation is essential

CONTRAINDICATIONS:Poor facial estheticsAbsence of antero-posterior functional shiftSevere skeletal problemsFamilial prognathismDivergent facial typeAssymetric condylar growthPatients with no growth potentialPatient not willing to cooperate

Interception during growth can be done by using one of the following techniques:1. MYOFUNCTIONAL APPLIANCES

Frankel III appliance can be used to intercept a class III malocclusion due to maxillary skeletal retrusion.Treatment using the Frankel III aplliance is more successful in patients with a functional shift of the mandible during closure of the jaw.It can corporate vestibular shields in upper & lower sulcus.The maxillary shields are placed away from the buccal plate thereby stretching the periosteum & allowing the forward growth of maxilla.Mandibular shields can be placed touching the alveolar process therfore they help in restricting the mandibular growth.The Frankel III aplliance also produces a dentoalveolar effect by proclination of uppper anteriors and retroclination of lower anteriors.It ca n also be used as retainer after face mask therapy for maxillary protraction.

Frankel III Appliance to

intercept Class III malocclusion due

to maxillary skeletal retrusion

2. CHIN CUP THERAPYUsed in the treatment of Class III malocclusion with protrusive mandible & normal maxilla.Two types:

Occipital pull chin cupVertical pull chin cup: Used in patients who exhibit a steep mandibular plane angle & excessive anterior facial height.

Effects of chin cup include:Backward repositioning of the mandibleRedirection of the mandibular growthRemodelling of mandible with closure of the gonial angle.

Chin cups with headgears are indicated in primary & mixed dentition periods.Force levels of 300-500gms per side are indicated for 12-14hours of wear everyday.

Occipital pull chin cup

Vertical pull chin cup

3. FACE MASK THERAPYAlso known as REVERSE PULL HEADGEARS.Used in the treatment of mild to moderate skeletal Class III malocclusion due to retrognathic maxilla & a hypodivergent mandible.It consists of two pads that take anchorage from the forehead & the chin.They are connected together by a midline wire frame that also has hooks that help in anchoring elastics that stretch from an intraoral splint which helps in the protraction of maxilla.The intraoral splint can include an expansion screw if expansion of maxillary arch is required.Protraction face mask is used for primary & mixed dentition periods.Force levels of 300-500gms per side are indicated for 12-14hours of wear everyday.Commonly used types: Delaire type, Tubinger type & Petit type face masks.

II. Treatment Using Fixed Appliances

Best done in mixed dentition, before the eruption of permanent canines.In patients with mild to moderate class III skeletal pattern, a combination of retroclination of lower incisors & proclination of upper incisors maybe required.Class III intermaxillary elastic traction from the lower labial segment to the upper molars can also be used to move the upper arch forwards & lower arch backwards. However, care is required to avoid extrusion of molars which will reduce overbite.

III. Treatment Of Anterior Crossbite

Mild anterior cross-bite can be treated using lower anterior inclined planes or removable appliances incorporating screws designed for anterior expansion.

IV. Treatment Of Posterior Crossbite

Class III malocclusion are often accompanied by posterior crossbite.It can be treated by rapid maxillary expansion.

V. Role Of ExtractionsClass III malocclusion characterized by mild mandibular prognathism & lower arch crowding can be treated by extracting the lower first premolars followed by fixed mechanotherapy.This is an orthodontic camouflage of the underlying skeletal malocclusion.

VI. Treatment Of Severe Class III Malocclusion

Severe class III malocclusion after growth completion is complete is treated by surgical & corrective procedures.Class III due to maxillary deficiency is treated by maxillary advancement procedures such as leFort I osteotomy.Class III malocclusion that are a result of mandibular prognathism are treated by mandibular set back procedures.

VII. Treatment of Pseudo Class III Malocclusion

Pseudo class III malocclusion that occurs as a result of occlusal prematurity improves on the removal of cause.

Thank You..!