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Class III Malocclusion
- 1. DEPARTMENT OF ORTHODONTICS Prepared By:Under the Guidance of: Priyanka Vadhera Dr. Rahul Paul Batch-2012 Dr. Vineet Golcha Roll No. 6083059 Dr. Deepti Dr. Siddhant Taneja Dr. Ankita Jhalani
- 2. CONTENTS Introduction Definition Features Of Class III Malocclusion Skeletal Features Of Class III Malocclusion Etiology Diagnosis Treatment I. Interception During Growth II. Treatment Using Fixed Appliance III. Treatment of Anterior Crossbite IV. Treatment Of Posterior Crossbite V. Role Of Extractions VI. Treatment Of Severe Class III After Growth VII. Treatment Of Pseudo Class III
- 3. INTRODUCTION Class III malocclusionis 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.
- 4. DEFINITION According toEdward 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.”
- 5. FEATURES OF CLASSIII 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
- 6. SKELETAL FEATURES OFCLASS 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.
- 7. ETIOLOGY True Class IIImalocclusion 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.
- 8. DIAGNOSIS The diagnosticprocedure 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
- 9. DIAGNOSIS – The patientswith 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.
- 10. TREATMENT Class III malocclusionshould 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.
- 11. Class III Malocclusion Growing Patient Skeletal ClassIII Maxillary retrognathis m Face mask to protract maxilla Mandibular prognathism & maxillary retrognathism Face mask followed by chin cap/ myofuntional appliances for Class III Mandibular prognathis m Chin cup therapy to restrict maxillary growth Dental Class III Orthodonti c 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
- 12. I. Interception DuringGrowth 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 esthetics Presence of antero- posterior functional shift Mild skeletal problem Absence of familial prognathism Convergent facial type Symmetric condylar growth Patients with growth still present Patient cooperation is essential CONTRAINDICATIONS: Poor facial esthetics Absence of antero- posterior functional shift Severe skeletal problems Familial prognathism Divergent facial type Assymetric condylar growth Patients with no growth potential Patient not willing to cooperate
- 13. Interception during growthcan 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
- 14. 2. CHIN CUPTHERAPY Used in the treatment of Class III malocclusion with protrusive mandible & normal maxilla. Two types: Occipital pull chin cup Vertical 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 mandible Redirection of the mandibular growth Remodelling 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
- 15. 3. FACE MASKTHERAPY Also 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.
- 16. II. Treatment UsingFixed 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.
- 17. III. Treatment OfAnterior Crossbite Mild anterior cross-bite can be treated using lower anterior inclined planes or removable appliances incorporating screws designed for anterior expansion.
- 18. IV. Treatment OfPosterior Crossbite Class III malocclusion are often accompanied by posterior crossbite. It can be treated by rapid maxillary expansion.
- 19. V. Role OfExtractions Class 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.
- 20. VI. Treatment OfSevere 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.
- 21. VII. Treatment ofPseudo Class III Malocclusion Pseudo class III malocclusion that occurs as a result of occlusal prematurity improves on the removal of cause.
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