7. class iii
- 1. BRITISH STANDRARDS INTITUTE CLASSIFICATIONCLASS III
- 2. Class IIIincisor relationship include those mal-occlusions where lower incisor’s edge occlude anterior to the cingulum plateau of the upper incisorsDefinition
- 4. SKLETAL PATTERNSOFT TISSUE PATTERNDENTAL FACTORSEtiology
- 5. = it is the most important factor=*class III mal-occlusion exhibit the following:-1.increased mandibular length2.more anteiorllyplaced glenoid fossa so that the condylerhead positioned more anteriorly leading to mandibular pergnathism. 3.decreased maxillary length4.more retruded position of the maxilla leading to maxillary retrusion*P.S. 1ST TWO FACTORS ARE THE MOST INFLUENTIAL Skeletal pattern
- 6. -Class III mal-occlusion occur in association with the arrange of vertical skeletal proportion ranging from increased to reduced.-A backward opening rotation pattern of facial growth will tend to result in reduction of over-bite. However a forward rotating pattern of facial growth will lead to increase in prominence of the chin
- 7. Soft tissue doesn’t play a major role in the majority of class III mal-occlusion cases.-soft tissue tend to tilt the upper and lower incisors towards each other which decrease the severity of mal-occlusion. -the main exception in pts with increased vertical skeletal proportion where the lips are more likely to be incompetent and anterior oral seal is often accomplished by tongue to lower lip contact SOFT TISSE PATTERN
- 8. class III malocclusions are often associated with a narrow upper arch and broad lower arch with the result that crowding is seen more commonly and to a greater degree in the upper arch than in lowerDental factors
- 9. Anterior cross bite of one or more of the incisors
- 10. Displacement of the mandible on closure from a premature contact into maximal interdigitation.
- 12. Crowding of the upper arch.
- 13. Dento-alveolar compensation : upper incisors proclinated and lower retroclinated.OCCLUSAL FEATURES
- 14. A number of factors should be considered:Pt’s opinion.Severity of skeletal pattern.Expected pattern of future growth.Dento-alveolar compensation.Degree of crowding.TTT planning
- 15. Accepting the incisors relationship.Proclination of upper labial segments.Retrodination of the lower labial segment with or without proclination of upper labial segmentSurgeryTTT OPTIONS
- 16. 1) Accepting the incisor relationship:Either if it was mild or severe but pt are unconcerned about their mal-occlusion ttt is directed towards achieving arch alignment
- 17. 2) PROCLINATION OF UPPER LABIAL SEGMENT*It can only be concidered in cases with:1.Class I or mild class IIIskeletal pattern.2. The upper incisors are not already significantly proclined.3. An adequate over-bite will be present at the end of ttt to retain the corrected position of upper incisors given that a reduction of over-bite will occur as the incisors are tipped labially.*if indicated it is best carried out in the mixed dentition.
- 18. 3) RETROCLINATION OF THE LOWER LABIAL SEGMENT WITH OR WITHOUT PROCLINATION OF THE UPPER LABIAL SEGMENTIn cases with mild to moderate class IIIskeletal pattern or when there is a reduced over-bite.
- 19. When orthodontic ttt alone cannot correct some cases of severe skeletal pattern &\or presence of reduced over-bite or an anterior open-bite 4) SURGERY
- 21. THANX