Occlusion and it's types and malocclusion

Occlusion is key to orthodontics and oral biology is queen of all dental sciences

1. OCCLUSION

2. Occlusion Contact relationship between upper and lower teeth during various activity of the mandible (Mastication, swallowing & Speech) Static and dynamic contact relationship between the occlusal surfaces of the teeth during function

3. Most commom sequance of eruption in maxillary arch 6-1-2-4-3-5-7-8 and 6-1-2-4-5-3-7-8 Most commom sequance of eruption in mandibular arch (6-1)-2-3-4-5-7-8 and (6-1)-2-4-3-5-7-8

4. Centric occlusion Maximum intercuspation between uppr and lower teeth Maximum intercuspation Maximum interdigitation of the maxillary teeth with mandibular teeth

5. Centric Relation It is the position of the mandible in which the condyle is resting in the most posterior or retrusive unstrained position in the glenoid fossa

6. Why we study Occlusion Occlusion helps in treatment of Maloclusion, Temporomandibular joint problems, proper construction of Dentures (Crown, bridge, Implant etc)

7. Occlusal Curvatures It allow the most efficient use of the forces of mastication Stabilizing and protecting the dental arch

8. Curve of Spee Antero-posterior curve Cusp of canine and follows buccal cusp of premolar and molars 2 dimensional curve Curve upward from anterior to posterior Inclination of individual posterior teeth

9. Curve of Wilson Medio-lateral curvature 2 dimensional curve Path of the condyles during movements of jaw Inclination of crown and root is confirmed by this curve Curvature is deeper in molars then permolars

10. Curve of Monson (Compensating Occlusal Curvature) Combination of curve of spee and curve of Wilson 3 dimensional curve Concave for mandibular arch Convex for maxillary arch

11. Dental Arch Formation Outline of maxillary arch is larger then mandibular arch So maxillary teeth overhang the mandibular teeth when the teeth are in centric occlusion Permits overbite and overjet relationship

12. Overjet Horizontal relationship of the upper teeth to the lower teeht in centric occlusion Overbite Vertical relation of the upper teeth to lower teeth in centric occlusion Importance Prevent soft tissue biting Guid the mandible through various lateral movement

13. Crossbite It is a condition in which one or more teeth abnormally malposed buccaly or lingually or labially with reference to opposing teeth.

14. Open bite It is the failure of a tooth or teeth to meet their antagonist in the opposite arch. It creats Difficulty in speech TMJ disorder Functional imbalance Bad aesthetics

15. Classification On the basis of region involve Anterior open bite Posterior open bite On the basis of etiological factors Skeletal open bite Dental open bite On the basis of molar relationship Class 1 open bite Class 2 open bite Class 3 open bite

16. Functional Cusps or Supporting Cusps The buccal cusp of mandibular posterior teeth and lingual cusp of maxillary posterior teeth are called functional cusp or supporting cusp. These cusp occlude in the central fossa and maintain the occlusal vertical height, these are also called centric cusp or holding cusp

17. Non Functional Cusps The lingual cusps of mandibular posterior teeth and buccal cusps of maxillary posterior teeth are non functional cusp Also called guiding cusps They guide the mandible in lateral movements

18. Leeway space The erupting premolars are smaller in mesiodistal dimension then the primary molars. The difference in size between the premolars and primary molars as well as deciduous canine called Leeway space

19. The average mesiodistal size of the deciduous in that area is 47mm, which when compared with the premolar dimension of 43.2mm, indicates an average gain of 3.8mm in available space. The leeway space must be utilized for alignment of lower incisors as these teeth erupt with an average of 1.6mm of crowding. The remainder of the space will be utilized by the mandibular molars

20. Freeway space The space between the occluding surfaces of the maxillary and mandibular teeth when the mandible is in physiologic resting position.

21. Angle Classification Class 1: Mesiobuccal cusp pf maxillary 1 st molar occlude in the buccal groove of mandibular 1 st molar Canine relationship : The mesial incline of the maxillary canine occludes with the distal incline of the mandibular canine. The distal incline of the maxillary canine occludes with the mesial incline of the mandibular first premolar

22. Class II: Mesiobuccal cusp of maxillary 1 st molar occlude anterior to the buccal groove of mandibular 1 st molar Division I: The maxillary anterior teeth are  protruded . Teeth are proclained and a  large overjet  is present.

23. Class II: The molar relationships are Class II where the maxillary central incisors are  retroclined . Division II: The maxillary lateral incisor teeth may be proclaimed or normally inclined

24. Class III Mesiobuccal cusp of maxillary 1 st molar occlude poterior to the buccal groove of mandibular 1 st molar

25. Andrew’s 6 keys of Normal Occlusion Correct molar relationship Correct (mesio-distally) crown angulation Correct (Labio-lingually) crown inclination No rotation No spaces Flat occlusal plane

26. Thank you