mandibular premolars.pptx

mandibular premolars, common triats and differences between mandibular first and second premolar. buccal aspect, lingual aspect, mesial aspect, distal aspect, occlusal aspect of mandibular premolars

1. Anatomy of Mandibular premolars

2. Type traits of mandibular premolars 1. 2- cusp type with 1 lingual cusp 2. 3-cusp type with 2 lingual cusps

3. Distinguishing characteristics of mandibular premolars Generally The mandibular 1 st premolar has a longer crown and a shorter root than the 2 nd premolars. The mandibular 1 st premolar is longer overall than 2 nd

4. Buccalaspect of mandibular premolars 1. Crown shape: (roughly pentagonal) 1 st premolar: nearly symmetrical except for a shorter mesial cusp ridge and a distal bulge of the crown

5. Buccal aspect of mandibular premolars 1. Crown shape: (roughly pentagonal ) 2 nd premolar: buccal cusp is less pointed and cusp slopes are less steep than on the mandibular premolar

6. Buccal aspect 2. Notches on the cusp ridges: Notches often seen on – mesiobuccal cusp ridge in mandibular 1 st premolars Notches often seen on distobuccal cusp ridge in mandibular 2 nd premolars

7. Buccal aspect 3. Cervical lines: The cervical line of the mandibular 1 st premolar is more rounded mesiodistally , while that of the 2 nd premolar is more flat

8. Buccal aspect 4. Contact areas – Mesial : 1 st and 2 nd premolars – near junction of occlusal and middle third

9. Buccal aspect 5. Contact area – Distal 1 st premolar distal contact area is more occlusal than the mesial contact area

10. Buccal aspect 6. Contact area – Distal 2 nd premolar has a distal contact located more cervical than the mesial contact area, as is usually the case with posterior teeth

11. Lingual aspect of mandibular premolars 1. Crown shape: Mandibular first premolar crown tapers (converges) to the lingual (narrower on lingual side that buccal )

12. Lingual aspect of mandibular premolars 1. Crown Shape: Mandibular 2 nd premolar with 1 lingual cusp, crown tapers to lingual Mandibular 2 nd premolar with 2 lingual cusps, crown is as wide or wider mesiodistally than the buccal

13. Lingual aspect 2. Cusp Size and Shape: Mandibular 1 st premolar lingual cusp is small and pointed Most of the occlusal surface can be seen from this aspect

14. Lingual aspect 2. Cusp Size and Shape: Mandibular 2 nd premolar with 1 lingual cusp: Lingual cusp is smaller than buccal cusp, but larger than lingual cusp of 1 st premolar

15. Lingual aspect 2. Cusp Size and Shape: Mandibular 2 nd premolar with 2 lingual cusps: Ml cusp is larger than the DL cusp, with the L groove between them and onto the lingual crown surface

16. Lingual aspect 3. Marginal Ridges: Mandibular 1 st premolar: Only tooth in the mouth where the mesial marginal ridge is more apical than the distal marginal ridge

17. Lingual aspect 3. Marginal Ridges: Mandibular 2 nd premolar: Mesial marginal ridge is more occlusal than the distal marginal ridge (as found in all other teeth)

18. Lingual aspect 4. Mesiolingual groove: Frequently seen on mandibular 1 st premolar only

19. Proximal aspect of mandibular premolars 1. Crown Shape – Rhomboid: The crowns of both premolars tilt lingually , but the mandibular 1 st premolar tilts more lingually than the mandibular 2 nd premolar

20. Proximal aspect of mandibular premolars 1. Crown Shape – Rhomboid: In both premolars, the lingual cusps are shorter than the buccal cusps

21. Proximal aspect 2. Mesiolingual groove: Often present on mandibular first premolar between the mesial marginal ridge and the mesial slope of the lingual cusp Not present in mandibular second premolar

22. Proximal aspect 3. Height of Contour: Mandibuar 1 st premolar Buccal - cervical 1/3 Lingual – middle 1/3

23. Proximal aspect 3. Height of Contour: Mandibular 2 nd premolar Buccal - junction of cervical and middle 1/3 Lingual – middle 1/3

24. Proximal aspect 4. Cervical Lines: Both premolars have greater curve on the mesial than the diastal

25. Proximal aspect 5. Root (proximal): Both premolars generally consists of one root The mandibular 1 st premolar occasionally will have a furcated root

26. Proximal aspect 6. Root Depressions: Mandibular 1 st premolar – have a shallow root depression in the apical and middle third of both mesial and distal root surface.

27. Proximal aspect 6. Root Depressions: Mandibular 2 nd Premolar – have a distal root depression in the middle third of the root, but no mesial depression

28. Occlusal aspect of mandibular first premolars 1. Outline: Have much variation in occlusal morphology Outline is not symmetrical (more bulky on the distal)

29. Occlusal aspect of mandibular first premolars 1. Outline: Often appears as if the mesial side has been pushed inward ( mesiolingual corner)

30. Occlusal aspect of mandibular first premolars 1. Outline: Tip of the buccal cusp is near the center from occlusal view Lacks a prominent buccal ridge Cusp ridges are nearly straight lines

31. Occlusal aspect of mandibular first premolars 1. Outline: Crown is somewat diamond shaped converging lingually Shape of the crown is asymmetrical

32. Occlusal aspect of mandibular first premolars 1. Outline: Mesial and distal marginal ridges may converge lingually

33. Occlusal aspect of mandibular first premolars 2 . Ridges, Fossae , Grooves: Due to size of cusp, the buccal triangular ridge is long Join the shorter lingual triangular ridge Often may meet smoothly and form a uninterrupted transverse ridge

34. Occlusal aspect of mandibular first premolars 2 . Ridges, Fossae , Grooves: The transverse ridge may be crossed by a shallow central groove extending from mesial to distal fossa This is rare

35. Occlusal aspect of mandibular first premolars 2. Ridges, Fossae , Grooves: The grooves of the first premolar are fewer in number, but may be deeper than those of the second premolar (just like the maxillary)

36. Occlusal aspect of mandibular first premolar 2. Ridges, Fossae , Grooves: Possess a mesial and distal fossa Both are circular, not triangular Distal fossa is usually larger and deeper.

37. Occlusal aspect of mandibular secdond premolar 1. Outline – Two cusp version: Crown is round or oval shaped with a square occlusal table

38. Occlusal aspect of mandibular secdond premolar 1. Outline – Two cusp version: Ther is slightly more bulk in the mesial half buccolingually than in the distal half

39. Occlusal aspect of mandibular secdond premolar 2. Ridges, Fossae , Grooves – two cusp version: Lingual cusp smaller than buccal cusp Possess more supplemental grooves

40. Occlusal aspect of mandibular secdond premolar 2. Ridges, Fossae , Grooves – two cusp version: Possess a curved central groove with no lingual groove This groove can be fairly straight

41. Occlusal aspect of mandibular secdond premolar 1. Outline – Three cusp version: When lingual cusps are large, the occlusal surface is broader on thwe lingual

42. Occlusal aspect of mandibular secdond premolar 1. Outline – Three cusp version: Often have greater bulk buccolingually in the distal not the mesial The ML cusp is usually larger than the dl cusp

43. Occlusal aspect of mandibular secdond premolar 2. Ridges, Fossae , Grooves – three cusp version: Possess three triangular ridges converging towards the central fossa There is no transverse ridge

44. Occlusal aspect of mandibular secdond premolar 2. Ridges, Fossae , Grooves – three cusp version: Has a central fossa (unique) shifted towards the distal Lacks a central groove Mesial groove present

45. Occlusal aspect of mandibular secdond premolar 2. Ridges, Fossae , Grooves – three cusp version: Possess a lingual groove that separates the two lingual cusps This groove completes the Y shaped occlusal groove pattern