Permanent Maxillary Premolars

1. PermanentMaxillary Premolars First Premolars

2. General Characteristics: • Arch position: 4th tooth from midline • Between the canine and 2nd premolar • Universal #5 and # 12

3. General Form • Proximal geometric form is trapezoidal • Occlusally, resembles 6-sided figure • Facially, similar to canine (5-sided)

4. Form & Functions: • Two fairly equal cusps: facial and lingual • Presence of an occlusal table • Assists in tearing and piercing • Essentially a “grinding” tooth

5. Development Timeline: • Initial calcification: 1 1/2 to 1 3/4 years • Enamel completed: 5 - 6 years • Eruption: 10 - 11 years • Root completed: 12 - 13 years

6. Facial View • Closely resembles canine • Prominent buccal ridge with depressions on either side • Facial HOC at cervical third

7. Facial view, mesial outline: • Mesial HOC at junction of occlusal-middle thirds • Outline cervical to contact area slightly concave

8. Facial view, distal outline: • Similar to mesial outline • Less cervical concavity • HOC slightly more cervical than mesial

9. Facial view, occlusal outline: • Similar to canine except: • Cusp tip not as prominent • Cusp tip located just distal to midline of root* • Longer MB cusp ridge • Shorter DB cusp ridge *(unique)

10. Lingual View • Lingual narrower M-D than facial • Lingual cusp slightly shorter than facial (shortest of maxillary premolar cusps) • Lingual cusp offset to mesial • Lingual HOC at middle third

11. Mesial View • Trapezoidal geometric form • F and L cusps centered over root trunk • Mesial marginal groove visible

12. Mesial view... • Mesial concavity from root trunk to cervical portion of crown* • Mesial contact area facial to F-L midline

13. Distal View • Similar to mesial view except: • Shorter O-C than mesial • Distal marginal ridge more cervical • More of occlusal surface visible • No distinct distal concavity • Distal contact area slightly more cervical

14. Occlusal View • Outline is hexagon • Wider F-L than M-D • Outline tapers towards lingual • Lingual cusp offset to mesial • Mesial marginal ridge shorter than distal marginal ridge

15. Occlusal view... • Mesial outline indented by mesial marginal groove • M and D pits well-separated • Less secondary grooves than 2nd maxillary premolar

16. Occlusal view... • DB cusp ridge and distal marginal ridge angle is acute • MB cusp ridge and mesial marginal ridge angle is 90o

17. Root Form • Single root (Type I) • Distinct mesial concavity • Cervical cross-section: kidney shape

18. Root form: • Bifurcated root (Type II) • Most common form • Short root trunk • Two roots: F and L, almost equal lengths

19. Root form: • Laminated root (Type III) • Resembles Type II except: • Longer root trunk • F and L roots joined by lamination • Mid-root cross-section: hour-glass shape

20. Root variations: • Trifurcation possible • 2 buccal roots and 1 lingual • Pulp canals: separate or connected • 2 pulp horns

21. How To Tell Right From Left: • Buccal cusp tipped distally* • MB cusp ridge longer than DB* • Mesial concavity* • Lingual cusp tipped mesially* • Mesial marginal groove*

22. Maxillary Second Premolar

23. General Characteristics: • Arch position: 5th tooth from midline • Universal #4 and #13

24. Differences between 1st and 2nd: • Crown dimensions of 2nd smaller than 1st • 1st more angular, 2nd more rounded* • F and L cusps more equal in height with 2nd*

25. Differences… • No mesial concavity or mesial marginal groove with 2nd* • 2nd normally single rooted • M and D pits closer together in 2nd* • More supplemental grooves in 2nd*

26. Developmental Timeline: • Initial calcification: 2 - 2 1/4 years • Enamel completed: 6 - 7 years • Eruption: 11 - 12 years • Root completed: 12 - 14 years

27. Facial View • Similar to 1st except: • Buccal cusp of 2nd not as long or pointed • Cusp tip mesial to root midline • MB cusp slope shorter than DB* • M and D contact areas slightly more cervical than 1st

28. Lingual View • Similar to 1st • Lingual cusp longer (equal to facial cusp) • Lingual cusp slightly offset to mesial

29. Mesial View • Similar to 1st except: • F and L cusps more equal height* • No mesial concavity* • Usually no mesial marginal groove • Mesial contact area more cervical

30. Distal View • Similar to 1st except: • F and L cusps more equal height • Distal contact area more cervical

31. Occlusal View • Line angles more rounded than 1st* • Central groove shorter* • M and D pits closer together* • More supplemental anatomy* • M and D halves appear more symmetrical

32. Root Form • Usually single rooted (bifurcation rare but possible) • No deep mesial depression* • Root cross-section is ovoid

33. How To Tell Right From Left: • Lingual cusp tipped mesially* • MB cusp ridge shorter than DB • Root apex deviation usually towards distal

34. How To Tell 1st from 2nd: • 1st usually bifurcated roots* • Occlusal outline of 1st more angular, more rounded with 2nd* • 1st has mesial concavity*

35. 1st from 2nd... • Central groove of 1st longer • M and D pits of 1st further apart* • MB cusp ridge of 1st longer than DB (opposite with 2nd) • Less supplemental grooves in 1st

36. Tooth ID Test

41. Differences between 1st and 2nd: • Crown dimensions of 2nd smaller than 1st • 1st more angular, 2nd more rounded* • F and L cusps more equal in height with 2nd*

42. Differences… • Buccal cusp tipped distally* • MB cusp ridge longer than DB* • Mesial concavity*

43. Differences… • No mesial concavity or mesial marginal groove with 2nd* • 2nd normally single rooted • M and D pits closer together in 2nd* • More supplemental grooves in 2nd*

45. #9 Item 1 Facial Mesial Lingual Distal Occlusal

46. #5 Item 2 Facial Mesial Lingual Distal Occlusal

47. #5 Item 3 Facial Mesial Lingual Distal Occlusal

48. #26 Item 4 Facial Mesial Lingual Distal Occlusal/Incisal

49. #13 Item 5 Facial Distal Lingual Mesial Occlusal

50. #5 Item 6 Facial Mesial Lingual Distal Occlusal