1. Waxing #12 on the Dentoform
Introduction to Posterior Occlusal Anatomy

2. Dental Arch Relationships
The maxillary arch is usually LONGER than the mandibular arch. So what?
Every maxillary tooth is more DISTAL than its opposing counterpart; therefore,
The only maxillary tooth with 1 opposing counterpart is the MAXILLARY THIRD MOLAR.
The only mandibular tooth with 1 opposing counterpart is the MANDIBULAR CENTRAL INCISOR.

3. Dental Arch Relationships
This is a useful diagram (“picket fence”) that you can easily draw on the margin of a test before you even look at the questions.

4. Ideal Class I Occlusion
Maxillary Posterior Teeth are ½ tooth distal to their mandibular counterpart. For example, the maxillary 1st premolar is ½ tooth distal to the mandibular 1st premolar. The Universal numbers of these pairs will add up to 33.

5. The tooth to tooth relationship is fixed and standardized in Class I Occlusion.
The occlusal contact scheme may vary slightly.

6. This drawing illustrates an occlusal scheme where the contacts are: cusp tips to marginal ridges & cusp tips to fossa. Cusp tip to fossa contacts require a tripod.

7. With very slight changes to the anatomy of the teeth you could have cusp-fossa contacts only. This scheme requires that every contact is a tripod.

8. Cusp tips that contact marginal ridge areas could also contact both adjacent marginal ridges simultaneously.

9. Another View (Cusp to Marginal Ridge) (Contemporary Fixed Prosthodontics, Rosenstiel, et al, 4th ed)

10. Another View (Cusp to Fossa) (Contemporary Fixed Prosthodontics, Rosenstiel, et al, 4th ed)

11. Critical Announcement!
If you expect to pass dental anatomy questions on Part I of the boards, you must know these relationships!
Which tooth touches which tooth/teeth?
This cusp touches where?
Start NOW!

12. All of these variations in occlusal schemes are fundamentally sound and result in stable occlusal contacts. You should be aware of these variations. Why? In order to:
Properly treat your patients. You have some flexibility in where to place your contacts.
Answer National Board questions. The questions may be based on any of the occlusal schemes mentioned.

13. All of the discussed occlusal schemes have a principle in common:
All of the contacts are either cusp tips contacting relatively flat areas or cusp tips contacting in a fossa with a tripod.

14. Your dentoform is not equilibrated at this point, occlusion has not been established. Any posterior wax-ups that we do on the dentoform are for anatomic form only. Leave these wax ups slightly out of occlusion.

15. Cusp Ridges – the ridges that connect the cusp tip to the marginal ridge. Note the mesial cusp ridge of #12 is longer than the distal cusp ridge.

16. The lingual cusp tips of the maxillary premolars appear to be angled toward the mesial.

17. The lingual cusps of the maxillary premolars, on the dentoform, are angled mesially to occlude in the distal fossa of the opposing premolars. Cusp-Fossa

18. Two other equally acceptable locations for occlusal contact in this situation would be:
Cusp tip on distal marginal ridge of #21
Cusp tip contacting both mesial MR of #20 and distal MR of #21

19. Add the thin coat of wax – beginning in the central fossa and working your way up the inclines.
Continue with the thin coat on down to the finish line. The occlusal “V” should still be visible.

20. Add band of wax at the margin.
Seal the wax at the finish line.
Project the emergence profile of the crown

21. Contouring and carving this band of wax should duplicate accurately the emergence profile of tooth that you are waxing.

22. You only need to develop about 2mm of properly carved emergence profile. This becomes your gingival or cervical reference for the rest of your waxing.

23. Using your unprepared tooth, mark the location of the proximal contacts both facially and from the occlusal view.

24. Connect the lines. This is a fairly accurate way to locate the proximal contact areas.

25. Build the wax extensions to the marks created.

26. Check from both the facial view and the incisal view.

27. Add a small ridge of wax on the proximal contact locators to create the facial and lingual embrasure forms.
Symmetrical form of embrasures

28. Distal – Wider Mesial – More Narrow

29. Wax in the proximal surfaces
Wax in the proximal surfaces RULE: Proximal surfaces are fairly straight from contact area to CEJ. Initially wax down over the finish line. Begin the carving at the finish line and move occlusally. Avoid removing the contact area.

30. Repeat the process for the mesial proximal surface.

31. Evaluate the gingival embrasures, they should be open and the proximal surfaces should be flat to slightly convex.

32. Next Step: Locate the buccal and lingual cusp tips
Next Step: Locate the buccal and lingual cusp tips. Use wax cones to facilitate this.
Begin with the lingual cone: Start to establish the height and location that you think is correct.

33. Check to see if the cone is in line with the linguoocclusal line.

34. With the dentoform closed, check the position of the lingual cusp cone
With the dentoform closed, check the position of the lingual cusp cone. It should be located in the distal fossa of #21, but not touching it. If contact is noted shave the height of the cone until it is just out of occlusion.

35. Lightly melt the wax on the tip of the cone and close the dentoform.

36. If you see a flat mark on the cusp tip it means the wax is in contact with the opposing tooth. Carve this mark away, the cusp tip should be just out of occlusion.

37. Locate the buccal cusp tip with a wax cone.
Try to establish the mesial-distal position and height using the facial view.

38. Contralateral side. A straight edge will nearly touch the cusp tips of the premolars and the mesiobuccal cusp of the 1st molar. This can be a general guide line for the height of the cone.

39. Buccolingual position of cusp tips: The cones should be in line with the buccoocclusal and the linguoocclusal lines.

40. Add Cusp Ridges: Connect the cusp tips to the marginal ridges.
Lingual cusp ridges / Occlusal view: Evaluate lingual embrasures. ML embrasure-look at contralateral embrasure.

41. Lateral view: compare the contour of the cusp ridges to the second premolar.

42. Add Buccal Cusp Ridges: Occlusal View
Pay particular attention to the buccal embrasures and the mesial and distal point angles that are established.

43. Buccal Cusp Ridges: Facial View
Evaluate the occlusal embrasures and the contour of the cusp ridges.

44. Add the mesial and distal facial line angles
Add the mesial and distal facial line angles. Also add wax along the central lobe (facial ridge) to establish the contour there.

45. Check the contour of the middle lobe (facial ridge) with the lateral view. The wax at this point does not line up well with the premolar behind it.

46. Adjust the central ridge of wax until it will very nearly superimpose on the profile of the tooth just distal to it.

47. Complete the facial surface using the marginal trim, line angles, cusp ridges and central lobe contour as guiding parameters.

48. Complete the lingual surface
Complete the lingual surface. The lingual embrasures are much more open compared to the facial embrasures and the line angles are less distinct.

49. This distal view is a good way to evaluate lingual contours
This distal view is a good way to evaluate lingual contours. Look at the contralateral side and compare. The wax is slightly over contoured at this point.

50. The final contour of the lingual surface should be very similar to the lingual contour of the second premolar.

51. Occlusal Surfaces ?
First identify the anatomical components.

52. Mesial & Distal Pits:
The deepest points on the occlusal surface.
Junctions for all of the major grooves.

53. Central Groove
Connects the mesial and distal pits.

54. Triangular Ridge Grooves
Every Triangular Ridge will have a groove on both sides, mesial and distal.

55. The central groove of the maxillary first premolar may extend across the mesial marginal ridge to form the mesial marginal groove.

56. Supplemental grooves are usually branches off of the triangular ridge grooves. Supplemental grooves are secondary anatomy.

57. Every cusp tip will have a triangular ridge
Every cusp tip will have a triangular ridge. These are convex structures. There are two triangular ridges on the maxillary first premolar.

58. Marginal ridges are also convex structures
Marginal ridges are also convex structures. They extend from the proximal contact areas to the respective pits. The marginal ridges and the triangular ridges make up the bulk of any occlusal surface.

59. Begin the occlusal surface by adding the two triangular ridges
Begin the occlusal surface by adding the two triangular ridges. Close the dentoform while the wax is still soft – avoid contacts.

60. Add wax to the marginal ridges, and fill and blend any voids.

61. Marginal ridge check: Evaluate occlusal embrasures, open & rounded

62. Triangular ridge check: Adjacent inclines should be very similar.

63. Use the pointed end of the #7 wax spatula to “lay out” the anatomy
Use the pointed end of the #7 wax spatula to “lay out” the anatomy. Hold the carver vertically while doing this. Locate the m&d pits by spinning the tip into the wax.

64. Roughly carve in the pits, the central groove, the triangular ridge grooves and the mesial marginal groove.

65. This is the angle that you initially used to carve in the grooves – vertical.

66. Keeping the tip of the carver in the groove, angle the carver to scrape and blend the edge with the existing contour.

67. Facial side of the central groove blended with the facial triangular ridge. Treat each side of each individual groove the same way.

68. Remove any wax shavings as you go
Remove any wax shavings as you go. Perfect each individual groove and using the side of the carver smooth each segment between grooves one at a time.

69. When both sides of a groove have been carved the groove becomes distinct. Grooves are actually the confluence of two inclines.

70. Continue around the occlusal surface defining grooves and smoothing the areas between grooves. Supplemental grooves may be added as you go.

71. The mesial marginal groove

72. Make final evaluations using a variety of views.

73. Check emergence profiles: There should be a smooth transition from tooth peg to wax margin. Reseal and re-carve margins if any discrepancies are noted.