1. Guiding plane and Occlusal rest seat Design & Preparation
Dr.Emad Hanbali

2. Guiding planes : two or more vertically parallel surfaces of abutment teeth, so shaped to direct a prosthesis during placement and removal.

3. Functions : . To provide for one path of placement and removal of the restoration. . To ensure the intended actions of other components of the RPD. . To eliminate gross food traps .

4. Width :
1/2 the width of the distance between the tips of adjacent buccal and lingual cusps.
1/3 the buccal lingual width of the tooth.
Height :
2/3 of the length of the enamel crown portion from the marginal ridge cervically.

6. Surveying at the selected path of insertion and removal of the RPD.

7. Zero tilt survey line
Insertion tilt survey line

10. F
Follow the bucco-lingual contour during the preparation. Do not slicew

17. Length of guiding plane 2-3 mm.

20. Occlusal rest seat Design & Preparation

21. Rest
A rigid component resting in a recessed preparation on the occlusal, lingual or incisal surface
Provides vertical support

22. Occlusal Rest Seat Form
Conventional Form: rounded triangle

23. Occlusal Rest Seat Form
Rounded triangular shape
Apex near center of tooth

24. Occlusal rest seat 3D: - Mesio - distally. - Bucco - lingually
Occlusal rest seat 3D: - Mesio - distally. - Bucco - lingually. - Occluso - gingivally

25. Dimensions:
Mesio – distally :
premolars 1 / molars 1 /4

26. Occlusal Rest Seat Form
Base of triangle should be one third the bucco-lingual width of the tooth

29. Occluso-gingivally ( depth )

30. Occlusal Rest Seat Form
Marginal ridge must be lowered and rounded 1-1.5mm
Bulk of metal to prevent fracture

31. Occlusal Rest Seat Form
Floor inclined towards the center
Angle formed by rest and minor connector should be less than 900

32. Occlusal Rest Seat Form
Deepest portion is central

33. Occlusal Rest Seat Form
Floor should be concave or spoon shaped ball-&-socket joint
Prevents horizontal stresses & torque

34. Occlusal Rest Seat Form
Directs the occlusal forces along the long axis of the tooth
Prevent orthodontic movement

35. Result of force applied when angle is greater than 90 degrees .

36. Preparation of Rest Seats
Occlusal Rest Seats
Diamonds
Medium round carbide burs
#2, #4

37. Preparation of Rest Seats
Keep in enamel
No anesthesia

43. Rounded triangle

44. Deepest part of rest seat

45. Marginal ridge reduction 1.5 mm

46. Molar occlusal rest seat
SAUSER SHAPE GP

47. Modified Occlusal rest seat

48. Occlusal Rest Seat Form
Adjacent Tooth
Rest not flared to facial line angle
Lingual flared more - space for minor connector

49. Double Embrasure Rest Seat Form
Adjacent teeth, the form is also modified
Flared more dramatically on facial and lingual line angles

50. Double Embrasure Rest Seat Form
Provides space for the retentive & bracing arms
Ensure all line angles are smoothed
Preserve the contact between the adjacent teeth

51. Interproximal Occlusal Rest Seats

55. Care must be exercised to avoid violation of contact point.

58. E N J O Y