Maxillo -Mandibular Relationships

1. Maxillo-Mandibular Relationships Occlusal Vertical Dimension And Hinge Axis Relation

2. Occlusal Vertical Dimension Amount of separation between mandible & maxilla when denture teeth contact

3. Hinge Axis Location Use earbow to record relationship of maxilla to transverse horizontal axis Locate anterior reference point

4. Centric Position Relationship of maxilla & mandible Anterior/posterior & medio-lateral) Maximum intercuspation of denture teeth

5. Programming the ArticulatorProtrusive Relationship • Simulate relationship of maxilla to mandible in excursions • Denture teeth set in harmonious relationship for function

6. Record Bases (Baseplates) and Occlusion Rims • Used to relate casts on an articulator • Record bases simulate the finished denture base

7. Record Bases and Occlusion Rims • Wax occlusion rims simulate the position of the teeth

8. Occlusion Rim Dimensions • Occlusion rims slightly bulkier • Provide additional stability during record making

9. Record Base Retention • Required for record making & phonetic tests • Inaccurate if loose • Use denture adhesive if slightly loose • Pronounced looseness - REMAKE

10. Record Base Retention • Causes of Poor Retention • Poor adaptation of resin to cast • Over- or under-extension • Excessive block-out

11. Occlusal Vertical Dimension Video

12. Arbitrary Adjustment of Occlusion Rims • Adjust separately using average dimensions: Maxillary - 23 mm Mandibular - 18 mm • ‘Starting Point’ • Fairly rapid adjustment ~ 15 minutes per arch

13. Use a Hot Scapel Blade

14. Use Hot Wax Former or Metal Spatula

15. Maxillary Occlusion Rim Adjustment • Maxillary rim slightly facial to compensate for ridge resorption

16. Maxillary Occlusion Rim Adjustment • Anterior height 1-2 mm below the lip at rest/when the patient slightly smiles

17. Wax rim/tooth display can be adjusted with sex, age, and lip length (Vig: JPD 1978). Lip Length Incisal Display Sex & Age FemaleMale Young +2 +1 Middle +1 0 Old 0 -1

18. Position of Maxillary Incisal Edge • Edge of rim touches wet line of lower lip when ‘F’ or ‘V’ sounds • Count ‘50-60’

19. Lip Support • Lips should be unstrained • Naso-labial angle ≈ 90° • Philtrum depressed • Vermilion border showing

20. Occlusion Rim Angulation • Occlusal plane parallel to the ala-tragus line

21. Occlusion Rim Occlusal Plane • Mediolaterally, parallels the pupils • Fox plane can be used

22. Fox Plane • Helps orient occlusal plane

23. Centered Occlusion Rim • Centered over ridge to maximize stability

24. Posterior Occlusion Rim Height • Posteriorly, the occlusion rim intersects 1/2 - 2/3 up the retromolar pad

25. Mandibular Rim Height • Anterior height even with the corners of mouth when lip is relaxed

26. Facial Occlusion Rim Relations • 1-2 mm horizontal overlap in anterior & posterior in centric position

27. Proper Lip Support • Unstrained lips • Vermilion border showing

28. Occlusal Vertical Dimension (OVD) • Distance between maxilla & mandible when teeth or wax rims contact in centric position

29. Physiologic Rest Position (PRP) • At rest, lips barely touching • Occlusion rims should not touch Intraorally no contact

30. Interocclusal Distance (ID) • Space between wax rims at physiologic rest position • Usually 2-4 mm

31. Establishing Occlusal Vertical Dimension PRP = ID + OVD

32. Establishing Occlusal Vertical Dimension 1. Measure difference between PRP & OVD 2. Feel to ensure movement of mandible 3. Phonetics tests ‘Closest Speaking Space’ Patient sitting bolt upright

33. Establishing Occlusal Vertical Dimension • Check with three techniques to ensure acceptable OVD • No one technique 100% correct

34. Patient Sits Bolt Upright Soft tissue position affected by posture

35. Measurements OVD & PRP • Use external points for ease of measurement • Small dots under columnella & mid-symphisis • Use Boley Gauge, not ruler

36. Measuring Occlusal Vertical Dimension • Measure the distance between dots • At PRP • At OVD • Difference is ID • Measurements change each day (position of dots)

37. Measuring Physiologic Rest Postion • Open and close until lips barely touch - Physiologic Rest Position (PRP) • Measure distance between dots

38. Measuring Occlusal Vertical Dimension • Open and close until rims touch • Measure distance between dots (OVD) • Measurement will be different each appointment

39. Establishing OVDFeel for Interocclusal Distance • Close until lips barely touch - PRP • Place finger on chin • Look away • Patient closes until rims touch (OVD) • Feel for movement of the mandible

40. Establishing OVDPhonetics Test • Closest Speaking Space • Confirms OVD • Sibilant sounds ("s", "z", sh", ch") • Rims should be at least 1 mm apart • Don’t worry about sounds yet

41. Excessive OVDWax Rims Too High • Insufficient interocclusal distance • Remove wax from one or both of the rims • Use large wax formers • #5 & #7 wax spatulas • Red-handled knife • Bunsen burner and torch

42. Wax Rim Adjustment at OVD • Flat even contact along entire occlusal surface • EXTREMELY CRITICAL • If uneven contact, patient may be forced into eccentric position

43. Adjusting Wax Rim Height • Scribe lines parallel to opposing occlusal rim • Use as a guides during reduction

44. Eliminating Record Base or Wax Rim Interferences • Patient in Centric Position • Scribe three widely separated lines between maxillary & mandibular rims

45. Establishing OVD • Remove, superimpose lines • Eliminate contacts between record bases, record base/occlusion rims/casts • Only contact should be rim to rim

46. Adjusting Occlusion Rims • Continue to adjust the rims until: • interocclusal distance is 2-4 mm • even contact along rims in centric position.

47. Excessive Occlusal Vertical Dimension • Sore muscles • Soft tissue sore spots • Rapid bone resorption • Dentures click during speech

48. Inadequate Occlusal Vertical Dimension • Collapsed Appearance - chin too close to the nose or protruding jaw • Fatigue when chewing • Sore muscles or joints

49. Hinge Axis Location • Face-bow or ear-bow used • Record relationship of maxilla to transverse horizontal hinge axis of mandible

50. Hinge Axis • Transferred to the articulator • Important to prevent occlusal errors, particularly when cusped teeth are used in dentures.