Denture Placement & Occlusion Correction

1. Denture Placement & Occlusion Correction Rola M. Shadid, BDS, MSc

2. Causes of Denture Errors • Clinical errors • Technical errors • Inherent deficiencies in the material itself

3. Evaluation Procedures • Processing • Polished surfaces • Tissue fit and comfort • Retention, stability and support • Jaw relations • Occlusion • Esthetics • Speech

4. Evaluation of Processing * • Inspect for processing errors, e.g. porosity • Inspect for inadequate polishing • Run your finger along the borders & impression surface to check if sharp edges or acrylic spicules exist • Examine frenal notches for sharp edges • Examine for adhered plaster or stone fragments

5. Patient Education & Preparation * • First oral feeling with fullness is normal & will disappear over time • Excessive salivation (compulsive spitting or rinsing should be avoided,instead swallowing encouraged to remove excess saliva)

6. Evaluation of Tissue Fit & Comfort Pressure Indicating Paste (PIP)* • Every new denture must be checked with PIP to identify and determine if pressure areas exist to reduce them.

7. Evaluation of Tissue Fit & Comfort • Never adjust unless you can see exactly where to adjust • Use indicator medium • (PIP, indelible marker, etc)

8. Place Paste with Streaks

9. How to Read PIP? • Streaks - no contact (N) • No Paste - Impingement (I) • Paste, no streaks - normal contact (C)

10. Evaluation of Tissue Fit & Comfort Severe undercuts • Cause abrasion and soreness in seating and removal • Management Relieve with extreme caution with aid of PIP

11. Evaluation of Tissue Fit & Comfort Overextended borders • Denture appears to rise or has inadequate retention • Management Identify the offending borders, mark with indelible marker inside the pt mouth and carefully reduce

12. Evaluation of Retention, Stability & Support • Test for retention* • Test for posterior palatal seal

13. Test for Rocking • Apply alternating finger pressure on occlusal surfaces of R & L sides • Rocking around fulcrum point • Midpalatalraphe is a common fulcrum point if inadequate relief has been provided *

14. Evaluation of Occlusion • Denture processing almost always causes changes in occlusion due to dimensional changes in resin • These changes are usually manifested as increase in OVD

15. Causes of Occlusal Errors • Errors in impressions • Ill-fitting trial denture bases • Inaccurate jaw relation records • Errors during transfer of the records to articulator • Incorrect arrangement of posterior teeth • Dimensional changes during curing • Processing faults……..*

16. Why is it difficult to detect occlusal errors in the mouth? * Negative attitude (assume an error exists and try to find it)

17. What is the ideal occlusal contact? At first contact, even maximum intercuspation at CR without denture shifting or instability & without pain *

18. Types of Occlusal Errors • CO not coincide with CR • Premature contact (high point) in one or both sides • Uneven distribution of occlusal contacts • Eccentric movement prematurities (protrusive & lateral)

19. What are the Methods of Detecting Occlusal Errors? • Touch & slide method (Refer to lecture 9) • Denture dislodges or shifts when pt occludes • Pt complains of pain beneath denture bases

20. Correction of Occlusal Errors • Laboratory remounting • Clinical remounting • Direct intraoral correction

21. Laboratory Remounting * Disadvantages Cannot correct errors made while recording jaw relations Cannot correct errors made while mounting the casts on the articulator Does not compensate changes caused by settling of the denture bases

22. Clinical Remounting with New Interocclusal Records * Advantages • Correct errors made during recording of jaw relations, or while mounting cast on articulator • Less chair side time • Corrections away from the patient’s view • No saliva which makes detection by articulating paper difficult • No shifting of dentures or incorrect closure by pt

23. The Aim of Clinical Remounting The prematurities are ground until multiple, uniformly distributed and even contacts are obtained bilaterally

24. Clinical remounting is currently the most commonly preferred method of occlusal correction

25. Clinical Remounting Procedure • Ask patient to bite on cotton rolls for 10 min. • Guide mandible into CR several times. • Bite registration material is placed on the post. teeth of the mandibular denture

26. Clinical Remounting Procedure • Guide mandible into CR • Obtain interocclusal record of CR.

27. Clinical Remounting Procedure • Mount upper denture using remounting jig • Mount lower denture

28. Clinical Remounting Procedure

29. Selective Spot Grinding * The art of reducing premature contacting surfaces, so that an equal pressure exists at all points with interference at no point.

30. How to Recognize Premature Contacts? • A dark ring with a light center usually denotes a premature contact • You should distinguish betw. marks made by normal occlusal contacts and those of premature contacts • Articulating paper should not be reused many times and should be changed often.

31. Selective Spot Grinding Make grinding until even (same intensity), stable, and multiple marks spread over wide area in both sides

32. Eliminating Occlusal Errors • Re-establishment of CO. • Correction of protrusive relation. • Correction of working side occlusal errors. • Correction of balancing side errors. Initially, centric occlusion errors are corrected, followed by protrusive, R & L lateral interferences.

33. Basic Tooth Positions Balancing Contacts Centric Occlusion Working Contacts

34. Selective Grinding Rules to Obtain CO • After the first few taps on the articulating paper only a few high contacts appear. • The marking process and the grinding are repeated until all except the anterior teeth contact in CO. • Ideally all holding cusps * of the maxillary and mandibular posterior teeth will make simultaneous contacts. • It is not uncommon for one or two functional cusps not to make contact after establishing the final CO. • It is not necessary to continue adjusting until these cusps make contacts because aggressive adjustment will sacrifice the established OVD

35. Selective Grinding Rules to Obtain CO • As far as possible, avoid grinding cusp tips especially centric holding cusps, instead grind the opposing fossae or marginal ridges where the centric holding cusps occlude • If the high contact is on the centric holding cusp inclines, the cuspal inclines can be reduced, thereby gradually moving the contact more toward the bearing cusp tip. • A centric holding cusp may be reduced when it interferes with another centric holding cusp or when makes interferences in centric and eccentric positions

36. Re-establishment of CO Problem: Teeth too long Solution: Deepen the fossae

37. Re-establishment of CO Problem: Teeth too nearly end to end Solution: Grind Inclines

38. Re-establishment of CO Problem: Too much horizontal overlap Solution: Broaden central fossae

39. After the CO re-establishment…. • DO NOT: • Reduce maxillary lingual cusps. • Reduce mandibular buccal cusps. • Deepen the fossae.

40. Correction of Protrusive Relation • The teeth are brought edge to edge • Any interferences to smooth anterior gliding of dentures are eliminated by grinding • Elimination of protrusive interferences along a path of 3 to 5 mm is sufficient

41. Correction of Working Side Occlusal Errors BULL rule buccal upper-lingual lower

42. Correction of Working Side Occlusal Errors • Reduce lingual inclines of buccal cusps of upper teeth. • Reduce buccal inclines of lingual cusps of lower teeth. ON WORKING SIDE ONLY!!!

43. Correction of Working Side Occlusal Errors Problem: Buccal and lingual cusps too long. Solution: Change inclines of balancing cusps.

44. Correction of Working Side Occlusal Errors Problem: Buccal cusps are too long Solution: Change lingual incline of maxillary buccal cusp

45. Correction of Working Side Occlusal Errors Problem: Lingual cusp too long. Solution: Change buccal incline of lingual cusp of mandibular tooth.

46. Correction of Balancing Side Errors On the balancing side, the cusps usually involved are the functional cusps and therefore grinding becomes more confusing

47. Correction of Balancing Side Errors • Decide which supporting cusp maintains CO and reduce its opponent.

48. Correction of Balancing Side Errors Grind the lingual incline of the mandibularbuccal cusp.

49. Direct Intraoral Correction Disadvantages • Requires a lot of pt cooperation • Pt should have good neuromuscular control • Saliva • Inaccurate closure by pt • Misleading due to resiliency of tissues and shifting of denture bases

50. References • Boucher's Prosthodontics Treatment for Edentulous Patients. Twelfth Edition.Chapter 20. • Dalhousie continual education • Complete Denture Prosthodontics, 1st Edition, 2006 by John Joy Manappallil, Chapter 19