Prosthetics.pptx, occlusal rims and jaw relations

Occlusal rims and jaw relations

1. OCCLUSAL RIMS AND JAW RELATIONS BY NALUGYA ANISA 21/U/0409, BDS 4 MODERATOR: DR.KIZITO UMARU

2. OUTLINE Introduction Design of maxillary and mandibular occlusal rims Jaw relations definition Methods used to record vertical and horizontal jaw relations Vertical dimension at rest, vertical dimension of occlusion and interocclusal distance

3. Introduction A denture consists of three surfaces, impression surface, occlusal surface and polished surface Neutral zone is the position of equilibrium the polished surface occupies among the muscles (tongue, lips, cheeks)

4. Occlusal rims Provisional substitutes for planned complete dentures or implant-supported prostheses Record the neutral zone and maxillomandibular relations Made on stone cast that represents denture supporting tissues Consist of a Trial D enture Base (provisional substitute for the eventual denture base) and a wax rim. TDB made of a hard baseplate wax or cold-curing acrylic

5. Purpose of occlusal rims Record maxillomandibular relations Establish neutral zone or arch form For arrangement of artificial teeth Establish level of occlusal plane

6. Design of maxillary occlusal rim • Should be parallel to the long axis of the tooth to be replaced. • Should follow the arch contour Anterior : Height – should be 22 mm from the highest portion of the labial flange to occlusal edge. Width – 4–6 mm . Inclination – the anterior border of the rim should be about 8 mm from the incisive papilla or a labial inclination of 5°. Relation to ridge – slightly labially .

7. Cont. Posterior : Height – should be 18 mm from highest portion of buccal flange to occlusal edge. Width – 8–10 mm. Inclination – 5° palatal (buccal aspect), perpendicular to occlusal plane (palatal aspect ). Extension – 1 cm anterior to hamular notch and angled down . Relation to ridge – slightly buccal

8. Design for mandibular occlusal rim • Should be parallel to the long axis of the tooth to be replaced and follow the contour of the arch. Anterior : Height – should be 18 mm from the deepest portion of the labial flange to occlusal edge. Width – 4–6 mm. Inclination – labial inclination of 5°. Relation to ridge – slightly labial.

9. Cont. Posterior : Height – up to retromolar pad. Width – 8–10 mm. Inclination – slight 5° lingual inclination of buccal aspect and buccal inclination of lingual aspect. Relation to ridge – on crest of ridge

10. Fabrication techniques Rolled wax technique- Most commonly used -A sheet of wax is softened over a flame and rolled to a width of 4mm -Avoid trapping air bubbles when rolling -Rolled wax is shaped in cylindrical form -This cylinder of wax is placed on the record base and is adopted and contoured to the shape of the arch Other techniques include, using metal occlusal rim formers and preformed occlusal rims

11. Clinical contouring of occlusal rims Maxillary rim Should be in harmony with the facial profile Slightly should be facial to compensate ridge resorption The vertical length in anterior region should be 2mm below the relaxed lip or low lip line The upper occlusal record anterior edge should touch vermillion border when ‘F’ or ‘V’ sounds Labial surface of wax anterior to incisive papilla 8-10mm

12. Cont. Lips should be unstrained Nasolabial angle should be 90 degrees The vertical length at the first molar region should be approximately 6 mm below the orifice of the Stensen’s duct. The height should also be in harmony with the occlusal plane . Antero-posteriorly, the occlusal plane should be parallel to the Camper’s line Occlusal plane parallel to interpupillary line (the pupils)

13. Mandibular rim Labially, the lip should be unstrained, with vermilion border showing, with proper support of mentolabial sulcus. • The anterior extension should be such that an overjet of 2 mm is present with the maxillary rim in position. • The height of the rim anteriorly should be at the level of corner of the mouth. • Buccally, the rim should contour slightly lingually from the cuspid region with provision for a buccal corridor

14. Jaw relations Any spatial relationship of the maxilla to the mandible ; Also called maxillomandibular relations Measure the extensibility and movements permissible to patient’s TMJ Classified as; -Orientation relations -Horizontal relations -Vertical relations

15. Orientation relations These establish the relationship of the maxilla to the cranium. The instrument that is used to record the center of condylar rotation along with a third reference point, thereby forming a plane to record the orientation relationship of the maxilla to the cranium, is called facebow

16. Horizontal relations This is the anteroposterior relation of the mandible to the maxilla in the horizontal plane. The horizontal relations can be classified as: Centric relation Eccentric relations – protrusive and lateral eccentric relations

17. 1.Centric relation Relation of mandible and maxilla when condyle articulates with the thinnest avascular portion of articular disc. The most retruded physiologic relation of the mandible to the maxillae to and from which the individual can make lateral movements Position independent of tooth contact

18. How to record : Retrude the mandible Passive method; patient guided to push mandible backwards Active method; Doctor guides the patient to retrude mandible by pushing it with his fingers

19. Methods of recording centric relations 1. Static methods Tactile/ interocclusal check method Wax rims Functional method Needle-House method Patterson method Swallowing technique Graphic method Gothic arch tracing Pantographic tracing 4 . Radiographic method

20. Tactile/inter-occlusal check method

21. Wax rims Nick notch method Stapler pin method (pinning)

22. Functional methods Needles-house method Patterson method

23. Swallowing technique

24. Graphic methods(intra and extra oral)

25. 2.Eccentric relation Any relationship of mandible to maxilla other than the centric relation. It includes protrusive and lateral relations. The main reason in making an eccentric jaw relation record is to adjust the horizontal and lateral condylar inclinations in the adjustable articulator, and to establish the balanced occlusion

26. How to record eccentric relation Protrusive records Functional methods Graphical methods Static methods Lateral methods Functional methods Graphical methods Interocclusal check methods

27. VERTICAL JAW RELATIONS DEFINITIONS Vertical jaw relation or vertical dimension is defined as the length of the face as determined by the amount of separation of the jaws under specified conditions Vertical dimension at rest : Length of face when mandible is in rest position Vertical dimension of occlusion or occlusal vertical dimension: Length of face when the teeth are in contact in maximal intercuspal position

28. Cont. Free way space : This is a small vertical space between the maxillary and mandibular teeth that normally occurs at rest Interocclusal distance : Distance between occluding surfaces of the maxillary and mandibular teeth when mandible is in a specified position

29. Purpose of recording optimal vertical dimension Maintain aesthetic harmony of the face Proper speech To satisfy functional requirements To provide comfort to the TMJ, masticatory muscles and residual ridge To preserve the residual ridge

30. Methods of determining vertical relations Mechanical methods A. Ridge relation Incisive papilla to mandibular incisors Parallelism of the ridges B. Measurement of the former dentures C. Pre-extraction records Profile radiographs Casts of teeth in occlusion Facial measurements Physiological methods Physiological rest position Phonetic and aesthetics as guides Swallowing technique Tactile sense

31. Vertical dimension at rest The distance between two selected point (one of which is on the middle of the nose and the other of which is on the lower face or chin) measured when the mandible is in the physiologic rest position. It is essential to record vertical dimension at rest as it acts as a reference point during recording vertical dimension at occlusion

32. Factors that influence the rest position Posture of patient A relaxed patient Neuromuscular disturbance Duration Use of several methods

33. Methods of measuring VDR 1.Facial measurements Two marks placed one on tip of nose and the other on the chin Patient assumes rest position and vertical distance between the two points measured with a divider or scale or special instruments like Willis gauge, Dakometer Assume rest position through Swallowing Tactile sense Phonetics Facial expression

34. 2. Measurement of anatomic landmarks Willis guide : states that the distance from the pupil of the eye to the rima oris (corner of mouth) should be equal to the distance from the anterior nasal spine to the lower border of the mandible, when the mandible is in physiological rest position

35. Vertical dimension of occlusion(VDO) The distance between two selected point, one related to maxilla and one related to the mandible, when the upper and lower teeth are in contact. The difference between the measurements of VDO and VDR is the freeway space. Freeway space was measured by both  Willis gauge and Sprung divider . The normal freeway space measures about 2-3mm at the molars and 4-6mm at the incisors.

36. Methods of measuring VDO PHYSIOLOGICAL METHODS Niswonger’s method (physiologic rest position) Swallowing threshold Phonetics Neuromuscular perception Aesthetics MECHANICAL METHODS Ridge relations Pre extraction records Measurements of former dentures

37. Niswonger’s method M ost commonly used method to establish occlusal vertical dimension. It uses the physiologic rest position (vertical dimension at rest) to determine the occlusal vertical dimension. Niswonger stated that; VD at Occlusion = VD at rest – freeway space (2–4 mm)

38. Relevance of freeway space in prosthodontics Freeway space is a primary prerequisite for comfort and optimum function of partial or complete dentures. The freeway space is generally recognized as a normal and necessary feature of normal occlusal function

39. Effects of excessively increased VD Increased lower facial height Difficulty in swallowing and speech Muscular fatigue Trauma caused by constant pressure on mucosa Loss of freeway space Clicking of complete dentures Patient discomfort Stretching if facial muscles produces expression of strain Excessive trauma to the lower denture-bearing area

40. Effects of excessively decreased VD • Decreased lower facial height • Angular cheilitis due to folding of corners of mouth • Difficulty in swallowing • Pain, clicking and discomfort of TMJ may result in TMJ pain dysfunction syndrome • Cheek biting • Loss of lip fullness • Loss of muscle tone • Drooping of corners of the mouth • Thinning of vermilion borders of the lip • Obstruction of Eustachian tube due to elevation of the soft palate

41. INTER OCCLUSAL DISTANCE Distance between the occluding surfaces of the maxillary and mandibular teeth with the mandible in physiologic rest position Methods of measuring inter occlusal distance Phonetic method Relaxation method Swallowing method

42. REFERENCES Textbook of PROSTHODONTICS deepak nallaswamy {first edition-2009 ( deepak nallaswamy veeraiyan , karthikeyan ramalingam , vinaya bhat )} Prosthodontic treatment for edentulous patient boucher {12 th edition george A. Zarb , charles L. Bolender , steven E. Eckert, rhonda F. Jacob, aaron H. Fenton, regina mericske -stern)} Google YouTube ; Dr. Teeth , 15 minutes dentistry