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abutment tooth prep part 2.pptx
- 1. ABUTMENT TOOTH PREPARATION Dr Ayesha Sadaf BDS (GOLD MEDALIST), FCPS (PK), MEMBER OF RCPS GLASGOW CONSULTANT PROSTHO SAUDI COMMISSION VOLUNTEER FOR CLEFT LIP & PALATE ASSOCIATION
- 2. Rest seat The prepared surface of the teeth on which the occlusal rest fits is called rest seat
- 3. Favorable surface for tooth support Objective of Rest seat
- 4. Objective of Rest seat Prevent Interference with occlusion
- 5. Objective Of Rest Seat Preparation Reduce the prominence of rest
- 6. TYPES OF REST SEATS • INTRACORONAL • EXTRACORONAL
- 7. TYPES OF REST SEAT OCCLUSAL REST SEAT
- 9. REQUIREMENTS OF OCCLUSAL REST SEAT • NO UNDERCUTS • SMOOTH AND POLISHED • CAVOSURFACE ANGLE IN SELF CLEANSING AREAS • PROVIDES POSITIVE SEATING OF REST SEAT
- 10. REQUIRMENTS OF REST SEATS SHOULD AVOID HABITUAL CONTACT AREA DUPLICATE THE NATURAL OCCLUSAL MORPHOLOGY SHOULD NOT BE ON THE INCLINED SURFACE
- 11. REQUIREMENTS OF OCCLUSAL REST SEAT NO UNDERCUTS
- 12. REQUIREMENTS OF OCCLUSAL REST SEAT DUPLICATE THE NATURAL OCCLUSAL MORPHOLOGY
- 13. REQUIREMENTS OF OCCLUSAL REST SEAT LOCATED IN SELF CLEANSING AREAS
- 14. REQUIREMENTS OF REST SEAT POSITIVE REST SEAT
- 15. DESIGN OF OCCLUSAL REST SEAT SPOON SHAPED/ SAUCER SHAPED SHAPE
- 16. DESIGN OF REST OCCLUSAL REST SEAT At the marginal ridge 1/2 to 2/3 of the distance between the tips of buccal and lingual cusp tips WIDTH
- 17. DESIGN OF OCCLUSAL REST SEAT MESIAL OR DISTAL FOSSA ON OCCLUSAL SURFACE ADJACENT TO EDENTULOUS AREA LOCATION
- 18. PREPARATION OF OCCLUSAL REST SEAT LOWERING OF MARGINAL RIDGE 1-1.5mm
- 19. EMBRASURE OCCLUSAL REST SEAT
- 20. Preparation of occlusal rest seat Floor should be inclined towards the center Angle formed by rest and minor connector should be less than 90 degree
- 21. HOW TO CHECK REST SEAT PREPARATION
- 22. INTRACORONAL REST SEAT MACHINE MADE REST SEAT PLACED INSIDE THE CROWN OR MAJOR RESTORATION
- 23. BOX SHAPED REST SEAT NOT RECOMMENDED DUE TO UNWANTED FORCES
- 25. Cingulum REST SEAT(OUTLINE FORM) INVERTED V SHAPE
- 26. PREPARATION OF CINGULUM REST SEAT LABIO-LINGUAL WIDTH: 2mm Depth: 1.5mm Mesio-distal width: 2.5mm
- 28. CINGULUM REST SEAT AVOID OCCLUSAL CONTACT AREAS
- 30. INCISAL REST SEAT( OUTLINE FORM) SHAPE: V SHAPED NOTCH WIDTH: 2.5mm Depth: 1.5mm
- 31. INCISAL REST SEAT PREPARATION
- 32. ABUTMENT PREPARATION USING CROWNS
Editor's Notes
- A rest placed on an inclined surface will tend to slide down the tooth under the influence of occlusal loads (1). The resulting horizontal force may cause a limited labial migration of the tooth with further loss of support for the denture. The provision of a rest seat (2) will result in a vertical loading of the tooth, more efficient support and absence of tooth movement.
- An occlusal rest placed at the arrow in (1) would create a premature occlusal contact (2), unless a rest seat was prepared to make room for it (3). Space for the rest should not usually be created by grinding the mandibular buccal cusp as this is a supporting cusp contributing to the stability of the intercuspal position.
- In addition, a rest placed on an unprepared tooth surface (1) will stand proud of that surface and may tend to collect food particles and possibly create difficulties in tolerating the denture. The preparation of a rest seat (2) will allow the rest to be shaped so that it blends into the contour of the tooth, is less apparent to the patient and also harmonises with the occlusal relationship.
- INTRACORONAL ARE PREPARED IN MAJOR RESTORATION LIKE CROWN OR INLAY, NEVER PREPARED IN A RESTORATION EXTRACORONAL REST SEATS ARE PREPARED INSIDE THE NATURAL TOOTH OR ANY MINOR RESTORATIION ON THE TOOTH
- he rest should be at least 1 mm thick for adequate strength. To check that sufficient enamel has been removed during rest seat preparation to accommodate this thickness of metal, the patient should be asked to occlude on a strip of softened pink wax. The thickness of wax in the region of the rest seat will indicate if adequate clearance has been achieve
- On maxillary anterior teeth, particularly canines, the cingulum is often well enough developed so that modest preparation to accentuate its form creates a rest seat without penetration of the enamel.
- The lingual surface of a mandibular anterior tooth is usually too vertical and the cingulum too poorly developed to allow preparation of a cingulum rest seat without penetration of the enamel. Incisal rest seats therefore have a wider application in this situation, in spite of their inferior appearance. The preparation is shown from the labial (1), lingual (2) and proximal (3) viewpoints.
- ncisal rest seats can be prepared using a tapered cylindrical diamond. Alternative, more aesthetic options are to produce a rest seat in composite applied to the cingulum area of the selected tooth, or to bond a cast metal cingulum rest seat to the tooth.
- Basic principles are same. Rest seat and guide planes are prepared and incorporated in the wax pattern of the tooth