| 0426 An Analysis of Pre-Clinical Preparations for Fixed Partial Dentures | ||
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T.V. CARNAGGIO1, J.M. PIPER, II2, H. ACOSTA3, Y. ISMAIL2, E. MCCARTHY2, J. CLOSE2, and W. YOUNG2, 1University of Pittsburgh, School of Dental Medicine, PA, USA, 2University of Pittsburgh, PA, USA, 3University of Pittsburgh, Munhall, PA, USA Objectives: The optimal degree of taper for crown preparations should approach parallel axial walls. This is fundamentally unattainable as some degree of convergence is necessary to allow the seating of crowns on their corresponding dies and/or teeth. Most authors recommended a 3°-6° taper or 6°-12° convergence angle. These convergence angles advocated by the experts are extremely difficult to achieve under clinical, as well as clinically-simulated conditions. Accordingly, the present study was conducted to investigate the ability of dental students to achieve the advocated crown preparation guidelines for convergence angles. Methods: Eighty-eight tooth preparations were completed on typodont teeth, by second- year dental students under proficiency testing conditions. A modified projector was used to reflect a shadow of tooth preparations onto a glass window apparatus from a distance of 36 inches. The images were traced onto clear paper, placed behind the glass window. The convergence angles were extended and measured with protractors. A 2 x 2 within cases ANOVA was used to test for mean convergence angle differences between teeth and location. Results: Results indicated convergence angles between -3° and 39° with a mean of 15.5° for tooth number 4. For tooth number 6 the convergence angles ranged between -4° and 51° with a mean of 20.7°. A highly significant tooth by location interaction was found (P£.0004). Tests for simple main effects found that MD and BL angles did not differ significantly on tooth #4, nor did tooth #4 significantly differ from tooth #6 on MD angle (P=.745). However, highly significant differences were found between MD and BL angles on tooth #6 (P£.0004). Conclusion: It was concluded that second-year students could not complete crown preparations within the 6°-12° criteria. Therefore, we recommended that a more realistic criterion should be established for the convergence and taper angles of crown preparations.
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| Seq #69 - Fixed Prosthodontic Research, Preparations, and Impressions 10:15 AM-11:30 AM, Thursday, 11 March 2004 Hawaii Convention Center Exhibit Hall 1-2 | ||
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