JOURNAL OF PROSTHETIC DENTISTRY THE

Vol. 98 No. 6      DECEMBER - 2007

ISSN: 0022-3913      UBIC: 171

RESUMEN

Statement of problem: Axial-wail inclination has been shown to affect the stability of a cemented restoration in function, resulting in early restoration failure. Purpose: The purpose of this study was to evaluate surface area improvement with the use of supplemental grooves in tooth preparations for complete crowns. Material and methods: The surface area preparation improvement in combinations of unfavorable/marginal height and axial-wail inclinations was quantified. A right regular pyramid was used to simulate a single mandibular molar tooth preparation with known axial-wail inclinations and vertical heights. Various combinations of these 2 variables allowed the calculation of surface areas with a formula for the area of a pyramid, cones, and right triangles through geometric/trigonometric manipulations. The pyramidal model system had a 9-mm square base with marginal and unfavorable vertical heights, 3 or4 mm, and axial-wail inclination angles from 2 to 25 degrees. Conical-shaped grooves of varying lengths and widths, depending on height and axial-wail inclinations, were introduced with a tapered fissure bur. The percentage of surface area gained or lost through the supplementation with tapered grooves and boxes served as the dependent variables, a-factors through . Results: Significant area gains were demonstrated in all a-level comparisons. The greatest change was found in the 4-mm height grouping, as a positive 35.2% gain in the 25-degree level with 4 grooves. Conclusions: Axial-wail groove and box supplementation were shown to improve the surface areas of simulated mandibular molar preparations with unfavorable axial-wail inclination and vertical height levels. (J Prosthet Dent 2007;98:436-444)

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