Evaluation of the retentive value of various designs of tooth preparation with the use of an epoxy resin model and zinc phosphate cement
Date
1993
DOI
Authors
Lima Verde, Marcus Aurelio Rabelo
Version
OA Version
Citation
Abstract
The discussion of the influence of different characteristics of a tooth preparation on the retention, stability, seating and marginal seal of cast crowns is probably as old as the history of fixed prosthodontics. There is a large number of interdependent factors that influence the final retention of a cemented crown; however, there are no reported studies of the influence of the geometry of the finish line and retention of the complete crown.
Human tooth structure is the ideal material for testing complete crown retention. Nevertheless, intact extracted teeth are difficult to obtain, and the unpredictable properties of dentin present problems when natural teeth are used to test luting media.
This study analyzed an epoxy resin model for testing with zinc phosphate cement. Variables included the width of the tooth preparation and marginal geometry; and the final retention of cast crowns was measured after cementation with zinc phosphate cement. Standard preparations were achieved through the use of a machinist's lathe and water cooled high-speed handpiece mounted in a custom jig.
The following conclusions were drawn from this study: (1.) Width had a significant influence on the retentive value of the preparations because 8 mm-wide preparations were more retentive than 6mm-wide preparations regardless of the marginal design or die material used (p[less than]0.0001). (2.) Shoulder marginal design was consistently more retentive than the shoulder bevel and chamfer marginal designs when only the die material was altered (p[less than]0.0001). (3.) The epoxy resin material was a suitable model for use with the zinc phosphate cement. (4.) Although human dentin had slightly superior retentive values, there was no statistically significant difference in retention between epoxy resin die material and dentin. (5.) The retentive values were not dependent on the other interactions (width X marginal design), (width X core material) and (width X marginal design X core material).
Description
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Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1993 (Prosthodontics).
Includes bibliographical references: (leaves 78-83).
Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1993 (Prosthodontics).
Includes bibliographical references: (leaves 78-83).
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.