Porcelain butt shoulder adaptation using a direct refractory die
Date
1973
DOI
Authors
Schneider, David M.
Version
OA Version
Citation
Abstract
Previous studies on the adaptation of porcelain margins have centered on the porcelain inlay. The purpose of this study was to measure the adaptation of the porcelain margin of a porcelain-fused-to-gold crown with a butt shoulder, constructed on a direct refractory die (Ceramco-Die System).
Polysulfide rubber impressions were taken of two prepared dentoform teeth and 11 refractory dies were poured and heat treated. Porcelain veneer crowns with porcelain butt shoulders were made on each die using as many firings as necessary to obtain the best possible marginal adaptation. The crowns were then clinically fitted to the original preparations and the marginal discrepancies measured at several random points using a micrometer eyepiece in a dissecting microscope.
The results showed that the mean marginal adaptation of the individual crowns varied from a high of 68.4 ± 31.8 microns to a low of. 9.6 ± 9.5 microns. The mean marginal opening for all the crowns was 38.8 ± 17.4 microns. Full seating of the crowns was occasionally impeded by rough crystals at the porcelain margins probably caused by imperfections at the refractory die shoulder area after repeated firings.
This study indicated that with great care and a limited number of firings, margins less than 25 microns could be attained. This is equal to, or better than, the thinnest margin theoretically obtainable using the traditional .001" platinum oil matrix.
Description
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.
Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1973. Prosthodontics.
Bibliography included.
Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1973. Prosthodontics.
Bibliography included.
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.