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Journal ArticleDOI

The estimation of cement film thickness by an in vivo technique.

03 Aug 1971-British Dental Journal (Br Dent J)-Vol. 131, Iss: 3, pp 107-111
About: This article is published in British Dental Journal.The article was published on 1971-08-03. It has received 1023 citations till now.
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Journal ArticleDOI
TL;DR: Weighing the light-body addition silicone is a convenient method for evaluating the 3-dimensional internal fit of dental crowns, but no significant difference was found among the 3 alloy groups evaluated for the internal gap width of sectioned crown specimens.
Abstract: Statement of problem Difficulties encountered during casting of base metal dental alloys limit their use. Application of these alloys might be enhanced if new techniques are used. Purpose The purpose of this study was to compare the internal fit of laser-sintered Co-Cr alloy crowns with base metal restorations prepared from another Co-Cr alloy and a Ni-Cr alloy using conventional casting techniques. Material and methods Internal fit of laser-sintered Co-Cr crowns was compared with the fit of conventionally cast Ni-Cr and Co-Cr alloy crowns. Twelve crown-shaped specimens were prepared on a stainless steel die representing a prepared maxillary right central incisor for each group. Fit of crowns was evaluated using 2 different techniques: (1) weighing the light-body addition silicone that simulated a cement material, and (2) measuring the internal gap width on a die for longitudinally sectioned specimens. One-way ANOVA followed by Tukey multiple comparison test was used for statistical analysis (α=.05). Results Significantly higher mean (SD) light-body silicone weights ( P P =.42). Conclusions Weighing the light-body addition silicone is a convenient method for evaluating the 3-dimensional internal fit of dental crowns. However, no significant difference was found among the 3 alloy groups evaluated for the internal gap width of sectioned crown specimens. (J Prosthet Dent 2009;102:253-259)

184 citations

Journal ArticleDOI
TL;DR: A statistically significant difference in mean film thickness was found between the two series of crowns with the best fit in the Oslo-series, and in both series the mean film Thickness was about 80% of that between crown and tooth.

174 citations

Journal ArticleDOI
TL;DR: This study validates a similar method that is of great clinical and experimental interest and compares different technical procedures of crown elaboration, using a light-body silicone supported by a heavy- body silicone.
Abstract: Summary Replication of the space between a tooth and its cast crown, using a light-body silicone supported by a heavy-body silicone, is a recognized technique to evaluate the quality of a restoration. This study validates a similar method that is of great clinical and experimental interest. Whatever the type of silicone used, comparison is possible between different technical procedures of crown elaboration (type of impression, type of material, method of spacing, etc.). If an appropriate silicone is used, the cement space may be reproduced and its thickness measured, whatever the localization (cervical, axial, occlusal).

170 citations

Journal ArticleDOI
TL;DR: Significant differences were found in the interfacial properties among the materials tested, that may lead to differences in their clinical performance.

167 citations


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  • ...[21] McLean JW, von Fraunhofer JA....

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Journal ArticleDOI
TL;DR: The heat-press group yielded the best marginal and internal crown adaptation results and the 30- or 60-μm spacer settings are recommended for the E4D CAD/CAM system.
Abstract: Statement of problem The accuracy of chairside computer-aided design and computer-aided manufacturing (CAD/CAM) restorations is questionable, and the effect of the die spacer settings is not well stated in the literature. Purpose The purpose of the study was to evaluate the marginal and internal adaptation of E4D crowns fabricated with different spacer thicknesses and to compare these crowns with those fabricated with the heat-press technique. Material and methods The E4D system was used to fabricate 30 crowns for the first 3 groups, with different spacer thickness settings: 30 μm, 60 μm, and 100 μm. In the fourth group, 10 lithium disilicate crowns were fabricated with the heat-press technique. The occlusal gap, axial gap, vertical marginal gap, and absolute marginal discrepancy were evaluated by x-ray microtomography. Statistical significance was assessed with the Kruskal-Wallis test (α=.05). For post hoc analyses, the Mann-Whitney U test was used alongside the Bonferroni correction for multiple comparisons (α=.008). Results Within the CAD/CAM groups, the 30-μm spacer thickness resulted in the lowest median axial gap (90.04 μm), whereas the 60-μm spacer thickness resulted in the lowest median occlusal gap (152.39 μm). The median marginal gap values of the CAD/CAM-60 group (49.35 μm) and CAD/CAM-100 group (46.65 μm) were lower than those of the CAD/CAM-30 group (55.18 μm). No significant differences among the CAD/CAM groups were observed for absolute marginal discrepancy. The heat-press group had significantly different values than those of the CAD/CAM groups. Conclusion The spacer thickness and fabrication technique affected the adaptation of ceramic crowns. The heat-press group yielded the best marginal and internal crown adaptation results. The 30- or 60-μm spacer settings are recommended for the E4D CAD/CAM system.

166 citations