The effect of different marginal configurations and scanning powders on the accuracy of the marginal adaptation of zirconia crowns
Abstract: ABSTRACT Introduction: The quality of a dental restoration is often assessed by its marginal adaptation and coverage. The importance of marginal adaptation lies in the protection of the tooth from such different types of biological failure as periodontal disease, caries, pulpal inflammation and consequent possible tooth loss. When viewing the literature, an opening of 50-120 microns is c... read moreonsidered clinically acceptable. CAD/CAM technology has been introduced to the dental world to make dentistry more efficient and pleasant. This technology can reduce clinicians' time spent on lab procedures and in the clinic . There are many variables to consider with this rather new technology, such as marginal design and the type of scanning material used. The purpose of this study was to compare such finish line designs as chamfer and shoulder and such imaging materials as 3M, Vita, and Sinbrio. Materials and methods: A pilot study was conducted to determine the sample size for the main study. Two different marginal configurations were tested (1mm chamfer, 1.5 shoulder) and three different types of imaging materials (3M high resolution powder, Vita powder spray, Sinbrio scanning paint) in various permutations. The sample size for the main study was determined to be 18 per group (n=18). Two typodonts were prepared and scanned using the 3M True Definition scanner and milled. A total of 108 zirconia crowns were milled. Finally, the replica technique and a high magnification microscope 92x were used to measure the marginal gap. Results: The means (standard deviation) for each group were 13.04 (1.66) μm for the chamfer and 3M powder group; 12.34 (1.77) μm for the chamfer and vita powder spray group; 12.45 (2.01) μm for the chamfer and Sinbrio scanning paint; 11.63 (1.25) μm for the shoulder and 3M powder group; 12.70 (1.43) μm for the shoulder and vita powder spray group; and 12.05 (2.69) μm for the shoulder and Sinbrio scanning paint group. The difference between marginal preparation designs was not statistically significant (p = 0.180), nor was the difference among imaging materials (p = 0.826). Conclusion: There was no significant difference between the finish line designs utilized and the types of imaging materials tested on the marginal adaptation of zirconia crowns.
Thesis (M.S.)--Tufts University, 2017.
Submitted to the Dept. of Posthodontics.
Advisor: Ala Ali.
Committee: Khaled Elrafie, Yukio Kudara, and Matthew Finkelman.
Keyword: Dentistry.read less