Assessment of marginal fit and the match of crowns made of various materials in the CAD/CAM technology to the abutment tooth
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Department of Prosthetic Dentistry, Medical University of Warsaw
Publication date: 2021-09-17
Prosthodontics 2021;71(3):216–227
Reverse engineering is the process of examining physical, real objects by introducing them into a virtual environment. It can be applied to inspect prosthetic restorations before their cementation.

To assess the marginal fit of prosthetic restorations made in vitro.

Material and methods:
The research material consisted of the substructures of prosthetic crowns, divided into three groups depending on the material used: Group I – three ZrO2 crowns, Group II – three CoCr alloy crowns, Group III – three PMMA crowns. The abutment tooth model and the models of the internal surfaces of the crowns were transferred to the measurement software. The next step was to analyse the accuracy of fitting the entire inner surface of the crowns with the original model.

In Group I, the lowest standard deviation was obtained (0.02 mm), but the space for the cement turned out to be much larger than the designed space (mean 0.09 mm). Group II was characterized by the mean closest to the assumed one, but its differentiation was clearly greater than in the case of Group I. For Group III, the same mean was obtained as for Group I, and the discrepancy in the results was the greatest in this group.

The use of reverse engineering methods enables a back control of the correctness of laboratory procedures. Crowns made of zirconium oxide are characterized by the lowest variability of the obtained results, which makes them suitable to be widely used in the clinical practice. Crowns made of cobalt-chrome alloy have the average cement space closest to the original design, which ensures high marginal fit.