Clinical marginal and internal gaps of zirconia all-ceramic crowns

Marginal and internal gaps of NobelProcera crown zirconia were clinically evaluated using silicone materials.

Ninety-one crowns were examined before final cementation, and white and black silicone materials were used to record the marginal and internal fit. The silicone materials were sectioned bucco-lingually and mesio-distally, and the thickness of the silicone layers was measured using a microscope. Sixteen reference points were measured on each specimen, and mean marginal and internal gaps were obtained. Mean marginal gaps among anterior, premolar, and molar tooth groups, in addition to mean gaps at the reference points within the groups, were compared using two-way ANOVA and Games-Howell analysis.

The marginal mean values were the smallest among all tooth groups, and the largest were at the rounded shoulders. There were no significant differences in the mean marginal gaps among the three tooth groups, while there were significant differences in the mean marginal and internal gaps of each tooth group.

The mean marginal gap of the NobelProcera crown zirconia was 44.2 μm, which is within clinically accepted standards.