Effect of Cement Type on Marginal Microleakage of Zirconia Crowns with or without Cervical Margin Relocation: An In Vitro Study
This study evaluated the microleakage in zirconia crowns cemented with bioactive vs resin cements at two margin locations: cementum/dentin deep margin and composite-elevated margins. Standardized mesial box cavities were prepared in 30 molar teeth, with proximal cavosurface margins placed 1 mm below the cemento-enamel junction (CEJ) and restored with resin composite. The teeth were prepared for zirconia crowns, with mesial margins on the composite and distal margins on tooth structure 1 mm below the CEJ. Following digitization and zirconia crown fabrication, the specimens were randomly allocated into five groups based on the type of cement used: one multistep adhesive resin, one self-adhesive resin, one bioactive hybrid ionic resin, and two bioceramic cements. Microleakage was evaluated by measuring the percentage of dye penetration depth at the interfaces, with data analyzed using two-way ANOVA. The results revealed a significant interaction between cement type and margin location, with elevated margins exhibiting less leakage than deep ones across all cement types (p≤0.001). However, the effect of margin location on microleakage varied depending on the cement type, with variations in microleakage scores at each margin location ranging from statistically nonsignificant (p>0.05) to statistically significant (p≤0.05). Adhesive resin and hybrid bioactive cements significantly outperformed others in reducing microleakage at both margin interfaces.SUMMARY
The CONSORT flow diagram of experimental procedure.
Image showing a prepared mesial box of a molar tooth embedded in a resin block, with the placement of an injectable bulk-fill composite restoration using a silicone index as a matrix.
Molar specimen prepared for the zirconia crown, with the mesial margin placed on the resin composite restoration and the distal deep margin on the cementum/dentin substrate: (A) mesial view and (B) occlusal view.
Basic fuchsin penetration at the crown interface for (A) elevated resin composite margin and (B) deep cementum/dentin margin.
Mean (SD) microleakage (%) for each cement at elevated and deep margins.
Pairwise comparisons of microleakage (%) among cements at each margin location. Uppercase letters indicate significant differences among cements at elevated margins. Lowercase letters indicate significant differences among cements at deep margins. Bars sharing a letter are not significantly different. Bars with no letters in common are significantly different (p < 0.05).
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