Purpose: To assess the influence of two preparation techniques on the microleakage, marginal fit, and cement thickness of lithium disilicate veneers.
Materials and methods: A total of 24 human maxillary central incisors were divided randomly into two groups according to preparation technique (n = 12): minimally invasive preparation with butt-joint design (0.3-mm depth) and a chamfer finish line (group MP); and no preparation (NP). All teeth were restored with lithium disilicate veneers cemented with photopolymerizable resin cement. Specimens were aged thermally (6,000 cycles of 5°C to 55°C) and mechanically (100,000 cycles at 100 N, 4 Hz). Specimens were immersed in fuchsin for 24 hours employing a standard dye penetration technique, then sectioned and evaluated under a stereomicroscope (x20). Data were analyzed by ANOVA and Kruskal-Wallis tests (P < .05).
Results: There was significant microleakage (P = .0163) at the cervical area compared to the proximal area. The marginal fit was similar, with no statistical difference (P = .212) between groups MP (153 ± 81 μm) and NP (111 ± 74 μm). Group MP showed a significantly (P = .006) reduced cement thickness at the cervical area (87 ± 27 μm) compared to group NP (210 ± 89 μm).
Conclusion: Although the preparation technique was shown to influence the cement thickness, it did not show any influence on microleakage or marginal fit.