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 each): a minimally invasive preparation with a butt-joint design (0.3-mm depth) and a chamfer finish line (group MP); and no preparation (group NP). All teeth were restored with lithium disilicate veneers cemented with photopolymerizable resin cement. Specimens were aged thermally (6,000 cycles of 5ºC to 55ºC) and mechanically (100,000 cycles at 100 N, 4 Hz). Specimens were immersed in fuchsin dye for 24 hours using a standard dye penetration technique, then sectioned and evaluated under a stereomicroscope (×20 magnification). 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.