Objectives: The aim of this study was to evaluate the influence of different dental bonding substrates and bonding methods on the marginal quality in mandibular molars restored using monolithic zirconia occlusal veneer after thermal aging.
Materials and Methods: Eighty extracted mandibular molars were collected and divided, based on type of dental bonding surface and bonding method, into eight groups. A non-retentive occlusal veneer preparation was performed to be either within enamel, dentin, dentin with intra-coronal cavity, or dentin with composite filling. 1-mm zirconia occlusal veneers were fabricated. For each specimen, the marginal gap was measured (x40) using a stereoscope. Each occlusal veneer was bonded to its corresponding tooth using either etch-and-rinse or self-etch system. All specimens were thermal aged (5̸55 °C) for 7500 cycles. The post-cementation marginal gap was measured. Two-way ANOVA test and post-hoc test were applied to test for significance in marginal gap values in relation to bonding substrates and bonding method.
Results: No statistically significant difference in pre-cementation marginal gap values was detected between different bonding surfaces. For post-cementation, two-way ANOVA test indicated significant differences in marginal gap values in relation to bonding substrates and bonding method.
Conclusions: The type of dental bonding surface (either enamel, dentin, dentin with composite filling, or dentin with intra-coronal cavity) can influence the marginal quality of zirconia occlusal veneers after thermal aging. Compared with self-etch, etch-and-rinse bonding method demonstrated superior marginal quality of zirconia occlusal veneer restoration after thermal aging.