Nanoleakage of CAD/CAM Ceramic Bonded to Dentin with Resin Cements

Objectives: To determine nanoleakage of CAD/CAM ceramic blocks bonded to dentin using self-adhesive resin cement and the effect of thermo-cycling on this bond. Methods: Eighteen sound extracted human molars were sterilized and sectioned to obtain 3mm thick dentin sections. Trilux Cerec Vitablocks (Vita Zanfabrik) were also sectioned into 3mm thick sections. Trilux sections were cemented to the dentin sections using 3 resin cements: Rely-X Unicem (3M/ESPE), BisCem (Bisco), and Calibra (Dentsply). Prior to bonding Trilux sections were surface-treated using 5% hydrofluoric acid-etchant and coated with silane ceramic primer (Vita Zanfabrik). Cements were used according to manufacturers' recommendations. Calibra was used in conjunction with Prime/Bond- NT adhesive (Dentsply) while the other 2 were used without dentin pre-treatment since they are self-adhesive. The bonded specimens were stored for 24h in distilled water at 37°C. Specimens were vertically sectioned into 1mm thick slabs yielding up to 6 slaps per specimen. Two central slaps were randomly chosen from each specimen to form a group with 12 slaps. Each group was subdivided into 2 subgroups (n=6), one of the subgroups was thermocycled (5-55°C) with 1 min dwell time for 500 cycles. Slabs were coated with nail polish up to 1mm from the interface, immersed in 50% silver nitrate solution for 24h and tested for nanoleakage using Quanta Environmental SEM and EDAX. Data was statistically-analyzed using two-way ANOVA and Tukey's post-hoc tests. Results: Rely-X Unicem and Calibra groups showed no significant difference in percentages of silver penetration while BisCem group showed significantly higher percentage of silver penetration (P<.05). Thermocycling (500 cycles) had no statistically-significant effect on percentage of silver penetration (p>.05). Conclusions: One self-adhesive resin cements showed similar sealing ability as compared to a standard resin cement that was used with separate adhesive. Thermo-cycling did not significantly increase dye penetration test conditions. Acknowledgments: 3M/ESPE, Dentsply, Bisco.