Bonding Effect of Immediate-Dentin-Sealing Applications on CAD/CAM Ceramic-Onlay Restoration
Objectives: The purpose of this study was to examine the bonding effect of immediate-dentin-sealing (IDS) applications on CAD/CAM ceramic-onlay restoration.
Methods: Standardized mesial-distal-occlusal-palatal cavities were prepared in 32 extracted human upper molars. Cavity specimens were divided into four groups: thin-sealing group (T), slope-sealing group (S), base-sealing group (B) and none-sealing group (N). The intra-cavity dentin walls of T, S and B groups were sealed with an all-in-one adhesive system (Scotchbond Universal Adhesive, 3M ESPE) and a flowable-resin-composite (Filtek Supreme Ultra Flowable Restorative, 3M ESPE). Optical-impressions for all cavities were scanned by CEREC AC Omnicam (SW v4.3, Dentsply Sirona) and then CAD/CAM onlays were fabricated from VITABLOCS Mark II by CEREC MC XL. Each onlay was cemented to individual cavity with an adhesive resin-cement (PANAVIA V5, Kuraray Noritake Dental). All restored specimens were subjected to cyclic-loading-stress at 157 N for 90 cycles/min, 3 × 105 cycles in total, in water at 37°C. Four standardized beam-shaped test specimens with a sectional-area of 1.0mm×1.0mm were obtained from each restored specimen, and the micro-tensile bond strength (μ-TBS) was measured. The μ-TBS data was examined using one-way ANOVA and Tukey’s HSD-test. When test specimens debonded during trimming before μ-TBS test (pretesting failure; ptf), the specimens were recorded as 0 MPa and included into the statistical analysis.
Results: The mean μ-TBS (S.D.) in MPa and [the number of ptf] of T/S/B/N were T;5.8(2.3)[3], S;11.5(2.1)[0], B;12.1(2.2)[0], N;4.4(1.5)[2]. The IDS application had a significant influence on the μ-TBS value. The μ-TBS of T, S and B were statistically greater than that of N. In addition, the μ-TBS of S and B were statistically bigger than that of T.
Conclusions: The IDS application to CAD/CAM ceramic-onlay restoration was effective to obtain the excellent intra-cavity bond strength. The slope- and base-sealing demonstrated the high performance to gain robust bonding.