Methods: Caries-free human extracted molars and premolars (n=48), were prepared from buccal and lingual aspects exposing coronal dentin. Gelatin capsules, filled with Filtek supreme XT (3M-ESPE) composite resin, were adhered to the dentin treated by either: SU-TE, SU-SE or SB according to manufacturer's instructions.
The 16 teeth in each group were subdivided into two groups and were immersed in distilled water for either one week (T0) or 6 month (T6). After each period Shear Bond Strength (SBS) was tested via Universal Testing Machine (Instron 4502) using crosshead speed of 1mm/min. After failure all samples were examined under light microscopy to evaluate failure mode and representative samples were examined also by SEM.
Results: At T0, SU-TE showed the highest SBS (15.5±2.1MPa). No statistically significant differences were found between SB and SU-SE (10.8±2.1MPa and 10.8±2.9MPa, respectively). At T6, no deterioration was found in SBS as compared to T0: 13.02 MPa, 10.94 MPa and 11.17 MPa for SU-TE, SU-SE and SB, respectively.
Mixed failure was the prevalent mode of failure for SU-TE both in T0 and T6. Adhesive failure was the prevalent mode of failure for SU-SE.
Conclusion: The results of this study support the use of SU for bonding to dentin in either TE or SE modes exhibiting durability and equivalence to fifth generation bonding system.