Bonding performance of a HEMA-free universal adhesive to dentin

Purpose: To evaluate in vitro the bonding potential, ultrastructural organization and endogenous enzymatic activity of dentin samples after application of a novel HEMA-free universal adhesive BeautiBond Xtreme (Shofu). Methods and Materials: Forty-eight non-carious sound human molars were cut to expose middle/deep coronal dentin. Groups were formed (n=8) as follows: 1) Beautibond Xtreme universal in self-etch mode (BXSE); 2) Beautibond Xtreme in etch-and-rinse mode (BXER); 3) iBond Universal (Kulzer) in self-etch mode (IBSE) 4) iBond Universal in ethc-and-rinse mode (IBER); 5) Scotchbond Universal (3M) in self-etch mode (SBSE); 6) Scotchbond Universal in etch-and-rinse mode (SBER). After 24h, the specimens were sectioned into 1-mm thick sticks and subjected to microtensile bond strength (µTBS) test and scanning electron microscope (SEM). To investigate the effect on MMPs activity, 3 additional molars per group were processed for the in situ zymography analysis at T0. Data were statistically analysed (p<0.05). Results: Adhesive (SBU>IB>BX) and application mode (SE>ER) significantly influenced the µTBS values (p<0.05). The endogenous enzymatic activity was also influenced by the adhesive and in the ER mode (BX>IB=SBU, p<0.05), while there were no differences between the adhesives in the SE mode (p>0.05). Conclusions: Within the limitations of this in vitro study, it may be concluded that ethanol-based SBU showed better bonding performance than acetone-based IB and BX. All the adhesives performed better in the SE mode, possibly due to the lower enzymatic activity compared to the ER mode.