Bond Strength and Ultramorphological Evaluation After Simplified Immediate Dentin Sealing

Aim: Traditionally, 3-step etch-and-rinse adhesive systems were proposed for performing Immediate Dentin Sealing (IDS) technique. In this study, the effect of “simplified” IDS technique achieved with more user-friendly, lightly-filled universal adhesives on microtensile bond-strength (µTBS) and dentinal endogenous enzymatic activity (MMPs) was investigated. Methods: The coronal dentin of 24 sound human molars was exposed. The following groups were formed according to the adhesive used for IDS (n=8): 1) Clearfil Universal Bond Quick (QB); 2) Scotchbond Universal Plus (SB); 3) no IDS (CTR). A provisional restoration (Caviton) was placed. After 1 week of artificial saliva storage, CAD/CAM hybrid ceramic onlays (Katana Avencia Block) were luted using a universal resin cement (Panavia SA Cement Universal) in self-adhesive mode. The specimens were cut into 1-mm2 thick slices and subjected to µTBS test and scanning electron microscope (SEM) analysis after 24 h (T0) or artificial aging (10.000 thermocycles 5-55°C; T1). In situ zymography was conducted on 3 additional molars per group at T0 and T1. Data were statistically analyzed (α=0.05). Results: At T0, QB showed a significantly higher µTBS than CTR and SB (p<0.05). Artificial aging negatively affected bond strength in QB and CTR, while bonding values increased in SB (p<0.05). Both experimental groups demonstrated higher bond strength compared with CTR after aging (p<0.05). At T0, the IDS with the tested adhesives significantly increased the level of MMPs (QB>SB>CTR; p<0.05). At T1, only QB generated a higher gelatinolytic activity compared with CTR (p<0.05). Conclusions: The hereby proposed "simplified" IDS achieved with universal adhesive systems can have a positive impact on immediate- and aged µTBS, although it may lead to activation of MMPs within coronal dentin.