30-Month performance of a 10-MDP based universal adhesive system under mechanical and biological perspectives

Strategies towards the long-term durability of dentin-adhesive interface is the goal of many investigations. As the universal dentin bonding systems (DBS) represents a promissory category, other approaches seem to be refrained. Besides their chemical capacity to bond to dentin, their ability in terms of suppression of dentin metalloproteinases of matrix at the interface is unclear. This study aimed to evaluate the long-term adhesive performance and gelatinolytic activity effect of a 10-MDP-based universal DBS compared with 2 % chlorhexidine digluconate (CHX) as control to connect the understanding of mechanical and biological mechanisms. For this, bond strength to dentin (μTBS) and in situ zymography (Z) at initial, 6-month, and 30-month aging times were run. 102 sound human molars were randomized according to DBS: Adper Single Bond 2 – (SB - MDP-free control); Adper Single Bond Universal in etch-and-rinse (SUER) and self-etching (SUSE) modes. They were subdivided according to dentin pretreatment: W- water or CHX-2% (30s-passive application). The specimens were restored according to the manufacturer's instructions. For μTBS (n = 12), beams (0.64 mm²) were obtained and tested (500N/0.5 mm/min). For Z (n = 5), 0.1 mm-thick slices were incubated with fluorescein-conjugated gelatin (24h/37 °C) and analyzed by confocal laser scanning microscopy. Data were analyzed by three-way ANOVA and Tukey's test (p < 0.05). At 6-month, CHX effectiveness was observed in some circumstances under both tests. However, 30-month assessments evidenced no difference neither among the groups regardless of DBSs nor pretreatment for all comparisons, despite some peculiarities detected under Z. It is concluded that the 10-MDP universal DBS present limited action over the proteolytic action.