Effects of diphenyliodonium salt addition on the adhesive and mechanical properties of an experimental adhesive.

Objectives: The aim of this study was to assess the microtensile bond strength (μTBS), nanoleakage (NL), nano-hardness (NH) and Young's modulus (YM) of resin-dentine bonding components formed by an experimental adhesive system with or without inclusion of diphenyliodonium salt (DPIH) in the camphorquinone-amine (CQ) system.

Methods: On 12 human molars, a flat superficial dentine surface was exposed by wet abrasion. A model simplified adhesive system was formulated (40 wt.% UDMA/MDP, 30 wt.% HEMA and 30 wt.% ethanol). Two initiator systems were investigated: 0.5 mol% CQ+1.0 mol% EDMAB and 0.5 mol% CQ+1.0 mol% EDMAB+0.2 mol% DPIH. Each adhesive was applied and light-cured (10s; 600 mW/cm(2)). Composite build-ups were constructed incrementally and resin-dentine specimens (0.8mm(2)) were prepared. For NL, 3 bonded sticks from each tooth were coated with nail varnish, placed in the silver nitrate, polished down with SiC papers and analysed by EDX-SEM. NH and YM were performed on the hybrid layer in 2 bonded sticks from each teeth. The remaining bonded sticks were tested on μTBS (0.5mm/min). The data from each test were submitted to a Student t-test (α=0.05).

Results: No significant difference was found for μTBS between groups (p>0.05). Significant lower NL and higher NH and YM were found in the hybrid layer and adhesive layer produced with the iodinium salt-containing adhesive (p<0.05).

Conclusions: The inclusion of the DPIH to the traditional CQ is a good strategy to improve the adhesive and mechanical properties of a simplified etch-and-rinse adhesive system.