Defy ageing: novel prime-and-rinse approach using MDP and MMPs inhibitors

Objectives: The study investigated the effect of a novel prime-and-rinse approach usingMDP (10-methacryloyloxydecyl dihydrogenphosphate) and matrix metalloproteinases (MMPs) inhibitors on the dentin bond durability of a self-etch adhesive and the activity of MMPs.
Methods: Eight primers were prepared with MDP and MMPs inhibitors (5%MDP, 5%MDP-BAC (1% benzalkonium chloride), 5%MDP-PVPA (1000μg/ml polyvinylphosphonic acid), 5%MDP-PA (15% proanthocyanidin), 15%MDP, 15%MDP-BAC, 15%MDP-PVPA, 15%MDP-PA (w/w)). The mid-coronal dentin surfaces of 54 human third molars were used. The dentin surfaces were applied with one of the above-mentioned eight primers for 30 s, water-sprayed and gently air-dried (prime-and-rinse approach), or without (control). Afterwards, the dentin surfaces were applied with a self-etch adhesive(Clearfil S³ Bond), and placed with a composite-resin (Majesty). The specimens were prepared into multiple micro-beams for the micro-tensile bond strengths (MTBS) tests after 24-h or 1-yr water storage. The SEM and TEM were used to analyze the resin-dentin interfaces. The inhibition effects of eight primers onsoluble recombinant human (rh) MMP-8, 9 were measured using the Sensolyte Generic MMP colorimetric assay. The data were analyzed by factorial design ANOVA, one-way ANOVA and LSD tests.
Results: Compared with the control, the primers containing 5%MDP-BAC, 15%MDP, 15%MDP-BAC, 15%MDP-PVPA, and15%MDP-PA could significantly increase the dentin MTBS after 24-hwater storage(P< 0.01), but the others could not. The dentin MTBS were not decreased after 1-yr water storage when the prime-and-rinse approach used (P< 0.05). The micro-gaps along the resin-dentin interface were detected only in the control group after 1-yr water storage. The smear layer could be detected in the control group, but not in the other groups. All the primers including MDP possessed the high inhibition ratio of rhMMP-8, 9, surpassing 83.8%.
Conclusions: The prime-and-rinse approach using MDP or MDP/MMPs inhibitors prior to application of the self-etch adhesive could defy the ageing of dentin bonding.