Objective. DentinalMMPshave been claimed to contribute to the auto-degradation of collagen
fibrils within incompletely resin-infiltrated hybrid layers and their inhibition may, therefore,
slow the degradation of hybrid layer. This study aimed to determine the contribution of a
synthetic MMPs inhibitor (galardin) to the proteolytic activity of dentinal MMPs and to the
morphological and mechanical features of hybrid layers after aging.
Methods. Dentin powder obtained fromhuman molarswas treated with galardin or chlorhexidine
digluconate and zymographically analyzed. Microtensile bond strength was also
evaluated in extracted human teeth. Exposed dentin was etched with 35% phosphoric acid
and specimens were assigned to (1) pre-treatment with galardin as additional primer for
30 s and (2) no pre-treatment. A two-step etch-and-rinse adhesive (Adper Scotchbond 1XT,
3M ESPE) was then applied in accordance with manufacturer’s instructions and resin composite
build-ups were created. Specimens were immediately tested for their microtensile
bond strength or stored in artificial saliva for 12 months prior to being tested. Data were
evaluated by two-way ANOVA and Tukey’s tests (˛ = 0.05). Additional specimens were prepared
for interfacial nanoleakage analysis under light microscopy and TEM, quantified by
two independent observers and statistically analyzed (2 test, ˛ = 0.05).
Results. The inhibitory effect of galardin on dentinal MMPs was confirmed by zymographic
analysis, as complete inhibition of both MMP-2 and -9 was observed. The use of galardin
had no effect on immediate bond strength, while it significantly decreased bond degradation
after 1 year (p < 0.05). Interfacial nanoleakage expression after aging revealed reduced silver
deposits in galardin-treated specimens compared to controls (p < 0.05).
