MMPs activity and bond strength in deciduous dentine-resin bonded interfaces

To determine effect of ageing on deciduous dentine-resin interfaces bond strength and the metalloproteinases (MMPs) activity at the hybrid layer compared to permanent dentine.

Microtensile bond strength (MTBS) tests were performed in human deciduous and permanent dentine after 24h, 3 and 6 months using an etch and rinse adhesive. C-terminal telopeptide concentrations (ICTP) were calculated, in order to determine MMPs mediated collagen degradation at the hybrid layer.

The highest MMPs-mediated collagen degradation values occurred in phosphoric acid demineralized dentine, ICTP values were similar for deciduous and permanent dentine after 1 week. Resin infiltration decreased collagen degradation in both dentins and ICTP values were similar to those attained by for untreated dentine. In resin infiltrated and untreated dentine specimens collagen degradation was always higher for deciduous dentine. At 24h, MTBS was higher in permanent dentine. After ageing MTBS decreased and performed similarly in both dentins.

Higher collagenollytic activity is found in deciduous than in permanent dentine. At 24h, collagen cleavage by MMPs at the hybrid layer is higher in deciduous dentine leading to a lower MTBS.

The presence of resin monomers reduced collagen degradation when applied on demineralized dentine, but exerted protection was lower in deciduous dentine.