The effect of AgBr/cationic polymer nanocomposite on matrix metalloproteinase activities

Objective This study was aimed to evaluate the effects of AgBr/cationic polymer nanocomposite (AgBr/BHPVP) on dentin matrix metalloproteinase (MMPs) . Methods Inactivation effects of AgBr/BHPVP at different concentrations on soluble recombinant human MMPs (rhMMPs) were evaluated using a colorimetric assay kit. Matrix-bound endogenous MMPs activity was evaluated via dry mass loss and C-terminal cross-linked telopeptide (ICTP) release of demineralized human dentin. Demineralized dentin beams or powder were respectively pretreated with 0.2% chlorhexidine (CHX) or AgBr/BHPVP at different mass%. Changes in ICTP release were examined after 3, 5 and 7 days, and loss of dry mass was measured after 30 days. Besides this, gelatin zymography was also used to evaluate the effects of different pretreated groups on MMP-2 and MMP-9. One-Way ANOVA test was applied to analyze the overall difference of inactivation function on rhMMPs and dry mass loss in each group. Repeated measures ANOVA was used to analyze the effects of time on the ICTP release in different groups, while Tukey′s test was used for the comparison between every two groups. Results AgBr/BHPVP exhibited inactivation function on soluble MMPs, with about 90% of inhibition on rhMMP-2, rhMMP-8 and rhMMP-9 at 1.5% AgBr/BHPVP concentration. Compared with control group and CHX group, AgBr/BHPVP pretreated demineralized dentin exhibited the lowest ICTP release after 7 days (F= 65.389, P<0.001) . Dentine beams incubated in 1.5% AgBr/BHPVP showed only (4.3 ± 0.98) % loss of dry mass vs. (16.34 ± 3.60) % loss for control. Except for AgBr group, other pretreated groups had obvious inhibition on gelatinase activity in gelatin zymography. Conclusions A moderate amount of AgBr/BHPVP is effective in inhibiting both soluble and matrix-bound MMPs. AgBr/BHPVP may have the potential to be used in dental materials and improve the resin-dentin bonding durability. Key words: Quaternary ammonium compounds; Matrix metalloproteinase; Enzyme inhibitors; Bromides, Silver compounds