Endogenous Enzymatic Activity in Dentin Treated with a Chitosan Primer

Abstract

The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth (n = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups (p < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time.

The Influence of Different Bleaching Protocols on Dentinal Enzymatic Activity: An In Vitro Study

“…However, MMPs are covered with apatite nanocrystals during dentin matrix mineralization, leaving them inactive. These proteases remain structurally stable as long as dentin is mineralized, but they can be reactivated after various dental procedures, due to caries, or local radiation therapy [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. The activation of the MMPs occurs through a conformational change in the active site of the enzyme that causes the release of the cysteine residue from the “cysteine switch” and allows the activity of the catalytic site and the cleavage of the substrate [ 23 , 38 ].…”