Effect of pretreatment with collagen crosslinkers on dentin protease activity

Objectives This study evaluated the effect of dentin pretreatment with collagen crosslinkers on matrix metalloproteinase (MMP) and cathepsin K mediated collagen degradation. Methods Dentin beams (1 mm × 2 mm × 6 mm) were demineralized in 10% H₃PO₄ for 24 h. After baseline measurements of dry mass, beams were divided into 11 groups (n = 10/group) and, were pretreated for 5 min with 1% glutaraldehyde (GA); 5% GA; 1% grape-seed extract (GS); 5% GS; 10% sumac (S); 20 μM curcumin (CR); 200 μM CR; 0.l% riboflavin/UV (R); 0.5% R; 0.1% riboflavin-5-phosphate/UV (RP); and control (no pretreatment). After pretreatment, the beams were blot-dried and incubated in 1 mL calcium and zinc-containing medium (CM, pH 7.2) at 37°C for 3, 7 or 14 days. After incubation, dry mass was reassessed and aliquots of the incubation media were analyzed for collagen C-telopeptides, ICTP and CTX using specific ELISA kits. Data were analyzed by repeated-measures ANOVA. Results The rate of dry mass loss was significantly different among test groups (p < 0.05). The lowest 14 day mean dry mass loss was 6.98% ± 1.99 in the 200 μM curcumin group compared to control loss of dry mass at 32.59% ± 5.62, p < 0.05, at 14 days. The ICTP release over the incubation period (ng/mg dry dentin) ranged between 1.8 ± 0.51 and 31.8 ± 1.8. CTX release from demineralized beams pretreated with crosslinkers was significantly lower than CM (5.7 ± 0.2 ng/mg dry dentin). Significance The results of this study indicate that collagen crosslinkers tested in this study are good inhibitors of cathepsin K activity in dentin. However, their inhibitory effect on MMP activity was highly variable.