Effect of Pretreatment With Quaternary Ammonium Silanes on Dentine Protease Activity

Objectives: Dentine matrices release ICTP and CTX fragments during collagen degradation. This study evaluated the effect of dentine pretreatment with Quaternary Ammonium Silanes (QAS) cavity disinfectants on matrix metalloproteinases (MMP) and cathepsin K-mediated collagen degradation.
Methods: Dentine beams (1 mm × 2 mm × 6 mm) were demineralized in 10 wt% H₃PO₄ for 24 h at 25^oC. After baseline measurements of dry mass, beams were divided into 5 groups (n = 10/group) according to the disinfectants. The beams were pre-treated for 5 min with 2% QAS, 5% QAS, 10% QAS; 2% chlorhexidine (CHX), and control (no pretreatment), blot-dried and incubated in 1 mL calcium and zinc-containing medium (pH7.2) at 37^oC for 3, 7 or 14 days. After incubation, the change in dry mass was calculated and aliquots of the incubation medium were analyzed for collagen C-telopeptides, ICTP and CTX using ELISA kits. Data was analyzed using two-way ANOVA and post hoc Tukey multiple test.
Results: The two factors (disinfectants and time) had significant effect on dry mass loss, ICTP and CTX release (p<0.001). The rate of dry mass loss increased with time and was significantly lower in the experimental groups (2% CHX, 2% QAS, 5% QAS, 10% QAS) when compared to control (p<0.001). No significant difference in dry mass loss was observed among the experimental groups at 7 and 14 days. The ICTP release decreased significantly with increasing QAS concentration at 7 days (p<0.001). No significant difference in ICTP and CTX release was observed among the experimental groups at 14 days.
Conclusions: Quaternary ammonium silanes tested in this study can be good inhibitors of matrix metalloproteinases and cathepsin K activities in dentine.