Effect of Acid or Laser Treatment on Degradation of Dentin Matrix

Purpose The objective of this study was to determine the effect of dental laser (DL) irradiation on the metalloproteinases (MMP)-mediated dentin collagen degradation. Methods Human dentin disks were prepared (0.3 × 5x6mm, n = 60) and subjected to different treatments ( n = 10/group): (1) control group (no treatment); (2) application of 37% phosphoric acid (PA) for 15 s; (3) irradiation with Er:YAG laser (120 mJ, 10 Hz); (4) irradiation with Er:YAG laser (120 mJ, 20 Hz); (5) irradiation with Er,Cr:YSGG laser (130mj, 30 Hz); and (6) irradiation with Er,Cr:YSGG laser (80mj, 50 Hz). After treatment, the total MMP activity and dry mass of each beam were measured, and after rehydration, they were incubated in 1 mL calcium- and zinc-containing incubation media for (a) one week and (b) three weeks. After each time point, dry mass changes were reassessed, and the aliquots of the incubation media were analyzed for pyridinoline-cross-link-containing degradation fragment of the C-terminal telopeptide of type I collagen (ICTP) using ELISA kits. All data were compared using ANOVA and Tukey’s test. Results ANOVA showed significant differences among tested groups ( p