Method: The dentin powder was prepared from extracted human third molars and divided into 10 groups. Two lots of dentin powder were treated with water as control (Group BC and Group I). Four were treated with 37% phosphoric acid (37%-H), 10% phosphoric acid (10%-H), 10% maleic acid (MA) or 2.5% Oxalate (O). Two lots were treated with etch-and-rinse adhesives, Single Bond 2(SB) or Prime & Bond(PB) respectively. Another two were mixed with SE Bond primer (SE) or Easy One (EO). After treatments, the proteins of each group were extracted. The total cathepsin activities in the extracts of each group were monitored spectrofluorometrically by the cathepsin-specific fluorogenic substrate Z-FR-MCA in a fluorescence reader (a specific inhibitor of cathepsin was introduced in Group I as negative control).
Result: The cathepsin activities of Group 37%-H, 10%-H, MA, O, SB, PB, SE, EO, I were 8%, 16%, 12%, 24%, 24%, 16%, 766%, 195%, 11% of the blank control group respectively (P<0.05). The 4 acid-etching groups and 2 etch-and-rinse adhesive-treating groups showed significantly proteolytic activity reduction of the blank control group(P<0.05). But there were no significant difference between those group (P>0.05). Treating the dentin powder with SE Bond primer or Single Bond 2 resulted in cathepsin activity increase, while the Group SE exhibited a higher increase (P<0.05).
Conclusion: The activities of cathepsins could be detected in dentin powder. Acid-etching or etch-and-rinse adhesives may reduce the activities of endogenous cathepsins in dentin. The self-etching adhesives may increase the proteolytic activity.