Effect of phosphoric acid on the degradation of human dentin matrix

This study determined if dentin proteases are denatured by phosphoric acid (pa) used in etch-and-rinse dentin adhesives. dentin beams were completely demineralized with edta for 30 days. we acid-etched experimental groups by exposing the demineralized dentin beams to 1,10,or 37 mass% pa for 15 sec or 15 min. control beams were not exposed to pa but were incubated in simulated body fluid for 3 days to assay their total endogenous telopeptidase activity,by their ability to solubilize c-terminal crosslinked telopeptides ictp and ctx from insoluble dentin collagen. control beams released 6.1 ± 0.8 ng ictp and 0.6 ± 0.1 ng ctx/mg dry-wt/3 days. positive control beams pre-incubated in p-aminophenylmercuric acetate,a compound known to activate prommps,released about the same amount of ictp peptides,but released significantly less ctx. beams immersed in 1,10,or 37 mass% pa for 15 sec or 15 min released amounts of ictp and ctx similar to that released by the controls (p > 0.05). beams incubated in galardin,an mmp inhibitor,or e-64,a cathepsin inhibitor,blocked most of the release of ictp and ctx,respectively. it is concluded that pa does not denature endogenous mmp and cathepsin activities of dentin matrices. © 2013 international & american associations for dental research.