Effect of Phosphoric Acid on the Degradation of Human Dentin Matrix

: Tezvergil-Mutluay A, Mutluay M, Seseogullari-Dirihan R, Agee KA, Key WO, Scheffel DLS, Breschi L, Mazzoni A, Tjaderhane L, Nishitani Y, Tay FR, Pashley DH

Publisher: SAGE PUBLICATIONS INC

: 2013

: Journal of Dental Research

: JOURNAL OF DENTAL RESEARCH

: J DENT RES

: 1

: 92

: 1

: 87

: 91

: 5

: 0022-0345

DOI: https://doi.org/10.1177/0022034512466264

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.