pH changes of self-etching primers mixed with powdered dentine

Abstract 

Objectives

The purpose of this study was to examine the pH changes of self-etching primers mixed with dentine powder.

Methods

Four self-etching primer adhesive systems were used: Clearfil SE Bond, Imperva Fluoro Bond, Mac Bond II, and Unifil Bond. Dentine discs obtained from extracted bovine incisors were milled and pulverized into a fine powder. The dentine powder was then mixed with solutions of self-etching primers diluted with distilled water. The pH changes of the primer–dentine powder mixtures were measured by a solid-state pH sensor connected to a pH meter at time points 10, 20, 30, 60, 120, 180, 300, and 600s after the start of mixing. Data were analyzed by the Tukey HSD test and the Dunnett test at a significance level of 0.05.

Results

The baseline pH values of the self-etching primers ranged from 1.83 to 2.34, with Mac Bond II exhibiting a significantly lower value than the other three products. After mixing with the dentine powder, the pH values significantly increased, ranging from 6.95 to 7.37 at 600s after mixing; there were no significant differences in these values among the self-etching primers used. An insoluble precipitate was formed in the case of Clearfil SE Bond, indicating a chemical reaction between the functional monomer and the dentine powder.

Conclusions

The dentine has a strong buffering capacity against the acidity of self-etching primers.

Keywords: Dentine, Self-etching primer, pH, Buffering action, Functional monomer, Insoluble precipitate, In vitro test, Adhesion, Bovine tooth, Solvent