A Comparison of shear Bonding Strength with Polyacrylic acid and Phosphoric acid Enamel Surface Conditioning

Roh, Joung Sub; Kim, Sang Cheol

Abstract

The purpose of this study was to compare in vitro shear bonding strength with three different enamel surface preparations: (1) 30% sulfated polyacrylic acid with 0.3M lithium sulfate (2) 40% sulfated polyacrylic acid with 0.3M lithium sulfate (3) 37% phosphoric acid. 105 extracted human premolar teeth were divided into each three groups of 35. Metal brackets were bonded to teeth in the three groups. The same self curing resin was used for all groups. A shearing force was applied to the teeth. After debonding, bases of bracket and enamel surfaces were examined under steroscopic microscope to determine the failure modes. Statistical analysis of the data was carried out with one way ANOVA and Student t-test. The results were as follows. 1. Shear bond strength values for the 30% polyacrylic acid and 40% polyacrylic acid group were approximately two thirds of the phosphoric acid group. It maintains clinically acceptable but not enough bond strength. 2. There was no statistically significant difference in shear bond strengths between 30% and 40% polyacrylic acid group. 3. The failure modes of brackets had some differences. In polyacrylic acid groups, the percentage of adhesive/enamel failure was higher than that of adhesive/bracket interface failure. On the contrary in phosphoric acid groups, the results were reversed. Further study of bond strength could be required. If polyacrylic acid enamel conditioning is used clinically.