A study on concentration and application time of lithium sulfate-contained polyacrylic acid for adequate crystal growth

Roh, Joung Sub; Kim, Sang Cheol; Tae, Ki Chul

Abstract

The purpose of this study was to compare shear bonding strengths and debonding patterns of the ceramic brackets attached on the crystal which were grown on the enamel surface of a tooth with different concentrations of lithium sulphate-contained polyacrylic acid in different application times. Four kinds of concentrations of mixed solutions were made and applied to the enamel surface on extracted human premolars. The solutions were made by adding 0.3M or 0.6M of lithium sulfate to 50% or 65% of polyacrylic acid with 0.3M sulfuric acid. The solutions were applied for 30 or 60 seconds. After bonding, a universal testing machine was used to measure the shear bond strength, and then observations were made of debonding patterns through the stereoscope. And the enamel surface was observed through the scanning electron microscope to examine the pattern of crystal growth and debonding. The results were as follows: 1, Shear bond strength in the enamel surface treated with 50% polyacrylic acid was higher than that with 65% polyacrylic acid. 2. There were no statistical differences in shear bond strength according to concentration of lithium sulfate and application time of solutions. 3. Enamel surface was almost free of resin debris after debonding. 4. Enamel surface treated with 50% polyacrylic acid showed higher density of crystal growth than that with 65% polyacrylic acid under scanning electron microscope.