The effect of contamination on bonding of orthodontic brackets with a self-etching primer/adhesive

Kim, Yu Shin; Lee, Hyung Soon; Lee, Hyun Jung; Jeon, Young Mi; Kim, Jong Ghee

Abstract

The purpose of this study was to investigate the influence of water, saliva, and blood contamination on the bonding strenght of metal brackets with a self-etching primer/adhesive to enamel. Ninety-six extracted human teeth were divided into four groups. The brackets were bonded to enamel with a self- etching primer (3M/Unitek Dental Products, Monorovia, California) according to one of four protocols. The teeth were bonded in a dry condition (group D) or in contamination with distilled water (group W), artificial saliva (group S), or fresh human blood (group B). Shear bond strengths were tested using an Instron Universal testing machine. After debonding, bracket and tooth surfaces were examined with a stereomicroscope. In each group, four samples were selected and examined with a Scanning electron microscope of the prepared enamel surface and resin-enamel interface. The results obtained were summarized as follows: Shear bond strength in group D (15.22 +/- 2.86 MPa) and W (16.20 +/- 3.85 MPa) were higher than in group B (12.56 +/- 2.94 MPa) (p < 0.05). There were no statistical differences in the shear bond strengths between groups D, W and S (p > 0.05). There was a tendency to have less residual adhesive remaining on the enamel surfaces of group B than group D. The SEM morphology of group D and W showed a more roughened etching pattern than group S and B. Water or saliva contamination on bonding of orthodontic brackets with Transbond plus self etching primer had almost no influence on bond strength. In this study, the blood contaminated group showed the lowest bond strength, but it was above the clinically acceptable bond strength (5.9-7.8 MPa, Reynold, 1975). The results of this study suggest that acceptable clinical bond strengths can be obtained in wet conditions when self-etching adhesives are used.