Comparison of Adhesive Remnant Index and Shear Bond Strength in Different Orthodontic Bonding Materials

Bond strength and adhesive remnant index (ARI) have been used to evaluate orthodontic materials. Objectives: It was the aim of this study to compare bond strength and ARI of traditional two-step orthodontic adhesives with one-step adhesives in both resin and resin-modified glass ionomer (RMGI) systems. Methods: Extracted third molars were randomly assigned to each of 4 groups (n=13). Traditional resin composite adhesive (Transbond XT) with acid etch and primer steps was used as the control (Group A) and a one-step self-etch/primer (SE) was also used with this adhesive (Group B). A RMGI adhesive (Fuji Ortho) was used in the traditional manner with its conditioner (Group C) and the RMGI was also used with the SE used in Group B (Group D). The teeth were mounted in acrylic resin leaving buccal surfaces exposed for bond strength testing. The enamel surfaces were treated according to manufacturer’s specifications, adhesive was applied to each prepared surface by dispensing the material into a cylindrical stainless steel mold (0.5 mm diameter), and the specimens were light-cured. The samples were shear-loaded with an Instron Testing Machine at a crosshead speed of 0.5mm/min and the data were analyzed with ANOVA and Tukey HSD (a =0.05). The buccal surfaces were then evaluated under 20x light microscopy and the ARI score (a 0-3 ordinal scale) was recorded and Sign test performed (a=0.05). Results: Mean bond strengths (MPa) were: A=5.79, B=12.93, C=8.32, D=8.05. Median ARI scores for each of the groups were: A=0, B=0, C=1, D=2. Bond strength from group B was significantly greater than the other 3 groups. Conclusions: While there were statistical differences within the ARI and shear bond strength data, there was no correlation between mean bond strength and ARI index in the orthodontic bonding materials investigated. Supported in part by UDMSD student project grant. theresacutler@hotmail.com.