Neethu Lekshmi.A, Shelly.E.D
Abstract: Direct bonding revolutionized orthodontic therapy and resin-based adhesives gained the most popularity as a direct bonding agent. However, resin-based composite adhesive systems involve certain amount of enamel demineralization due to the acid etching step involved. Glass ionomer cements (GICs) and amorphous calcium phosphate (ACP) containing resin composites were introduced to overcome this disadvantage but the variability in the bond strengths of these materials have always been topics of discussion. This study was conducted to measure the bond strengths of these materials under in-vivo conditions. Brackets were bonded in vivo using split mouth random technique in 12 patients. The first premolars from the first quadrant, taken as the control group (group1) were bonded with Transbond XT while first premolars from the second and third quadrant were bonded with Aegis Ortho (ACP containing adhesive) and Fuji Ortho light cure (Resin-modified GIC) adhesive respectively. Teeth were extracted after 30 days using periotom to avoid contact with the brackets. An instron universal testing machine was used to measure the shear bond strength at a crosshead speed of 5mm/min. The results of the study were subjected to statistical analysis. Analysis of variance (ANOVA) was used to find the significance of the three study groups and Post-hoc test was used to find the pair wise significance between the three groups. Mean results and standard deviations for the groups 1, 2 and 3 in MPa were 17.15 7.14, 5.593.07 and 12.474.02 respectively. ANOVA test revealed a significant difference between the three groups (P<0.001). Group 1 was significantly different from group 2 (P<0.001) while group 1 and 3 showed only a difference of suggestive significance (P=0.074+). Groups 2 and 3 also showed significant difference from each other (P=0.006) ). This study concluded that the bond strength of Fuji ortho LC was less than Transbond XT but significantly higher than ACP containing adhesive. Aegis ortho had shear bond strength higher than that recommended by Reynolds required for orthodontic bonding. Aegis Ortho and Fuji Ortho LC is potentially adequate for orthodontic bonding needs.
Keywords: Glass ionomer cement, amorphous calcium phosphate, ANOVA, Analysis of variance, Fuji Ortho