Effect of Saliva on Bonding of All-in-one Adhesive treated Dentin

Objectives: This study was to evaluate the influence of saliva contamination on bond strength of all-in-one adhesive treated dentin and find out a suitable technique for improving bond strength. Materials and Methods: 35 extracted human molars with the occlusal superficial dentin exposed and divided into 7 groups: Group 1: G-Bond application under manufactory's instructions (control); Group 2: saliva contamination after G-Bond application, drying and light-curing; Group 3: the same as Group 2, washing and drying; Group 4: saliva contamination after light-curing of G-Bond, drying; Group 5: the same as Group 4, washing and drying; Group 6: the same as Group 3 with re-application of G-Bond. Composite resin (Solare) was piled onto the surface to 4mm in thickness, light-cured, immersed in water (37˚C, 24h) and sectioned to 1mm x 1mm sticks for microtensile test at a crosshead speed of 1.0 mm/min. The fractured surfaces of each specimen and resin-dentin interface of each group were observed by SEM to calculate the failure ratio. One-way ANOVA and Fisher's PLSD test were performed for statistic analysis. Results: The bond strength of Groups 2 and 3 were lower than Groups 1, 4 and 5 with no significance, whereas Group 6 showed significantly higher bond strength than other Groups. The fractured surfaces among Groups 1-5 showed in adhesive failure while no adhesive failure seen in Group 6. Conclusion: The results indicate that saliva contamination decreases the bond strength to dentin while this shortcoming can be recovered by re-application of adhesive to enhance the bond strength.