The Significance of the Positional Relationship Between the Surface of the Dentin Substrate and the Bonding Agent on the Bond Strength to Dentin

Abstract

60 non carious, extracted human teeth were used in this study, for evaluating the shear bond strength of composite resin to dentin using the all in one adhesive system (prompt L-Pop). All teeth were divided into four groups to represent four different surface substrate inclinations. Analysis of variance (ANOVA) test was performed to assess the presence of significant differences in mean shear bond strengths at different surface substrate inclinations (whether the different inclinations of surface substrate produced significant effect on the mean shear bond strengths). Student-Newman-Keuls test and the least significant difference procedure were used for pair wise comparison between means to find out which means were significantly different. The above tests were separately performed for the groups of specimens that were immediately investigated; those that were stored for one week and those that were stored for one month. ANOVA test, also, was performed to study the effect of time on the shear bond strengths of all groups of specimens at each substrate inclination through all time periods. results: Within each time period, the results revealed that different inclinations of surface substrate produced statistically significant changes in the mean shear bond strengths, (P < 0.001). The mean shear bond strengths of the group of specimens to which the application of the adhesive system was performed with the occlusal plane of the lower jaw of the phantom head parallel to the floor (group A 4 ), were significantly higher than the other 3 groups (P < 0.05). Group A 2 (the group of specimens to which the application of the adhesive system was performed with the occlusal plane of the upper jaw of the phantom head making a forty five degree angle with the floor), came next. The ranking of groups according to the mean shear bond strengths was : A 4 > A 2 > A 1 > A 3 . Regarding the effect of storage time (one week and one month) on the mean shear bond strengths of the adhesive system used, it was found that there were no significant differences among the shear bond strengths of any of the tested groups, at any substrate inclination, through all time periods (T 0 , T 1 , T 2 ) (P > 0.05).