Effect of Triple Antibiotic Paste on Bond Strength of Composite to Dentin: An In Vitro Study

Considering the increasing use of antibiotics in root canal therapy and the possible effects of intracanal medicaments on the bond strength of composite restorations, the aim of this study was to evaluate the effect of triple antibiotic paste on shear bond strength of three types of composite resins to dentin. In this in-vitro, experimental study, the enamel of 60 extracted premolars was ground parallel to the longitudinal axis of the teeth in order to produce flat dentin surfaces (5 mm2 minimum surface area). The samples were divided into six groups. In the control group, dentin surfaces were stored in saline solution and in the experimental groups, dentin surfaces were exposed to triple antibiotic paste for 10 days. After washing and drying, Single Bond was applied for dentin bond to Z100 and Z350 composites. Adhesive resin was used for bond to to P90 composite. Composites were applied on the dentin surfaces in six groups and cured in four directions. The shear bond strength was measured by Instron machine. The data were analyzed by t-test, one-way ANOVA and Tukey’s test. The highest mean shear bond strength was found in Z350 composite group following the use of triple antibiotic paste (38.75 MPa) and the lowest mean strength was found in Z100 composite group following the use of triple antibiotic paste (14.64 MPa). The mean shear bond strength of P90 and Z100 composites (in contrast to Z350 composite) was higher in the saline compared to the triple antibiotic paste groups (P=0.1). The differences between saline and antibiotic groups were not significant (P=0.959) but the difference in this regard among the three types of composites was significant. The results of this study showed that use of triple antibiotic paste has no effect on the shear bond strength of composite to dentin but the type of composite significantly affects the shear bond strength.