Zahra Jaberi Ansari
Maryam Moezzizadeh
Haleh Valizadeh Haghi

Background: Blood contamination could interfere with the bonding of resin materials to different substrates. Objectives: The purpose of this study was to evaluate the effects of various methods of removing blood contamination between composite resin increments on resin-resin micro-shear bond strength. Methods: ۹۰ composite blocks (Valux Plus, ۳M ESPE) measuring ۲ × ۲ × ۸ mm were prepared in ۶ groups: one group was not contaminated as the control (group ۱); for other groups the surface was contaminated with blood then rinsed and dried. One group only received this treatment (group ۲) and others were etched with phosphoric acid (group ۳), phosphoric acid and a bonding agent (Margin Bond, Coltene) (group ۴), cleaned with ۹۸% ethanol (group ۵), and had ۰.۵ mm of their outer surface removed (group ۶). Next, the second increments of composite were applied in the form of cylinders of ۰.۷ mm diameter and ۱ mm height on the top surfaces of the specimens and were then light cured. Specimens underwent micro-shear bond strength testing. Data were analyzed by Kolmogorov-Smirnov and analysis of variance (ANOVA) tests. Results: The mean value of bond strength was ۲۳ ± ۳.۶۰ MPa for the control group, ۱۷.۸۹ ± ۶.۵۲ MPa for group ۲, ۱۹.۴۰ ± ۶.۰۸ MPa for group ۳, ۲۰.۲۰ ± ۵.۷۲ MPa for group ۴, ۲۰.۰۱ ± ۶.۸۳ MPa for group ۵, and ۱۹.۱۰ ± ۶.۲۰ MPa for group ۶. There were no significant differences between the groups. Conclusions: All the decontamination methods in this study could increase the resin-resin bond strength to the level of the control group.