Effects of blood contamination on resin–resin bond strength

Objective. Incremental placement and curing of resin composites has been recommended. However, this requires longer operating time, and therefore, increased risk of contamination. The purpose of this study was to evaluate the effects of blood contamination on microtensile bond strengths (μTBS) between resin interfaces and to determine the best decontamination method to re-establish the original resin–resin bond strength. Materials. The top surfaces of 64, 4-mm composite blocks (Z-250, Renew, APX, Pertac II) were untreated as the control, or were treated as follows: blood applied and dried on the surface (Treatment 1), blood applied, rinsed, dried (Treatment 2), blood applied, rinsed, and an adhesive applied (Single Bond, One-Step, Clearfil SE, Prompt L-Pop) (Treatment 3). Fresh composite was applied and light-cured in 2-mm increments. After 24 h storage in water, the specimens were sectioned into 0.7-mm thick slabs, trimmed to a cross-sectional area of 1 mm 2, and loaded to failure at a crosshead speed of 1 mm/min using an Instron universal testing machine. Data were analyzed using two-way ANOVA and Fisher's PLSD test ( p