Effect of blood contamination and decontamination procedures on marginal adaptation and bond strength of composite restorations

Abstract

Purpose: To evaluate the effect of blood contamination and different decontamination procedures on marginal adaptation and bond strength of a two-step total-etch adhesive system to dentin. Methods: A total of 135 bovine incisors had the labial surfaces ground to receive cylindrical cavities, and were randomly divided into a control and 8 experimental groups (n=15) according to contamination and decontamination procedures. Freshly collected human blood was applied onto the cavity either before or after light-curing of the adhesive. Four decontamination protocols were tested (drying with paper, water rinsing, phosphoric acid etching, and 10% NaOCl rinsing). The cavities were restored with Adper Single Bond and Filtek Z250 (3M ESPE).The specimens were subjected to thermal cycling before the dye staining test. The cavity floor was removed and the restorations were subjected to a push-out test. Data were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results: Blood contamination after adhesive light-curing increased marginal gap and yielded lower push-out bond strength values (P<0.01). Conclusion: Water rinsing seems to be a reliable procedure for cavity decontamination. The decontamination procedures tested do not recover marginal sealing and bond strength when blood contamination occurs after light-curing of the adhesive.