Effect of blood contamination with 1-step self-etching adhesives on microtensile bond strength to dentin
Howard E. Strassler, DMD
Yoo HM, Pereira PN. Oper Dent. 2006;31(6): 660-665.
This study evaluated the effect of blood contamination and decontamination methods on the microtensile bond strength of 1-step self-etching adhesive systems to dentin contaminated after adhesive application and light curing. Three commercially available “all-in-one” adhesives (One Up Bond F, Xeno III, and Adper Prompt L-Pop) and 1 resin composite (Clearfil AP-X) were used. Third molars that had been stored in distilled water with 0.5% thymol at 4°C were ground with #600 SiC paper under running water to produce a standardized smear layer. The specimens were randomly divided into groups according to the 3 adhesive systems. The adhesive systems were used under 3 conditions: no contamination, which was the control (C); contamination of the light-cured adhesive surface with blood and re-application of adhesive (Contamination 1) and contamination of the light-cured adhesive surface with blood, then washing, drying, and re-application of the adhesive (Contamination 2). Following light curing of the adhesive, the resin composite was placed in 3 increments up to a 5-mm-thick layer on the bonded surface. All specimens were stored in distilled water at 37°C for 24 hours. The microtensile bond strength was measured using a universal testing machine (EZ test), and data were analyzed by 1-way ANOVA followed by the Duncan test to make comparisons among the groups (p = 0.05). After debonding, 5 specimens were selected from each group and examined in a scanning electron microscope to evaluate the modes of fracture. For all adhesives, contamination groups showed lower bond strength than the control (p < 0.05). There was no statistically significant difference among the control groups (p > 0.05). For Xeno III and Adper Prompt L-Pop, contamination group #2 showed the lowest bond strength among the groups (p < 0.05). For One Up Bond F, contamination group #2 showed higher bond strength than contamination group #1 but showed no statistical significance between them (p > 0.05).
Controlling the operative field when placing adhesive restorations has always been a critical element to achieve clinical success. Although dental dam isolation affords the best opportunity to control the field, there are many times when it is difficult to place. When the preparation is at the gingival margin or subgingival, alternative methods of isolation may need to be employed. Sin-gle-step self-etching adhesives have become more popular because of the reduction in the number of steps for the adhesive procedure, which in turn reduces the risk of contamination during restoration placement.
This study provides some insight into one of the major challenges that face a clinician during adhesive restoration placement—blood contamination with a 1-step self-etching adhesive. The assumption that rinsing, drying, and reapplying the adhesive will counteract any contamination needed to be evaluated with these adhesives. This study compared three different 1-step self-etching adhesives following three different protocols—no contamination, contamination with blood and reapplication, and contamination with blood then washing, drying, and reapplication. For the three adhesives tested, all had a significant drop-off in adhesion to dentin after both contamination protocols. Neither method of treatment with adhesive brought the bond strength values back to the values achieved with an uncontaminated surface. Based on this study, blood contamination of a tooth preparation should be avoided at all costs during the adhesive procedure when using a 1-step self-etching adhesive.
|About the Author|
Howard E. Strassler, DMD