The effect of a dental unit waterline treatment regimen on the shear bond strength of resin-based composite

Background. Numerous methods of disinfecting dental waterlines have been suggested. This study evaluates the effects of one disinfecting technique on the strength of resin-based composite's bond to enamel and to dentin. Methods. The authors bonded resin-based composite cylinders to enamel and dentin surfaces similarly mounted and prepared using three irrigation solutions. After undergoing acid etching, the tooth surface was rinsed with either distilled water, water from a municipal water source or a mixture of distilled water and mouthwash concentrate, The authors shear-tested the samples and analyzed the data statistically. Results. The group rinsed with distilled water mixed with mouthwash exhibited the lowest shear bond strengths. However, a one-way ANOVA indicated no statistically significant differences in the mean values among the treatment groups for either enamal (P = .295) or dentin (P = .393). Specimens bonded to enamel demonstrated primarily adhesive fracture at the tooth/composite interface. Those bonded to dentin showed a similar pattern, with some sites of cohesive fracture in the resin-based composite. Conclusions. There was no difference in shear bond strengths of resin-based composite to tooth strucrture when rinsed with distilled water mixed with mouthwash, distilled water or water from a municipal source. Clinical Implications. Dental unit waterlines disinfected using a diluted mouthwash solution may be used while bonding resin-based composite to either enamel or dentin.