Dental unit waterline antimicrobial agents': Effect on dentin bond strength

Background. In response to concerns of bacterial biofilm colonization of dental unit waterlines, a wide range of commercial intermittent and continuous chemical treatments for dental unit waterlines have been developed and marketed. There has been little research on the possible effect of continuous chemical treatment regimens on dentin-bonding agents. The authors evaluate the effect of four proposed antimicrobial agents used in dental unit waterlines on dentin bond strength. Methods. The authors used a fifth-generation dentin-bonding agent to bond composite cylinders to molar dentin surfaces. They then used selected antimicrobial agents as rinsing agents after conditioning. The composite cylinders were shear tested, and their fracture strengths were compared statistically. Results. All proposed antimicrobial agents reduced dentin bond strength. Proposed waterline treatment regimens of a diluted mouthrinse and chlorhexidine significantly reduced dentin bond strength compared with sodium hypochlorite and citric acid regimens. Conclusion. Dental professionals should be aware of potential interactions between dental unit waterline antimicrobial agents and dentin-bonding agents. Further research in this area is warranted, as the clinical implications are uncertain at this time. Clinical Implications. Dental unit waterline antimicrobial agents may adversely affect dentin bonding strength.