Oxidising agents and its effect on human dentine fluorescence diagnostic measurements

BACKGROUND: The ability to determine the effectiveness of root canal disinfection in real-time prior to the final root filling could significantly influence the management and treatment outcomes of root canal therapy. Laser fluorescence devices can detect bacterial fluorescence in real-time, however since quenching of fluorescence is a possible confounding factor, this study explored the effects of oxidising endodontic irrigants on laser fluorescence in dentine. METHODS: A total of 78 transverse 2 mm thick sections were prepared from the crowns of sterilised extracted non-functional third molars that had been embedded in acrylic resin. The dentine sections where then treated with different concentrations of sodium hypochlorite and hydrogen peroxide, with or without further rinsing with distilled water wash. Fluorescence values were recorded over 24 h using the DIAGNOdent laser fluorescence device. RESULTS: Both sodium hypochlorite and hydrogen peroxide cause quenching of fluorescence readings of human dentine, with reductions of 30-60% in fluorescence readings. The quenching effect occurred quickly, and recovery to baseline readings took from 1 h to 24 h. Rinsing with water reduced but did not eliminate the quenching effect. CONCLUSION: The use of laser fluorescence to reliably detect root canal bacteria porphyrins in real-time could significantly influence the management of teeth needing root canal therapy. This study highlighted the quenching effects of some root canal irrigants on human teeth root dentine, a variable that should be considered and controlled prior to using lasers to assist in assessing root canal sterility.