Effects of tetracycline hydrochloride on measurements with the laser fluorescence device DIAGNOdent: in vitro and in vivo studies.

Dental materials that fluoresce affect the reading of the laser fluorescence device DIAGNOdent. Tetracycline hydrochloride (TCH) shows fluorescence and is retained in teeth. The aim of this study was to evaluate the effects of TCH on the DIAGNOdent reading. Filter-paper discs that contained various amounts of TCH were prepared (0.16-10 mg per disc). One-day-old newborn rats were subcutaneously injected with TCH for 29 days, and their mandibles were then removed. The DIAGNOdent values (D-V) of the discs and first molars of the rats were measured before and after they were subjected to ultraviolet irradiation (UV). The D-V of discs containing TCH increased depending on the amount of TCH. The D-Vs of discs with lower amounts of TCH (0.16-1.25 mg) were approximately 10-15, and these values increased to 30-40 under UV. In addition, the D-Vs of molars after UV were twofold greater than those before UV. These results suggest that TCH might affect the readings obtained by DIAGNOdent.