In Vitro Red Fluorescence as an Indicator of Caries Lesion Activity

This in vitro study examined the utility of comparing red fluorescence between active and inactive caries lesions and investigated whether changes in red fluorescence and fluorescence loss are influenced by lesion activity following remineralization. Sixty-two noncavitated smooth surface caries lesions on extracted human teeth were classified into active or inactive lesions using the Nyvad system prior to a 12-day pH-cycling procedure. Quantitative light-induced fluorescence-digital images were used to measure fluorescence parameters before and after pH cycling. At baseline, the intensity (ΔR) and area (A_ΔR) of red fluorescence were 1.5- and 2.2-fold higher in active lesions than in inactive lesions (p<0.05). The ratio of A_ΔR to lesion area was associated with classification of active lesions (odds ratio = 1.031; 95% confidence interval = 1.005-1.058). After pH cycling, the active lesions showed about 2- and 8-fold greater reductions in the median values of A_ΔR and fluorescence loss related to lesion volume (ΔQ) compared with inactive lesions (p<0.05). In conclusion, red fluorescence differs depending on lesion activity, and the red fluorescence area and lesion volume change following remineralization. The results suggest that measuring red fluorescence may be a useful way of objectively evaluating lesion activity of smooth surface lesions.