Red biofluorescence revealed by dental bleaching in discolored pits and fissures of occlusal caries.

Objective: Distinguishing between cariogenic and noncariogenic discoloration is crucial to avoid unnecessary removal of dental tissue. This study aimed to investigate the efficacy of biofluorescence bleaching (BF-bleaching) for identifying cariogenic discoloration in human teeth with naturally discolored pits and fissures.

Methods: Sixty-nine extracted human permanent teeth with discolored pits and fissures associated with suspected occlusal caries were included. A dental bleaching agent (15% HO, BeauTis 15 whitening gel, Osstempharma, Seoul, Republic of Korea) was applied in 5-minute intervals for 20 mins. Pit and fissure sites (n = 197) were classified as noncariogenic discoloration (NCD) or cariogenic discoloration (CD) based on histological findings. CD was further divided by the presence of red biofluorescence before bleaching as masked and exposed CD. Biofluorescence was quantified using red biofluorescence intensity (ΔR) and hue angle (h°). Their diagnostic performance was also assessed, including sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC).

Results: Prebleaching ΔR values were significantly lower in the NCD and masked CD groups (p < 0.001). ΔR in masked CD increased by 15% after 5 mins (p < 0.001), becoming similar to those in exposed CD. ΔR in NCD and exposed CD showed no significant changes at any time point. The h° value of masked CD decreased by 2.05°, shifting from orange to red after 20 mins. In contrast, the h° of NCD group remained stable within the orange hue range. After 5 mins, ΔR sensitivity increased from 0.79 to 0.90, and h° AUC improved from 0.69 to 0.93.

Conclusion: Bleaching of pits and fissures exhibiting caries-related discoloration effectively removes the overlying stains, revealing the lesion's underlying red biofluorescence. Thus, BF-bleaching can be a useful method for the objective diagnosis and monitoring of cariogenic discoloration.

Clinical Significance: Using BF-bleaching for accurate evaluation of CD will help provide minimally invasive preventive and treatment options.