In vitro validation of carious dentin removed using different excavation criteria.

Purpose: To compare directly the extent of cavity preparation instigated by either clinical hardness or a caries detector dye. Caries removal was histologically validated against the autofluorescence of carious dentin within the same samples.

Methods: 50 human molars were sectioned longitudinally through occlusal lesions, color photomicrographs obtained and the pre-excavation autofluorescent signatures captured using a confocal laser scanning microscope (488 nm excitation, > 515 nm emission). The hydrated lesions were excavated using sterile hand instruments until the dentin cavity surface was hard to a dental probe. Color photomicrographs were obtained and then caries detector dye was then placed in the cavities and excavation continued until no pink stain was visible. Final color photomicrographs were obtained.

Results: Digital image superimpositions indicated that the extent of cavities prepared using the clinical hardness criterion correlated closely to the corresponding autofluorescent signal outlines of the original lesions. Caries detector dye-assisted excavation resulted in over-prepared cavities by as much as 58.2% relative to the validating autofluorescence outline. In conclusion, the use of caries dyes can lead to clinically significant over-preparation of cavities when compared to those prepared using clinical hardness.