Autofluorescence — a potential method for the in vitro validation of carious dentine

Key Points

• Carious dentine excavation is an essentially subjective procedure.

• The hardness of carious dentine is an in vivo parameter that should be used to help guide tissue removal.

• The autofluorescence of carious dentine is an objective, reproducible, in vitro parameter that correlates well with the microhardness of carious dentine.

• This autofluorescence has the potential to be used as an in vitro validation method for carious dentine requiring excavation.

Abstract

Objective

An in-vitro study to examine the correlation between the distribution of the autofluorescent signal emitted from carious dentine (detected using confocal laser scanning microscopy) and its microhardness, within the depths of human dentine lesions.

Materials and methods

Twelve carious teeth were sectioned longitudinally, the cut faces marked with a grid reference line system and colour photomicrographs taken. The same samples were imaged using confocal laser-scanning microscopy for autofluorescence and then subjected to microhardness testing using a Knoop microhardness indenter. Adjacent sound dentine was used as a control reference. Digital image superimposition allowed direct comparisons to be made between the colour, autofluorescence and microhardness of each lesion.

Results

Sound enamel and dentine did not autofluoresce. Autofluorescence distribution from carious dentine correlated with the highly softened tissue (detected using the Knoop indenter) and terminated at a level superficial to the translucent zone. This zone was still pigmented. Normal, sound dentine hardness levels were found deep to the translucent zone.

Conclusions

A correlation existed between the zone of autofluorescence and carious dentine that was markedly softened by the carious process. These findings highlighted a possibility that the autofluorescence might be used as an in-vitro, objective histological marker for the softened, carious dentine requiring clinical excavation.

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