Correlation between fissure discoloration, Diagnodent measurements, and caries depth: an in vitro study

This in vitro study was performed to correlate the presence of discoloration on occlusal surfaces with its histological depth and assess its influence on Diagnodent measurements in a group of permanent and primary teeth.

Ninty-five primary and 95 permanent third molars were randomly selected from a pool of macroscopically intact teeth. One site of the fissure on each occlusal surface was selected and categorized according to its discoloration. Each site was measured 3 times with Diagnodent. The teeth were prepared histologically and evaluated according to their caries extent under a microscope (final magnification x 12.8).

In the group of permanent teeth with dark brown or black discoloration (N=23), 13% showed dentinal caries, 57% were sound or had an initial enamel lesion, and 30% had a deep enamel lesion. In the group of primary teeth with dark brown and black discoloration (N=19), 42% presented dentinal caries, 42% showed deep enamel caries, and 16% had an initial enamel lesion. The difference between permanent and primary teeth was statistically significant (P<.05). Discolored fissures showed higher Diagnodent values than nondiscolored or opaque fissures in both groups (independent of their caries status).

The presence of brown or dark spots on fissures were not useful for the prediction of dentinal caries for permanent teeth. In primary teeth, however, a higher correlation between fissure discoloration and dentinal lesions was found. Diagnodent tends to overscore discolored surfaces.