Detection of occlusal caries with impedance spectroscopy and laser fluorescence before and after placement of fissure sealants: An in vitro study.

Purpose: To (1) investigate the influence of fissure sealants on impedance spectroscopy (ACIS) and laser fluorescence (LF) readings, (2) compare the performance of the ACIS device with the LF technique and visual inspection (ICDAS) in permanent molars with various degrees of occlusal caries, and (3) validate all methods against radiographs and histological hemi-sectioning.

Methods: 102 permanent molars were randomly selected to represent different stages of occlusal caries, from clinically sound to minor cavities. The teeth were examined by one trained examiner and scored with CarieScan PRO, the DIAGNOdent pen and ICDAS at baseline, after bleaching, etching and placement of a clear fissure sealant. A digital radiograph was exposed at baseline. After the assessments, the actual lesion depth was histologically determined.

Results: Bleaching did not affect the readings but significantly higher ACIS and LF-pen values were recorded after acid etching (P< 0.05). The placement of a fissure sealant increased the LF-pen readings significantly (P< 0.05) while no values could be obtained with the ACIS device. Both the baseline ACIS and LF-pen values were significantly associated (P< 0.05) with the lesion depth but visual inspection displayed the best correlation with radiographs and histology. The ACIS technology displayed high sensitivity and specificity for detecting extensive occlusal lesions.

Clinical Significance: The findings demonstrated that placement of a fissure sealant had a significant impact on the ACIS and LF-pen readings. Both methods mirrored the actual histological and radiographic lesion depth to various extents but could not match the performance of visual inspection.