Validation of micro-CT against the section method regarding the assessment of marginal leakage of sealants

Background: The aim of this study was to validate the micro-CT and related software against the section method using the stereomicroscope for marginal leakage assessment along the sealant-enamel interface. Methods: Pits and fissures of the occlusal surface of 10 teeth were sealed with a resin-fissure sealant material without acid etching, thermocycled for 5000 cycles, immersed in 50% silver nitrate for three hours and scanned using micro-CT. Teeth were embedded in epoxy resin and cut in three sections. The middle section was subjected to micro-CT and stereomicroscopy. Images were taken from the left and right sides of the sealant-enamel interface at both the left and the right site of the section. Two experienced evaluators assessed marginal leakage. Results: Both assessment instruments observed no leakage in 37 out of the 40 images evaluated. Leakage at the sealant-enamel interface was observed in three stereomicroscopy images only. A fracture line in the sealant was seen on eight stereomicroscopy images and observed in only two micro-CT images. Conclusions: The quality of the micro-CT and related software used in the present study does not qualify it to replace the section method as the gold standard for marginal leakage assessment at the sealant-enamel interface of permanent teeth.