Validation of DIAGNOdent for quantification of smooth-surface caries: an in vitro study

The aims were 1) to validate a laser-based device, KaVo DIAGNOdent, for qua ntification of caries lesions on smooth surfaces, using histopathologic and microradiographic analyses as the gold standard, and 2) to test inter- and intra-observer agreements. We also investigated the influence on DIAGNOden t readings of the storage medium used for extracted teeth. Two observers me asured independently the tooth surfaces of 40 extracted premolars that had been stored in the thymol-saturated saline. After subsequent storage in neu tral-buffered formalin for 14 days they were re-measured. The teeth were th en sectioned for histopathologic and microradiographic analysis. The Spearm an rank correlation coefficients between lesion depth and DIAGNOdent readin gs were 0.78-0.83 and 0.85 for teeth stored in thymol-saturated saline and formalin, respectively. Inter- and intra-observer agreements were 0.91 and 0.95 when die teeth were stored in thymol-saturated saline. The DIAGNOdent reading was almost 1.5 times higher for teeth stored in formalin than for t hose stored in thymol saline. The Spearman rank correlation coefficient bet ween mineral loss in enamel (DeltaZ) and DIAGNOdent readings ranged from 0. 01 to 0.08. It was concluded that DIAGNOdent may be helpful for assessing s mooth-surface caries, bur thc cut-off points need to be assessed under clin ical conditions. The increase in fluorescence associated with storage of te eth in formalin warrants further investigation.