Changes in Diagnodent Scores in Smooth Surface Enamel Carious Lesions in Primary Teeth: A Longitudinal Clinical Study

Purpose: To evaluate correlations between Diagnodent laser fluorescence readings and clinical scores for smooth (buccal and lingual) surfaces of primary canines and molars, with particular interest in white spot lesions.Materials and Methods: A total of 17,088 primary molars and canines in 712 children aged 5 to 7 years residing in the Bayside Health Service District, Queensland, Australia were examined on an annual basis over a 3-year period by one calibrated examiner. Clinical scores and Diagnodent readings were assigned after overlying deposits of plaque had been removed.Results: Data from a total of 33,029 sites were subjected to frequency analysis using SPSS. Combining buccal and lingual surfaces together, the mean Diagnodent values were: sound (ICDAS 0): 3.3; visible white spot lesion (ICDAS 1+2): 7.7; decay with cavitation into dentine (ICDAS code 5): 37.2; and gross decay with an open cavity (ICDAS code 6): 62.0. Diagnodent scores did not, however, follow Gaussian distributions. White spot lesions showed a significant increase in Diagnodent scores, compared with sound enamel. Longitudinal analyses showed a similar proportion of sites which worsened in both caries score and in Diagnodent score. The same was true for sites which showed improvement over time, indicative of reversal, where Diagnodent scores reduced by 10 or more.Conclusions: This large-scale clinical study establishes that there is a progression in laser fluorescence scores with increasing severity of smooth surface enamel lesions in primary teeth, from sound smooth surface enamel through white spot lesions and subsequently to cavitation; however, the Diagnodent should not be relied on as the sole means for caries diagnosis because of the possibility of false positive readings if plaque remains on the surface. The joint findings of increased scores with incipient decalcified lesions affecting enamel, and changes in readings aligning with caries reversal or progression lend some support to the clinical use of Diagnodent as an aid in monitoring the progress of early stages of the caries process on smooth surfaces.