Grey levels and radiolucent lesion depth as cavity predictors for approximal dentin caries lesions in primary teeth

OBJECTIVES: This study investigated grey levels and radiolucent lesion depth as cavity predictors for approximal dentin caries lesions in primary teeth. METHODS: 51 children (4-10 years old), presenting with radiolucency in the outer half of the dentin on the approximal surfaces of deciduous molar teeth and approximal anatomic contact with the adjacent tooth (without restoration or cavitated caries lesion), participated in the study. Bitewing radiographs were made, and temporary tooth separation was performed and an impression taken to detect cavitation. Radiographs were scanned (300 dpi) and grey levels were measured in carious and sound dentin. Impressions were also scanned and the size of cavity opening was measured in square millimetres. RESULTS: Grey levels of carious dentin (115.27+/-33.52) were significantly lower compared with sound dentin (151.88+/-30.99). No significant differences were observed in the dentin degree of radiolucency between "cavitated" and "non-cavitated" carious dentin. Cavitated lesions showed deeper radiolucent lesions compared with non-cavitated ones (P=0.03). There was no association between the size of cavitation and radiolucent lesion depth. CONCLUSIONS: Grey levels did not indicate cavitation in the outer half of the approximal dentin lesions. However, extension of a radiolucent lesion deep into the outer half of the dentin was associated with cavitated lesions independently of the size of cavitation. A computer-aided image analysis may help clinicians in monitoring caries progression and evaluating the probability of occurrence of cavitated caries lesions.