OBJECTIVE: To evaluate the relationship between caries experience measured by the decayed missing filled teeth (DMFT) index and the radiographic density of dental hard tissues measured by cone beam computed tomography (CBCT) with a novel calibration tool for individuals aged > 20 to 25 years. MATERIALS AND METHODS: The sample consisted of 40 patients. Their DMFT ranged from 1 to 16 (mean = 6.5, standard deviation = 3.4). CBCT was performed for all patients, and an extracted tooth covered with self-cured acrylic resin was used as a radiographic density calibration tool. The gray values of the enamel, coronal and radical dentine regions of all the teeth were measured by two examiners. The average values of enamel and dentine radiographic density of incisors, canines, premolars and molars in each jaw and both jaws were calculated, and correlated with DMFT. RESULTS: The radiographic density of mandibular incisors and all incisors of both jaws had the highest Pearson correlation coefficients with DMFT (0.33 < r < 0.42, P-value = 0.016). Neither the coronal nor the radicular dentine radiographic density was correlated with the DMFT according to any examiner. CONCLUSION: Enamel, not dentine, radiographic density calculated from incisors via CBCT scans was correlated with DMFT in individuals aged > 20 to 25 years. The strengths of these correlations were moderate. CLINICAL RELEVANCE: The enamel radiographic density of incisors, measured by CBCT using a novel calibration tool, was correlated with dental caries status in young adults aged 20-25 years. Thus, this study provides deeper insight into the radiographic density of dental hard tissues as a determinant of dental caries. This factor is also measurable in a clinical setting.