Dental age estimation of the living is limited because observing the histological structure of teeth is difficult. Therefore, several methods have been proposed to estimate age by observing changes on dental radiographs of pulpal size caused by secondary dentin deposition. This study aims to evaluate the validity of the Kvaal method to estimate the ages of Korean subjects using digital panoramic radiographs and formulate regression equations for use in Korean subjects. We included 266 Korean subjects (age 21-69 years) visiting Chosun University Dental Hospital (Gwangju, South Korea). The pulpal size and width of six tooth types (maxillary central incisor, lateral incisor, second premolar, mandibular lateral incisor, canine, and first premolar) were measured on digital panoramic radiographs according to the Kvaal method. Statistical interobserver/intraobserver reliabilities were calculated to evaluate the reproducibility of the measured values, and correlations between actual ages and measured values were identified. The differences between the predicted ages and the actual age were analyzed. Paewinsky method was also applied and its validity was evaluated. In addition, a series of new regression equations for the age estimation of Korean subjects was produced. When both methods were applied directly to the teeth of the subjects, significant differences were observed between the estimated and chronological ages. The length-related parameters of the teeth of subjects calculated by the original Kvaal method showed no significant correlation. A regression equation derived from the width parameters without the length ratios is proposed for use in Korean subjects.

This study investigated the relationships of morphology and locations of the nose and nasal aperture by using major craniofacial landmarks on the human skull and face for craniofacial reconstruction/approximation of Koreans. In the frontal view, the positions of bony landmarks on the skull, including the nasal aperture, were correlated with the positions of nasal landmarks vertical to the transverse plane. In profile, the positions of bony landmarks on the skull were correlated with the positions of nasal landmarks horizontal to the coronal plane. Overall, 26 of the 76 measurements demonstrated significant correlations between the corresponding landmarks on the nose and nasal aperture. Simple regression equations were produced from the results. This study showed that the nose and nasal aperture are significantly related to each other in terms of their morphology and location in Koreans. The prediction guidelines, produced as regression formulas, can be applied to craniofacial reconstruction/approximation and bio-anthropological research of Korean skulls. The study results can also be used clinically in rhinoplasty and nasal reconstruction surgery.

Given that tooth loss is a degenerative change, the number of residual teeth may be used to specify a particular age range as a marker for age estimation. This study examined changes in the number of teeth with age using a nationwide oral survey database and derived the age distribution of the Korean population according to the number of teeth. Data on the number of teeth and age were extracted from the oral examination data of the Korean National Health and Nutrition Examination Survey (KNHANES) from 2016 to 2018. Statistical analyses of a complex sample survey were performed using weighted values. The distribution range of the number of teeth by age was broad. The proportion of young people decreased progressively as the number of remaining teeth decreased. In contrast, the proportion of those from the older age group decreased slightly as the number of teeth increased. The number of teeth was subdivided into groups of four, age was categorized into 5-year intervals, and the distribution of age groups by the number of teeth was analyzed. We attempted to determine the age group threshold at approximately 95th percentile for age. In summary, we found that if there were ≤4, 5-12, and 13-20 residual teeth, the estimated age was ≥60, ≥55, and ≥50 years, respectively, with an approximately 95% probability. When many teeth are lost and it is difficult to apply conventional dental age estimation methods, our method may assist in narrowing the age range, although it is not an accurate age determination method.

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The dental age estimation of children is performed using dental maturity. Postmortem missing of the anterior teeth or the distortion of image of the anterior teeth in panoramic radiographs can make it difficult to analyze the development of the anterior teeth. This pilot study was conducted to derive a new age estimation method based only on the developmental stage of mandibular posterior teeth.Methods: Methods: This study was conducted using panoramic radiographs of 650 subjects aged 3 to 15 years old. The dental developmental stages of the lower left first premolar, second premolar, first molar and second molar were evaluated according to the Demirjian's criteria. The intra-/inter-observer reliability was evaluated, and multiple linear regression analyses were performed including the developmental stage of each tooth as an independent variable. Results: Results:The intra-/inter-observer reliability was 0.9626 and 0.8877, respectively, and showed very high reproducibility. Multiple linear regression analyses were performed for males and females, and the age calculation table was derived by obtaining the intercept and the coefficient according to the development stage of each tooth. The coefficient of determination (r 2 ) of the age calculation method was 0.9634 for male and 0.9570 for female subjects, and the mean difference between chronological age and estimated dental age was -0.42 and -0.21, respectively.Conclusions: Conclusions: This pilot study evaluated the developmental stages of four lower posterior teeth in the Korean group according to Demirjian's criteria, and derived age estimation method. The accuracy was lower than when more teeth were used, but it will be useful to estimate age of children when the anterior teeth are difficult to accurately analyze.