Dental Age Research Of Adolescents From Shanghai Based On CBCT Data

OBJECTIVE:The aim of this study was to investigate the association between chronological age and the PTR(pulp/tooth volume ratio)of specific teeth using CBCT enhanced with Materialise-Mimics Research software 21.0in children and young adult population from Eastern China.METHODS:In this retrospective study,CBCT scans of 272 patients(139 males,133females),aged 8.08-19.92 years in this retrospective study.Among them,230 samples with CBCT data were included in the training group and the rest with CBCT data and panoramic radiographs taken on the same day were included in the validation group.The volumetric analysis of the pulp and calcified tissues was performed on the maxillary left central incisors and canines of all samples from training group by two well-trained students from graduate school using CBCT data.The ICC(intraclass correlation coefficient)value was calculated to test the intra-and inter-examiner reproducibility.Firstly,the PTR value of upper left central incisor and canine of each sample from training group was measured and calculated for volumetric analysis of pulp and calcified tissues.Next,the derived PTR value and chronological age of each sample were served as two parameters to conduct the correlation relationship and regression analysis.Next,the central incisor and canine model were compared with each other to explore which one was better.Lastly,the different models were tested and compared with Willems’ method using the samples from validation group.RESULTS:The ICC values were calculated for intra-and inter-observer agreement,which were 0.973(95%CI(L)=0.973,95%CI(U)=0.993)and 0.989(95%CI(L)=0.955,95%CI(U)=0.997)respectively.The Pearson correlation analysis showed a strong coefficient of correlation(r)for central incisors(-0.70 for boys and-0.63 for girls)as compared to maxillary left canines(-0.87 for boys and-0.81 for girls).Regarding performance,the canine model was more powerful than the central incisor model.The derived cubic polynomial regression equation from maxillary left canines had the highest coefficients of determination(0.8119 for males and 0.6779 for females).In the validation process,it is demonstrated that adopting the derived canine linear and cubic polynomial regression model regression in dental age estimation had an average overestimation for 1.14 and 1.07 years respectively,adopting Willems method had an average underestimation for 1.34 years.The mean absolute error of canine linear model,canine cubic polynomial model and Willems method was 2.10,2.08 and 1.52 years respectively.CONCLUSIONS:Our study proved that the PTR value of canines had a negative correlation relationship with a subadult’s chronological age and volumetric analysis of CBCT scans using the software may become a quite efficient method to estimate the chronological age of children and young adults.However,this derived estimation models could not replace Willems method in dental age estimation or meet the accuracy requirement for forensic dental age estimation for the present.