Validation of data mining models by comparing with conventional methods for dental age estimation in Korean juveniles and young adults.

Teeth are known to be the most accurate age indicators of human body and are frequently applied in forensic age estimation. We aimed to validate data mining-based dental age estimation, by comparing the accuracy of the estimation and classification performance of 18-year thresholds with conventional methods and with data mining-based age estimation. A total of 2657 panoramic radiographs were collected from Koreans and Japanese populations aged 15 to 23 years. They were subdivided into a training and internal test set of 900 radiographs each from Koreans, and an external test set of 857 radiographs from Japanese. We compared the accuracy and classification performance of the test sets from conventional methods with those from the data mining models. The accuracy of the conventional method with the internal test set was slightly higher than that of the data mining models, with a slight difference (mean absolute error < 0.21 years, root mean square error < 0.24 years). The classification performance of the 18-year threshold was also similar between the conventional method and the data mining models. Thus, conventional methods can be replaced by data mining models in forensic age estimation using second and third molar maturity of Korean juveniles and young adults.

Polyethylene wear and osteolysis after cementless total hip arthroplasty with alumina-on-highly cross-linked polyethylene bearings in patients younger than thirty years of age.

BACKGROUND: We asked whether cementless total hip arthroplasties that made use of alumina-on-highly cross-linked polyethylene bearings would improve hip score and functional activity and reduce the prevalence of polyethylene wear, osteolysis, and aseptic loosening. METHODS: Consecutive primary total hip arthroplasties were performed in fifty patients (a total of sixty hips among thirty-four men and sixteen women) who were younger than thirty years of age. The average age at the time of the index arthroplasty was 28.3 years (range, twenty-one to twenty-nine years). The average follow-up was 10.8 years (range, ten to twelve years). Osteolysis and polyethylene wear rates were evaluated with use of radiography and computed tomography. RESULTS: The mean Harris hip score, which was 38 points (range, 6 to 45 points) preoperatively, had improved to 95 points (range, 85 to 100 points) at a mean follow-up time of 10.8 years. The mean penetration (and standard error of the mean) of the polyethylene liner was 0.031 ± 0.004 mm per year. No hip had osteolysis or aseptic loosening. CONCLUSIONS: At a minimum of ten years and an average of 10.8 years postoperatively, the current generation of cementless acetabular and femoral components with alumina-on-highly cross-linked polyethylene bearings was functioning well and was not associated with the development of osteolysis in our group of patients younger than thirty years of age. While the long-term prevalence of polyethylene wear and osteolysis remains unknown, the midterm data are promising.

Pancreatic neoplasms in childhood and adolescence.

Pancreatic neoplasms are rare in children and adolescents; thus, our understanding of these tumors is still quite limited. We retrospectively reviewed clinical features and outcomes of all patients below 18 years of age with pancreatic neoplasms who were treated at Asan Medical Center between December 1994 and March 2010. Thirty-two patients were identified. Abdominal pain was the most common symptom. The median duration of diagnostic delay was 21 days. Nineteen patients were diagnosed with solid pseudopapillary tumors, 3 with lymphomas, 2 with pancreatoblastomas, 2 with poorly differentiated carcinomas, 2 with acinar cell cancers, 2 with endocrine tumors, 1 with peripheral (primitive) neuroectodermal tumor, and 1 with hemangioendothelioma. Gross complete resection of the primary tumor was achieved in 24 patients (75%), and 8 patients (25%) received chemotherapy. At a median follow-up of 34 months, the 5-year overall survival rate was 92.0 ± 5.5%. On multivariate analysis, histologic type was the only factor significantly predictive of survival (P=0.009). Patients with poorly differentiated carcinoma showed the worst survival probability. In cases of solid pseudopapillary tumors, surgical resection was generally curative and the prognosis was excellent. Patients with other malignant tumors, however, may require therapeutic strategies other than surgery.