Age assessment in the living using modified Gustafson's criteria in a northern Chinese population.

Regressive dental changes appear to be suitable for age assessment in living adults. In 2012, Olze et al. showed that several criteria presented by Gustafson for extracted teeth can also be applied to orthopantomograms. The objective of this study was to test the applicability and reliability of this method in a Chinese population. For this purpose, 1300 orthopantomograms of 650 female and 650 male Chinese aged between 15 and 40 years were evaluated. The characteristics of secondary dentin formation, periodontal recession, attrition, and cementum apposition were reviewed in all the mandibular premolars. The sample was split into a training and test dataset. Based on the training set, the correlation of the individual characteristics with chronological age was studied with a stepwise multiple regression analysis, in which individual characteristics formed the independent variable. According to the results, the R values amounted to 0.80 to 0.83; the standard error of estimate was 4.29 to 4.75 years. By analyzing the test dataset, the accuracy of the present study, Olze's and Timme's formulas were determined by the difference between the estimated dental age (DA) and chronological age (CA). Taking both mean differences and mean absolute differences into account, the Chinese age estimation formula did not always perform better compared with Olze's and Timme's formulas for both males and females. It was concluded that this method can be used in Chinese individuals for age assessment. However, the applicability of the method is limited by the quality of the X-ray images, and the method should only be applied by experienced forensic odontologists.

[Fitting of the reconstructed craniofacial hard and soft tissues based on 2-D digital radiographs].

PURPOSE: In this study, we reconstructed the craniofacial hard and soft tissues based on the data from digital cephalometric radiographs and laser scanning. The effective fitting of the craniofacial hard and soft tissues was performed in order to increase the level of orthognathic diagnosis and treatment, and promote the communication between doctors and patients. METHODS: A small lead point was put on the face of a volunteer and frontal and lateral digital cephalometric radiographs were taken. 3-D reconstruction system of the craniofacial hard tissue based on 2-D digital radiograph was used to get the craniofacial hard tissue model by means of hard tissue deformation modeling. 3-D model of facial soft tissue was obtained by using laser scanning data. By matching the lead point coordinate, the hard tissue and soft tissue were fitted. RESULTS: The 3-D model of the craniofacial hard and soft tissues was rebuilt reflecting the real craniofacial tissue structure, and effective fitting of the craniofacial hard and soft tissues was realized. CONCLUSIONS: The effective reconstruction and fitting of the 3-D craniofacial structures have been realized, which lays a foundation for further orthognathic simulation and facial appearance prediction. The fitting result is reliable, and could be used in clinical practice.

Bone regeneration by nanohydroxyapatite/chitosan/poly(lactide-co-glycolide) scaffolds seeded with human umbilical cord mesenchymal stem cells in the calvarial defects of the nude mice.

In the preliminary study, we have found an excellent osteogenic property of nanohydroxyapatite/chitosan/poly(lactide-co-glycolide) (nHA/CS/PLGA) scaffolds seeded with human umbilical cord mesenchymal stem cells (hUCMSCs) in vitro and subcutaneously in the nude mice. The aim of this study was to further evaluate the osteogenic capacity of nHA/CS/PLGA scaffolds seeded with hUCMSCs in the calvarial defects of the nude mice. Totally 108 nude mice were included and divided into 6 groups: PLGA scaffolds + hUCMSCs; nHA/PLGA scaffolds + hUCMSCs; CS/PLGA scaffolds + hUCMSCs; nHA/CS/PLGA scaffolds + hUCMSCs; nHA/CS/PLGA scaffolds without seeding; the control group (no scaffolds) (n = 18). The scaffolds were implanted into the calvarial defects of nude mice. The amount of new bones was evaluated by fluorescence labeling, H&E staining, and Van Gieson staining at 4 and 8 weeks, respectively. The results demonstrated that the amount of new bones was significantly increased in the group of nHA/CS/PLGA scaffolds seeded with hUCMSCs (p < 0.01). On the basis of previous studies in vitro and in subcutaneous implantation of the nude mice, the results revealed that the nHA and CS also enhanced the bone regeneration by nHA/CS/PLGA scaffolds seeded with hUCMSCs in the calvarial defects of the nude mice at early stage.