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Objective To evaluate the therapeutic effect of dental autotransplantation with the application of digital design combined with 3D printing of donor tooth models and recipient alveolar fossa model preoperatively. Methods Twelve cases that could not be retained due to tooth fracture or extensive absorption of alveolar bone were recruited in the study. Cone-beam computed tomography (CBCT) data were imported into Mimics software for digital design, and the best-matched third molar was selected as the donor tooth. Replicas of the donor teeth and the recipient socket were printed out with three-dimensional (3D) printing technologies as a simulation model for recipient tooth socket preparation. During tooth autotransplantation, preparation of the recipient tooth socket and the donor tooth were guided by the 3D-printed replicas sequentially. Then, the donor tooth was implanted into the recipient tooth pocket. Patients were followed up at 3, 6 and 12 months after the operation, with CBCT examination to evaluate the status of bone reconstruction and periodontal ligaments at each time point. Results Twelve patients were transplanted with an autogenous third molar with the apical foramen completely closed. Among them, 7 patients had alveolar fossa infection before the operation, of which 1 had extensive resorption of the alveolar bone due to the infection. All 12 patients recovered well after the operation and were followed up for at least 12 months. In total, 11 caseswere successful in tooth autotransplantation with normal mastication, and 1 case had root resorption 14 months postoperation. Conclusion Digital design combined with 3D printing technology can assistin the selection of thebest-matched donor tooth and preparation of the recipient socket before tooth transplantation proceduresand reduce the extra-alveolar exposure time of the donor tooth and number of trial placementsintothe alveolar fossa. Thus, this combined strategy can effectively improve the outcome of dental autotransplantation.

Abstract: A comprehensive analytical method based on isotope dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of acrylamide residue in cosmetics. Water-soluble cosmetic sample was extracted with water, and the extract was centrifuged, then the upper solution was cleaned up by an Oasis HLB solid phase extraction cartridge. Oil-soluble cosmetic sample was extracted by liquid-liquid partition with n-hexane and water. The qualitative and quantitative analyses were carried out for the analyte in the multiple reaction monitoring (MRM) mode after the chromatographic separation on a Waters Atlantis T3 column (150 mm x 2.1 mm, 3 microm). The quantification was performed with 13C3-acrylamide as internal standard. The limit of quantification (LOQ) for acrylamide was 0.1 mg/kg. The mean recoveries were 87.7%-95.8% at the spiked levels of 0.1-1.0 mg/kg with the intra-day precision less than 10% and the inter-day precision less than 12%. The method is suitable for the determination of acrylamide in cosmetics.