BACKGROUND:In orthodontic treatment,full-mouth treatment is usually used to treat single-root severely twisted teeth,and single-tooth treatment is less common.OBJECTIVE:To design a personalized orthodontic device based on biomechanical principles to address the rotation of teeth 11,12,13,21,22,and 23,and evaluate the device's impact on tooth movement using three-dimensional finite element method.METHODS:Based on the biomechanical principle of tooth rotation and movement,a personalized orthodontic device was made by digital design combined with three-dimensional printing,so that the personalized orthodontic device and the tooth formed an anchorage system.The absolute anchorage of the micro-implant was used to precisely control the single-root twisted tooth in the three-dimensional direction.The CBCT data of the maxillary alveolar bone and tooth tissue of a female volunteer were collected.The three-dimensional finite element models of the twisted tooth-periodontal ligament-maxillary bone-personalized orthodontic device were established using Mimics,Geomagic Wrap,SolidWorks,3-matic Research 15.0,and Ansys Workbench software.The equivalent stress distribution characteristics of the personalized orthodontic device,the movement trend of the tooth,and the equivalent stress distribution characteristics of the periodontal ligament were calculated under a thrust of 60 g.RESULTS AND CONCLUSION:(1)The maximum equivalent stress observed on the personalized orthodontic device was 47.71 MPa.(2)The initial tooth displacement under the device demonstrated a rotational trend.The peak equivalent stress in the periodontal ligament was concentrated at the neck,while lower stress was observed in the apex region.(3)The safety and feasibility of the personalized orthodontic device designed in this study for severely rotated single-rooted teeth were preliminarily verified through finite element analysis.

BACKGROUND:In orthodontic treatment,full-mouth treatment is usually used to treat single-root severely twisted teeth,and single-tooth treatment is less common.OBJECTIVE:To design a personalized orthodontic device based on biomechanical principles to address the rotation of teeth 11,12,13,21,22,and 23,and evaluate the device's impact on tooth movement using three-dimensional finite element method.METHODS:Based on the biomechanical principle of tooth rotation and movement,a personalized orthodontic device was made by digital design combined with three-dimensional printing,so that the personalized orthodontic device and the tooth formed an anchorage system.The absolute anchorage of the micro-implant was used to precisely control the single-root twisted tooth in the three-dimensional direction.The CBCT data of the maxillary alveolar bone and tooth tissue of a female volunteer were collected.The three-dimensional finite element models of the twisted tooth-periodontal ligament-maxillary bone-personalized orthodontic device were established using Mimics,Geomagic Wrap,SolidWorks,3-matic Research 15.0,and Ansys Workbench software.The equivalent stress distribution characteristics of the personalized orthodontic device,the movement trend of the tooth,and the equivalent stress distribution characteristics of the periodontal ligament were calculated under a thrust of 60 g.RESULTS AND CONCLUSION:(1)The maximum equivalent stress observed on the personalized orthodontic device was 47.71 MPa.(2)The initial tooth displacement under the device demonstrated a rotational trend.The peak equivalent stress in the periodontal ligament was concentrated at the neck,while lower stress was observed in the apex region.(3)The safety and feasibility of the personalized orthodontic device designed in this study for severely rotated single-rooted teeth were preliminarily verified through finite element analysis.

OBJECTIVE To investigate the genetic feature of meticillin-resistant Staphylococcus aures isolated from earthquake victims and compare them with those of common patients.METHODS The MRSA isolates underwent SCCmec(Staphylococcal Cassette Chromosome mec) multi-PCR and PVL gene detection.Diversilab method was used for homology comparison and antibiotic resistance was also analyzed.RESULTS All the MRSA isolates were confirmed to be type Ⅲ SCCmec with PVL gene negative.Homology analysis showed relatively consistent with community-acquired MRSA confirmed to be ST8 by MLST typing.CONCLUSIONS There may be cross-spread of MRSA between hospital and community.We should pay more attation even in emergent time.