BACKGROUND:Clear aligners,due to their special material properties,are more prone to the"roller coaster effect"during the process of extracting the maxillary first premolar and closing the gap by retracting the anterior teeth,tilting and moving the teeth,leading to deepening of the anterior overjet and opening of the posterior teeth.There are fewer related studies at present concerning whether the thickness or stiffness of the aligner can be changed to reduce the"roller coaster effect"and better control the orthodontic tooth movement,.OBJECTIVE:To analyze the differences in tooth movement control ability of clear aligners of different thicknesses and stiffness when internally retracting maxillary anterior teeth by means of the three-dimensional finite element method.METHODS:Cone beam CT data of patients with convex profile were imported into Mimics and other software to simulate clinical cases.Three-dimensional finite element models were constructed to remove the first premolars,including the maxilla,teeth,and periodontal ligaments,while the diaphragms of clear aligners with thicknesses of 0.50 mm and 0.75 mm were assembled.Four sets of working conditions were created by loading the material properties of two Young's modulus of 1 000 MPa and 2 000 MPa.According to the clinical design to close of the extraction gap,and analyze the distribution of periodontal ligament stress,the displacement trend and the initial displacement of the teeth after loading and calculating in Workbench 2023 R1 software.RESULTS AND CONCLUSION:(1)The Von-Mises stress distribution pattern of periodontal ligament was consistent among the four working conditions,with the maximum value mainly distributed at the cervical part of teeth.The thicker diaphragm of the aligner,the higher the Von-Mises stress;the higher Young's modulus of the aligner,the higher the Von-Mises stress.(2)Under the four working conditions,the overall displacement trend of the maxillary dentition was that the crowns of the anterior teeth moved towards the lingual side and the roots towards the labial side,while the crowns of the posterior teeth moved towards the proximal-medial side and the roots towards the distal-medial side,and it was observed that the crown-root displacements of the teeth were in the opposite direction in all the conditions,and that the displacement of the crowns was greater than the displacement of the roots.Except for canines,the thicker the aligner diaphragm,the lower the R/C value(root-crown displacement ratio);the higher the modulus of elasticity of the aligner diaphragm,the lower the R/C value.(3)The results showed that when the maxillary anterior teeth were internally retracted using invisible aligners,the teeth showed a tendency to tilt and move without incisor torque compensation being designed;the greater the thickness of the aligner and the elastic modulus,the greater the control of the teeth,and the tendency of the teeth to tilt and move decreased;and the cuspids had to be controlled by other auxiliary means.

BACKGROUND:Clear aligners,due to their special material properties,are more prone to the"roller coaster effect"during the process of extracting the maxillary first premolar and closing the gap by retracting the anterior teeth,tilting and moving the teeth,leading to deepening of the anterior overjet and opening of the posterior teeth.There are fewer related studies at present concerning whether the thickness or stiffness of the aligner can be changed to reduce the"roller coaster effect"and better control the orthodontic tooth movement,.OBJECTIVE:To analyze the differences in tooth movement control ability of clear aligners of different thicknesses and stiffness when internally retracting maxillary anterior teeth by means of the three-dimensional finite element method.METHODS:Cone beam CT data of patients with convex profile were imported into Mimics and other software to simulate clinical cases.Three-dimensional finite element models were constructed to remove the first premolars,including the maxilla,teeth,and periodontal ligaments,while the diaphragms of clear aligners with thicknesses of 0.50 mm and 0.75 mm were assembled.Four sets of working conditions were created by loading the material properties of two Young's modulus of 1 000 MPa and 2 000 MPa.According to the clinical design to close of the extraction gap,and analyze the distribution of periodontal ligament stress,the displacement trend and the initial displacement of the teeth after loading and calculating in Workbench 2023 R1 software.RESULTS AND CONCLUSION:(1)The Von-Mises stress distribution pattern of periodontal ligament was consistent among the four working conditions,with the maximum value mainly distributed at the cervical part of teeth.The thicker diaphragm of the aligner,the higher the Von-Mises stress;the higher Young's modulus of the aligner,the higher the Von-Mises stress.(2)Under the four working conditions,the overall displacement trend of the maxillary dentition was that the crowns of the anterior teeth moved towards the lingual side and the roots towards the labial side,while the crowns of the posterior teeth moved towards the proximal-medial side and the roots towards the distal-medial side,and it was observed that the crown-root displacements of the teeth were in the opposite direction in all the conditions,and that the displacement of the crowns was greater than the displacement of the roots.Except for canines,the thicker the aligner diaphragm,the lower the R/C value(root-crown displacement ratio);the higher the modulus of elasticity of the aligner diaphragm,the lower the R/C value.(3)The results showed that when the maxillary anterior teeth were internally retracted using invisible aligners,the teeth showed a tendency to tilt and move without incisor torque compensation being designed;the greater the thickness of the aligner and the elastic modulus,the greater the control of the teeth,and the tendency of the teeth to tilt and move decreased;and the cuspids had to be controlled by other auxiliary means.

Objective To investigate the biomechanical characteristics of orthodontic tooth movement at different alveolar bone heights and provide a theoretical reference for orthodontic clinical treatment.Methods Four groups of mandibular dentition finite element models were established:the normal alveolar bone height,and 1/3,1/2,and 2/3 reductions in height.The lingual,distal,and intrusion movements of the mandibular central incisor were simulated under different loads.The distribution and variations in periodontal stress and tooth displacement were analyzed.Results Under three movements,the degree of stress concentration in the cervical area of the tooth and the periodontal equivalent force increased as the alveolar bone height decreased and the orthodontic force increased.Meanwhile,the displacement at each observation point and the crown-root displacement difference increased,and the tendency for inclination movement of the teeth aggravated.When the alveolar bone height was reduced to 2/3,the orthodontic force under lingual and distal movement increased to 150 g and that under intrusion movement increased to 100 g.The periodontal equivalent force increased to the maximum value,and the tendency of tooth inclination movement was most significant.Conclusions A reduction in the alveolar bone height aggravates the stress concentration at the top of the alveolar ridge and the tendency for inclination movement of the teeth.For orthodontic patients with an inferior periodontal condition,the orthodontic force should be reduced according to the alveolar bone height to ensure a safe and effective orthodontic treatment.

Objective To observe the effect of preoperative muscle strength training combined with postoperative BIODEX balance function training in improving the motor function of patients with total hip arthroplasty (THA). Methods A total of 110 patients with THA from January 2021 to December 2022 were selected as research objects, and were divided into observation group and control group by the simple randomization method, with 55 cases in each group. The control group received conventional postoperative rehabilitation training, while the observation group was treated with muscle strength training and BIODEX balance function training. Imaging indicators (acetabular abduction angle, anterior inclination angle, proportion of acetabular cup in safe zone, and centering rate of femoral prosthesis) at 5 days after surgery were compared between two groups; the joint motor function (Harris score for hip joint), balance ability [Berg Balance Scale (BBS)] and daily activity ability [Activities of Daily Life Scale (ADL)] before treatment and one month after treatment were compared between the two groups. Results There were no significant differences in acetabular abduction angle, anterior inclination angle, proportion of acetabular cup in safe zone and centering rate of femoral prosthesis between the two groups at 5 days after surgery (P>0.05); after one month of treatment, the Harris score for hip joint, the BBS score and ADL score in both group increased significantly, and the scores in the observation group were significantly higher than those in the control group (P < 0.05). Conclusion Preoperative muscle strength training combined with postoperative BIODEX balance function training shows a significant therapeutic effect, which can effectively improve the hip motor function and enhance the balance control ability in patients with THA.

Objective:By observing the loss(LORR)and recovery of righting reflex(RORR)in mice after anes-thesia and the exploration of Y-maze,explore the role of oxytocin(OXT)in promoting arousal in mice.Methods:The expression of oxytocin receptor(OXTR)in the cell bodies and tyrosine hydroxylase(TH)positive immunoreactive neu-rons in locus coeruleus(LC)was verified by immunofluorescence staining.Using the function of intraperitoneal injec-tion anesthesia and gas anesthesia,and intraperitoneal injection,intrathecal injection,and right LC single tube catheter administration,OXT or saline given as experimental group and control group,respectively,explored the time needed in the induction anesthesia period and anesthesia recovery period of mice after administration,and conducted Y-maze test on groups with statistically different anesthesia results,then explored the exploration of novel arm in Y-maze after 6,9,18 and 24 hours of RORR.Results:In LC,TH and OXTR positive neurons had double labeling.There was no differ-ence in the time of RORR after intraperitoneal injection and intrathecal injection of OXT and saline respectively,and no difference in the time of LORR and RORR after single-tube cannula administration of OXT and saline with intraperitone-al anesthesia and gas anesthesia.Compared with the control group,the recovery time of mice in the experimental group under gas anesthesia given OXT with single cannula was reduced(P＜0.05).In this group,the exploration activities of Y-maze novel arm increased after 9 hours of anesthesia recovery(P＜0.05),but there was no significant statistical difference in the exploration activities of Y-maze novel arm at 6,18 and 24 hours.Western Blot showed that compared with the control group,the expression of TH in LC in the experimental group increased significantly within 9 hours after anesthesia(P＜0.05),and then began to decrease after 9 hours(P＜0.01).Conclusion:OXT can promote the arousal of mice,and the cognitive degree of mice given OXT recovered better after waking up for 9 hours after anesthe-sia.

Objective To investigate the biomechanical characteristics of orthodontic tooth movement at different alveolar bone heights and provide a theoretical reference for orthodontic clinical treatment.Methods Four groups of mandibular dentition finite element models were established:the normal alveolar bone height,and 1/3,1/2,and 2/3 reductions in height.The lingual,distal,and intrusion movements of the mandibular central incisor were simulated under different loads.The distribution and variations in periodontal stress and tooth displacement were analyzed.Results Under three movements,the degree of stress concentration in the cervical area of the tooth and the periodontal equivalent force increased as the alveolar bone height decreased and the orthodontic force increased.Meanwhile,the displacement at each observation point and the crown-root displacement difference increased,and the tendency for inclination movement of the teeth aggravated.When the alveolar bone height was reduced to 2/3,the orthodontic force under lingual and distal movement increased to 150 g and that under intrusion movement increased to 100 g.The periodontal equivalent force increased to the maximum value,and the tendency of tooth inclination movement was most significant.Conclusions A reduction in the alveolar bone height aggravates the stress concentration at the top of the alveolar ridge and the tendency for inclination movement of the teeth.For orthodontic patients with an inferior periodontal condition,the orthodontic force should be reduced according to the alveolar bone height to ensure a safe and effective orthodontic treatment.

Objective:By observing the loss(LORR)and recovery of righting reflex(RORR)in mice after anes-thesia and the exploration of Y-maze,explore the role of oxytocin(OXT)in promoting arousal in mice.Methods:The expression of oxytocin receptor(OXTR)in the cell bodies and tyrosine hydroxylase(TH)positive immunoreactive neu-rons in locus coeruleus(LC)was verified by immunofluorescence staining.Using the function of intraperitoneal injec-tion anesthesia and gas anesthesia,and intraperitoneal injection,intrathecal injection,and right LC single tube catheter administration,OXT or saline given as experimental group and control group,respectively,explored the time needed in the induction anesthesia period and anesthesia recovery period of mice after administration,and conducted Y-maze test on groups with statistically different anesthesia results,then explored the exploration of novel arm in Y-maze after 6,9,18 and 24 hours of RORR.Results:In LC,TH and OXTR positive neurons had double labeling.There was no differ-ence in the time of RORR after intraperitoneal injection and intrathecal injection of OXT and saline respectively,and no difference in the time of LORR and RORR after single-tube cannula administration of OXT and saline with intraperitone-al anesthesia and gas anesthesia.Compared with the control group,the recovery time of mice in the experimental group under gas anesthesia given OXT with single cannula was reduced(P＜0.05).In this group,the exploration activities of Y-maze novel arm increased after 9 hours of anesthesia recovery(P＜0.05),but there was no significant statistical difference in the exploration activities of Y-maze novel arm at 6,18 and 24 hours.Western Blot showed that compared with the control group,the expression of TH in LC in the experimental group increased significantly within 9 hours after anesthesia(P＜0.05),and then began to decrease after 9 hours(P＜0.01).Conclusion:OXT can promote the arousal of mice,and the cognitive degree of mice given OXT recovered better after waking up for 9 hours after anesthe-sia.

Objective To explore the application effect of chronic disease management mode for rheumatism in patients with rheumatoid arthritis.Methods From May 2014 to May 2016, by retrospective study, 40 rheumatoid arthritis patients volunteered to participate in the chronic disease management for one year. Patients' awareness of the disease, quality of life and complications were compared between the two groups.Results After implementation of chronic disease management mode, the number of patients with basic knowledge on the disease, on drug treatment and disease monitoring was significantly higher than the number before the intervention; the patients' good behaviors, such as smoking quitting, alcohol limiting, diet and compliance of subsequent visit were significantly better than before; incidence of joint redness and swelling, and frequent urination was significantly lower than before (P<0.05). Also, the patients' scores in various dimensions of the life quality scale were significantly higher than before (P<0.05).Conclusions After implementation of the chronic disease management mode, patients with rheumatoid arthritis are better aware of knowledge related to the disease. Their behavior, compliance of subsequent visit and quality of life are all improved significantly.