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.

BACKGROUND:There is an increasing demand for orthodontic treatment,and periodontally accelerated osteogenic orthodontics(PAOO)technique can make it possible to move orthodontic teeth that are limited by thin alveolar bone. OBJECTIVE:To investigate the biomechanics of orthodontic tooth movement before and after periodontally accelerated osteogenic orthodontics(PAOO)surgery to increase alveolar bone volume using the three-dimensional finite element method. METHODS:A patient undergoing PAOO surgery before orthodontic treatment to increase bone volume on the labial side of the mandibular anterior region was selected.The patient was under invisible orthodontics.Two three-dimensional finite element models were constructed based on the patient's preoperative and 6-month postoperative cone beam CT data.Both models simulated the movement of tooth 33:experiment Ⅰ:distal-central movement of 0.25 mm;experiment Ⅱ:lingual movement of 0.25 mm;and experiment Ⅲ:intrusion movement of 0.10 mm.The stress distribution and initial displacement trend of tooth 33,periodontal ligament and surrounding alveolar bone under the action of the invisible aligner were analyzed before and after the PAOO procedure. RESULTS AND CONCLUSION:Dental stress analysis:In the same orthodontic tooth movement,the maximum Von-Mises stress and overall stress values of tooth 33 were all higher before surgery than after surgery;there were similar distribution areas of maximum equivalent stress and overall distribution trends of Von-Mises stress before and after surgery.Periodontal ligament stress analysis:In the same orthodontic tooth movement,the maximum Von-Mises stress and overall stress values of the periodontal ligament were higher before surgery than after surgery,and there were similar distribution areas of the maximum equivalent stress and overall distribution trends of Von-Mises stress before and after surgery.Alveolar bone stress analysis:In the same orthodontic tooth movement,the maximum Von-Mises stress values of the alveolar bone around tooth 33 were higher before surgery than after surgery,while the equivalent stress distribution showed a gradual decrease from the top of the alveolar ridge to the root.Initial displacement analysis:In the same orthodontic tooth movement,the initial displacements in the main displacement direction for all six observation points of tooth 33 were smaller before surgery than after surgery,and showed a tendency to gradually decrease from the tooth tip to the apex.Therefore,there were differences in the biomechanical characteristics of orthodontic tooth movement before and after the PAOO surgery.With the clear aligner,the postoperative equivalent stress values on the dentition,periodontal ligament,and surrounding alveolar bone were lower than before the surgery,and the initial displacements of the orthodontic teeth after the surgery are larger than before.These findings suggest that PAOO can release the restriction of thin alveolar bone on the movement of orthodontic tooth by increasing alveolar bone thickness,effectively improving the force on the roots,periodontal ligament,and alveolar bone,avoiding the stress concentration on orthodontic tooth in the thin alveolar bone area that can cause complications when moving,and improving the efficiency of tooth movement.

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 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.

Sclerostin, a protein secreted from osteocytes, negatively regulates the WNT signaling pathway by binding to the LRP5/6 co-receptors and further inhibits bone formation and promotes bone resorption. Sclerostin contributes to musculoskeletal system-related diseases, making it a promising therapeutic target for the treatment of WNT-related bone diseases. Additionally, emerging evidence indicates that sclerostin contributes to the development of cancers, obesity, and diabetes, suggesting that it may be a promising therapeutic target for these diseases. Notably, cardiovascular diseases are related to the protective role of sclerostin. In this review, we summarize three distinct types of inhibitors targeting sclerostin, monoclonal antibodies, aptamers, and small-molecule inhibitors, from which monoclonal antibodies have been developed. As the first-in-class sclerostin inhibitor approved by the U.S. FDA, the monoclonal antibody romosozumab has demonstrated excellent effectiveness in the treatment of postmenopausal osteoporosis; however, it conferred high cardiovascular risk in clinical trials. Furthermore, romosozumab could only be administered by injection, which may cause compliance issues for patients who prefer oral therapy. Considering these above safety and compliance concerns, we therefore present relevant discussion and offer perspectives on the development of next-generation sclerostin inhibitors by following several ways, such as concomitant medication, artificial intelligence-based strategy, druggable modification, and bispecific inhibitors strategy.

Objective:To compare the clinical effects of rapid maxillary expansion between tooth-borne and hybrid-borne expanders.Methods:PubMed,Cochrane Library,EMbase,CBM,CNKI,VIP and WanFang Data were searched from the date of their establishment to October 31,2015,to find clinical trials about comparison of rapid maxillary expansion by tooth tissue-borne versus hybrid-borne expanders.The quality of the included studies was evaluated by 2 independent reviewers,and Meta-analysis was performed by using RevMan 5.3 software.Results:8 articles with 206 cases were included.The results of Meta-analysis showed that:there were significant differences between the 2 groups in the changes of the right first molar dental inclination [MD =-1.62,95 ％ CI (-3.18,-0.07)],inter first premolar width [SMD =-0.86,95％ CI(-1.47,0.25)] and molar alveolar inclination [SMD =-0.86,95％ CI(-1.10,-0.20)].There was no significant difference between the 2 groups in the changes of inter first molar ~dth [SMD =-0.08,95％ CI (-0.6l,0.45)],the left first molar dental inclination [MD =-1.12,95％ CI(-2.57,0.33)],maxillary width [SMD =-0.30,95％ CI(-1.08,0.47)].Conclusion:The effect between tooth-borne and hybrid-borne expanders in the expansion of maxillary dental arch is similar.However,tooth-borne expanders may cause greater inclination of first molar and alveolar process.

Objective: To evaluate the transverse displacement, stress distribution and tendency of change in tooth, alveolar bone and mid-palatal suture using three kinds of rapid maxillary expansion methods. Methods: Cone-beam CT image data was obtained by scanning skulls of a volunteer. Three-dimensional models of maxillary complex were re-established using Mimics and Geomagic Studio and models of Hyrax expander, Haas expander and miniscrew-assisted rapid palatal expander (MARPE) were established using ANSYS Workbench. Stress distribution, displacement and tendency of change in tooth, alveolar bone and mid-palatal suture were evaluated. Results: Hyrax expander brought 0.105 mm lateral displacement of crown, 0.022 mm mid-palatal suture width increase, wedge opening and clockwise rotation tendency of maxilla. Haas expander created uniform stress distribution, 0.216 mm lateral displacement of crown, and 0.031 mm mid-palatal suture width increase. In MARPE model, the lateral displacement of crown was 0.267 mm, and mid-palatal suture width increased 0.315 mm. The maximum of mid-palatal suture expansion and stress distribution appeared in the middle region, and maxilla had tendency of counterclockwise rotation. Conclusions The lateral changes of teeth and bones brought by MARPE were the most significant. Haas expander had some advantages in comparison with Hyrax.

Primary failure of eruption(PFE) is an unusual dental disease.Clinically,it is difficult to distinguish PFE from Mechanical failure of eruption (MFE),and the diagnosis is especially challenging since misdiagnosis and mistreatment always take place.The present paper reports the treatment experience of a case of PFE.

An adolescent patient,in the peak of growth and development,with severe skeletal Class Ⅲ malocclusion and maxillary impacted canines was treated by removable and fixed appliances in the upper and lower dental arches.After treatment,the crossbite was relieved,the facial contour was improved,the integrity of the denture was kept and the Class Ⅰ molar relationship was achieved.