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.

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 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.

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.

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.

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.

An adult patient with skeletal crossbite and mandibular deviation was treated by mandibular molar distalization using micro-im-plant and intermaxillary traction.After treatment,the facial contour of the patient was improved,the Class Ⅰ molar and cuspid relationship was achieved.

Objective To investigate the stress distribution on the maxillary anterior teeth retracted with sliding mechanics and micro-implant anchorage using different retraction hook heights and positions.Methods DICOM image data including maxilla and upper teeth were obtained with cone-beam CT.The three-dimensional finite element model was constructed using Mimics software.Brackets and archwire model were constructed using Creo software.The models were instantiated using Pro/Engineer software.Abaqus software was used to simulate the sliding mechanics by loading 2 N force on 0,2,4,6,8,10 mm retraction hooks and three different positions,repectively.Rotation of the occlusal plane,the initial displacement and stress distribution of teeth were analyzed.Results Lingual rotation of maxillary central incisor(0.021°),gingival movement of the maxillary first molar(0.005 mm),and clockwise rotation of the maxillary occlusal plane(0.012°) were observed when the force application point located at the archwire level (0 mm).In contrast,0.235° labial rotation of the maxillary central incisor,0.015 mm occlusal movement of the maxillary first molar,and 0.075° anti-clockwise rotation of the maxillary occlusal plane were observed when the force application point located at the higher level(10 mm retraction hook).The more the force application point was located posteriorly at the archwire level,the less lingual rotation of the maxillary central incisor and the more buccal displacement of maxillary first molar was observed.Conclusions Maxillary anterior tooth rotation and retraction,vertical displacement of posterior segment,and rotation of the occlusal plane could be controlled by adjusting the height and position of the retraction hook in space closure using miniscrew and sliding mechanics.

To construct a three-dimensional finite element model comparing between one-step and two-step methods in torque control of anterior teeth during space closure.Methods Dicom image data including maxilla and upper teeth were obtained though cone-beam CT.A three-dimensional model was set up and the maxilla,upper teeth and periodontium were separated using Mimics software.The models were instantiated using Pro/Engineer software,and Abaqus finite element analysis software was used to simulate the sliding mechanics by loading 1.47 Nforce on traction hooks with different heights(2,4,6,8,10,12 and 14 mm,respectively) in order to compare the initial displacement between six maxillary anterior teeth (one-step method) and four maxillary anterior teeth(two-step method).Results When moving anterior teeth bodily,initial displacements of central incisors in two-step method and in one-step method were 29.26× 10-6 mm and 15.75× 10-6 mm,respectively.The initial displacements of lateral incisors in two-step method and in one-step method were 46.76× 10-6 mm and 23.18× 10-6 mm,respectively.Under the same amount of light force,the initial displacement of anterior teeth in two-step method was doubled compared with that in onestep method.The root and crown of the canine couldn't obtain the same amount of displacement in one-step method.Conclusions Two-step method could produce more initial displacement than one-step method.Therefore,two-step method was easier to achieve torque control of the anterior teeth during space closure.

Objective To evaluate the outcome of patients with skeletal Class Ⅲ malocclusion treated with extraction of mandibular third molars and distalization of molars using implant anchorage combined with MBT appliance.Methods Fifteen patients(mean age 24.0 ± 5.8) with skeletal Class Ⅲ malocclusion were selected.The mandibular third molars were extracted and the mandibular molars were moved distally using implant combined with MBT appliance.Cephalometric analysis was carried out before and after treatment.Results After active treatment,ANB,Wits distance,AB-NP and the distance between upper and lower lip position to SnPg' increased by 1.65°± 1.04°,(4.39± 1.93) mm,3.20°± 1.61° and (1.13±0.99) mm,respectively.The differences were statistically significant(P ＜ 0.05).Conclusions The skeletal Class Ⅲ patients in the permanent dentition could be treated successfully with extraction of mandibular third molars and distalization of mandibular molars using implant anchorage combined with MBT appliance.The soft-tissue profile was improved.