Objective To investigate the mechanical effects of various height combinations of canine long-arm hooks and micro-im-plant anchorage on the retraction of maxillary anterior teeth in clear aligner treatment.It focuses on analyzing the stress distribution within the periodontal ligament and the movement tendencies of the anterior teeth,providing scientific evidence for optimizing orthodon-tic treatment strategies.Methods Three-dimensional finite element models were developed using CBCT scan data of patients and soft-ware including Mimics,Geomagic Studio,and Hypermesh.The models incorporated 16 different configurations of canine long-arm hooks(4,6,8,10 mm)and micro-implant anchorage(6,8,10,12 mm).Elastic traction forces of 3/16,3.5 oz were applied to these models.Simulations assessed how these variables influenced periodontal ligament stress distribution and the movement patterns of the maxillary anterior teeth.Results Stress during anterior teeth retraction was predominantly concentrated in the cervical and apex re-gions of the periodontal ligament,where it interfaced with the alveolar bone,indicating significant local concentration.Increasing the height of micro-implant anchorage and traction hooks markedly reduced positional changes in both the crown and apex.Specifically,when hooks exceeded 8 mm and anchorage heights surpassed 10 mm,canine movement became more uniform,preventing extrusion and minimizing the deepening of the overbite.Additionally,combinations of high traction hooks and high micro-implant anchorage promoted more uniform tooth movement,reducing unnecessary tipping and rotation.Conclusion In the retraction of maxillary anterior teeth with clear aligners,using high-position micro-implant anchorage and high-position traction hooks significantly enhances torque control of anterior teeth and effectively prevents deepening of the overbite.

Objective To investigate the mechanical effects of various height combinations of canine long-arm hooks and micro-im-plant anchorage on the retraction of maxillary anterior teeth in clear aligner treatment.It focuses on analyzing the stress distribution within the periodontal ligament and the movement tendencies of the anterior teeth,providing scientific evidence for optimizing orthodon-tic treatment strategies.Methods Three-dimensional finite element models were developed using CBCT scan data of patients and soft-ware including Mimics,Geomagic Studio,and Hypermesh.The models incorporated 16 different configurations of canine long-arm hooks(4,6,8,10 mm)and micro-implant anchorage(6,8,10,12 mm).Elastic traction forces of 3/16,3.5 oz were applied to these models.Simulations assessed how these variables influenced periodontal ligament stress distribution and the movement patterns of the maxillary anterior teeth.Results Stress during anterior teeth retraction was predominantly concentrated in the cervical and apex re-gions of the periodontal ligament,where it interfaced with the alveolar bone,indicating significant local concentration.Increasing the height of micro-implant anchorage and traction hooks markedly reduced positional changes in both the crown and apex.Specifically,when hooks exceeded 8 mm and anchorage heights surpassed 10 mm,canine movement became more uniform,preventing extrusion and minimizing the deepening of the overbite.Additionally,combinations of high traction hooks and high micro-implant anchorage promoted more uniform tooth movement,reducing unnecessary tipping and rotation.Conclusion In the retraction of maxillary anterior teeth with clear aligners,using high-position micro-implant anchorage and high-position traction hooks significantly enhances torque control of anterior teeth and effectively prevents deepening of the overbite.

Objective To investigate the differences in treatment experience and quality of life between adolescent orthodontic pa-tients using clear aligners and fixed braces.Methods A total of 104 adolescent patients were selected who underwent orthodontic treat-ment with either clear aligners or fixed braces at Nanjing Medical University Affiliated Stomatological Hospital from January 2022 to June 2022.The patients were divided into two treatment groups based on the type of orthodontic appliance,with 52 patients in each group.Within a 6-month period of using clear aligners or fixed braces,adolescent orthodontic patients were surveyed using the child oral health impact profile-short form 19(COHIP-SF19)and other individual items.The differences in mean satisfaction,quality of life,and statistical scores were compared using independent samples t-tests,while the differences in subjective responses were compared using the Wilcoxon rank-sum test.Results There were no significant differences in mean quality of life and statistical scores between the two groups,but patients in the clear aligner group reported higher satisfaction.The clear aligner group reported greater difficulty with eating,while patients with fixed braces were more likely to experience negative emotions.Additionally,there were no significant differences between the two groups in terms of adaptation time to the appliance,maintaining dental hygiene,and feeling attractive.Conclusion Patients in both groups were generally satisfied with their treatment.Adolescent orthodontic patients treated with clear a-ligners or fixed braces for at least 6 months exhibit similar overall quality of life.