Advancements in biomechanics and orthodontic strategies for clear aligner therapy

doi:10.7518/hxkq.2025.2025379

Abstract

Abstract:

Clear aligner therapy (CAT) is increasingly used in orthodontic practice. However, the biomechanical effectiveness and predictability of tooth movement in complex cases should be further clarified and enhanced. This article provides a systematic review of the biomechanical mechanisms underlying four common complex treatment modalities in CAT, namely, molar distalization, arch expansion, vertical tooth movement, and extraction cases, and summarizes current clinical strategies, such as overcorrection design, attachment, mini-screw-assisted anchorage, and intra-/inter-arch elastic traction. The role of these strategies in improving tooth movement control and treatment efficacy is elucidated, and potential future developments is discussed. The findings can offer a theoretical basis and practical guidance for optimizing CAT and improving the control ability and predictability of treatment outcomes.

Key words: clear aligner therapy, biomechanics, treatment strategy optimization

CLC Number:

R783.5

Lei Xiao, Jin Fang. Advancements in biomechanics and orthodontic strategies for clear aligner therapy[J]. West China Journal of Stomatology, 2026, 44(1): 17-28.

References 90

[1]	Kesling HD. The philosophy of the tooth positioning appliance[J]. Am J Orthod Oral Surg, 1945, 31(6): 297-304.
[2]	Caruso S, De Felice ME, Valenti C, et al. An evaluation of the Invisalign® Aligner Technique and consideration of the force system: a systematic review[J]. Syst Rev, 2024, 13(1): 43.
[3]	Brezniak N. The clear plastic appliance[J]. Angle Orthod, 2008, 78(2): 381-382.
[4]	Hahn W, Engelke B, Jung K, et al. Initial forces and moments delivered by removable thermoplastic appliances during rotation of an upper central incisor[J]. Angle Orthod, 2010, 80(2): 239-246.
[5]	Upadhyay M, Arqub SA. Biomechanics of clear alig-ners: hidden truths & first principles[J]. J World Fed Orthod, 2022, 11(1): 12-21.
[6]	Sachdev S, Tantidhnazet S, Saengfai NN. Accuracy of tooth movement with in-house clear aligners[J]. J World Fed Orthod, 2021, 10(4): 177-182.
[7]	Gazzani F, Pavoni C, De Razza FC, et al. Clear aligner treatment in adult patients with class Ⅲ malocclusion: lower distalization and class Ⅲ elastics vs class Ⅲ elastics alone—a RCT[J]. Eur J Orthod, 2025, 47(4): cjaf052.
[8]	Martina H, Stefano Adriana A, Ernesto B, et al. Lower molar distalization using clear aligners: Is it effective? A systematic review[J]. J Orthod Sci, 2024, 13: 11.
[9]	Ravera S, Castroflorio T, Garino F, et al. Maxillary molar distalization with aligners in adult patients: a multicenter retrospective study[J]. Prog Orthod, 2016, 17: 12.
[10]	Elfouly D, El-Harouni NM, Ismail HA, et al. Tip, torque and rotation of maxillary molars during distalization using Invisalign: a CBCT study[J]. BMC Oral Health, 2024, 24(1): 797.
[11]	Jiang T, Wang JK, Jiang YY, et al. How well do integra-ted 3D models predict alveolar defects after treatment with clear aligners[J]. Angle Orthod, 2021, 91(3): 313-319.
[12]	Miao Z, Yang Y, Zhang H, et al. Anchorage loss in ma-xillary premolar and anterior teeth during maxillary molar distalization in clear aligner treatment[J]. Am J Orthod Dentofacial Orthop, 2025, 167(6): 690-702.
[13]	Li L, Guo R, Zhang L, et al. Maxillary molar distalization with a 2-week clear aligner protocol in patients with ClassⅡ malocclusion: a retrospective study[J]. Am J Orthod Dentofacial Orthop, 2023, 164(1): 123-130.
[14]	Elfouly D, El-Harouni NM, Ismail HA, et al. Does maxillary sinus proximity affect molar root resorption during distalization using Invisalign? A CBCT study[J]. BMC Oral Health, 2023, 23(1): 905.
[15]	程鑫燚, 桑婷, 伍军. 种植体间接支抗辅助无托槽隐形矫治远移磨牙效果的锥形束CT分析[J]. 中华口腔医学杂志, 2022, 57(7): 724-732.
	Cheng XY, Sang T, Wu J. Cone-beam CT evaluation of the effect of indirect anchorage of mini-screw assisted clear aligner on molar distalization[J]. Chin J Stomatol, 2022, 57(7): 724-732.
[16]	Guo R, Li L, Lam XY, et al. Tooth movement analysis of maxillary dentition distalization using clear aligners with buccal and palatal mini-screw anchorages: a finite element study[J]. Orthod Craniofac Res, 2024, 27(6): 868-876.
[17]	Mao B, Tian Y, Zhou H, et al. The effect of canine lingual attachments during maxillary arch distalization wi-th clear aligner: a 4D finite element analysis and in vitro simulator study[J]. BMC Oral Health, 2025, 25(1): 707.
[18]	Kuguoglu A, Akarsu-Guven B. Evaluation of the effects of the third molar on distalization and the effects of attachments on distalization and expansion with clear ali-gners: three-dimensional finite element study[J]. Korean J Orthod, 2025, 55(1): 69-81.
[19]	Song B, Qi Y, Sun J, et al. Force distributions associated with different elastic traction methods for maxillary dentition distalization by clear aligners: an in-vitro study[J]. BMC Oral Health, 2025, 25(1): 587.
[20]	Gao H, Luo L, Liu J. Three-dimensional finite element analysis of maxillary molar distalization treated with clear aligners combined with different traction methods[J]. Prog Orthod, 2024, 25(1): 47.
[21]	Tang X, Wang M, Hu X, et al. The effects of palatal anchorage device on molar distalization with clear aligner: three-dimensional finite element analysis[J]. Am J Orthod Dentofacial Orthop, 2025, 168(4): 413-422.
[22]	胡忆戎, 宋保龙, 李博, 等. 无托槽隐形矫治磨牙远中移动不同设计方式上颌牙列的三维受力分析[J]. 中华口腔医学杂志, 2023, 58(3): 265-270.
	Hu YR, Song BL, Li B, et al. Three-dimensional analysis of maxillary dentition during molar distalization with clear aligners under different movement designs: an in vitro experiment[J]. Chin J Stomatol, 2023, 58(3): 265-270.
[23]	Zhang Y, Wang P, Jiang C, et al. Biomechanical effects of clear aligners with different distal coverage designs combined with ClassⅡelastic traction for maxillary first molar distalization: a finite element study[J]. BMC Oral Health, 2025, 25(1): 1033.
[24]	Mao B, Tian Y, Liu D, et al. The effect of maxillary premolar distalization with different designed clear aligners: a 4D finite element study with staging simulation[J]. Prog Orthod, 2024, 25(1): 46.
[25]	Ma Y, Fan X, Liu X, et al. Biomechanical effects of pe-riodontal status on molar sequential distalization with clear aligners: a finite element study[J]. Prog Orthod, 2025, 26(1): 15.
[26]	Lione R, Balboni A, Di Fazio V, et al. Effects of pendulum appliance versus clear aligners in the vertical dimension during ClassⅡmalocclusion treatment: a randomi-zed prospective clinical trial[J]. BMC Oral Health, 2022, 22(1): 441.
[27]	Auladell A, De La Iglesia F, Quevedo O, et al. The efficiency of molar distalization using clear aligners and mini-implants: two clinical cases[J]. Int Orthod, 2022, 20(1): 100604.
[28]	Balboni A, Cretella Lombardo E, Balboni G, et al. Vertical effects of distalization protocol with Clear aligners in ClassⅡpatients: a prospective study[J]. Minerva Dent Oral Sci, 2023, 72(6): 291-297.
[29]	Lin G, Chen M, Guo N, et al. Three-dimensional measurement and analysis of Mandibular Molar Distalization assisted by micro-implant anchorage combined with clear aligner[J]. Pak J Med Sci, 2024, 40(3Part-Ⅱ): 455-460.
[30]	Almagrami I, Almaqrami M, Zhu L, et al. Class Ⅲ correction and enhanced periodontal health with aligner treatment in a 53-year-old patient[J]. Angle Orthod, 2024, 95(4): 452-463.
[31]	Li Y, Wu M, Xing X, et al. Effects of maxillary molar distalization using clear aligners during the mixed dentition and early permanent dentition with 3 types of Class Ⅱ traction: a three-dimensional finite element analysis[J]. BMC Oral Health, 2025, 25(1): 717.
[32]	Rocha AS, Gonçalves M, Oliveira AC, et al. Efficiency and predictability of coronal maxillary expansion repercussion with the aligners system: a retrospective study[J]. Dent J (Basel), 2023, 11(11): 258.
[33]	赵祥, 汪虹虹, 杨一鸣, 等. 无托槽隐形矫治上颌扩弓效率及其影响因素初探[J]. 中华口腔医学杂志, 2017, 52(9): 543-548.
	Zhao X, Wang HH, Yang YM, et al. Maxillary expansion efficiency with clear aligner and its possible influencing factors[J]. Chin J Stomatol, 2017, 52(9): 543-548.
[34]	Zhou N, Guo J. Efficiency of upper arch expansion with the Invisalign system[J]. Angle Orthod, 2020, 90(1): 23-30.
[35]	Cretella Lombardo E, Paoloni V, Fanelli S, et al. Evaluation of the upper arch morphological changes after two different protocols of expansion in early mixed dentition: rapid maxillary expansion and Invisalign® first system[J]. Life (Basel), 2022, 12(9): 1323.
[36]	Loberto S, Pavoni C, Fanelli S, et al. Predictability of expansion movements performed by clear aligners in mi-xed dentition in both arches: a retrospective study on digital casts[J]. BMC Oral Health, 2024, 24(1): 694.
[37]	Bowman E, Bowman P, Weir T, et al. Evaluation of the predicted vs. achieved occlusal outcomes with the Invi-salign® appliance: a retrospective investigation of adult patients[J]. Int Orthod, 2023, 21(2): 100746.
[38]	Lione R, Cretella Lombardo E, Paoloni V, et al. Upper arch dimensional changes with clear aligners in the early mixed dentition: a prospective study[J]. J Orofac Orthop, 2023, 84(1): 33-40.
[39]	Macrì M, Medori S, Festa F. Evaluation of maxillary dentoalveolar expansion with clear aligners: a retrospective CBCT study[J]. Diagnostics (Basel), 2025, 15(13): 1586.
[40]	韦梦瑶, 胡心怡, 李晅. 无托槽隐形矫治对替牙期上颌横向发育不足患者扩弓的骨性效应[J]. 山西医科大学学报, 2023, 54(5): 702-706.
	Wei MY, Hu XY, Li X. Skeletal expansion effect of clear aligners in mixed dentition patients with constricted ma-xilla[J]. J Shanxi Med Univ, 2023, 54(5): 702-706.
[41]	Zhang Y, Hui S, Gui L, et al. Effects of upper arch expan-sion using clear aligners on different stride and torque: a three-dimensional finite element analysis[J]. BMC Oral Health, 2023, 23(1): 891.
[42]	吕秦毅, 高子琦, 冯青辰, 等. 替牙期无托槽隐形矫治器扩弓治疗改良设计的有限元分析[J]. 上海交通大学学报 (医学版), 2024, 44(8): 935-943.
	Lü QY, Gao ZQ, Feng QC, et al. Optimizing arch expansion with clear aligners in the mixed dentition based on finite element analysis[J]. J Shanghai Jiao Tong Univ (Med Sci), 2024, 44(8): 935-943.
[43]	Li N, Wang C, Yang M, et al. Effects of different tooth movement patterns and aligner thicknesses on maxillary arch expansion with clear aligners: a three-dimensional finite element study[J]. Front Bioeng Biotechnol, 2024, 12: 1424319.
[44]	Tang Z, Long H, Liu L, et al. Influence of attachment position and torque overcorrection on arch expansion in clear aligner treatment: a three-dimensional finite element analysis[J]. Angle Orthod, 2025, 95(4): 397-404.
[45]	Duncan LO, Piedade L, Lekic M, et al. Changes in mandibular incisor position and arch form resulting from Invisalign correction of the crowded dentition treated nonextraction[J]. Angle Orthod, 2016, 86(4): 577-583.
[46]	Yao S, Jiang W, Wang C, et al. Improvements of tooth movement efficiency and torque control in expanding the arch with clear aligners: a finite element analysis[J]. Front Bioeng Biotechnol, 2023, 11: 1120535.
[47]	Olteanu ND, Romanec C, Cernei ER, et al. Scoping review—The effectiveness of clear aligners in the management of anterior open bite in adult patients[J]. Medicina (Kaunas), 2025, 61(6): 1113.
[48]	Shahabuddin N, Kang J, Jeon HH. Predictability of the deep overbite correction using clear aligners[J]. Am J Orthod Dentofacial Orthop, 2023, 163(6): 793-801.
[49]	Goh S, Dreyer C, Weir T. The predictability of the mandibular curve of Spee leveling with the Invisalign appliance[J]. Am J Orthod Dentofacial Orthop, 2022, 162(2): 193-200.
[50]	Geramy A, Safari F. Effect of clear aligner type on maxillary full-arch intrusion: 3D analysis using finite element method[J]. BMC Oral Health, 2024, 24(1): 231.
[51]	Harris K, Ojima K, Dan C, et al. Evaluation of open bite closure using clear aligners: a retrospective study[J]. Prog Orthod, 2020, 21(1): 23.
[52]	Finkleman S, Cohanim B, Tai SK, et al. Does planned molar intrusion with aligners assist with closure of an-terior open bite[J]. Am J Orthod Dentofacial Orthop, 2024, 166(4): 330-349.e1.
[53]	Moshiri S, Araújo EA, McCray JF, et al. Cephalometric evaluation of adult anterior open bite non-extraction treatment with Invisalign[J]. Dental Press J Orthod, 2017, 22(5): 30-38.
[54]	Liu L, Zhan Q, Zhou J, et al. Effectiveness of an anterior mini-screw in achieving incisor intrusion and palatal root torque for anterior retraction with clear aligners[J]. Angle Orthod, 2021, 91(6): 794-803.
[55]	Haouili N, Kravitz ND, Vaid NR, et al. Has Invisalign improved? A prospective follow-up study on the efficacy of tooth movement with Invisalign[J]. Am J Orthod Dentofacial Orthop, 2020, 158(3): 420-425.
[56]	Tang Z, He K, Shen Y, et al. Evaluating the effectiveness of clear aligner therapy in leveling the curve of spee: a comparative study of extraction vs. non-extraction patients[J]. BMC Oral Health, 2025, 25(1): 629.
[57]	Li Y, Xiao S, Jin Y, et al. Stress and movement trend of lower incisors with different IMPA intruded by clear aligner: a three-dimensional finite element analysis[J]. Prog Orthod, 2023, 24(1): 5.
[58]	Wen S, Han X, He X, et al. Predictability of curve of Spee levelling and vertical tooth movements in the lo-wer arch with clear aligners based on cone-beam computed tomography[J]. Clin Oral Investig, 2025, 29(7): 336.
[59]	Liu L, Song Q, Zhou J, et al. The effects of aligner overtreatment on torque control and intrusion of incisors for anterior retraction with clear aligners: a finite-element study[J]. Am J Orthod Dentofacial Orthop, 2022, 162(1): 33-41.
[60]	康芙嘉, 张茜雅, 余磊, 等. 微种植体辅助无托槽隐形矫治器压低上颌前牙的三维有限元分析[J]. 口腔医学, 2023, 43(9): 796-802.
	Kang FJ, Zhang XY, Yu L, et al. Three-dimensional finite element analysis of maxillary anterior teeth intrusionby clear aligner assisted with micro-implant[J]. Stomatology, 2023, 43(9): 796-802.
[61]	黄钖钖, 王诗语, 刘浩, 等. 无托槽隐形矫治下前牙压低过矫治的回归分析研究[J]. 口腔医学, 2024, 44(5): 329-333.
	Huang YY, Wang SY, Liu H, et al. A regression analysis of the overcorrection for the mandibular anterior teeth in trusion with clear aligners[J]. 2024, 44(5): 329-333.
[62]	Alawdi GM, Al Fahad MF, Al Muzher SB, et al. Does Invisalign outperform fixed appliance in treating vertical discrepancies[J]. Cureus, 2024, 16(8): e65973.
[63]	Chamberland S, Nataf N. Noninvasive conservative ma-nagement of anterior open bite treated with TADs versus clear aligner therapy[J]. Clin Oral Investig, 2024, 28(4): 236.
[64]	陈达, 徐国祥, 刘露, 等. 隐形矫治中上颌第一磨牙压低的生物力学分析[J]. 实用口腔医学杂志, 2022, 38(4): 479-485.
	Chen D, Xu GX, Liu L, et al. Biomechanical analysis of the maxillary first molar intrusion with clear aligners[J]. J Pract Stomatol, 2022, 38(4): 479-485.
[65]	Liu J, Wei T, Zhao Y, et al. Efficacy of maxillary molar intrusion and quantification of related external apical root resorption—A comparison of two approaches[J]. Orthod Craniofac Res, 2024, 27(5): 733-739.
[66]	Greco M, Rossini G, Rombolà A. Simplifying the approach of open bite treatment with aligners and selective micro-osteoperforations: an adult case report[J]. Int Orthod, 2021, 19(1): 159-169.
[67]	曹丽, 方东煜, 张莉, 等. 附件位置对上颌伸长磨牙压低效果影响的有限元分析[J]. 北京口腔医学, 2025, 33(3): 164-169.
	Cao L, Fang DY, Zhang L, et al. The effect of different attachment positions for maxillary first molar intrusion: a finite element analysis[J]. Beijing J Stomatol, 2025, 33(3): 164-169.
[68]	Sawamura M, Nakano H, Shiogama M, et al. Using digital image correlation to measure displacement and strain during involving distal movement of anterior teeth with clear aligner[J]. Dent Mater J, 2023, 42(4): 493-500.
[69]	Song JH, Lee JH, Joo BH, et al. Treatment outcome comparison of Invisalign vs fixed appliance treatment in first premolar extraction patients[J]. Am J Orthod Dentofacial Orthop, 2024, 165(4): 399-413.
[70]	Qiang R, Gao J, Wang Y, et al. Anchorage loss of the posterior teeth under different extraction patterns in maxillary and mandibular arches using clear aligner: a finite element study[J]. BMC Oral Health, 2024, 24(1): 1204.
[71]	Qian Y, Tang Z, Chen Y, et al. The ‘roller coaster effect’ in premolar extraction cases: clear aligners vs. straight-wire appliance[J]. Eur J Orthod, 2024, 47(1): cjae072.
[72]	Ren L, Liu L, Wu Z, et al. The predictability of ortho-dontic tooth movements through clear aligner among first-premolar extraction patients: a multivariate analysis[J]. Prog Orthod, 2022, 23(1): 52.
[73]	Liu JQ, Zhu GY, Wang YG, et al. Different biomechanical effects of clear aligners in closing maxillary and mandibular extraction spaces: finite element analysis[J]. Am J Orthod Dentofacial Orthop, 2023, 163(6): 811-824.e2.
[74]	Qiang R, Wu J, Gao J, et al. An integrated approach to posterior anchorage preparation and incisor torque compensation in premolar extraction cases using clear aligners[J]. BMC Oral Health, 2025, 25(1): 558.
[75]	Yang Y, Tang Z, Yan X, et al. Determination of optimal incisor overtreatment and molar anchorage preparation for first-premolar extraction patients treated with clear aligners[J]. Eur J Orthod, 2025, 47(4): cjaf049.
[76]	Li J, Yang Y, Tang Z, et al. Biomechanical analysis of the effect of Class Ⅱ traction configurations and aligner overtreatment on molar distalization: a finite-element study[J]. Eur J Orthod, 2024, 46(6): cjae055.
[77]	Yang Y, Yang R, Liu L, et al. The effects of aligner anchorage preparation on mandibular first molars during premolar-extraction space closure with clear aligners: a finite element study[J]. Am J Orthod Dentofacial Orthop, 2023, 164(2): 226-238.
[78]	Feng X, Jiang Y, Zhu Y, et al. Comparison between the designed and achieved mesiodistal angulation of maxillary canines and posterior teeth and influencing factors: first premolar extraction treatment with clear aligners[J]. Am J Orthod Dentofacial Orthop, 2022, 162(2): e63-e70.
[79]	Zhu GY, Zhang B, Yao K, et al. Finite element analysis of the biomechanical effect of clear aligners in extraction space closure under different anchorage controls[J]. Am J Orthod Dentofacial Orthop, 2023, 163(5): 628-644.e11.
[80]	Yan X, Zhang X, Ren L, et al. Effectiveness of clear aligners in achieving proclination and intrusion of incisors among ClassⅡ division 2 patients: a multivariate analysis[J]. Prog Orthod, 2023, 24(1): 12.
[81]	Kang F, Wu Y, Cui Y, et al. The displacement of teeth and stress distribution on periodontal ligament under different upper incisors proclination with clear aligner in cases of extraction: a finite element study[J]. Prog Orthod, 2023, 24(1): 38.
[82]	Zhu Y, Hu W, Li S. Force changes associated with differential activation of en-masse retraction and/or intrusion with clear aligners[J]. Korean J Orthod, 2021, 51(1): 32-42.
[83]	Tang Z, Chen W, Mei L, et al. Relative anchorage loss under reciprocal anchorage in mandibular premolar extraction cases treated with clear aligners[J]. Angle Orthod, 2023, 93(4): 375-381.
[84]	施则安, 夏恺, 罗良语, 等. 无托槽隐形矫治器联合微种植体内收并压低上前牙的三维有限元分析[J]. 华西口腔医学杂志, 2022, 40(5): 589-596.
	Shi ZA, Xia K, Luo LY, et al. Three-dimensional finite element analysis of upper anterior teeth retraction and intrusion using clear aligners and mini-implants[J]. West China J Stomatol, 2022, 40(5): 589-596.
[85]	Baek SE, Kim K, Choi YK, et al. Effects of clear aligner edentulous space design on distal canine movement: an iterative finite element analysis in cases involving extraction[J]. Korean J Orthod, 2025, 55(3): 193-201.
[86]	唐昕月, 须敏依, 华滢婕, 等. 无托槽隐形矫治上颌前牙分步内收和整体内收的三维有限元分析[J]. 中华口腔医学杂志, 2023, 58(7): 669-675.
	Tang XY, Xu MY, Hua YJ, et al. Three-dimensional finite element study on the effects of maxillary anterior two-step retraction and en-masse retraction with clear aligners[J]. Chin J Stomatol, 2023, 58(7): 669-675.
[87]	Li N, Lei X, Cao Y, et al. The effect of increasing the gaps between the front teeth on torque and intrusion control of the incisors for anterior retraction with clear alig-ners: a prospective study[J]. BMC Oral Health, 2024, 24(1): 115.
[88]	Liang L, Liu L, Cao Y, et al. The effects of anterior spa-ces on the intrusion of mandibular incisors with clear aligners in extraction cases: a finite-element analysis[J]. BMC Oral Health, 2025, 25(1): 1097.
[89]	Tang XY, Jiang T, Su H, et al. Effects of canine movement on maxillary anterior en-masse retraction with clear aligners: a finite element study[J]. BMC Oral Heal-th, 2025, 25(1): 337.
[90]	Eurutairat S, Vongtiang N, Wonghinkong S, et al. Predictability of maxillary canine retraction comparing po-wer arm and non-power arm using 24 sets of In-house clear aligner in premolar extraction case: a randomized controlled trial[J]. BMC Oral Health, 2025, 25(1): 719.