Background: Clear aligner therapy (CAT) has become an increasingly popular alternative to fixed appliances, yet its effectiveness in achieving complex orthodontic tooth movements remains limited. Composite attachments are routinely incorporated to enhance biomechanical control, but the optimal attachment shape, position, and dimension for maximizing movement efficiency are still unclear. Objective: To evaluate how the shape, position, and dimensions of composite attachments influence the efficacy and predictability of orthodontic tooth movements in clear aligner therapy. Methods: This systematic review followed PRISMA guidelines and was registered in INPLASY (INPLASY 202570109). Electronic databases including PubMed, Scopus, Cochrane Library, and ScienceDirect were searched for studies published between January 2014 and January 2025. Eligible studies included human research evaluating attachment design variables. Exclusion criteria were finite element simulations, case reports, reviews, and non-English/French publications. Nine studies met inclusion criteria. Risk of bias was assessed using MINORS for non-randomized studies and the Cochrane tool for randomized clinical trials. Results: Nine clinical studies were included. Overall, attachment design significantly influenced tooth movement predictability, although effects varied by movement type. Ellipsoid and cylindrical shapes showed favorable force distribution for extrusion, intrusion, and anterior retraction, while rectangular attachments improved torque and mesio-distal angulation. Optimized attachments enhanced rotational performance in some studies, though evidence remained inconsistent. Attachment position played a critical role: lingual placement consistently provided better torque control and reduced unwanted rotations compared with buccal placement. Larger and more prominent attachments improved force transmission but increased wear and the risk of open gingival embrasures; similarly, a greater number of attachments enhanced anchorage yet did not reliably improve rotational movements. Conclusion: Composite attachments are essential auxiliaries for enhancing the biomechanical performance of clear aligners. However, their effectiveness is movement-specific. Ellipsoid/cylindrical shapes favor vertical movements, rectangular attachments optimize torque, and lingual positioning offers superior control for complex biomechanics. Evidence remains heterogeneous, highlighting the need for standardized clinical trials to determine optimal attachment configurations.
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Sair, S. , Chkhayess, D. , Quars, F. E. and Mabrak, A. E. (2026). Shape, Position, Dimension of Attachments in Clear Aligners: A Systematic Review. Open Access Library Journal, 13, e14791. doi: http://dx.doi.org/10.4236/oalib.1114791.
Momtaz, P. (2016) The Effect of Attachment Placement and Location on Rota-tional Control of Conical Teeth Using Clear Aligner Therapy. https://digitalscholarship.unlv.edu/thesesdissertations/2712/
Comba, B., Parrini, S., Rossini, G., Castroflorio, T. and Deregibus, A. (2017) A Three-Dimensional Finite Element Analysis of Upper-Canine Distalization with Clear Aligners, Composite Attachments, and Class II Elastics. Journal of Clinical Orthodontics, 51, 24-28.
Jiang, Q., Li, J., Mei, L., Du, J., Levrini, L., Abbate, G.M., et al. (2018) Periodontal Health during Orthodontic Treatment with Clear Aligners and Fixed Appliances: A Meta-Analysis. The Journal of the American Dental Association, 149, 712-720.e12. https://doi.org/10.1016/j.adaj.2018.04.010
Rossini, G., Parrini, S., Castroflorio, T., Deregibus, A. and Debernardi, C.L. (2014) Periodontal Health during Clear Aligners Treatment: A Systematic Review. The European Journal of Orthodontics, 37, 539-543. https://doi.org/10.1093/ejo/cju083
Papadimitriou, A., Kakali, L., Pazera, P., Doulis, I. and Kloukos, D. (2019) Social Media and Orthodontic Treatment from the Patient’s Perspective: A Systematic Review. European Journal of Or-thodontics, 42, 231-241. https://doi.org/10.1093/ejo/cjz029
Simon, M., Keilig, L., Schwarze, J., Jung, B.A. and Bourauel, C. (2014) Treatment Outcome and Efficacy of an Aligner Technique—Regarding Incisor Torque, Premolar Derotation and Molar Distalization. BMC Oral Health, 14, Article No. 68. https://doi.org/10.1186/1472-6831-14-68
Haouili, N., Kravitz, N.D., Vaid, N.R., Ferguson, D.J. and Makki, L. (2020) Has Invisalign Improved? A Prospective Follow-Up Study on the Efficacy of Tooth Movement with Invisalign. American Journal of Orthodontics and Dentofacial Orthopedics, 158, 420-425. https://doi.org/10.1016/j.ajodo.2019.12.015
Gomez, J.P., Peña, F.M., Martínez, V., Giraldo, D.C. and Cardona, C.I. (2015) Initial Force Systems during Bodily Tooth Movement with Plastic Aligners and Composite Attachments: A Three-Dimensional Finite Element Analysis. The Angle Orthodontist, 85, 454-460. https://doi.org/10.2319/050714-330.1
Skaik, A., Wei, X.L., Abusamak, I. and Iddi, I. (2019) Effects of Time and Clear Aligner Removal Frequency on the Force Delivered by Different Polyethylene Terephthalate Glycol-Modified Mate-rials Determined with Thin-Film Pressure Sensors. American Journal of Ortho-dontics and Dentofacial Orthopedics, 155, 98-107. https://doi.org/10.1016/j.ajodo.2018.03.017
Hassanaly, T., Rabal-Solans, A., Mediero-Pérez, M. and Nieto-Sánchez, I. (2024) A Comparison of the Upper Anterior Teeth Movements with Optimized and Conventional Attachment. Journal of Clinical and Experimental Dentistry, 16, e480-e484. https://doi.org/10.4317/jced.61466
Dai, F., Xu, T. and Shu, G. (2019) Comparison of Achieved and Predicted Tooth Movement of Maxillary First Mo-lars and Central Incisors: First Premolar Extraction Treatment with Invisalign. The Angle Orthodontist, 89, 679-687. https://doi.org/10.2319/090418-646.1
Karras, T., Singh, M., Karkazis, E., Liu, D., Nimeri, G. and Ahuja, B. (2021) Efficacy of Invisalign At-tachments: A Retrospective Study. American Journal of Orthodontics and Den-tofacial Orthopedics, 160, 250-258. https://doi.org/10.1016/j.ajodo.2020.04.028
Smith, J.M., Weir, T., Kaang, A. and Farella, M. (2022) Predictability of Lower Incisor Tip Using Clear Aligner Therapy. Progress in Orthodontics, 23, Article No. 37. https://doi.org/10.1186/s40510-022-00433-4
Zhang, Y., Wang, X., Wang, J., Gao, J., Liu, X., Jin, Z., et al. (2023) IPR Treatment and Attachments Design in Clear Aligner Therapy and Risk of Open Gingival Embrasures in Adults. Progress in Orthodontics, 24, Article No. 1. https://doi.org/10.1186/s40510-022-00452-1
Stephens, C., Weir, T., Llewellyn, S., Freer, E. and Kerr, B. (2022) Clinical Expression of Programmed Mandibular Canine Rotation Using Various Attachment Protocols and 1- vs 2-Week Wear Protocols with Invisalign SmartTrack Aligners: A Retrospective Cohort Study. American Journal of Orthodontics and Dentofacial Orthopedics, 162, e103-e115. https://doi.org/10.1016/j.ajodo.2022.06.015
Alhasyimi, A.A., Ayub, A. and Farmasyanti, C.A. (2023) Effectiveness of the Attachment Design and Thickness of Clear Aligners during Orthodontic Anterior Retraction: Finite Ele-ment Analysis. European Journal of Dentistry, 18, 174-181. https://doi.org/10.1055/s-0043-1761452
Hong, K., Kim, W., Eg-han-Acquah, E., Lee, J., Lee, B. and Kim, B. (2021) Efficient Design of a Clear Aligner Attachment to Induce Bodily Tooth Movement in Orthodontic Treat-ment Using Finite Element Analysis. Materials, 14, Article No. 4926. https://doi.org/10.3390/ma14174926
Kim, W., Hong, K., Lim, D., Lee, J., Jung, Y. and Kim, B. (2020) Optimal Position of Attachment for Removable Thermoplastic Aligner on the Lower Canine Using Finite Element Analysis. Ma-terials, 13, Article No. 3369. https://doi.org/10.3390/ma13153369
Laohachaiaroon, P., Samruajben-jakun, B. and Chaichanasiri, E. (2022) Initial Displacement and Stress Distribu-tion of Upper Central Incisor Extrusion with Clear Aligners and Various Shapes of Composite Attachments Using the Finite Element Method. Dentistry Journal, 10, Article No. 114. https://doi.org/10.3390/dj10060114
Li, Q. and Yang, K. (2024) Surface Wear of Attachments in Patients during Clear Aligner Therapy: A Prospective Clinical Study. Progress in Orthodontics, 25, Article No. 7. https://doi.org/10.1186/s40510-023-00506-y
Cai, Y., He, B., Yang, X. and Yao, J. (2015) Optimization of Configuration of Attachment in Tooth Translation with Transparent Tooth Correction by Appropriate Mo-ment-to-Force Ratios: Biomechanical Analysis. Bio-Medical Materials and Engi-neering, 26, S507-S517. https://doi.org/10.3233/bme-151340
