Contemporary Clear Aligner Therapy: a Review
Keywords:
Clear Aligner Therapy (CAT), invisalign, biomechanics, 3D printing, polymers, biocompatibility
Abstract
Clear Aligner Therapy (CAT) has revolutionized orthodontic speciality by providing an esthetic and comfortable treatment option to patients of all age groups. Though the notion of aligner therapy came as early as 1940s, rapid technological advancements in 3 Dimensional (3D) printing, computer-aided design (CAD) and manufacturing (CAM) and material advancements over the past two decades has increased the scalability and access to patients making it a popular treatment choice. Aligners consist of a series of custom-made clear plastic trays each worn for a period of 1-2 weeks to bring about necessary tooth movements to correct malocclusion. Various attachments and auxiliaries are employed to exert the desired forces and enhance specific tooth movements or to aid in retention of aligner. Inspite of numerous different aligner brands upcoming in this field, proper patient selection, treatment planning, patient compliance, material used and its manufacturing method and clinician experience remain the mainstay of treatment outcome. This review paper comprehensively explores the origin, types of clear aligners, different materials available along with their properties and behavior in oral environment, clear aligner biomechanics, advantages,clinical effectiveness and latest advancements to provide an understanding of role of CAT in modern orthodontic practice and its future directions.
References
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Kesling HD. Coordinating the predetermined pattern and tooth positioner with conventional treatment. Am J Orthod Oral Surg 1946;32:285–93.
Ponitz RJ. Invisible retainers. Am J Orthod. 1971;59:266–72. doi: 10.1016/0002-9416(71)90099-6.
Nahoum H. Forces and moments generated by removable thermoplastic aligners. Am J Orthod Dentofacial Orthop. 2014;146:545–6. doi: 10.1016/j.ajodo.2014.08.006
Mc Namara JA, Kramer KL, Juenker JP. Invisible retainers. J Clin Orthod. 1985;19(8):570–8.
Sheridan JJ, LeDoux W, McMinn R. Essix retainers: fabrication and supervision for permanent retention. J Clin Orthod 1993;27:37–45.
Align Technology and Ortho Clear Complete Definitive Agreement. Available from: www.aligntechnology.com.
Graber LW, Vanarsdall RL, Vig KWL, Huang GJ. Orthodontics: Current Principles and Techniques. 6th ed. St. Louis Missouri: Elsevier; 2017. 779-780 p.
Zhang N, Bai Y, Ding X, Zhang Y. Preparation and characterization of thermoplastic materials for invisible orthodontics. Dent. Mater. J. 2011;30(6) 964-959.
Tartaglia GM, Mapelli A, Maspero C, Santaniello T, Serafin M, Farronato M, Caprioglio A. Direct 3D printing of clear orthodontic aligners: current state and future possibilities. Materials. 2021;14:1799.
Macrì M, Murmura G, Varvara G, Traini T and Festa F (2022) Clinical Performances and Biological Features of Clear Aligners Materials in Orthodontics. Front. Mater. 9:819121.doi: 10.3389/fmats.2022.819121
Kapila S, Sachdeva R. Mechanical properties and clinical applications of orthodontic wires. Am J Orthod Dentofacial Orthop. 1989 Aug;96(2):100-9. doi: 10.1016/0889-5406(89)90251-5. PMID: 2667330.
Condò R, Mampieri G, Giancotti A, Cerroni L, Pasquantonio G, Divizia A, Coveretino A, Mecheri B, Maiolo L. SEM characterization and ageing analysis on two generation of invisible aligners. BMC Oral Health 21, 316 (2021). https://doi.org/10.1186/s12903-021-01676-z
Dupaix RB, Boyce MC. Finite strain behavior of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG), Polymer 46 (13) (2005) 4827–4838.
Frick A, Rochman A. Characterization of TPU-elastomers by thermal analysis (DSC). Polym. Test. 23 (4) (2004) 413–417.
Poomali S, Sureshac B, Lee JH. Mechanical and three-body abrasive wear behavior of PMMA/TPU blends. Mater. Sci. Eng., A. 2008;492(1–2):486–490.
Prasad S, Kader NA, Sujatha G, Raj T, Patil S. 3D Printing in Dentistry. Journal of 3D Printing in Medicine (2018). 2(3), 89–91. https://doi.org/10.2217/3dp-2018-0012
Abdallah MN, Lou T, Retrouvey JM, Suri S. Biomaterials used in orthodontics: brackets, archwires, and clear aligners. Advanced Dental Biomaterials, Elsevier, Philadelphia, 2019, pp. 541–579.
Kwon JS, Lee YK, Lim BS, Lim YK. Force delivery properties of thermoplastic orthodontic materials. Am. J. Orthod. Dentofacial Orthop. 133 (2) (2008) 228–234.
Elshazly TM, Keilig L, Salvatori D, Chavanne P, Aldesoki M, Bourauel C. Effect of Trimming Line Design and Edge Extension of Orthodontic Aligners on Force Transmission: An in Vitro Study. J. Dent. 2022, 125, 104276.
Upadhyay M, Arqub SA. Biomechanics of clear aligners: hidden truths & first principles. Journal of the World Federation of Orthodontists (2021) Volume 11, Issue 1, 12 - 21
Lombardo L, Marines E, Mazzanti V, Arreghini A, Molica F, Siciliani G. Stress relaxation properties of four orthodontic aligner materials: a 24-hour in vitro study. Angle Orthod. 2017;87(1):11–18.
Bakdach WMM, Haiba M, Hadad R. Changes in Surface Morphology, Chemical and Mechanical Properties of Clear Aligners during Intraoral Usage: A Systematic Review and Meta-Analysis. Int. Orthod. 2022, 20, 100610.
Liu CL, Sun WT, Liao W, Lu WX, Li QW, Jeong Y, Liu J, Zhao ZH. Colour stabilities of three types of orthodontic clear aligners exposed to staining agents. Int. J. Oral Sci. 2016;8(4):246–253.
Bernard GP, Rompré, Tavares JR, Montpetit A. Colorimetric and spectrophotometric measurements of orthodontic thermoplastic aligners exposed to various staining sources and cleaning methods. Head Face Med. 2020;16(1):2.
Zafeiriadis AA, Karamouzos A, Athanasiou AE, Eliades T, Palaghias G. An in vivo spectrophotometric evaluation of Vivera and Essix clear thermoplastic retainer discoloration. Aust. Orthod. J. 2018;34(1):3–10
Talic NF, Almudhi AA. The effect of dietary pigmentation on the esthetic appearance of clear orthodontic elastomeric modules. J. Orthod. Sci. 2016;5(2):70–73.
Iijima M, Kohda N, Kawaguchi K, Muguruma T, Ohta M, Naganishi A, Murakami T, Mizoguchi I. Effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviors and crystal structures. Eur. J. Orthod. 2015;37(6):665–670.
ISO 10993-1:2018; Biological Evaluation of Medical Devices—Part 1: Evaluation and Testing within a Risk Management Process. ISO: Geneva, Switzerland, 2018.
ISO 7405:2018; Dentistry: Evaluation of Biocompatibility of Medical Devices Used in Dentistry. ISO: Geneva, Switzerland, 2018.
Eliades T, Pratsinis H, Athanasiou AE, Eliades G, Kletsas D. Cytotoxicity and estrogenicity of Invisalign appliances. Am. J. Orthod. Dentofacial Orthop. 2009;136(1):100–103.
Burkhardt F, Spies BC, Wesemann C, Schirmeister CG, Licht EH, Beuer F, Steinberg T, Pieralli S. Cytotoxicity of Polymers Intended for the Extrusion-Based Additive Manufacturing of Surgical Guides. Sci. Rep. 2022, 12, 7391.
Andjela L, Abdurahmanovich VM, Vladimirovna SN, Mikhailovna GI, Yurievich DD, Alekseevna MY. A Review on Vat Photopolymerization 3D-Printing Processes for Dental Application. Dent. Mater. 2022, 38, e284–e296.
Drake C, McGorray S, Dolce C, Nair M, Wheeler T. Orthodontic Tooth Movement with Clear Aligners. ISRN Dent. 2012 doi: 10.5402/2012/657973. doi: 10.5402/2012/657973.
Boissere W, Morton J, Ojima K. Aligner Orthodontics: Diagnostics, Biomechanics Planning and Treatment. Hanover: Quintescence Publishing; 2015. pp. 26–30.
Djeu G, Shelton C, Maganzini A. Outcome assessment of invisalign and traditional orthodontic treatment compared with the American board of orthodontics objective grading system. Am J Orthod Dentofacial Orhop. 2005;128:292–8. doi: 10.1016/j.ajodo.2005.06.002.
Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi C. Efficacy of Clear Aligners in controlling Orthodontic Tooth Movement. Angle Orthod. 2015;85:881–9. doi: 10.2319/061614-436.1.
Kravitz N, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop. 2009;135:27–35. doi: 10.1016/j.ajodo.2007.05.018.
Zhang X-J He L Guo H-M Tian J Bai Y-X Li S. Integrated three-dimensional digital assessment of accuracy of anterior tooth movement using clear aligners. Korean J Orthod. 2015; 45: 275-281.
Schupp W, Haubrich J, Klingberg M, Boisserée W, Sim U, Kim H. Shape memory aligners: A new dimension in aligner orthodontics. Journal of Aligner Orthodontics 2023;7(2):113–127.
Border M, Strait R, Vega L. Clear Aligner Orthognathic Splints (CAOS) and Custom Maxillary Fixation Plates for Surgery-First or Surgery-Only cases. Journal of Oral and Maxillofacial Surgery, Volume 79, Issue 7, e6 - e11.
Vaid NR, Sabouni W, Wilmes B, Bichu YM, Thakkar DP, Adel SM. Customized adjuncts with clear aligner therapy: "The Golden Circle Model" explained! J World Fed Orthod. 2022 Dec;11(6):216-225. doi: 10.1016/j.ejwf.2022.10.005. Epub 2022 Nov 15. PMID: 36400659.
Batra P, Gribel BF, Abhinav BA, Arora A, Raghavan S. OrthoAligner “NAM”: A Case Series of Presurgical Infant Orthopedics (PSIO) Using Clear Aligners. The Cleft Palate Craniofacial Journal. 2020;57(5):646-655. doi:10.1177/1055665619889807
Hartshorne J, Wertheimer M B. Emerging insights and new developments in clear aligner therapy: a review of the literature. Am. J. Orthod. Dentofacial Orthop. Clin. Companion., 2 (4) (2022), pp. 311-324
Tamer İ, Öztaş E, Marşan G. Orthodontic Treatment with Clear Aligners and The Scientific Reality Behind Their Marketing: A Literature Review. Turk J Orthod. 2019 Dec 1;32(4):241-246. doi: 10.5152/TurkJOrthod.2019.18083. PMID: 32110470; PMCID: PMC7018497.
Narongdej P, Hassanpour M, Alterman N, Rawlins-Buchanan F, Barjasteh E. Advancements in Clear Aligner Fabrication. A Comprehensive Review of Direct-3D Printing Technologies. Polymers. 2024; 16(3):371. https://doi.org/10.3390/polym16030371
Jindal P, Juneja M, Siena FL, Bajaj D, Breedon P. Mechanical and geometric properties of thermoformed and 3D printed clear dental aligners. Am J Orthod Dentofacial Orthop. 2019 Nov;156(5):694-701. doi: 10.1016/j.ajodo.2019.05.012. PMID: 31677678.
Lee SY, Kim H, Kim HJ, Chung C J, Choi YJ, Kim SJ, Cha JY. Thermo-mechanical properties of 3D printed photocurable shape memory resin for clear aligners. Sci Rep 12, 6246 (2022). https://doi.org/10.1038/s41598-022-09831-4
Bichu YM, Alwafi A, Liu X, Andrews J, Ludwig B, Bichu AY, et al. Advances in orthodontic clear aligner materials. Bioact Mater. 2023;22:384–403.
AbdulMajeed, AlMogbel. Clear Aligner Therapy: Up to date review article. Journal of Orthodontic Science 12(1):37, September 2023. DOI: 10.4103/jos.jos_30_23
Kesling HD. Coordinating the predetermined pattern and tooth positioner with conventional treatment. Am J Orthod Oral Surg 1946;32:285–93.
Ponitz RJ. Invisible retainers. Am J Orthod. 1971;59:266–72. doi: 10.1016/0002-9416(71)90099-6.
Nahoum H. Forces and moments generated by removable thermoplastic aligners. Am J Orthod Dentofacial Orthop. 2014;146:545–6. doi: 10.1016/j.ajodo.2014.08.006
Mc Namara JA, Kramer KL, Juenker JP. Invisible retainers. J Clin Orthod. 1985;19(8):570–8.
Sheridan JJ, LeDoux W, McMinn R. Essix retainers: fabrication and supervision for permanent retention. J Clin Orthod 1993;27:37–45.
Align Technology and Ortho Clear Complete Definitive Agreement. Available from: www.aligntechnology.com.
Graber LW, Vanarsdall RL, Vig KWL, Huang GJ. Orthodontics: Current Principles and Techniques. 6th ed. St. Louis Missouri: Elsevier; 2017. 779-780 p.
Zhang N, Bai Y, Ding X, Zhang Y. Preparation and characterization of thermoplastic materials for invisible orthodontics. Dent. Mater. J. 2011;30(6) 964-959.
Tartaglia GM, Mapelli A, Maspero C, Santaniello T, Serafin M, Farronato M, Caprioglio A. Direct 3D printing of clear orthodontic aligners: current state and future possibilities. Materials. 2021;14:1799.
Macrì M, Murmura G, Varvara G, Traini T and Festa F (2022) Clinical Performances and Biological Features of Clear Aligners Materials in Orthodontics. Front. Mater. 9:819121.doi: 10.3389/fmats.2022.819121
Kapila S, Sachdeva R. Mechanical properties and clinical applications of orthodontic wires. Am J Orthod Dentofacial Orthop. 1989 Aug;96(2):100-9. doi: 10.1016/0889-5406(89)90251-5. PMID: 2667330.
Condò R, Mampieri G, Giancotti A, Cerroni L, Pasquantonio G, Divizia A, Coveretino A, Mecheri B, Maiolo L. SEM characterization and ageing analysis on two generation of invisible aligners. BMC Oral Health 21, 316 (2021). https://doi.org/10.1186/s12903-021-01676-z
Dupaix RB, Boyce MC. Finite strain behavior of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate)-glycol (PETG), Polymer 46 (13) (2005) 4827–4838.
Frick A, Rochman A. Characterization of TPU-elastomers by thermal analysis (DSC). Polym. Test. 23 (4) (2004) 413–417.
Poomali S, Sureshac B, Lee JH. Mechanical and three-body abrasive wear behavior of PMMA/TPU blends. Mater. Sci. Eng., A. 2008;492(1–2):486–490.
Prasad S, Kader NA, Sujatha G, Raj T, Patil S. 3D Printing in Dentistry. Journal of 3D Printing in Medicine (2018). 2(3), 89–91. https://doi.org/10.2217/3dp-2018-0012
Abdallah MN, Lou T, Retrouvey JM, Suri S. Biomaterials used in orthodontics: brackets, archwires, and clear aligners. Advanced Dental Biomaterials, Elsevier, Philadelphia, 2019, pp. 541–579.
Kwon JS, Lee YK, Lim BS, Lim YK. Force delivery properties of thermoplastic orthodontic materials. Am. J. Orthod. Dentofacial Orthop. 133 (2) (2008) 228–234.
Elshazly TM, Keilig L, Salvatori D, Chavanne P, Aldesoki M, Bourauel C. Effect of Trimming Line Design and Edge Extension of Orthodontic Aligners on Force Transmission: An in Vitro Study. J. Dent. 2022, 125, 104276.
Upadhyay M, Arqub SA. Biomechanics of clear aligners: hidden truths & first principles. Journal of the World Federation of Orthodontists (2021) Volume 11, Issue 1, 12 - 21
Lombardo L, Marines E, Mazzanti V, Arreghini A, Molica F, Siciliani G. Stress relaxation properties of four orthodontic aligner materials: a 24-hour in vitro study. Angle Orthod. 2017;87(1):11–18.
Bakdach WMM, Haiba M, Hadad R. Changes in Surface Morphology, Chemical and Mechanical Properties of Clear Aligners during Intraoral Usage: A Systematic Review and Meta-Analysis. Int. Orthod. 2022, 20, 100610.
Liu CL, Sun WT, Liao W, Lu WX, Li QW, Jeong Y, Liu J, Zhao ZH. Colour stabilities of three types of orthodontic clear aligners exposed to staining agents. Int. J. Oral Sci. 2016;8(4):246–253.
Bernard GP, Rompré, Tavares JR, Montpetit A. Colorimetric and spectrophotometric measurements of orthodontic thermoplastic aligners exposed to various staining sources and cleaning methods. Head Face Med. 2020;16(1):2.
Zafeiriadis AA, Karamouzos A, Athanasiou AE, Eliades T, Palaghias G. An in vivo spectrophotometric evaluation of Vivera and Essix clear thermoplastic retainer discoloration. Aust. Orthod. J. 2018;34(1):3–10
Talic NF, Almudhi AA. The effect of dietary pigmentation on the esthetic appearance of clear orthodontic elastomeric modules. J. Orthod. Sci. 2016;5(2):70–73.
Iijima M, Kohda N, Kawaguchi K, Muguruma T, Ohta M, Naganishi A, Murakami T, Mizoguchi I. Effects of temperature changes and stress loading on the mechanical and shape memory properties of thermoplastic materials with different glass transition behaviors and crystal structures. Eur. J. Orthod. 2015;37(6):665–670.
ISO 10993-1:2018; Biological Evaluation of Medical Devices—Part 1: Evaluation and Testing within a Risk Management Process. ISO: Geneva, Switzerland, 2018.
ISO 7405:2018; Dentistry: Evaluation of Biocompatibility of Medical Devices Used in Dentistry. ISO: Geneva, Switzerland, 2018.
Eliades T, Pratsinis H, Athanasiou AE, Eliades G, Kletsas D. Cytotoxicity and estrogenicity of Invisalign appliances. Am. J. Orthod. Dentofacial Orthop. 2009;136(1):100–103.
Burkhardt F, Spies BC, Wesemann C, Schirmeister CG, Licht EH, Beuer F, Steinberg T, Pieralli S. Cytotoxicity of Polymers Intended for the Extrusion-Based Additive Manufacturing of Surgical Guides. Sci. Rep. 2022, 12, 7391.
Andjela L, Abdurahmanovich VM, Vladimirovna SN, Mikhailovna GI, Yurievich DD, Alekseevna MY. A Review on Vat Photopolymerization 3D-Printing Processes for Dental Application. Dent. Mater. 2022, 38, e284–e296.
Drake C, McGorray S, Dolce C, Nair M, Wheeler T. Orthodontic Tooth Movement with Clear Aligners. ISRN Dent. 2012 doi: 10.5402/2012/657973. doi: 10.5402/2012/657973.
Boissere W, Morton J, Ojima K. Aligner Orthodontics: Diagnostics, Biomechanics Planning and Treatment. Hanover: Quintescence Publishing; 2015. pp. 26–30.
Djeu G, Shelton C, Maganzini A. Outcome assessment of invisalign and traditional orthodontic treatment compared with the American board of orthodontics objective grading system. Am J Orthod Dentofacial Orhop. 2005;128:292–8. doi: 10.1016/j.ajodo.2005.06.002.
Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi C. Efficacy of Clear Aligners in controlling Orthodontic Tooth Movement. Angle Orthod. 2015;85:881–9. doi: 10.2319/061614-436.1.
Kravitz N, Kusnoto B, BeGole E, Obrez A, Agran B. How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop. 2009;135:27–35. doi: 10.1016/j.ajodo.2007.05.018.
Zhang X-J He L Guo H-M Tian J Bai Y-X Li S. Integrated three-dimensional digital assessment of accuracy of anterior tooth movement using clear aligners. Korean J Orthod. 2015; 45: 275-281.
Schupp W, Haubrich J, Klingberg M, Boisserée W, Sim U, Kim H. Shape memory aligners: A new dimension in aligner orthodontics. Journal of Aligner Orthodontics 2023;7(2):113–127.
Border M, Strait R, Vega L. Clear Aligner Orthognathic Splints (CAOS) and Custom Maxillary Fixation Plates for Surgery-First or Surgery-Only cases. Journal of Oral and Maxillofacial Surgery, Volume 79, Issue 7, e6 - e11.
Vaid NR, Sabouni W, Wilmes B, Bichu YM, Thakkar DP, Adel SM. Customized adjuncts with clear aligner therapy: "The Golden Circle Model" explained! J World Fed Orthod. 2022 Dec;11(6):216-225. doi: 10.1016/j.ejwf.2022.10.005. Epub 2022 Nov 15. PMID: 36400659.
Batra P, Gribel BF, Abhinav BA, Arora A, Raghavan S. OrthoAligner “NAM”: A Case Series of Presurgical Infant Orthopedics (PSIO) Using Clear Aligners. The Cleft Palate Craniofacial Journal. 2020;57(5):646-655. doi:10.1177/1055665619889807
Published
2025-02-10
How to Cite
Sharma, N. (2025). Contemporary Clear Aligner Therapy: a Review. UNIVERSITY JOURNAL OF DENTAL SCIENCES, 11(1). https://doi.org/10.21276/ujds.2025.11.1.16
Section
Review Article
