Keywords
biocompatibilidad
degradación de polímeros
materiales ortodóncicos
microplásticos
How to Cite
Abstract
Abstract
Introduction: Clear orthodontic aligners, used as an alternative to conventional fixed appliances, enable the application of controlled orthodontic forces and are primarily manufactured from thermoplastic polymers. However, prolonged exposure to the oral environment may induce material degradation processes, potentially leading to the release of chemical compounds and microplastic particles. Objective: To synthesize the available scientific evidence regarding the degradation of orthodontic aligner materials, the potential release of chemical compounds and microplastics, and their possible biological implications. Methods: A narrative literature review was conducted following methodological principles for high-quality narrative reviews and the recommendations of the SANRA scale. The search was performed in PubMed/MEDLINE, Web of Science, and the Cochrane Library using terms related to orthodontic aligners, material degradation, chemical release, and microplastics. Results: The available evidence indicates that materials used in aligners may undergo surface and mechanical changes during intraoral use, including increased roughness and the formation of microcracks. Some experimental studies have demonstrated the potential release of chemical compounds and microplastic particles under conditions of mechanical wear; however, most of these data are derived from in vitro models. Conclusions:
Orthodontic aligners exhibit a clinically favorable safety profile, although they are not completely inert from a physicochemical perspective. Longitudinal clinical studies and the development of standardized analytical methods are needed to more accurately assess real exposure and its potential biological implications.
References
1. Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of clear aligners in controlling orthodontic tooth movement: A systematic review. Angle Orthodontist. Allen Press Inc.; 2015. p. 881–9. doi:10.2319/061614-436.1 PubMed PMID: 25412265.
2. Papadimitriou A, Mousoulea S, Gkantidis N, Kloukos D. Clinical effectiveness of Invisalign® orthodontic treatment: a systematic review. Progress in Orthodontics. Springer Berlin Heidelberg; 2018. doi:10.1186/s40510-018-0235-z PubMed PMID: 30264270.
3. Ke Y, Zhu Y, Zhu M. A comparison of treatment effectiveness between clear aligner and fixed appliance therapies. BMC Oral Health. 2019 Jan 23;19(1). doi:10.1186/s12903-018-0695-z PubMed PMID: 30674307.
4. Lombardo L, Arreghini A, Ramina F, Huanca Ghislanzoni LT, Siciliani G. Predictability of orthodontic movement with orthodontic aligners: a retrospective study. Prog Orthod. 2017 Dec 1;18(1). doi:10.1186/s40510-017-0190-0 PubMed PMID: 29130127.
5. Elkholy F, Schmidt S, Amirkhani M, Schmidt F, Lapatki BG. Mechanical Characterization of Thermoplastic Aligner Materials: Recommendations for Test Parameter Standardization. J Healthc Eng. 2019;2019. doi:10.1155/2019/8074827 PubMed PMID: 31275537.
6. Weir T. Clear aligners in orthodontic treatment. Aust Dent J. 2017;62 Suppl 1:58-62. doi:10.1111/adj.12480.
7. Eliades T, Bourauel C. Intraoral aging of orthodontic materials: The picture we miss and its clinical relevance. American Journal of Orthodontics and Dentofacial Orthopedics. 2005;127(4):403–12. doi:10.1016/j.ajodo.2004.09.015 PubMed PMID: 15821684.
8. Lombardo L, Martines E, Mazzanti V, Arreghini A, Mollica F, Siciliani G. Stress relaxation properties of four orthodontic aligner materials: A 24-hour in vitro study. Angle Orthodontist. 2017 Jan 1;87(1):11–8. doi:10.2319/113015-813.1 PubMed PMID: 27314603.
9. Gerard Bradley T, Teske L, Eliades G, Zinelis S, Eliades T. Do the mechanical and chemical properties of InvisalignTM appliances change after use? A retrieval analysis. Eur J Orthod. 2016 Feb 1;38(1):27–31. doi:10.1093/ejo/cjv003 PubMed PMID: 25740599.
10. Thompson RC, Olsen Y, Mitchell RP, Davis A, Rowland SJ, John AWG, et al. Lost at Sea: Where Is All the Plastic? [Internet]. Report No. Available from. doi: 10.1126/science.1094559
11. Wright SL, Kelly FJ. Plastic and Human Health: A Micro Issue? Environ Sci Technol. 2017 Jun 20;51(12):6634–47. doi:10.1021/acs.est.7b00423 PubMed PMID: 28531345.
12. Cox KD, Covernton GA, Davies HL, Dower JF, Juanes F, Dudas SE. Human Consumption of Microplastics. Environ Sci Technol. 2019 Jun 18;53(12):7068–74. doi:10.1021/acs.est.9b01517 PubMed PMID: 31184127.
13. Prata JC, da Costa JP, Lopes I, Duarte AC, Rocha-Santos T. Environmental exposure to microplastics: An overview on possible human health effects. Science of the Total Environment. Elsevier B.V.; 2020. doi:10.1016/j.scitotenv.2019.134455 PubMed PMID: 31733547.
14. van Landuyt KL, Nawrot T, Geebelen B, de Munck J, Snauwaert J, Yoshihara K, et al. How much do resin-based dental materials release? A meta-analytical approach. Dental Materials. 2011. p. 723–47. doi:10.1016/j.dental.2011.05.001 PubMed PMID: 21664675.
15. Schuster S, Eliades G, Zinelis S, Eliades T, Bradley TG. Structural conformation and leaching from in vitro aged and retrieved Invisalign appliances. American Journal of Orthodontics and Dentofacial Orthopedics. 2004 Dec;126(6):725–8. doi:10.1016/j.ajodo.2004.04.021 PubMed PMID: 15592222.
16. 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. International Orthodontics. Elsevier Masson s.r.l.; 2022. doi:10.1016/j.ortho.2022.100610 PubMed PMID: 35090857.
17. Bichu YM, Alwafi A, Liu X, Andrews J, Ludwig B, Bichu AY, et al. Advances in orthodontic clear aligner materials. Bioact Mater. 2023 Apr 1;22:384–403. doi:10.1016/j.bioactmat.2022.10.006
18. Lorusso M, Esperouz F, di Carlo G, Tepedino M, Esposito R, Pappalettera G, et al. Cytotoxicity of Printed Aligners: A Systematic Review. Dentistry Journal. Multidisciplinary Digital Publishing Institute (MDPI); 2025. doi:10.3390/dj13070275
19. Kolenc L, Oblak J, Ovsenik M, Oblak Č, Ovsenik R. Biocompatibility and Safety of Orthodontic Clear Aligners and Thermoplastic Retainers: A Systematic In Vitro Review (2015–2025). Applied Sciences (Switzerland). Multidisciplinary Digital Publishing Institute (MDPI); 2025. doi:10.3390/app152312494
20. Koletsi D, Panayi N, Laspos C, Athanasiou AE, Zinelis S, Eliades T. In vivo aging-induced surface roughness alterations of Invisalign® and 3D-printed aligners. J Orthod. 2022. doi:10.1177/14653125221145948 PubMed PMID: 36573484.
21. Jaggy F, Zinelis S, Polychronis G, Patcas R, Schätzle M, Eliades G, et al. ATR-FTIR analysis and one-week stress relaxation of four orthodontic aligner materials. Materials. 2020 Apr 1;13(8). doi:10.3390/MA13081868
22. Peter E, Monisha J, George SA. Bisphenol-A release from thermoplastic clear aligner materials: A systematic review. J Orthod. 2023 Sep 1;50(3):276–86. doi:10.1177/14653125231160570 PubMed PMID: 36922722.
23. Alhendi A, Khounganian R, Almudhi A, Ahamad SR. Leaching of Different Clear Aligner Systems: An In Vitro Study. Dent J (Basel). 2022 Feb 1;10(2). doi:10.3390/dj10020027
24. Wendl T, Leitner E, Wendl B, Proff P. Analysis of orthodontic aligner biocompatibility: leachable compounds of different aligner materials. Biomedizinische Technik. 2025 Feb 1. doi:10.1515/bmt-2025-0131 PubMed PMID: 40966312.
25. Yazdi M, Daryanavard H, Hashemi Ashtiani A, Moradinejad M, Rakhshan V. A systematic review of biocompatibility and safety of orthodontic clear aligners and transparent vacuum- formed thermoplastic retainers: Bisphenol-A release, adverse effects, cytotoxicity, and estrogenic effects. Dental Research Journal [Internet]. 2023. Report No. PMID: 37180685
26. Vitores-Calero A, García-Sanz V, Paredes-Gallardo V, Zamora-Martínez N, Tarazona-Álvarez B. Quantification of Bisphenol A in the Saliva of Patients Wearing Clear Aligners. Dent J (Basel). 2025 Dec 1;13(12). doi:10.3390/dj13120599
27. Barile C, Cianci C, Paramsamy Kannan V, Pappalettera G, Pappalettere C, Casavola C, et al. Experimental assessment of damage and microplastic release during cyclic loading of clear aligners. PLoS One. 2025 Feb 1;20(2 February). doi:10.1371/journal.pone.0318207 PubMed PMID: 39908302.
28. de Stefano AA, Horodynski M, Galluccio G. Can Clear Aligners Release Microplastics That Impact the Patient’s Overall Health? A Systematic Review. Materials. Multidisciplinary Digital Publishing Institute (MDPI); 2025. doi:10.3390/ma18112564
29. Quinzi V, Orilisi G, Vitiello F, Notarstefano V, Marzo G, Orsini G. A spectroscopic study on orthodontic aligners: First evidence of secondary microplastic detachment after seven days of artificial saliva exposure. Science of the Total Environment. 2023 Mar 25;866. doi:10.1016/j.scitotenv.2022.161356 PubMed PMID: 36603638.
30. Zecca PA, Borgese M, Raspanti M, Zara F, Fastuca R, Serafin M, et al. Comparative microscopic analysis of plastic dispersion from 3D-printed and thermoformed orthodontic aligners. Eur J Orthod. 2025 Jun 1;47(3). doi:10.1093/ejo/cjaf014 PubMed PMID: 40211725.
31. Chen DDS, Peng TY, Huang PY, Kaku M, Cheng JHC. Advances in clear aligner therapy: comparative evaluation of the optical properties and bacterial adhesion of 3D direct-printed and thermoformed aligners. Prog Orthod. 2025 Dec 1;26(1). doi:10.1186/s40510-025-00600-3 PubMed PMID: 41410724.
32. Ferreira M, Costa H, Veiga N, Correia MJ, Gomes ATPC, Lopes PC. Do Clear Aligners Release Toxic Chemicals?—A Systematic Review. Journal of Functional Biomaterials. Multidisciplinary Digital Publishing Institute (MDPI); 2025. doi:10.3390/jfb16050173
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