Journal of Korean Dental Science

Korean Academy of Dental Science (대한치의학회)
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Force Assessment of Thermoformed and Direct-printed Aligners in a Lingual Bodily Movement of a Central Incisor Over Time: A 14-day In Vitro Study

  • Received : 2022.12.16
  • Accepted : 2023.02.09
  • Published : 2023.06.30
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Abstract

Purpose: This study aims to investigate the force delivery profile of thermoformed aligners (TFA) compared with direct-printed aligners (DPA) and to explore the effect of different activation amounts on forces and moments of respective groups. A secondary objective is to observe the amount of stress relaxation that occurs over the 7~14 days when aligners are maintained in a simulated intraoral environment. Materials and Methods: An in vitro setup was created to quantify forces and moments. It consisted of a three dimensional-printed base plate and segmented maxillary teeth, placed in a semi-enclosed chamber to maintain a temperature of 37℃. Ninety clear aligners were divided into nine groups of ten aligners each based on material types (Zendura, ATMOS, TC-85) and activation amounts. Aligners were created with 0.00, 0.25- and 0.50-mm activations for lingual bodily movement of the upper left central incisor and kept on models in the "stressed" position in a 37℃ water bath. Three force components acting on the upper left lateral incisor, upper left central incisor, and upper right central incisor were measured for each time point, beginning from the initial baseline measurement, 8 hours, 16 hours, 24 hours, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, and lastly, 14 days. Result: TC-85 aligners in every activation group showed less force on teeth than Zendura and ATMOS. Significant force levels from 0.0 mm activation were present and stayed consistent over the course of 14 days. Comparisons made for baseline measurements to 7-days and 14-days showed statistically significant change from the baseline force level. Conclusion: TC-85 aligners demonstrated lower, more consistent forces with fewer side effects. Aligners can generate forces even when no activation is programmed. No major decreases in force levels over time were observed; the intra-oral clinical simulated environment and length of observation time could contribute to this.

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References

  1. Bollen AM. Effects of malocclusions and orthodontics on periodontal health: evidence from a systematic review. J Dent Educ. 2008; 72: 912-8.  https://doi.org/10.1002/j.0022-0337.2008.72.8.tb04567.x
  2. Kaur S, Singh R, Soni S, Garg V, Kaur M. Esthetic orthodontic appliances - A review. Ann Geriatr Educ Med Sci. 2018; 5: 11-4.  https://doi.org/10.18231/2348-7240.2018.0003
  3. Thai JK, Araujo E, McCray J, Schneider PP, Kim KB. Esthetic perception of clear aligner therapy attachments using eye-tracking technology. Am J Orthod Dentofacial Orthop. 2020; 158: 400-9.  https://doi.org/10.1016/j.ajodo.2019.09.014
  4. 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 (Basel). 2021; 14: 1799. 
  5. Upadhyay M, Arqub SA. Biomechanics of clear aligners: hidden truths & first principles. J World Fed Orthod. 2022; 11: 12-21.  https://doi.org/10.1016/j.ejwf.2021.11.002
  6. Xiang B, Wang X, Wu G, Xu Y, Wang M, Yang Y, Wang Q. The force effects of two types of polyethylene terephthalate glyc-olmodified clear aligners immersed in artificial saliva. Sci Rep. 2021; 11: 10052. 
  7. Bichu YM, Alwafi A, Liu X, Andrews J, Ludwig B, Bichu AY, Zou B. Advances in orthodontic clear aligner materials. Bioact Mater. 2022; 22: 384-403.  https://doi.org/10.1016/j.bioactmat.2022.10.006
  8. Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL. Efficacy of clear aligners in controlling orthodontic tooth movement: a systematic review. Angle Orthod. 2015; 85: 881-9.  https://doi.org/10.2319/061614-436.1
  9. Hertan E, McCray J, Bankhead B, Kim KB. Force profile assessment of direct-printed aligners versus thermoformed aligners and the effects of non-engaged surface patterns. Prog Orthod. 2022; 23: 49. 
  10. Koenig N, Choi JY, McCray J, Hayes A, Schneider P, Kim KB. Comparison of dimensional accuracy between direct-printed and thermoformed aligners. Korean J Orthod. 2022; 52: 249-57.  https://doi.org/10.4041/kjod21.269
  11. 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 Orthod. 2017; 87: 11-8.  https://doi.org/10.2319/113015-813.1
  12. Lee SY, Kim H, Kim HJ, Chung CJ, Choi YJ, Kim SJ, Cha JY. Thermo-mechanical properties of 3D printed photocurable shape memory resin for clear aligners. Sci Rep. 2022; 12: 6246. 
  13. Kwon JS, Lee YK, Lim BS, Lim YK. Force delivery properties of thermoplastic orthodontic materials. Am J Orthod Dentofacial Orthop. 2008; 133: 228-34; quiz 328.e1.  https://doi.org/10.1016/j.ajodo.2006.03.034
  14. Stephens C, Weir T, Llewellyn S, Freer E, Kerr B. 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. Am J Orthod Dentofacial Orthop. 2022; 162: e103-15.  https://doi.org/10.1016/j.ajodo.2022.06.015
  15. Haouili N, Kravitz ND, Vaid NR, Ferguson DJ, Makki L. Has Invisalign improved? A prospective follow-up study on the efficacy of tooth movement with Invisalign. Am J Orthod Dentofacial Orthop. 2020; 158: 420-5.  https://doi.org/10.1016/j.ajodo.2019.12.015
  16. Kravitz ND, 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.  https://doi.org/10.1016/j.ajodo.2007.05.018
  17. Heo WS. Initial force system delivered by a clear aligner during a bodily tooth movement of a maxillary central incisor [master's thesis]. St. Louis: Saint Louis University; 2019. 
  18. Proffit WR, Fields HW, Sarver DM. Contemporary orthodontics. 5th ed. St. Louis: Elsevier/Mosby; 2013. 
  19. Al-Nadawi M, Kravitz ND, Hansa I, Makki L, Ferguson DJ, Vaid NR. Effect of clear aligner wear protocol on the efficacy of tooth movement. Angle Orthod. 2021; 91: 157-63. https://doi.org/10.2319/071520-630.1