Treatment of severe deep overbite with nonextraction treatment with Invisalign or conventional fixed appliance. Some points to be considered for clinical comparison

Regarding the recent publication, “Comparison of clinical outcomes between Invisalign and conventional fixed appliance therapies in adult patients with severe deep overbite treated with nonextraction,” which was published in April 20221Fujiyama K. Kera Y. Yujin S. Tanikawa C. Yamashiro T. Guo X. et al.Am J Orthod Dentofacial Orthop. 2022; 161: 542-547Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar, we would like to first congratulate the authors for the publication and interesting article, although we would also like to point some things out and raise some questions. The authors set no standard for the malocclusion of the participants or the severity of overbites. The only information provided was that the overbite was ≥5 mm and 60% deep; however, if these data are not accessed or accessible regarding the severity of malocclusion, the results may contain bias if 1 group receives more severe and complex treatment. Another missing point is the number of orthodontists who treated the 50 patients and their experience, which may affect the treatment time and technique used for conventional brackets and the amount of time between the tray change for the Invisalign group. In addition, the authors stated, “3 deepbite patients treated during that period by fixed appliance, patients were excluded for early treatment finish.” Why were they excluded? If they finished early, why is this not a suitable result? In the discussion section, the authors state, “In contrast to the fixed appliance group, the Invisalign group exhibited less extrusion of mandibular molars.” Class II elastics were generally used in the fixed appliance group, and there is a known extrusion vector,2Janson G. Sathler R. Fernandes T.M.F. Branco N.C.C. de Freitas M.R. Correction of Class II malocclusion with Class II elastics: a systematic review.Am J Orthod Dentofacial Orthop. 2013; 143: 383-392Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar which may not affect the Invisalign group because, as the authors reported, “aligner trays provide occlusal coverage, molars tend to intrude rather than extrude.” We would like to know if the extrusion found in the results was caused by the lateral effect of incisor intrusion mechanics or by Class II elastics. Furthermore, regarding the esthetic advantages, the literature suggests it depends on the number of attachments.3Thai J.K. Araujo E. McCray J. Schneider P.P. Kim K.B. Esthetic perception of clear aligner therapy attachments using eye-tracking technology.Am J Orthod Dentofacial Orthop. 2020; 158: 400-409Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar As for better oral hygiene, a clinical trial showed no evidence that Invisalign is more hygienic,4Chhibber A. Agarwal S. Yadav S. Kuo C.L. Upadhyay M. Which orthodontic appliance is best for oral hygiene? A randomized clinical trial.Am J Orthod Dentofacial Orthop. 2018; 153: 175-183Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar whereas for shorter treatment time, authors concluded, “Invisalign patients finished treatment faster than did those with fixed appliances. However, it appears that Invisalign may not be as effective as fixed appliances in achieving ‘great improvement’ in a malocclusion.”5Gu J. Tang J.S. Skulski B. Fields Jr., H.W. Beck F.M. Firestone A.R. et al.Evaluation of Invisalign treatment effectiveness and efficiency compared with conventional fixed appliances using the Peer Assessment Rating index.Am J Orthod Dentofacial Orthop. 2017; 151: 259-266Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar In addition, intrusion of incisors can be considered one of the most inaccurate movements with Invisalign.6Papageorgiou S.N. Koletsi D. Iliadi A. Peltomaki T. Eliades T. Treatment outcome with orthodontic aligners and fixed appliances: a systematic review with meta-analyses.Eur J Orthod. 2020; 42: 331-343Crossref PubMed Scopus (55) Google Scholar Therefore, to achieve this great improvement in malocclusion, refinement would be required (ie, a longer treatment time). The results were available by cephalometric measurements. In our opinion, cephalograms are important for orthodontic appraisal and must be combined with clinical evaluation. This must be considered because “orthodontic treatment with aligners is associated with worse treatment outcome compared to fixed appliances in adult patients. Current evidence does not support the clinical use of aligners as a treatment modality equally effective to the gold standard of braces.”7Charalampakis O. Iliadi A. Ueno H. Oliver D.R. Kim K.B. Accuracy of clear aligners: A retrospective study of patients who needed refinement.Am J Orthod Dentofacial Orthop. 2018; 154: 47-54Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar Moreover, the L1-Mp measurement in the fixed appliance group is 91.2° and 94.0° in the Invisalign group, which shows that the mandibular incisor is more protruded in the Invisalign group. Clinically this may represent a smaller overbite in relation to a more upright mandibular incisor (91.2°). The conclusion is controversial as it states that “Invisalign therapy may be preferable over conventional fixed appliance therapy in patients with high angle and deep overbite” but, “however, because this study had a retrospective design, the results should be viewed with caution.” It is noticeable that the use of clear aligners is increasing and achieving better results; however, we must remember that it is not the aligners or the brackets that move teeth, but instead the orthodontists with extensive training and knowledge who have the ability and the skills to do so. Biology and biomechanics have not changed with clear aligners. Comparison of clinical outcomes between Invisalign and conventional fixed appliance therapies in adult patients with severe deep overbite treated with nonextractionAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 161Issue 4PreviewThe use of aligner therapy for orthodontic treatment has increased substantially in the past decade. However, no study has compared treatment outcomes between the conventional fixed appliance and Invisalign therapies in patients with a severe deep overbite. Full-Text PDF Authors’ responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 163Issue 1PreviewWe thank the authors for their comments on our manuscript. Full-Text PDF