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. 2021 Sep 25;51(5):329-336.
doi: 10.4041/kjod.2021.51.5.329.

External apical root resorption 6 months after initiation of orthodontic treatment: A randomized clinical trial comparing fixed appliances and orthodontic aligners

Katia Cristina Toyokawa-Sperandio  1 , Ana Cláudia de Castro Ferreira Conti  1 , Thais Maria Freire Fernandes  1 , Renata Rodrigues de Almeida-Pedrin  1 , Marcio Rodrigues de Almeida  1 , Paula Vanessa Pedron Oltramari  1
Affiliations

External apical root resorption 6 months after initiation of orthodontic treatment: A randomized clinical trial comparing fixed appliances and orthodontic aligners

Katia Cristina Toyokawa-Sperandio et al. Korean J Orthod. .

Abstract

Objective: To compare the magnitude of external apical root resorption (EARR) 6 months after starting orthodontic treatment using orthodontic aligners (OAs) and fixed appliances (FAs).

Methods: This parallel randomized clinical trial included 40 patients randomized into two groups: OA group (n = 20, 160 incisors) and FA group (n = 20, 160 incisors). For evaluation of the tooth length, periapical radiographs and standardized linear measurements of the maxillary and mandibular incisors were acquired before (T0) and 6 months after treatment initiation (T1). EARR was calculated through the difference in length between the two time points (T1-T0). Statistical comparisons were performed by means of using t-tests, chi-squared test and covariance analysis (a = 5%).

Results: Rounding of the root apex was observed in both groups; the resorption involved 2.88% of the root length, so 97.12% of the tooth length remained intact. Intragroup comparisons between the two time points revealed a significant difference, with (T1-T0) ranging from -0.52 to -0.88 mm in the FA group and from -0.52 to -0.85 mm in the OA group. In the intergroup comparisons, only tooth #21 presented a statistically significant difference (OA: -0.52 ± 0.57 mm, FA: -0.86 ± 0.60 mm); however, the overall differences between groups were not clinically relevant, ranging from 0.03 to 0.35 mm.

Conclusions: OA and FA treatment resulted in a similar degree of EARR in the maxillary and mandibular incisors at 6 months after treatment initiation. However, the amount of resorption was small and does not impair tooth longevity.

Keywords: Clear aligner; Fixed appliance; Orthodontics; Root resorption.

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Conflict of interest statement

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

Figures

Figure 1
Figure 1
Linear measurements of the tooth length (in millimeters) from the root apex to the incisal edge.
Figure 2
Figure 2
Consolidated Standards of Reporting Trials (CONSORT) diagram showing the flow of patients through the trial.
See this image and copyright information in PMC

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