Korean J Orthod.  2021 Sep;51(5):329-336. 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

• Toyokawa-Sperandio KC
• Ferreira Conti ACdC
• Fernandes TMF
• Almeida-Pedrin RRd
• Freirde Almeida MR
• Pedron Oltramari PV

• KMID: 2520375
• DOI: http://doi.org/10.4041/kjod.2021.51.5.329

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.

Keyword

Orthodontics; Root resorption; Clear aligner; Fixed appliance

Figure

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  Figure 1 Linear measurements of the tooth length (in millimeters) from the root apex to the incisal edge.

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  Figure 2 Consolidated Standards of Reporting Trials (CONSORT) diagram showing the flow of patients through the trial.

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