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Table. 2.

Intragroup comparisons of the tooth length in the orthodontic aligner (OA) and fixed appliance (FA) groups

Group FDI tooth number T0 T1 Variation (T1–T0) p-value
Mean SD Mean SD mm %
OA (n=19) 12 25.38 2.20 24.84 2.16 −0.53 −2.10 < 0.001*
11 26.39 2.24 25.82 2.17 −0.56 −2.14 < 0.001*
21 26.44 2.42 25.92 2.40 −0.52 −1.95 0.001*
22 25.74 1.75 25.09 1.88 −0.65 −2.54 < 0.001*
32 24.45 1.34 23.79 1.53 −0.66 −2.70 < 0.001*
31 23.12 1.39 22.38 1.33 −0.73 −3.18 < 0.001*
41 23.18 1.42 22.33 1.41 −0.85 −3.67 < 0.001*
42 24.52 1.46 23.75 1.45 −0.77 −3.15 < 0.001*
FA (n=20) 12 24.19 2.40 23.48 2.38 −0.72 −2.96 < 0.001*
11 24.72 2.58 24.19 2.59 −0.53 −2.14 < 0.001*
21 25.28 2.27 24.41 2.17 −0.86 −3.42 < 0.001*
22 24.61 2.36 23.74 2.55 −0.87 −3.53 < 0.001*
32 24.05 2.56 23.53 2.49 −0.52 −2.16 0.001*
31 22.09 2.17 21.28 2.17 −0.81 −3.68 < 0.001*
41 22.21 1.94 21.33 1.81 −0.88 −3.94 < 0.001*
42 23.97 2.44 23.32 2.52 −0.66 −2.75 < 0.001*

The variation (T1−T0) represents the degree of external apical root resorption.

p-values were calculated using the dependent t-test.

FDI, Federation Dentaire Internationale; T0, before treatment initiation; T1, 6 months after treatment initiation; SD, standard deviation.

*Statistically significant difference (p < 0.05).

Korean J Orthod 2021;51:329~336 https://doi.org/10.4041/kjod.2021.51.5.329
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