Objectives

To elucidate the relationships and factors affecting the proximity between the incisive canal (IC) and maxillary central incisors and to predict the probable outcomes after anterior tooth retraction using cone beam computed tomography (CBCT).

Materials and Methods

Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction.

Results

All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC.

Conclusions

Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.

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Author notes

a

Postgraduate Student, Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; and Postgraduate Student, Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University (CU), Bangkok, Thailand.

b

Assistant Professor, Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.

c

Associate Professor, Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University (CU), Bangkok, Thailand.

d

Clinical Fellow, Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.

e

Professor and Chair, Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.