Factors affecting treatment duration of labial inversely impacted maxillary central incisors

A labial inversely impacted maxillary central incisor is a relatively rare occurrence. The crown of the tooth is directed upward, and its palatal aspect is facing labially. This typical orientation can be the result of trauma to the deciduous incisor transmitted to the palatal side of the crown of the permanent incisor. Labial inversely impacted maxillary central incisors are most commonly combined with labial-lingual root dilacerations. The aim of this study was to examine factors that affect the surgical-orthodontic treatment duration of labial inversely impacted maxillary central incisors.

The records of 35 consecutively treated patients were retrospectively evaluated. Cone-beam computed tomography images were taken before treatment, and factors affecting treatment time, including age, length, crown-root angle, crown height and depth, angle of inversion, rotation to axial plane, and distance and angle to midline, were measured using Dolphin Imaging software (version 11.8; Patterson Supply, St Paul, Minn). Treatment duration was evaluated for each patient, and logistic regression analyses were applied.

The 15 boys and 20 girls had a mean age 8.36 ± 1.36 years. The mean orthodontic traction duration was 11.28 ± 3.08 months. Multiple regression analyses indicated that factors resulting in a longer duration were age (β = 0.779; P = 0.043), crown height (β = 0.344; P = 0.007), crown-root angle (β = -0.037; P = 0.018), and tooth length (β = -0.623; P = 0.038).

Surgical-orthodontic correction of labial inversely impacted maxillary incisors requires an average of 1 year. Assessments of age, crown height, root dilaceration, and length of incisor can help the orthodontist to better predict treatment duration during consultations with patients and parents.