This retrospective study aimed to evaluate the further development of the lateral incisor and its associated periodontium adjacent to the treated labial inversely impacted maxillary central incisor.
We enrolled 23 participants (average age, 8.24 ± 1.43 years) undergoing a mean follow-up period of 31.10 ± 13.05 months. Each participant had an unimpacted lateral incisor and a successfully treated unilateral labial inversely impacted maxillary central incisor. The contralateral lateral incisors served as controls. Cone-beam computed tomography data were available for treatment completion and follow-up stages. The variables (including root length, dental age, root canal width, root-crown angulation, and alveolar bone loss and thickness) were evaluated with Dolphin Imaging software (version 11.95; Dolphin Imaging and Management Solutions, Chatsworth, Calif).
At the follow-up stage, the lateral incisors in the impacted side had significantly longer root lengths, smaller root canal widths, and thinner labial bone widths at the apex than at the posttreatment stage (P <0.001, P = 0.036, and P = 0.001, respectively). A significant lateral incisor root length reduction was noted when comparing the impacted and contralateral sides, although no variation was observed in root canal width. Similarly, crown-root angulation of the lateral incisor on the impacted side was significantly larger than that of the contralateral lateral incisor. The lateral incisor on the impacted side also had thicker labial and thinner lingual bone widths at the apex than the contralateral lateral incisor.
The lateral incisor adjacent to the successfully treated labial inversely impacted maxillary central incisor showed continuous growth during follow-up stages, exhibiting a similar morphology and alveolar bone quality but shorter root length, larger root angulation, and thinner lingual bone width at the apex than those of the contralateral lateral incisors.

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