Effect of impacted maxillary canines on adjacent lateral incisor root resorption: Association with alveolar bone thickness, incisor angulation, and traction difficulty: A retrospective CBCT study.

OBJECTIVE

To evaluate the relationship between maxillary impacted canines and root resorption of adjacent lateral incisors, considering resorption severity and location, alveolar bone thickness, incisor angulation, and traction difficulty assessed by the KPG index using cone-beam computed tomography (CBCT).

METHODS

This observational analytical study included 100 CBCT scans obtained between 2022 and 2025, yielding 119 impacted maxillary canines. Root resorption of adjacent lateral incisors was classified by severity and location. Alveolar bone thickness was measured at buccal and palatal surfaces at apical, middle, and cervical levels. Lateral incisor-palatal plane angulation and KPG index scores were recorded. Intra-observer reliability was assessed. Statistical analyses included chi-square tests, independent t tests, one-way ANOVA, repeated-measures ANOVA, and appropriate post-hoc tests (α=0.05).

RESULTS

Root resorption was absent in 57.1% of cases (95% CI: 48.3-65.9), whereas 42.9% (95% CI: 34.1-51.7) presented some degree of resorption, predominantly in the apical and middle thirds. Resorption severity and location were not associated with sex. Palatal alveolar bone thickness at the apical level showed a mean value of 4.05mm (95% CI: 3.36-4.74) and was significantly greater than buccal thickness. Increased severity of lateral incisor root resorption was significantly associated with reduced palatal alveolar bone thickness at the apical level (P=0.003), whereas buccal bone thickness showed no significant association. Lateral incisor-palatal plane angulation presented a mean of 68.5° (95% CI: 66.3-70.7). The KPG index demonstrated a mean score of 12.5 (95% CI: 11.9-13.1) and showed limited ability to predict the presence or severity of root resorption.

CONCLUSIONS

Lateral incisor root resorption associated with impacted maxillary canines occurs mainly at the apical and middle thirds and is significantly related to reduced palatal alveolar bone thickness. CBCT provides essential three-dimensional information for identifying anatomical risk factors and supporting safer and more predictable clinical decision-making in impacted canine cases.