Agenesis of maxillary lateral incisors: Bone formation by orthodontic tooth movement and long-term stability of the edentulous alveolar ridge at 12-15 years after treatment.

INTRODUCTION: The primary aim of this study was to assess the amount and long-term stability of orthodontically created bone in patients with agenesis of maxillary lateral incisors after canine distalization. The secondary aim was to explore the impact of patient age on the process of alveolar bone resorption. METHODS: A group of patients with agenesis of the maxillary permanent lateral incisor was examined at 4 time points: the beginning of orthodontic treatment (T1, n = 80), the end of treatment (T2, n = 80), 2-5 years after treatment (T3, n = 79), and 12-15 years after treatment (T4, n = 32). The width of the edentulous alveolar bone was measured from study casts at the level of the bone ridge (point A) and 5 mm apically from the alveolar ridge (point B). Alveolar ridge height was also recorded using panoramic radiographs at all time points. Paired t tests, 2-sample t tests, Friedman test with Bonferroni correction, Spearman;s correlation, and linear regression tests were used to analyze the data. RESULTS: The alveolar ridge width was reduced by an average of 0.44 mm at point A and 0.47 mm at point B during the 12-15 years after treatment (T2-T4) and by 0.21 mm and 0.19 mm during the last 10 years (T3-T4). The alveolar ridge height was reduced by 0.59 mm between T2 and T4 and by 0.05 mm between T3 and T4. All reductions in ridge width and height were statistically significant (P <0.05). However, no significant correlation was observed between patient age and changes in alveolar bone parameters (P >0.05). CONCLUSIONS: Although the reductions in alveolar ridge dimensions were statistically significant, the orthodontically created bone after canine distalization remained stable 12-15 years after treatment in both the horizontal and vertical dimensions. Patient age did not significantly influence alveolar bone changes.