This study aimed to gather statistically validated information on the changes in orthodontic variables in patients with bilateral upper lateral incisor aplasia treated with isolated orthodontic space closure. Data were collected from 25 (15 females, 10 males) consecutively treated, unselected adolescents [mean age at the end of treatment 16.4 years, standard deviation (SD) 1.3] after orthodontic space closure using push-and-pull mechanics (PPM). The changes in the relevant parameters were determined by comparing baseline and final lateral headfilms and casts. Following verification of normal distribution by means of a Kolmogorov-Smirnov test, a two-tailed t-test for related data was performed. SNA, ANB, OcP-NL, OcP-ML, upper space balance, overbite, overjet, bilateral molar relationship, and L1-NB changed significantly (P <= 0.05) during treatment. The changes in overbite, overjet, spatial conditions, and molar relationship were in line with the targeted treatment objectives and within the normal range. Although the change in L1-NB was probably due to treatment, it was not clinically relevant given that the mean final values were close to normal at 22.8 degrees (SD 5.8 degrees) for L1-NB and 95 degrees (SD 8 degrees) for L1-ML. Isolated orthodontic space closure for bilateral upper lateral incisor aplasia using PPM can be regarded as a valid alternative to prosthetic solutions. Long-term use of Class III elastics does not lead to significant changes in relevant orthodontic parameters.
