Upper arch forms in cases with bilaterally missing upper lateral incisors after space closure

Introduction Patients with missing upper lateral incisors are challenging to treat and an ideal result does not exist, although there is evidence that good results may be achieved with both canine mesialization and space opening. The aim of this retrospective study was to evaluate if the closure of the spaces in bilateral agenesis of the upper lateral incisors may affect the final upper arch form. Methods The initial and final dental casts of 26 adult patients (20 women and 6 men) with bilaterally missing lateral incisors treated with space closure (study group) were collected by the archives of four different orthodontists and were chosen based on the high-quality final results. Results were compared with those achieved by the same orthodontists on the initial and final casts of 26 adult patients with full dentition (20 men and 6 women) treated without extractions (control group). All upper dental casts were scanned to retrieve arch-forms, determine spatial coordinates, and perform quantitative measurements to interpolate the curves representing the form of the arches. Results Closure space treatment induces great changes in the arch length, no changes in intercanine width, and a little reduction of intermolar distance. When compared with those found in the control group, the final upper arches of the experimental group were flattened in the anterior zone and reduced in the anteroposterior dimension. This result was independent from the technique (type of brackets, prescriptions in the brackets, archwire sequence, archform) used by the four orthodontists who had treated the cases. Conclusions When spaces were closed in cases with bilaterally missing lateral incisors, the anteroposterior dimension suffered the most important modifications.