Evaluation of the Transverse Dimensions in the Maxilla and Mandible of Patients in the Mixed Dentition Phase Treated with Upper Removable Orthodontic Appliance

Abstract

Objective: To evaluate the effects of slow maxillary and mandibular expansion using upper removable orthodontic appliance with symmetric and median expanding screw in the occlusal, gingival and alveolar regions of young patients with narrow maxilla. Method: The sample consisted of 18 Caucasian children (11 females and 7 males; mean age at the beginning of treatment: 8 years and 10 months) with narrow maxilla associated or not with unilateral or bilateral posterior crossbite in the mixed dentition phase. All patients were treated during a mean period of 15.4 (± 7.6) months with upper removable orthodontic appliances with symmetric and median expanding screw. Maxillary and mandibular cast models (36 pairs) obtained at two moments (T1: beginning of the treatment and T2: end of the treatment) were used to evaluate the influence of the treatment in the measurements of the points demarcated in the occlusal, gingival and alveolar regions. For each patient, the transverse distances in the occlusal region between primary canines, primary first molars and first premolars, and between the permanent maxillary and mandibular molars were measured in ambos times. In order to determine whether the movement occurred due to inclination and translation, measurements in the gingival and alveolar regions were also taken. The obtained data were analyzed statistically by the Student’s t-test for paired samples at a significance level of 5%. Results: All distances measured for the occlusal, gingival and alveolar regions in T2 presented significantly higher values (p<0.05) than those obtained in T1. Conclusion: The upper removable orthodontic appliance is effective in cases of slow maxillary expansion, also acting indirectly in the transverse dimensions of the mandibular arch.