Evaluation of craniofacial effects of mini-implant supported maxillary expansion and conventional bonded maxillary expansion with computed tomography

Maxillary deficiency is a common problem in orthodontic patients and is usually accompanied by bilateral or unilateral posterior crossbite, narrow nasal cavity and crowding. Rapid maxillary expansion is one of the techniques most frequently used for the correction of maxillary atresia. The aim of this study were investigated mini-implant supported maxillary expansion and conventional maxillary expansion appliances effect with three dimensional computed tomography30 patients (16 female, 14 male, mean age; 13.03 years) with the indication of maxillary expansion due to bilateral or unilateral posterior cross-bite were included in this prospective, randomized study. Patients were divided into two groups and in the first group (11 female, 4 male, mean age: 12.66±1.89 years) was applied mini-implant supported maxillary expansion appliance (MISME), the second group (5 females, 10 males, mean age: 13.29±0.98 years) was applied conventional bonded maxillary expansion appliance. In the first group, subsequent to placement of 4 mini-implants (1.6 mm in diameter and 8 mm in length, Tomas, Dentaurum, Germany) in the palatal region, an acrylic expansion device was bonded on the screws. Photograph, dental cast and computed tomographic (CT) scan was obtained before treatment (T0) and after 6-months from the end of maxillary expansion (T1), with the cross-sectional tomogram (Siemens Sensation 16 Dedector Multislice CT, Germany). All CT data were transferred to a computer; using Dolphin 11.5 software. Nasal cavity volume and maxillary area changes were evaluated at T0 and T1. Statistical analyses were performed using SPSS 11.5 program. The difference between the measurements at T0 and T1 were undertaken with a Wilcoxon Signed Rank Test and between the groups were assessed with Mann Whitney U Test.The decrease in overbite value was less in the first group but no statistically significant difference was observed between the groups. Skeletal maxillary expansion was significantly more in the first group group (p<0.001), whereas dentoalveolar expansion was more evident in the second group (p<0.01). At the level of canine and first molar, expansion of the nasal floor width and nasal width was more in the first group compared with the second.According to the results of this study, the MISME appliance provided a more skeletal maxillary expansion, while less tipping of the posterior teeth.