Comparison of Two Miniscrew Anchored Maxillary Protraction Protocols

Class III malocclusion treatment in growing patients is challenging. A new treatment for maxillary protraction using skeletal anchorage reported an efficient maxillary protraction in the late mixed dentition an early permanent dentition. Therefore, the aim of this study is to compare the dentoskeletal effects produced by two maxillary protraction protocols anchored on miniscrews. The sample will be recruited at the Orthodontic Clinic of Bauru Dental School, University of São Paulo, Brazil. A sample of thirty-five patients, between 9 and 13 years old will be selected. The inclusion criteria are: Class III malocclusion associated with anterior crossbite. The participants will be allocated into 2 groups. Group 1 will comprise 20 individuals treated with a tooth-bone-borne expander and 2 miniscrews in the mandible Group 2 will comprise 15 individuals treated with a tooth-borne expander and 2 miniscrews in the mandible. Digital models and cone-beam computed tomography (CBCT) will be obtained before (T1) and 12 months after treatment (T2). Occlusal radiographs and partial (canine to canine) models will be obtained before and immediately after expansion. Two-dimensional cephalometric evaluations will be performed in the Dolphin® software. The arch width, arch perimeter and arch length will be analyzed with the Orthoanalyzer® software. Three-dimensional superimposition at the cranial base of T1 and T2 CBCT images will be performed. The inter incisor diastema will be evaluated by occlusal radiographs and dental models. Discomfort, pain and quality of life will evaluated by questionnaires. After verifying the normal distribution, the intragroup comparison will be performed with paired t test and intergroup comparison will be performed with t test. In the case of lost to follow-up patients, intention to treat analysis will be used. A significance level of 5% will be regarded for all tests. Temporary pain and discomfort are possible after the installation of the miniscrews. Patients and legal guardians will be informed. After the consent, the treatment can be stoped at any time.