Objective: the aim of this study is to compare the perception of pain and discomfort of patients and their guardians after treatment with miniscrew-anchored maxillary protraction therapy using hybrid and conventional Hyrax expanders. Material and Methods: Two groups will be assessed. Group HH was composed of 18 subjects (8 female, 10 male; initial age of 10.80 years) with Class III malocclusions treated with a hybrid hyrax expander with two miniscrews in the maxilla and two miniscrews in the anterior region of the mandible. Class III elastics were used from the maxillary first molar to the mandibular miniscrews until anterior crossbite correction or a maximum of 12 months of treatment. The group CH was composed of 14 subjects (6 female, 8 male; initial age of 11.44 years) treated with a similar protocol except for the conventional Hyrax expander in the maxilla. Pain and discomfort were assessed using a visual analog scale (VAS). Patients and guardians were asked about the degree of pain and discomfort caused by the therapy. The level of pain and discomfort was investigated immediately after the device was installed, one day after, at the end of the active expansion, and one month after the device was placed. The paired t-test will be used in the intragroup comparison, while the independent t-test will be used in the intergroup comparison. A significance level of 5% will be regarded for all tests. (AU).
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