Correction of unilateral posterior crossbite in the mixed dentition: A randomized controlled trial

Introduction: From an evidence-based point of view, correction of posterior crossbite is not sufficiently evaluated. Thus, the aims of this study were to compare and evaluate the effectiveness of different treatment strategies to correct unilateral posterior crossbite in the mixed dentition by using the randomized clinical trial methodology with an untreated control group. Methods: Sixty patients participated in the study. All met the following inclusion criteria: mixed dentition, unilateral posterior crossbite, no sucking habits, and no previous orthodontic treatment. The patients were randomized into 4 groups: quad-helix, expansion plate, composite onlay, and untreated control. The success rates, amounts of maxillary and mandibular expansion, and treatment times were registered. Results: The quad-helix appliance was superior to the expansion plate in success rate and treatment time. Treatment with the expansion plate was unsuccessful in one third of the subjects. Crossbite correction with composite onlay in the mixed dentition was ineffective, and spontaneous correction in the mixed dentition did not occur. Conclusions: If unilateral posterior crossbite is planned to be corrected in the mixed dentition, this study clearly confirmed that treatment with the quad-helix is an appropriate and successful method.