Orthodontic Interceptive Appliance for Unilateral Posterior Crossbite in Mixed Dentition: A Case Report

Introduction: Unilateral posterior crossbite is a type of malocclusion that often occurs at the deciduous and mixed dentition stages. Researches indicate that 0-9 % of posterior crossbite can be corrected by itself in mixed dentition, so early intervention is important. The quad-helix orthodontic appliance is a solution to widen the maxilla in the skeletal and dental transverse direction to produce orthopedic and orthodontic movements. The utilization of the growth and development phases can accelerate the success of the treatment. Objective: To describe a unilateral posterior crossbite case using a quad-helix orthodontic appliance in mixed dental stages. Case report: A 7-year-old female patient complaining of an irregular arrangement of teeth with habits of long-term pacifier sucking and supporting the left chin. There was a diagnosis of Angle class I skeletal malocclusion and class II dental subdivision, accompanied by anterior and posterior crossbite shifting the mandibular midline 4 mm to left and facial asymmetry. Quad-helix treatment was carried out for 6 months with a retention phase for 3 months and continued with a fixed orthodontic phase. Unilateral posterior crossbite correction was achieved. Conclusion: A quad-helix orthodontic appliance can be an alternative for early treatment for unilateral posterior crossbite in mixed dentition.