LAUSR

OBJECTIVES To evaluate the costs of quad-helix (QH) and removable expansion plate (EP) treatments performed either in specialist or general dentistry for the correction of unilateral posterior crossbite with functional shift in the mixed dentition. TRIAL DESIGN Four-arm parallel group multicentre randomized controlled trial. MATERIALS AND METHODS One hundred and ten patients with unilateral posterior crossbite with functional shift were recruited. The patients were randomized by an independent person not involved in the trial. The randomization used blocks of 20 and into the following four groups: QH treatments in specialist orthodontic clinics (QHS), QH treatments in general dentistry (QHG), EP treatments in specialist orthodontic clinics (EPS), and EP treatments in general dentistry (EPG). Blinding was accomplished of the outcome assessor and data analyst. A cost analysis was performed with reference to intention-to-treat (ITT), regarding direct costs, indirect costs, and societal costs (the sum of direct and indirect costs) for calculations of successful treatments alone and for retreatments when required. To determine which alternative has the lower cost, a cost-minimization analysis was undertaken, based on that the outcome of the treatment alternatives were broadly equivalent, so the difference between them reduces to a comparison of costs. RESULTS In the QHS group, 28 of 28 patients were successfully corrected compared to 23 of 27 in the QHG group. Treatment with expansion plate was less successful: 18 of 27 patients in the EPS group and 18 of 28 in the EPG group. QH treatment performed in specialist orthodontic clinics had significantly lower costs than QH or EP treatment accomplished in general dentistry as well as EP treatments in specialist orthodontic clinics. LIMITATIONS Costs depend on local factors and should not be directly extrapolated to other locations. CONCLUSION Treatment of unilateral posterior crossbite in the mixed dentition is recommended to be performed by a specialist orthodontist using the QH appliance. TRIAL REGISTRATION The trial was not registered.