Aim: The aim of this study was to compare the clinical effectiveness in reducing large overjet between a prefabricated functional appliance (PFA) and a slightly modified Andresen activator (AA).
Methods: A multicenter, prospective and randomized clinical trial is conducted in 12 general dental practices. Until now seventy four subjects (34 girls, 40 boys) mean age 10.4 years with overjet ≥ 6mm and a Class II, division1 malocclusion have been randomly selected to treatment with either a PFA or a AA. The PFA and AA group consists of 41 subjects (18 girls, 23 boys) and 32 subjects (15 girls, 17 boys) respectively. Overjet, trauma, lip seal and treatment discomfort are recorded before and at 3, 6 and 12 months after start of treatment. The endpoint of treatment was set to overjet ≤ 3mm and after this a 6 months retention period followed.
Results: No difference was noted in overjet correction between the two groups. The vertical correction was larger in the PFA group while the sagittal molar relation improved more in the AA group. The treatment of 15 patients with PFA and 12 with AA were considered unsuccessful due to poor compliance or other factors.
Conclusion: Prefabricated functional appliances are just as effective as Andresen activators in correcting overjet more effective in correcting overbite but less effective in correction the Class II molar relationship. The advantage with the PFA is that no impressions are needed and the cost is about 1/3 of that of the AA.