Treatment Effects of the Forsus Fatigue Resistance Device and Twin Block Appliance in Patients with Class II Malocclusions: A Cephalometric Comparison Study
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Introduction: Class II malocclusions are of interest to the practicing orthodontists because they constitute a significant percentage of the cases they treat. Over the years, a substantial number of approaches and appliances had been developed for Class II malocclusion treatment. The concept of fixed functional appliance such as Forsus appliance was suggested as an option to overcome the lack of compliance with some patients. Many studies were published about Twin Block but only few studies have evaluated the treatment effects of the Forsus Appliance. Objectives: This study will evaluate the effects of the Forsus appliance in comparison with Twin Block appliance and a non-treated control group for the treatment of Class II malocclusion. Methods: The present retrospective study was carried out on three groups: Twin Block group (37 subjects, mean age 11.2 Y ), Forsus group (30 subjects, mean age 12.9 Y), and a non-treated control group (25 subjects, mean age 12.6 Y). The study was based on the evaluation of the lateral cephalometric radiographs of pre-treatment, as well as at T2 (posts appliance removal/ equivalent timeframe in controls. Cephalometric changes were evaluated using the Clark analysis including 27 measurements. Results: The results showed that sagittal correction of Class II appeared to be mainly achieved by dentoalveolar change changes only in Forsus group. The Twin Block appliance therapy was able to induce both skeletal and dentoalveolar changes. A favourable influence on the facial convexity could be achieved in both groups. In the Twin Block group, skeletal alterations that contributed to skeletal correction mainly took place in the mandibular ramus, while these changes were significant different form the controls. The effects on the upper incisors varied between the two functional appliances. Large significant upper incisors retroclination occurred with the Twin Block (-12.42 degree) while - 4° only observed in Forsus group. The lower incisors were proclined slightly more in Forsus than Twin Block group. No significant change of the incisor position of the controls was present. Incisor overjet reduction was larger in amount in Twin Block (7.03 mm) and 4 mm in the Forsus group. The overjet correction was about 60% of the initial overjet in both experimental groups. Molar relation was corrected in both functional groups resulting in a Class I relation, while no change appeared in the control sample.