Comparison of forsus fatigue resistant device and crown herbst in treatment of class ii malocclusion
Allaymouni, Mhd Amer
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Objectives: The purpose of this study is to evaluate and compare the skeletal and dentoalveolar effects of the Stainless Steel Edgewise Crown Herbst, and the Forsus Fatigue Resistant Device in the treatment of the class II malocclusion in adolescent patients. Materials and methods: This study is a retrospective clinical trial which was conducted on records for Class II patients who were treated with two different appliances. Results were compared with an untreated control group. The first group consists of 30 patients (mean age 12.9 + 1.18) who were treated with Forsus FRD, the second group consists of 28 patients (mean age 11.7+1.66) who were treated with edgewise crown Herbst, and the third group was a class II untreated control group which had 25 subjects (mean age 12.6+ 0.91). Lateral cephalograms were taken before functional appliance placement [T1] and after functional appliance removal [T2] to evaluate treatment effects. Analyses of Variances (ANOVA) followed by TukeyHSD post-hoc test were used to compare changes between groups at p < 0.05. Results: Herbst appliance showed more favorable skeletal effects in normalizing class II relations in comparison with Forsus appliance; in Herbst group, the profile convexity decreased -1.98mm; and the Mx/Md difference increased 2.88 mm more than the Forsus group. Both Herbst and Forsus caused significant lower incisors protrusion (1.97 mm in Forsus and 2.93 mm in Herbst) and upper incisors retrusion (-1.40 mm in Forsus and -1.61 mm in Herbst), there was no statistically differences between the two appliances in term of the incisor position changes. Conclusions: Both appliances led to successful correction of the class II relations; The Herbst appliance showed significant favorable skeletal effects on both the maxilla and the mandible. In Forsus FRD protocol, class II correction was mainly obtained by dentoalveolar changes on both upper and lower dental arches. Key words: Functional appliance, Class II malocclusion, Forsus, Herbst.