Clinical Study Of Forsus In Treatment Of Class â…¡ Malocclusion With Retrusive Mandible

Objectives ClassⅡmalocclusion with mandibular retrusion are frequently observed in orthodontic practice.Most patients had missed the best time,only extracting or orthognathic surgery could be done to this kind of patients.The most common characteristic of classⅡmalocclusion is mandibular retrusion.Stimulating the mandibular growth is the importance of treatment.Nineteen classⅡpatients with retrusive mandible were treated with Forsus appliance in the late permanent dentition. Lateral cephalograms and study models and electromyography of masseter muscle were obtained after the leveling phase and at time for the removal of the appliances. To investigate the skeletal and dental arches changes and approach the relationship between the balance of muscle function and the rebuilt of osseous tissue and to evaluate the efficacy of this appliance.Methods The patient selection criteria were ClassⅡmalocclusion caused by retrognathic mandible,normal or low-angle growth pattern,and postpeak growth period.The study sample consisted of 19 subjects(age 14-16.5)Lateral cephalograms and study models and electromyography of masseter muscle were obtained after the leveling phase and at time of the removal of the appliances.Students' t-test was used to determine if there were significant differences between pre-treatment and post -treatment.Result This study demonstrated the skeletal,dental and softtissue effects of the Forsus used in patient of postpeak growth period.1 There were no significant changes in skeletal parameters.The mandibular incisors were protruded and intruded,whereas the maxillary incisors were retruded and extruded.The upper molars tipped distally as the lower molars tipped mesially. Because of these changes,the occlusal plane rotated in the clockwise direction. Overbite and overjet were reduced,and the soft-tissue profile improved significantly. The results revealed that,in late-adolescent patients,the Forsus corrected ClassⅡdiscrepancies mostly through dentoalveolar changes.2 The upper and lower dental arches were broadened during treatment with the Forsus appliance.The upper jaw broadened by 1.54±0.78mm anteriorly and 2.16±0.96mm posteriorly.The lower jaw broadened by 1.23±0.89mm anteriorly and 2.00±0.88mm posteriorly.This broadening of the dental arch was statistically significant.3 The character of the electromyographies of the 19 children were as follows:(1) There was no obvious changes in the stadium invasionis and the extended stationary phase tended to be normal.(2)The graph of the mandibular postural position was table and there was no abnormal graph.(3)The intercuspal position tight bite changed from mixed phase to interfere phase(normal),the graph was intensive and the wave amplitude raised.(4)The abnormal stop was decreased or dissapeared in the food broken phase of masticatory cycle,the graph was fairly uniform and intensive,the wave amplitude increased.(5)The total time course of masticatory cycle tended to decrease.Conclusion This study demonstrated the skeletal,dental and softtissue effects of the Forsus used in patient ofpostpeak growth period.1 There were no significant changes in skeletal.2 Forsus appliance cause significant incisor and molar movements,and these dentoalevor changes are more affective than the skeletal changes in attaining classⅠmalar relation ship.It is suggested that this treatment method could be an alternative to orthognathic surgery in borderline classⅡcases.3 The results showed a significant improvement in the facial profile because of retraction of the upper lip.4 It also expanded the dental arches during the treatment.5 After the change of mandibular position by Forsus appliance guided the mandibular forwards,the activity of masstor muscle increased,the rule of electromyography tended to be normal.