Application Of J Hook In The Treatment Of Maxillary Protrusion

Objective:To investigate the clinical effect of J hook and straight wire appliance in the treatment of maxillary protrusion in adolescents.Method:A case of adolescent patients treated with Dr.Dalian dental Clinic 2014 in May,female,12 years of age,7 months,high angle,maxillary protrusion.Maxilla,mandibular hypoplasia,soft tissue convexity,maxillary incisor lip inclination.Covering 6mm,overbite 4.5mm,caninesis bilateral relationship between neutral,neutral molar relationship,the arch is neutral,maxillary crowding 9mm,mandibular crowding 3mm.Spee curve 4mm,Bolton anterior ratio 78.3%,molar ratio 87.4%.In this case,extracting four mandibular first premolars,the whole orthodontic headgear,application of J hook recovery of maxillary anterior teeth closed the gap.At the same time,make the front of the gums to move,adjust the cover to normal.The closure of extraction space,fine adjustment after removal of orthodontic appliances,maxillary thermoplastic retainer,mandibular lingual fixed retainer.X ray cephalometric radiographs were compared before and after treatment.Result : The treatment ocurse lasted for 30 months.The tooth leveling and alignment,the closure of extraction space,after treatment of overbite and overjet returned to normal,crowded get lifted,bilateral molar and canine relationship are neutral,the profile is a convex face type,soft tissue had obvious improvement.Before and after treatment for periodontal ligament fragments,continuous,alveolar bone and root had no obvious absorption.Condylar morphology did not change significantly.X-ray cephalometric measurements show that the comparison before and after treatment:The SNA,SNB showed no significant change,Y decreased 2.2 degree axis,FMA decreased 1.5 degree,MP and SN decreased 2.3 degree,indicating the mandibular plane counter clockwise direction.The U1-SN decreased 12.6 degree,U1-NA U1-NB decreased 14.8degree,reduced by 3.1 degrees,that the lip inclination of anterior teeth decreases under the anterior teeth axis upright.The Z angle from 63 increased to 68 degrees,upper lip protrusion decreased 1.5mm,3.3mm on the lower lip,lower lip relations more harmonious nature.The front,behind the high specific surface.Conclusion: The high angle maxillary protrusion in adolescent patients in the treatment,the extraction of four first premolars,prior to using Nance support and TPA control the molar height after application of headgear J hook closure gap and in the recovery of anterior teeth and anterior teeth intrusion,So that the jaw can rotate counterclockwise,and ultimately to achieve good occlusal relationship,get good profile.