The Treatment Of An Adolescent Patient With A High Angle Skeletal Class â…¡ Malocclusion

Objective: To investigate the treatment result of four first premolar extraction,strong anchorage devices as Nance, TPA and J hook headgear in Skeletal ClassⅡmalocclusion adolescent patients with high angle.Method: One adolescent patient treated at Dalian Doctor’s Dental Clinic in theyear of2010was recruited into the study. Femal,10years and3months old, SkeletalClassII, high angle. Convex profile, retruded mandible, extra mentalis muscle strainand small mentolabial sulcus.She had normal maxilla, mandible deficiency4mmoverjet and1mm overbite. Abnormal position of left lateral incisor, erupting leftincisors and left second mandible premolar, Class I molar relationship and ClassIIcanine relationship,1mm Spee depth and2mm shifted maxillary midline to the right.Four first premolars were extracted and fixed appliance was bonded in this case.Nanceand TPA were used to maintain the length of upper arch and spring also used to gainspace. J hook was applied to move incisors backward and Class II elastic applied for amore proper intermaxillary relationship. Cephalometric comparison was analysedbetween the beginning and the end of experiment.Results: The treatment duration was34months.Dentition was properly alignedand leveled. A good anteroposterior relationship was achieved with a3mm overjet and2mm overbite. There was no crowding and the molar and canine relationship wereboth class I.Comparison between the pretreatment and the posttreatment panoramicratiographs, there was no obvious resorption of the roots of all the teeth.Thepretreatment and posttreatment cephalometric tracings showed that: SNA、SNB haveno obvious change; FMA decreased by3.3，MP-SN decreased by4°，the mandiblerotated anticlockwise; N-ANS increased by4mm, ANS-Me/N-Me increased by1.6%.Co-Po increased3mm,posterior facial height increased by8mm, anterior facial height increased by1mm,the ratio increase by1%; U1-SN°increased by5°、U1-NAhad no obvious change， L1-NB°decreased by7°、 L1-NBdecreased by2mm, themaxillary anterior teeth flared and anterior teeth of the mandible retroinclined;Zangle increased from63°to65.6°， H angle decreased from18°to14.6°； ULEPdecreased4mm and LLEP decreased by2mm respectively. Protrusion of lips wasdecreased. AsUL-FH increased by10°, PosBs-FH increased by10.4°indicatingcoordinated relationship of the lip and chin. Wit’s changed from-2mm to0mm posttreatment.Conclusion: During the treatment of Skeletal ClassⅡ malocclusion adolescentpatients with high angle, with the help of four first premolar extraction, stronganchorage devices as Nance, TPA and J hook headgear, profile esthetics and smilefullness would be achieved perfectly.