| Objective: The purpose of this study was to evaluate the clinical treatment effectof an adolescent patient with an Angle’s Class II malocclusion and crowding usingonly maxillary extraction.Method: A patient with Angle’s Class II deformity was admitted to DalianDoctor’s Dental Clinic in2010. The patient was a twelve years and three months oldmale, with mild skeletal class II discrepancy and normal mandibular angle, mandiblewas retruded. The canine and molar relationship of the left side were in class IIrelationships, the molars of the right side were in class II relationships. There was a II°overbite and I°overjet. The canines of right side were bucally placed, no space to erupt.The maxillary mid line was deviated1mm to the right, the mandibular middle line wasdeviated2mm to the left. The upper crowding was8.5mm, the lower crowding was1.5mm and the curve of Spee was3mm. According to measurement of cephalometricradiograph and calculation: SNA angle was73.7°, SNB angle was67.7°, ANB anglewas6°; U1-SN was92.7°, NP-FH was86°, NA-PA was15.7°, U1-NA was19.7°,L1-NB was27.7°; EI was151, Wits was1.7mm, ANS-Ptm was51mm, Co-Po was 104.8mm, Y axis was62°, FMA was30°. In this case, according to the results of theclinical examination, model analysis results and cephalometric radiograph analysis,extraction of the maxillary first premolars and no extraction in lower arch wasconsidered using Straight wire technique, Self-ligating brackets, the NiTi wire wasused to level and align the dentition, open the deep bite and the extraction spaces wereclosed by sliding mechanics. Class II elastics were used to help in the correction ofanteroposterior disharmony. In the finishing and detailing stage the position and axialinclination of the teeth were adjusted. According to the pre and post treatmentcephalometric radiograph and superimposition tracings were done to judge the changesof soft and hard tissue before and after treatments.Results: The treatment duration was25months. Dentition was properly alignedand leveled. The maxillary space was closed and the maxillary dental midlinecoincided with the facial midline. A good anteroposterior relationship was achievedwith a2mm overbite and2mm overjet,a proper occlusion was obtained.Class I caninerelationship and Class II molar relationship was obtained. Comparision of thepretreatment and post treatment panoramic radiographs revealed: no resorption in theroots of all the teeth, roots were parallel to each other. Due to the application ofself-ligating brackets, as well as the patient’s cooperation, oral health was in goodcondition after treatment with good periodontal are health. The cephalometric tracingsindicates:(1) SNA angle increased by1.3°, SNB angle increased by2.3°, ANB angledecreased by1°(from6°to5°), Wit’s value decreased by0.5mm, indicating skeletalclass II pattern change; ANS-Ptm increased by2.8mm, Co-Po increased by7.4mm, the upper facial height increased by1.7mm, the lower facial height increased by7mm,indicating maxillary and mandibuar growth.;FMA only increased by0.3°indicatinggood vertical control.(2) The maxillary incisors were retracted with extrusion.U1-NA°decreased by8.7°, U1-NA distance decreased by0.7mm. The mandibularincisors were labially inclined, with L1-NB increase by3.3°, L1-NB distance increaseby0.25mm. U1-L1increased by6°(3) The soft-tissue profile changed slightly: Hangle increased by4.3°, ULEP increased by2.27mm, LLEP increased by0.4mm, Zangle decreased by1°(from66.5°to65.5°) but within the normal range. Overall sideprofile had little change. The patient and the family members were satisfied with theresults of the treatment.Conclusions: In treatment of adolescent patient with Angle’s class IImalocclusion, mild skeletal class II pattern and average mandibular plane angleextraction in only maxillary arch can effectively correct the crowding. No extraction inmandibular arch, decrease the possibility of further retruding the mandible. Slightlyflare the mandiular incisors to reduce the crowding, the overjet and overbite overallgiving a good clinical outcome. |
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