The Treatment Of An Adult Patient With A Skeletal Class Ⅱ Malocclusion Using Miniscrew Anchorage

Objective: The purpose of this study was to evaluate the clinical treatment effect ofminiscrew anchorage on an adult patient with a skeletal class Ⅱmalocclusion usingstraight wire technique.Method:An adult patient with skeletal deformity admitted to Dalian Doctor’s DentalClinic in2010was selected.The patient was a23-year-old female,skeletal class Ⅱdiscrepancy with normal mandibular angle.Her maxillary incisors were protruded,lipswere incompetent.The profile was convex,with short upper lip and increasedlabiomental fold of the lower lip.The chin was well developed. There was a5mmoverbite and overjet of7mm.On the left side,mandibular first molar was missing, witha7mm edentulous space and inclined second molar.On the right side,molarrelationship was mesial because of congenital absence of the lower secondpremolar.The canines were in class Ⅱrelationships on both sides.The curve of Speewas6mm.Dental midline of both jaw coincides with the facial midline.Treatment planwere drawn according to the analysis results: extract the maxillary first premolars andmandibular third molar on the right side,apply straight wire technique and miniscrewanchorage,self-ligating brackets were bonded on all the teeth,contrary curve of Speewere used on wire for leveling and aligning,the extraction spaces were closed bysliding mechanics.ClassⅡ elastics were used to help in the anteroposteriordisharmony.The cephalometric radiograph pretreatment and posttreatment were tracedand analyzed.Results: The treatment duration was34months.Dental midline of both jawcoincides with the facial midline. Dentition was properly aligned and leveled.maxillaryspace is closed,mandibular space is decreased.A good anteroposterior relationship wasachieved with a2mm overbite and2mm overjet.The posterior occlusal relationshipswere improved,slight class Ⅱmolar and canine relationship were obtained.The posttreatment panoramic ratiographs show that there was little or no resorption of theroots of all the teeth.Comparison of the pretreatment and posttreatmentcephalometric tracings indicates:(1)Most craniofacial bone measurement values havelittle change, SNA, SNB respectively has a slight decrease, ANB maintained7°.Thefacial height and FMA has not changed.(2)The maxillary incisors were retractedpalatally and retroclined significantly, U1-NA°decreased10.2°, U1-NA distancereduced3.5mm.The mandibular incisors were slightly retracted and retroclined.L1-NB°decreased1.3°, L1-NB distance decreased1.5mm, U1-L1°increased11.3°.(3)The soft-tissue profile has a remarkable improvement. Z angle increased from71.1°to78.8°，H angle decreased from15.5°to10.7°.ULEP, LLEP decreased by3.8mm and5.6mm respectively.Protrusion of lips was decreased.lower lip inclination (BsLL-FH)increased significantly, labiomental fold angle (PosBs-FH)decreases,labiomental foldof the lower lip was decreased.lip and chin relationship tends to be coordinated.Conclusion: Miniscrew anchorage is useful for retraction and intrusion of upperincisors in cases of maxillary protrusion with severe adult class Ⅱskeletalmalocclusion.