Extraction Treatment For Classâ… Malocclusion With Dental Crowding

Objective: The purpose of this study was to investigate the clinical treatment effectof extraction on a Class I patient with dental crowding.Method: An adolescent patient admitted to Dalian Doctor’s Dental Clinic in2010was selected. The patient was a11-year-old female with skeletal Class I, normalmandible plane angle, crowding and in growing stage.The dental crowding in maxillaryarch was4.3mm indicating moderate crowding and the crowding on mandibular arch(including leveling of curve of Spee and lower incisor proclination) was8.0mmindicating a severe crowding.There was3.7mm overjet and II degree overbite onanterior teeth. The second molar on maxilla was unerupted. IMPA was80degreeindicating lingual inclination of lower incisors. The relationship of canine and molarwas both Class I on both the sides. The dental midline of both jaw coincided with thefacial midline. The curve of Spee was1.5mm on both sides. Treatment plan was drawnaccording to clinical examination and analysis results: Bilateral extraction of firstpremolars on maxilla and second premolars on mandible. Ceramic bracket system wasused. Bonding of maxillary arch was done initially and mandibular teeth was bondedlater for alignment of teeth.During space closure mesial movement of maxillary andmandibular teeth was controlled. The anchorage requirement in posterior teeth was theweak one and space closure was done by sliding mechanics. J hook Headgear and ClassII elastics was used to correct the deep overbite and control direction of growth ofmaxilla. After completion of treatment, the pre and postreatment cephalometricsuperimposition tracings were compared and analyzed. Results: The treatment duration was31months. There was well aligned dentition onmaxillary and mandibular arch with no space. Dental midline of both jaw coincidedwith the facial midline. The overjet on anterior teeth decreased by2.9mm obtaining anormal overjet and overbite. The second molar on maxilla erupted to achieve normalocclusion with lower molars. There was normal oral function and TMJ was also normalwith no tenderness or joint clicking. Comparison of pre-treatment and post treatmentcephalometric tracing indicates:(1) normal growth of jaws. ANB decreased from4to3.(2)The upper incisors inclined labially with U1-SN increase by2and there wassignificant labial inclination of lower incisor.(3)The height of both jaw increasedduring the treatment including mandibular ramus. Ramus height increased by3mm.ANS-Me increased from58mm to60mm. FHI changed from65%to70%. The verticalproportion of jaws were in harmony with each other.(4)The length of jaw both increasedin treatment. ANS-PNS increased by1mm. Co-Po increased by5mm.(5)Soft tissueprofile change was harmonious. Z angle increased from64to71. ULEP and LLEPboth decreased by4mm. Overall chin and lip relationship improved, enhancingaesthetics. ANS-PNS increased by1mm. Co-Po increased by5mm.Conclusion: It’s good clinical effect for the Class I adolescent patient with dentalcrowding to choose the reasonable extraction style through analyzing measure resultsand treatment goal completely.