Tweed-merrifield Technique For Correction Of Adult Skeletal Class ? Dentition With Bimaxillary Protrusion:A Case Report

Objective:Tweed-Merrifield technique was used to treat adult patients with class ? dentition and double maxillary protrusion.The changes of facial profile and oral soft and hard tissue were compared before and after correction.To evaluate the effect of Tweed-Merrifield correction technique in order to provide some reference for clinical work.Methods:A case of adult osteogenic type ? dentition with bimaxillary protrusion in orthodontic department of the affiliated Stomatology Hospital of Nanchang University was selected.Female patients with 15/25 caries were found to be 18 years old,both molars and canines were neutral,and the upper and lower teeth were moderately overcrowded.The upper and lower anterior teeth were declinated,the anterior teeth were deeply overoccluded with I °,and the anterior teeth were covered by I° deep overbite.The position and sagittal direction of the upper and mandibular bone relative to the cranium are normal and mean angle.Protruding side,open lips and teeth.Two second premolars,two mandibular first premolars and four third molars were subtracted from the maxilla.The technique of directional correction with Tweed-Merrifield 's square wire arch was used to correct the two second premolars,the mandibular first premolars and four third molars.Results:The total course of correction was 32 months.After treatment,the maxillary and mandibular dentition were neatly arranged,the right molar was neutral,the left molar was slightly distal,the anterior teeth were I ° deep overbite,and the upper and lower midline were aligned with the middle line of the face.The degree of upper and lower lip protrusions was significantly decreased,the open lip denuded disappeared,and the facial shape was greatly improved.Cephalometric values showed that the FMA of the patients before and after treatment was basically unchanged.Cephalometric overlap showed that the posterior teeth Anchorage was little lost at the end of treatment,but was still in the category of strong Anchorage.Conclusion:The application of Tweed-Merrifield technique to the treatment of adult patients with class I dentition with bimaxillary protrusion can control the three dimensional direction of the teeth and improve the facial shape significantly.