Using Tweed-Merrifield Technique To Correct The Anterior Open-Bite:A Case Report

Objective:Use the Tweed-Merrifield technique to treat and evaluate the clinic effect of an adult anterior open-bite.Materials and methods: A female patient(38 years old)with anterior open-bite malocclusion was selected from Dalian Ortho clinic in August 2013.Her anterior open-bite is 3.5mm with convex profile,high-angle,classⅡrelationship.Her 25 and48 congenital absence.Maxillary bilateral second molar scissors bite;Through the patient’s clinical examination,cephalometric analysis and model analysis,we decided to extract 14,35,44,18,28,38 with Tweed-Merrifield technique finally.Results:The total treatment takes 25 months.Comparing the changes between pre-treatment and post-treatment,we find that the molar relationship was changed to class I;the anterior open-bite lifted;overbite and overjet corrected;maxillary molars distally moved and intruded,Mandibular molars upright and intruded.The FMA of this patient decreased 1°,which reflect vertical control is good.The upper and lower incisors convexity reduced,Reverse rotation of the mandible.Z angle increased9°and facial profile is greatly improved.We reached a satisfactory result.Conclusion: For the treatment of high angle with anterior open-bite,the vertical control is very important.Applying Tweed-Merrifield Technique can precisely controls the teeth movement in 3D.Thus make molar lower,incisors convexity reduced and improved profile,which means patient obtain good treatment result.