Treatment Of Bimaxillary Protrusion With Tweed-Merrifield Technology In Teenager

Objective:This longitudinal study was designed to study the changing in soft tissue profile after orthodontic treatment of bimaxillary protrusion adolescents.We use Tweed-Merrifield technology.The other purpose of this study was to evaluate the relationship between the soft and hard tissue changes caused by orthodontic treatment and growth.By discussing the prediction of soft-tissue profile changes,we try to provide some reference for clinical treatments.Materials and methods:A female patient with bimaxillary protrusion was selected from Dalian Ortho Clinic in August 2013.She is 12 years old with sever over jet,over bit and classⅠocclusion relationship.Finally,the patient was treated by extracting four second molars and four first premolars with Tweed-Merrifield technology.We use a headgear through out the treatment.Results:After 26 months,all the teeth were well aligned with normal overbite and overjet.Molar relationship were maintained and good occlusal relationship were also reliazed.There are 14 controls what were put forward by Tweed and 15 soft tissue controls are contrasted before and after orthodontic treatment.We found that significant improvement in upper and lower incisor protrusion,nasolabial angle,upper and lower lip length,and upper and lower lip protrusion.Pitchfork Analysis shows upper first molars and lower first molar were distally tipped and mesially moved,less than 1/4 of the extraction space,which could meet the request of maximum anchorage.So the upper and lower molars anchorage were controlled well.Comparing the changes of cephalometric film shows that: the vertical was in good control.Also,growth promoted the orthodontic treatment.Conclusion:Finally,Using Tweed-Merrifield technology for the corrections of bimaxillary protrusion,we found that the upper and lower incisors became more retroclined and retrusive,resulting in a greatly improved facial profile.