Objective:
Facial esthetics is always the main issue for class III patient who seeks for orthodontic treatment. To develop an effective and efficient mechanism in order to meet patient’s expectation is important, especially in borderline non-surgical cases.
Cases:
A 26 year-old female came to our department and complained of her prominent chin and the facial profile. Clinical assessment showed class III skeletal pattern with mandible prognathism and average FMA. Patient rejected orthognathic surgery and wanted orthodontic treatment alone. We therefore decided to apply “mandible backward rotation technique (MBRT)” mechanism to reduce the chin prominence. MBRT comprises TADs in the lower arch for whole arch distalization and class II elastics for lower molars and upper incisors extrusion. At the end of treatment, mandible has been rotated backward significantly and positive smile arc was created.
Discussion and Summary:
In this case, MBRT provided a backward rotation mechanism by incorporating class II elastics in the process of lower arch distalization. Conventionally, lower arch distalization from TADs on the buccal shelf will inevitably cause a molar-intrusion-and-incisor-extrusion rotation. This rotation will result in mandible forward rotation and make chin more prominent. By wearing class II elastics at this stage will compensate the side effects of lower molar intrusion and encourage upper incisor extrusion. Positive smile arc can be built during this process and mandible can be rotated backward. Thus, MBRT provides a good alternative way on class III cases to reduce chin prominence and to enhance upper incisor show.