A new protocol of Tweed-Merrifield directional force technology with microimplant anchorage

Tweed-Merrifield directional force technology with microimplant anchorage is a useful treatment approach for a patient with a Class I or Class II dentoalveolar-protrusion malocclusion. It can create a favorable counterclockwise skeletal change and a balanced face without patient compliance. In contrast, headgear force with high-pull J-hook can obtain similar results but depends on patient cooperation. This case report presents the treatment of a patient with Class I canine and molar relationships, a convex profile with retrognathic mandible and marked lip protrusion, and excessive lower anterior facial height. Good facial balance was obtained by Tweed-Merrifield directional force technology with microimplant anchorage, which provided horizontal and vertical anchorage control in the maxillary and mandibular posterior teeth, and intrusion and torque control in the maxillary anterior teeth, resulting in a favorable counterclockwise mandibular response.