RESUMEN
Tweed-Merrifield directional force technology is a very useful concept, especially for the treatment of Class II malocclusion. It has contributed to creating a favorable counter-clockwise skeletal change and balanced face, while head gear force using high pull J-hook (HPJH) in an appropriate direction is also essential to influence such results. Clinicians have encountered some problems concerning patients' compliance; however skeletal anchorage has been used widely of late because it does not necessitate patients' compliance, yet produces absolute anchorage. In this case, a good facial balance was obtained by Tweed-Merrifield directional force technology using HPJH together with skeletal anchorage, which provided anchorage control in the maxillary posterior area, torque control in the maxillary anterior area, and mandibular response. This indicates that skeletal anchorage can be used to reinforce sagittal and vertical anchorage in the maxillary posterior area during the retraction of anterior teeth. The author used HPJH for torque control, intrusion, and the bodily movement of maxillary anterior teeth during en masse movement. However, it is thought that such a result may also be achieved by substituting mini- or microscrews for HPJH. Consequently, Tweed-Merrifield directional force technology using skeletal anchorage for the treatment of Class II malocclusion not only maximizes the result of treatment but can also minimize patients' compliance.