Orthodontic force systems: technical refinements for increased efficiency.

The efficiency of the Begg technique suffers because Class II elastics overwhelm anchor bends, which normally do not yield enough force for vertical control of maxillary incisors. This can be improved by attention to detail and modifications. Bite-opening bends in the arch wires distal to canines and lateral incisors, long (6.5 mm.) mesiogingivally angulated molar tubes, and placement of intermaxillary elastics at the distal ends of the tubes are all helpful. Intermaxillary "check elastics," having one end over the posterior end of the maxillary arch wire, both strands under the end of the mandibular arch wire, and the other end up to the maxillary anterior teeth, reinforce anchor bends and extrude upper and lower molars while keeping them upright. They augment bite opening in Stage I and counteract the adverse affects of the auxiliaries in Stage III.