Pilot study evaluating the effects of a cervical headgear on the C-axis: the growth axis of the dentomaxillary complex.

The C-axis, a growth vector for the dentomaxillary complex, is a means of quantifying complex maxillary growth in the sagittal plane through 3 key cephalometric measurements. This pilot study examined the effect of a cervical headgear, worn 8 to 10 hours per day, on the growth axis. The mean velocity of C-axis length increase in normally growing boys in the age range studied is 1.

Condylar displacement related to mandibular symphyseal distraction.

This study was undertaken to determine the true nature of condylar displacements associated with mandibular symphyseal distraction osteogenesis. Earlier investigators have assumed that each mandibular half rotated about a point near the center of each condyle as viewed on a submental radiograph. In a 12-patient sample, 10 with tooth-borne symphyseal distraction and 2 with bone-borne symphyseal distraction, it was found that each condyle was laterally displaced in direct relationship to the amount of symphyseal distraction.

The biomechanics of rapid maxillary sutural expansion.

Micro-displacements (fringe patterns) in the bones of the craniofacial complex as seen through laser holography during midpalatal sutural expansion with the Hyrax appliance are used to define the centers of rotation of the maxillary halves in both the frontal and occlusal views. Biomechanical analyses of the maxillary expansion force system are concomitant with the holographic findings and strongly suggest that the stainless steel wires joining the teeth to any expansion device be of the largest diameter possible. In addition, in the case of the Hyrax expansion device, it is recommended that the manufacturer increase the diameter of the activating screw as well as those of the 2 adjacent wire guides.