The effect of bite-blocks with and without repelling magnets studied histomorphometrically in the rhesus monkey (Macaca mulatta).

The effect of bite-blocks with and without repelling magnets as proposed for the treatment of open bite was analyzed. Twelve male juvenile monkeys were divided into three groups of four. Group A was used as control, group B was given bite-blocks containing samarium cobalt disks, and group C received identical bite-blocks without active magnets. The monkeys were observed for 24 weeks before death. Histomorphometric evaluation was then performed on the molar roots, their periodontal tissues, the zygomaticotemporal suture, and the pterygomaxillary suture. The root surfaces of the molars in both the bite-block group and the magnetic group were characterized by pronounced resorption that sometimes was active and occasionally undergoing repair with bony tissue. The sutures also clearly reflected the effect of both appliances used, although more markedly in the cases of bite-blocks containing active magnets. The surface density expressing the sutural area, was increased significantly, possibly as an adaptation to the altered functional demand. The cellular activity of the sutural surfaces also was increased markedly in both appliance groups, reflecting an ongoing adaptation. A steady state had not been reached. The study demonstrated a widespread effect of the force developed by bite-blocks with and without magnets. The final quantity and the reversibility of the effect is not known, however. More long-term studies should be undertaken to obtain this information.