Bone response to early orthodontic loading of endosseous implants.

This study evaluated the clinical, radiographic, and histologic responses of tissues surrounding implants loaded with a heavy force of 500g for 20 weeks after a 1-week healing period. Unilateral mandibular and maxillary alveolar ridges in the premolar areas of a male dog and the bilateral mandibular alveolar ridges of a female dog were chosen for implant placement. The control implants (1 in the maxilla, 3 in the mandible) were placed in these quadrants after a 12-week healing period following extraction. The test implants (1 in the maxilla, 3 in the mandible) were implanted in the same quadrants after a 4-month osseointegration period of the control implants. Abutments were attached to the control and test implants after a 1-week healing period for the test implants. Superelastic nickel-titanium coil springs, producing a force of 500g (≈5 N), were activated between control and test implants for 20 weeks. Light microscopic assessment revealed that all implants were well integrated with the bone. Histologic analysis showed no definitive differences between test and control implants in the corticalization of bone trabeculae. The mean bone-implant contact values of the control implants for compression and tension sides were 55.99% and 64.04%, respectively. In the test implants, the bone-implant contact value was 57.27% for the compression side and 62.96% for the tension side. Potential clinical applications of these radiologic and histologic results include the possibility of minimizing the healing duration, even for high orthodontic forces, and the possibility of postorthodontic use of these implants as abutments for supporting prosthetic reconstruction.