Osteodynamics around orthodontically loaded short maxillary implants. An experimental pilot study.

The aim of this study was to investigate experimentally the effect of long-term orthodontic loading on the activity and location of osteodynamic changes around short titanium screw implants. For this purpose 6 maxillary premolars (1P1, 2P2, 3P3) were extracted from each of 2 foxhounds. After a 16-week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously 2 implants (1 per dog) were positioned in the palatal suture. After an 8-week implant healing period the fixtures in the P1/P2 areas (n = 4) and the palate (n = 2) were loaded (test implants) by means of Sentalloy traction springs (approximately 2 N continuous force). The fixtures in the P2/P3 areas served as controls (n = 4). The osteodynamic changes during the force application period (26 weeks) were recorded with bone labeling fluorochromes. Histological evaluation revealed a tendency towards higher remodeling activity within the peri-implant bone (up to 500 microns from the implant surface) of the loaded compared with the unloaded sample. This higher activity was found on both sides facing the loading direction as well as on the opposite sides. Furthermore, within the bone adjacent to the marginal halves of the implants on the loading direction sides, this higher remodeling activity extended more than 1000 microns from the respective implant surfaces. The results suggest that long-term orthodontic loading of short maxillary implants may increase the remodeling activity within the peri-implant bone.