Endosseous titanium implants as anchors for mesiodistal tooth movement in the beagle dog

The purpose of this study was to determine the anchorage potential of titanium implants (Branemark; 3.75 x 7 mm) with the use of a sectional arch wire technique for orthodontic mesiodistal tooth movement, as assessed by the osseointegration of implants and tooth movement. Two implants were surgically placed in healed mandibular extraction sites of the second and third premolars on each side in 4 adult male beagle dogs. The implants were surgically uncovered 18 weeks later, and second-stage abutments with soldered edgewise tubes were attached. Segmented edgewise rectangular archwires (0.017 x 0. 025 inch) with a T-loop or an L-loop were placed between the implants and the fourth premolars on both sides as the anchorage unit. One segment in each dog served as a loaded side, and the archwire was calibrated to produce 200 g of lateral force on the fourth premolar. The contralateral segment served as an unloaded side and was not subjected to orthodontic force. Sectional wires were activated biweekly 24, 28, 28, and 32 weeks, respectively, depending on the magnitude and the appearance of mesial tipping movement of the fourth premolar. After mandibular impressions were taken to measure the distance between the first molar and the fourth premolar, the animals were euthanized and dissected mandibles were prepared. The specimens were then embedded in polyester resin and cut to take backscattered electron images. On the basis of these images, the percentage of peri-implant bone volume was calculated and defined as an index of osseointegration. The differences between the initial and final fourth premolar to first molar distances varied (7.40, 8.85, 10.50, and 3.30 mm) on the loaded side, whereas the unloaded side showed no movement. Not only was there no statistical difference in the percent of peri-implant bone volume between the loaded and unloaded sides, but there was also no statistical difference between the compression and tension sides in both loaded and unloaded implants, which suggests that the implants maintained rigid osseointegration. In conclusion, the present study demonstrated that endosseous titanium implants can function as anchors for long-term orthodontic mesiodistal movement.