Distraction osteogenesis and histogenesis in beagle dogs: The effect of gradual mandibular osteodistraction on bone and gingiva

Background: No study has systematically evaluated the effect of distraction osteogenesis on the gingival tissues. Therefore, this study was designed to analyze the newly formed bone and gingiva during the consolidation period of mandibular osteodistraction using standard histologic techniques. Methods: Seventeen skeletally mature male beagle dogs underwent 10 mm of bilateral interdental mandibular lengthening. After distraction, the regenerates were allowed to consolidate for 0, 2, 4, 6, or 8 weeks, then the animals were sacrificed and tissues harvested for analysis. Results: Mineralization began at the host bone margins at the end of the distraction period, followed by a progressive increase in bone surface area, with a concomitant decrease in fibrous tissue. The gingiva initially underwent mild inflammatory and reactive changes during distraction and during the first few weeks of consolidation. The rate of bone formation gradually increased from the end of distraction to the fourth week of consolidation, at which time it remained constant until sometime before the eight week, when it tapered off slightly as remodeling began. From the second through the eighth week of consolidation, regenerative changes and neohistogenesis were seen in the gingival tissues. Conclusions: Osteodistraction has the potential to drastically decrease the total treatment time for alveolar bone augmentation prior to dentoalveolar implant placement since the regenerate bone rapidly mineralizes within approximately 8 to 10 weeks after the distraction period and the gingiva responds favorably to increased length by regeneration rather than by degeneration. Although the results appear favorable, similar data should be evaluated in human clinical trials.