Expression of osteocalcin during surgically assisted rapid orthodontic tooth movement in beagle dogs

To investigate the expression of osteocalcin during rapid orthodontic tooth movement aided by alveolar surgery in beagle dogs.

Eight male beagles were used, and bilateral mandibular second premolars were extracted for distalization of the first premolars against the third premolars by orthodontic NiTi coil spring with a force of 100 gm. Right and left mandibular sides were randomly assigned to experimental and sham sides, and alveolar surgery was performed only on the experimental side to reduce the osteal resistance on the mesial side of the extraction socket. Distance of tooth movement was measured once a week during the first 4 weeks. Two beagles were sacrificed after 1, 2, 4, and 8 weeks of orthodontic force application, and expression of osteocalcin was demonstrated by immunohistochemistry and quantified with computer-aided image analysis.

The average total movement of the first premolars in 4 weeks on the experimental side (1.868 +/- 0.022 mm) was approximately double that on the sham side (1.008 +/- 0.057 mm). As regards the average total anchorage loss, no significant difference (P > .05) was revealed. Dynamic osteocalcin concentrations presented at 4 time periods (P < .05). The staining intensity of osteocalcin on the experimental sides was higher than the corresponding sham sides, and that on the compression sites higher than the corresponding tension sites (P < .05).

The results suggested that alveolar surgery might serve as an effective and safe way to accelerate orthodontic tooth movement, and promote the rate of bone remodeling as revealed by the expression of osteocalcin.