Cystatins and cathepsin B during orthodontic tooth movement.

Introduction: The lysosomal cysteine protease cathepsin B is known to play an important role in the resolution of organic matrix, a final step in bone resorption. Cystatins function as an inhibitor of cathepsin B. Determining the correlation between cathepsin B and cystatin levels in gingival crevicular fluid at various times might provide a better understanding of both the dynamics and the metabolic stages of orthodontic tooth movement.

Methods: Human gingival crevicular fluid was collected at the distal sulcus from the canines of persons not in orthodontic treatment, in retention, and in retraction at various times (initial, 1 day, 1 week, and 1 month postretraction). Cathepsin B and its inhibitor, cystatin, were found with fluorometry.

Results: The level of cathepsin B was varied in the retraction group; this was different from the retention and the nonorthodontic groups. Significant initial decreases after force application and subsequent increases by 1 month posttreatment were observed in the retraction group. The variations and differences among groups were negatively correlated with cystatin.

Conclusions: The balance between enzyme and inhibitor might reflect the clinical status of orthodontic tooth movement and provide valuable information for the assessment of recall intervals and retention procedures.