Quantification of osteocyte apoptosis during experimental tooth movement as revealed by immunohistochemistry of Caspase 3

Abstract

Objective: To investigate the time course of osteocyte apoptosis in a rat model of orthodontic tooth movement as revealed by the caspase-3 activation pathway. Materials and Methods: Fifteen male Sprague Dawley rats (6–9weeks old) were loaded with an orthodontic appliance. A spring delivering 10–12 g of force was placed between the maxillary first molar and the incisor to displace the first molar mesially. The animals were equally divided into three time points: 24 hours, 3 and 7 days of orthodontic loading. Five animals served as 0 day group. Caspase 3 immunostaining, was performed on histologic sections of the first molars. The labeling was quantified in osteocytes on the mesial and distal sides of the alveolar bone in each group. Results: Caspase 3 labeling at the mesial side significantly increased at 1, 3 and 7 days after orthodontic loading compared to the control group. No peak increase was observed. There was no significant difference in caspase 3 labeling at the distal side. Conclusions: Osteocyte apoptosis during orthodontic tooth movement could be revealed by caspase 3 immunostaining. This suggest that caspase 3 apoptotic pathway is involved in osteocyte death during orthodontic tooth movement.