Immunohistochemical localization of epidermal growth factor in cat paradental tissues during tooth movement

Epidermal growth factor enhances proliferation and differentiation of cells during growth, maturation, and tissue healing. The objectives were to loca lize the epidermal growth factor in paradental cells and to determine the e ffect of orthodontic treatment on its concentrations in periodontal ligamen t fibroblasts, alveolar bone surface lining cells, and epithelial rests of Malassez. Sixty male cats, 1 year old, were divided into 2 groups: active a nd sham, and further divided into 10 time groups. In the active group, 1 ma xillary canine was retracted by 80 g force; in the sham group, the animals received an inactive appliance. Sagittal sections of each half maxilla were stained for epidermal growth factor; staining intensity was measured micro photometrically in 10 periodontal ligament fibroblasts, alveolar bone surfa ce lining cells, and epithelial rests of Malassez cells in sites of periodo ntal ligament tension and compression, and in corresponding sites near cont rol and sham canines. The overall mean staining intensity of the cells of t he active group animals was 30.47%, whereas that of the sham group was 21.7 8% (P < .0001). In all 3 types, cells near the actively treated canines sta ined significantly darker (P < .0001) than cells near the sham or control c anines, particularly between 12 hours and 7 days. These results demonstrate that orthodontic forces increase epidermal growth factor concentrations in paradental cells, suggesting that epidermal growth factor participates in the tissue remodeling that facilitates tooth movement.