RESUMEN
<p><b>OBJECTIVE</b>To investigate the combined effects of platelet-derived growth factor-BB (PDGF-BB) and insulin-like growth factor-I (IGF-I) on the expression of integrin (beta3 protein in the periodontal tissues of the compressing side of orthodontic tooth in rats.</p><p><b>METHODS</b>Establishing orthodontic movement model in Sprague-Dawley rats, which were injected with 10 ng PDGF-BB, 200 ng IGF-I alone or in combination in the buccal submucosal area of the orthodontic tooth. The injection was applied every other day. The experiment continued for ten days and then the rats were sacrificed. The expression of integrin (beta3 protein in periodontal ligament tissues of the compressing side was detected by immunohistochemical techniques.</p><p><b>RESULTS</b>The expression of integrin (beta3 protein in periodontal ligament tissues of the compressing side of each experimental group was significantly increased compared with that of the control group (P<0.01). Meanwhile the maximum mean optical density value of integrin (beta3 protein expression was attained in the combination group which showed a significant increase compared with the PDGF-BB group (P<0.05) and the IGF-I group (P<0.01).</p><p><b>CONCLUSION</b>The combination of exogenous PDGF-BB and IGF- I in orthodontic tooth movement may enhance the expression of integrin (beta3 protein in periodontal ligament cells and PDGF-BB and IGF-I may have a synergistic effect during orthodontic tooth movement.</p>