ABSTRACT
<p><b>OBJECTIVE</b>To explore the combined effects of orthodontic force and inflammation on the remodelling of periodontal tissues.</p><p><b>METHODS</b>The upper first molars underwent mesial orthodontic force on 48 rats suffering experimental periodontitis and 48 rats injected lipopolysaccharide, respectively.</p><p><b>RESULTS</b>The TNF-alpha protein expression in the compressed periodontal tissues fluctuated during 0, 2, 12 hours and 2, 7, 14 days stages, the OD value got to the peak in the compressed periodontal tissues in 2 days.</p><p><b>CONCLUSION</b>The mechanical remodelling effects were hindered due to the circumstance of acute or chronic inflammation. The research suggests that the orthodontic treatment to adult patients with periodontal inflammation should be taken carefully.</p>