Objective To evaluate gene transcription and expression of c-fos in mandibular condyle cartilage after anterior disc displacement（ADD）. Methods Thirty-two healthy adult Japanese rabbits were used in this study. Twenty-five rabbits were subjected to surgical anterior disc displacement in the right tem porom andibular joints, every 5 rabbits were sacrificed 1, 2, 4, 8, 12 weeks post-operation, 5 rabbits were used as sham -operative control and the other two without operation were used as norm al control. The gene transcription and expression of c-fos in condyle cartilage were studied by in situ hybridization and im m unohistochem ical m ethods and m easured with Image Computer A nalysis Software. Results The discs displaced anteriorly were observed successfully in the experim ental rabbits. 1 week after ADD , the data of staining by in situ hybridization and im m unohistochem ical m ethods were 57.66±4.80, 144.12±12.43 respectively, gene transcription and expression of c-fos increased significantly（P<0.05）. Four weeks after ADD , the gene transcription and expression of c-fos began to decrease, 8-12 weeks after A D D , the gene transcription and expression of c-fos alm ost cam e back to the level before A D D , the data of staining by in situ hybridization and im m unohistochem ical m ethods were 16.64±0.08, 46.72±5.23 respectively, gene transcription and expression of c-fos had no significant differences（P>0.05）. C onclusion In the early stage of A D D , the level of c-fos gene expression and transcription in m andibular condyle cartilage increased significantly. It m ay suggest that c-fos m ight play an im portant role in the signal transduction in the rem odeling of the m andibular condyle cartilage after A D D .
