Abstract: Objective To study the expression of Wnt3a in chronic periodontitis patients and its clinical significance. Methods Wnt3a expression was examined by RT-PCR and Western-Blot in 15 cases of chronic periodontitis gingival tis⁃ sues and 15 normal tissues. Probe depth and attachment loss were also compared between these two groups. Correlation be⁃ tween Wnt3a expression and attachment lose were also analyzed. Results Probe depth was deeper in chronic periodonititis groups than that in control group（mm：7.93±1.56 vs 1.83±0.37）. Attachment loss was（7.76±1.34）mm in chronic periodonti⁃ tis group while it was not seen in control gorup. Wnt3a was lower both in transcription level（0.49±0.03 vs 0.36±0.04）and expression level（0.57±0.14 vs 0.43±0.17, P < 0.05) in chronic periodonitis tissue compared with that in normal tissues. The higher clinical attachment loss was negatively correlated with expression of Wnt3a（r=- 0.564，P=0.028）. Conclusion Wnt3a is expressed less in chronic periodontitis than that in control group. Wnt3a plays an important role in attachment loss and bone absorption.

Key words: periodontitis, chronic disease, gingiva, Wnt proteins, Wnt3a, clinical attachment loss