Figure 1.

Tumor necrosis factor–α (TNF-α) expression is elevated by bacterial infection of the human tooth. (A) TNF-α (25 kD) is significantly upregulated during carious progression. A bar graph shows the quantification of the relative TNF-α expression (TNF-α/β-actin) between control, caries, and pulpitis groups (***P < 0.001). (B) Immunohistochemistry staining shows a similar result as the Western blot. Expression of TNF-α is increased in the tooth crown of the caries group and the pulpitis group. However, in the region of the tooth root, the pulpitis group displays a much stronger positive signal of TNF-α than the caries group. Lower inserts show higher magnification in each panel. Bar represents 50 µm.