Expression of TNF-á in Normal and Inflamed Human Dental Pulps

Objectives: The main objective of this investigation was to analyze the gene expression of tumor necrosis factor-alpha (TNF-α) in human dental pulps, under normal and inflammatory conditions and to examine the association between any observed alterations in the expression of this cytokine with the severity of the inflammation. Methods: Pulp was isolated from a total of eighteen single-rooted teeth, obtained from patients from 13.5 to 40 years old. Six of the teeth had been diagnosed with irreversible pulpitis, 6 with reversible pulpitis and 6 contained normal pulp. Clinical and radiographic examination excluded any evidence of pulp necrosis, periapical lesions, periodontal diseases or dental injuries. TNF-á gene expression was quantified with a method of competitive RT-PCR, whereby DNA complementary to the cytokine transcript is simultaneously amplified with that of â-actin, in the same reaction mixture. The amplified DNA was electophoretically separated in a 1.5% gel. The relative intensity of the TNF-á and â-actin bands was analyzed through computer – assisted densitometry. Statistical analysis of the results was performed by using one-way ANOVA test, followed by the Bonferroni post-hoc tests. Results: TNF-á expression was detected in all three groups of dental pulp. Statistical analysis provided evidence of a significant increase of TNF-á gene expression associated with irreversible inflammation compared to controls (P < 0.001). No such difference was detected in reversibly inflamed pulp in comparison to healthy teeth (P = 1.000). Conclusions: TNF-á gene expression in the human dental pulp is positively associated with the severity of inflammation.