Systemic neutrophil response resulting from dental plaque accumulation

Background: There is considerable current interest in putative relationships between oral and systemic diseases. Since the host response to oral bacteria may be the critical link in this association, our hypothesis was that dental plaque accumulation in healthy subjects would elicit a systemic inflammatory response. Methods: Twenty-three healthy subjects, aged 18 to 25, participated in a 4-phase study. An initial hygiene phase was followed by a 21-day experimental phase (the so-called experimental gingivitis model) in which subjects refrained from all oral hygiene practices, thus permitting the accumulation of bacterial plaque. At days 0, 7, and 21 total and differential peripheral white blood cell (wbc) counts, together with full mouth plaque and gingivitis scores, were recorded. Following a 28-day recovery phase, in which normal oral hygiene practices were resumed, subjects entered the final 21-day control phase which mirrored the experimental phase but with subjects maintaining normal oral hygiene practices. Results: The experimental model performed as anticipated with a correlation between plaque and gingivitis scores of 0.95, also reflecting subject compliance. Total wbc and neutrophil counts increased during the experimental phase. Furthermore, comparison of neutrophil counts between the experimental and control phases demonstrated a significantly higher cell count for the experimental phase on both days 7 and 21 (P = 0.0301 and 0.009, respectively). For total wbc, this was significant on day 21 (P = 0.0262). Conclusion: The results of this study support the hypothesis that the accumulation of dental plaque can result in a measurable systemic inflammatory response, providing further in vivo data to support a mechanistic relationship between oral and systemic pathology.