Multiple Apical Periodontitis Influences Serum Levels of Cytokines and Nitric Oxide

This study evaluated whether apical periodontitis (AP) in a single tooth or in multiple teeth affected serum levels of inflammatory mediators and influenced blood homeostasis.

Thirty male Wistar rats were divided into 3 groups of 10 rats each: control group, healthy rats; 1AP group, rats with AP in 1 tooth; and 4AP group, rats with AP in 4 teeth. After 30 days, the rats were anesthetized, and their blood was collected through cardiac puncture to quantify tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-17, IL-23, and nitric oxide (NO) levels. The rats were then sacrificed by administering an anesthetic overdose. Their maxillary and mandibular molars were collected and processed for histologic analysis with hematoxylin-eosin and for immunohistochemical staining of the cytokines and NO-producing enzyme nitric oxide synthase. Results of these analyses were statistically analyzed; P < .05 was considered statistically significant.

Rats in the 1AP and 4AP groups showed increased IL-6, IL-17, IL-23, TNF-α, IFN-γ, and NO synthase expression; inflammatory cell infiltration; and moderate bone resorption in affected teeth. Serum TNF-α, IL-6, IL-17, and IL-23 levels were higher in rats in the 4AP group than in those in the control group (P < .05). Serum NO levels were significantly lower in rats in the 1AP and 4AP groups than in those in the control group (P < .05). Serum IFN-γ levels were not different among rats in the 3 groups (P > .05).

These results suggested that AP affected blood homeostasis by altering the serum levels of inflammatory cytokines and NO.