Multiple Apical Periodontitis Influences Serum Levels of Cytokines and Nitric Oxide

•Our previous research has shown that systemic alterations occur because of the associated presence of apical periodontitis and periodontal disease.•Although periodontal disease or AP on a single tooth did not lead to significant systemic changes, alterations were detected in some parameters when these infections affected 2 teeth.•This study aimed to evaluate whether the presence of 1 tooth or multiple teeth with apical periodontitis affects serum levels of inflammatory mediators tumor necrosis factor alpha, interferon gamma, interleukin (IL)-6, IL-17, IL-23, and nitric oxide.•The results suggest that apical periodontitis interferes with blood homeostasis by altering serum levels of inflammatory mediators and nitric oxide.

IntroductionThis study evaluated whether apical periodontitis (AP) in a single tooth or in multiple teeth affected serum levels of inflammatory mediators and influenced blood homeostasis.MethodsThirty 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.ResultsRats 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).ConclusionsThese results suggested that AP affected blood homeostasis by altering the serum levels of inflammatory cytokines and NO.