Increased serum interleukin 6 in experimental periapical periodontitis associated with metabolic bone disease

Authors: Antonela Berar1, Smaranda Buduru1, Tudor Valentin Mîrza2, Simona Iacob1,

Dragomir-Cosmin David2, Luminita Matros3, Mariana Constantiniuc1


 1Department of Prosthodontics, Faculty of Dental Medicine, “Iuliu Hatieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania

2National Institute of Public Health – Regional Centre of Public Health, Cluj-Napoca, Romania 

3Department of Microbiology, Faculty of Medicine, “Iuliu Hatieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania 


Background. Inflammatory cytokines such as interleukin 6 (IL-6) have implications in the pathogenesis of metabolic bone disorders and also in periapical disease. Both metabolic bone diseases and periapical periodontitis (PP) share a common fea­ture represented by inflammation-mediated bone loss; however, the specific role of these cytokines is not always consistent. 

Aims. The aim of the study was to assess the serum IL-6 levels and investigate the associations with histomorphometric changes in the alveolar bone around the molar roots in a rodent experimental model of PP. 

Methods. The research was conducted on 3 groups of animals: group A – animals without any pathology, group B – animals with PP, and group C – animals with PP and simulated metabolic bone disease treated with alendronate (ALD). Peripheral blood was collected for biochemical analysis of IL-6 interleukin levels and the lower jaws were removed for histomorphometric analysis. 

Results. Serum IL-6 levels were significantly increased in the experimental groups compared to the control group (p <0.05). In group B, a moderate inflammatory infiltrate and a medium number of osteoclasts were present, while in group C, discrete inflammatory infiltrates accompanied by a low number of osteoclasts were confirmed by histomorphometric analysis. 

Conclusions. The induction of PP determines elevated circulating levels of IL-6 with repercussions on the systemic state, maintaining a low degree of inflammatory response. The administration of ALD in female rodents contributes to the diminish­ing rate of extension in PP, limiting the destruction of the tissues. 

Key words: interleukin 6, periapical periodontitis, bone metabolism, estrogen deficiency.