Apical periodontitis - a chronic inflammatory disease of the periradicular tissues - is caused by the complex interactions between the root canal microbiota, microbial virulence factors and host immune response.
Apical periodontitis manifests itself in different ways, ranging from completely asymptomatic - detected as a periapical radiolucency on a radiograph - to being symptomatic - presenting with pain and abscesses.
Apical periodontitis prevalence
Globally, apical periodontitis prevalence is 52%, meaning that more than half of the world's population has at least one affected tooth. The NHS in England and Wales has reported that over 1 million teeth received root canal treatment (RCT) between 2001 and 2004, costing the NHS around £50.5 million. According to the American Association of Endodontists, more than 25 million root canal treatments are performed each year in the United States and, in Europe, it is reported that almost 23 million endodontic treatments are undertaken yearly. Therefore, the global burden of root canal treatment is high. RCT for apical periodontitis may also require re-intervention, as failure rates are still unacceptably high (17% primary RCT; 20% re-treatment.
The effect of apical periodontitis extends beyond dental implications. It can result in translocation of microbes and inflammatory mediators into the circulatory system. Elevated levels of inflammatory bioactive molecules can induce persistent low-grade systemic inflammation, impacting patients' general health.
The effect of apical periodontitis on general health
Novel research led by Dr Sadia Niazi - funded by the British Endodontic Society (BES) and European Society of Endodontology (ESE) - has raised the significance of apical periodontitis as a co-morbidity and modifiable risk factor for the development of cardiometabolic diseases. These are a leading cause of death worldwide, responsible for about 30% of total global mortality, though this is expected to rise by approximately 10% over the next 20 years, with a threefold increase in healthcare costs.
This longitudinal interventional cohort study confirmed the increased systemic inflammatory burden of cardiovascular disease risk biomarkers including high-sensitivity C-reactive protein (hs-CRP), fibroblast growth factor-23, Interleukin-1β, and asymmetric dimethylarginine (ADMA), along with metabolic syndrome indicators in apical periodontitis patients compared to controls. The effect on these serum inflammatory mediators is dose-dependent and can be affected by an increase in the size of periapical pathology. At two years post endodontic treatment (root canal re-treatment and peri-apical surgery), when complete resolution of clinical symptoms and periradicular healing was achieved, the serum levels of specific cardiovascular disease risk biomarkers (hs-CRP, ADMA and Matrix Metalloprotease‐2) significantly reduced, along with improvement in metabolic syndrome indicators and better glycaemic control. These results also reveal that these are potential prognostic biomarkers of successful root canal re-treatment and peri-apical surgery, as they reduced at two year recall in cases which showed evidence of clinical and radiographic success.
Unpublished research compared the microbiome of intracanal and blood samples. Targeted 16SrRNA gene sequencing was used, which revealed similarities between blood with intracanal microbiomes. Interestingly, bacteraemia was detected in some pre- and all post-endodontic treatment blood samples, with a rise in the relative abundance of endodontic microbes in blood after treatment. Further to this, blood bacteraemia significantly correlated with both serum inflammatory markers and serum metabolites. This highlights the role of the bacteraemia associated with apical periodontitis in driving the systemic inflammatory and metabolite response that can result in an adverse systemic health effect.
Looking to the future of endodontics
This research highlights the importance of a successful clinical and radiographic outcome, which is dependent on well-executed endodontic treatment. This is fundamental in improving patients' general health by achieving a reduction in systemic inflammation, and improving metabolic syndrome indicators.
The BES Grant for Research Work was crucial in supporting this research. When Dr Niazi began her research in 2017, there was no strong evidence to support a link between endodontic infections and the risk of cardiovascular disease. The Grant enabled Dr Niazi to access and utilise the cutting-edge research facilities and support at King's College London needed to show that apical periodontitis does extend beyond dental implications - increasing the systemic inflammatory burden of cardiovascular disease risk biomarkers.
It shows that a dentist's role is elevated far beyond saving the teeth. Good oral health, including the abrogation of apical periodontitis, will support patients' general health. Early career dentists should engage in CPD courses to enhance their knowledge of and skills in endodontics - enabling them to perform successful RCT. Dentists must educate their patients and raise public awareness about maintenance of good oral health, and the timely treatment of caries to prevent the development of root canal infections, and well as early treatment of root canal infections to prevent their impact on general health. Clear guidelines for the treatment of symptomatic and asymptomatic cases are required, especially in vulnerable patients, to reduce the risk of developments of adverse systematic health.
