Reactive oxygen species can be traced locally and systemically in apical periodontitis: A systematic review

Objectives: The aim of this systematic review was to summarize the existing evidence on the local production and systemic traces of reactive oxygen species (ROS) in apical periodontitis (AP). Design: A search of MEDLINE-PubMed and EMBASE was conducted up to January 12 of 2021 to identify studies in 6 different languages. Eligibility was evaluated and data were extracted from the eligible studies following the predefined objective. The Newcastle-Ottawa Scale was used for quality assessment of the included studies. Results: After screening, 21 papers met the inclusion criteria. Six studies were about systemic oxidative stress, 14 studies examined local production of reactive oxygen species and one studied both. ROS modulate cell signalling and cause oxidant imbalance locally at the site of AP. Cell signalling leads to a pro-inflammatory response, activation of MMPs and formation and progression of the AP lesion. Simultaneously, these oxidative stress biomarkers are also found in blood and saliva of subjects with AP. Conclusions: Understanding the mechanism of ROS generation, involved in chronic inflammation, can provide us with important information to enhance local and systemic healing and possibly improve diagnostic tools. Future research considerations would be to use antioxidants to accelerate the return to oxidative balance.