Oxidative stress and salivary physico-chemical characteristics relative to restorative treatment in children

Introduction: Saliva plays a crucial role in maintaining the homeostasis of the oral environment. Among its functions that contribute to caries prevention are the removal of food debris and microbial byproducts from the tooth surfaces, the supply of calcium and phosphate ions that enable the remineralization of demineralized areas, and the stabilization of pH at neutral levels through its bicarbonate and phosphate buffering systems. In addition to serving as an indicator of various pathological conditions, saliva can also be used to assess oxidative stress. Many studies investigating salivary oxidative stress in relation to dental caries and dental treatment focus on parameters such as total antioxidant capacity (TAC), malondialdehyde (MDA), uric acid, and superoxide dismutase (SOD). Beyond these biomarkers, isoprostanes represent reliable indicators of oxidative stress due to their chemical stability and specificity as byproducts of lipid peroxidation. Aim: The present study was conducted to determine the levels of 8-Epi-prostaglandin F2 alpha, a chemically stable and highly specific biomarker of lipid peroxidation, in the saliva of children with active dental caries, both before and after the application of restorative dental treatment. Additionally, salivary flow rate, pH, buffering capacity, and conductivity were examined. Possible associations between these parameters, oxidative stress, and dental treatment were evaluated. Notably, this is the first study to employ 8-isoprostane as a biomarker for assessing oxidative stress in relation to dental treatment, thereby addressing a significant gap in the literature and proposing a new, reliable indicator for evaluating oxidative stress in caries-related processes. Materials and methods: The study sample included 26 children with caries, aged 4–12 years, who attended the Pediatric Dentistry Clinic of Aristotle University of Thessaloniki (Jan–Dec 2023). The dental examination was carried out by two calibrated dentists using the WHO caries assessment form. Children with ≥5 carious tooth surfaces were classified as caries-active. All participants were systemically healthy. The same measurements were repeated after treatment. Results: The rise of the concentration of 8-isoprostane was statistically significant post treatment. Dental treatment led to an increase in salivary conductivity and buffer capacity, along with a decrease in 8-isoprostane levels. The main findings of the study revealed statistically significant increases in salivary conductivity, pH, and buffering capacity, as well as a decrease in 8-isoprostane levels following restorative treatments. Caries treatment is one of several factors that may contribute to the improvement of the physicochemical properties of saliva and the reduction of oxidative stress within the oral environment. Restorative dental treatment was associated with improvements in key salivary parameters—such as increased conductivity and buffering capacity—along with reduced 8-isoprostane levels. These findings suggest that the restoration of carious lesions supports the enhancement of oral homeostasis and may reduce the oxidative burden within the oral cavity. Overall, the study provides new insights into the role of 8-isoprostane in the caries process and underscores the need for further research with larger samples and additional biomarkers to clarify the mechanisms through which oxidative stress contributes to the pathogenesis of dental caries.