Saliva is an interesting alternative diagnostic body fluid with several specific advantages over blood. These include non-invasive and easy collection and related possibility to do repeated sampling. One of the obstacles that hinders the wider use of saliva for diagnosis and monitoring of systemic diseases is its composition, which is affected by local oral status. However, this issue makes saliva very interesting for clinical biochemistry of oral diseases. Periodontitis, caries, oral precancerosis, and other local oral pathologies are associated with oxidative stress. Several markers of lipid peroxidation, protein oxidation and DNA damage induced by reactive oxygen species can be measured in saliva. Clinical studies have shown an association with oral pathologies at least for some of the established salivary markers of oxidative stress. This association is currently limited to the population level and none of the widely used markers can be applied for individual diagnostics. Oxidative stress seems to be of local oral origin, but it is currently unclear whether it is caused by an overproduction of reactive oxygen species due to inflammation or by the lack of antioxidants. Interventional studies, both, in experimental animals as well as humans indicate that antioxidant treatment could prevent or slow-down the progress of periodontitis. This makes the potential clinical use of salivary markers of oxidative stress even more attractive. This review summarizes basic information on the most commonly used salivary markers of oxidative damage, antioxidant status, and carbonyl stress and the studies analyzing these markers in patients with caries or periodontitis.

Background. Thiobarbituric reacting substances (TBARS) are markers of lipoperoxidation. The best-known specific TBARS is malondialdehyde (MDA). Results from our previous studies have shown that TBARS can be measured in saliva and are increased in patients with gingivitis. Whether MDA is the main TBARS in saliva from patients with altered parodontal status is unknown. Aim. To observe the relationship between the parodontal status and TBARS, MDA and the number of epithelial cells in saliva. Subjects & Methods. In Study I saliva and plasma samples of 15 patients (8F, 7M) suffering from inflammatory periodontal diseases were gathered and TBARS levels were measured in these samples. In Study II saliva samples from 217 consecutive stomatologic patients were collected and analysed for TBARS spectrofluorometrically, MDA by high-performance liquid chromatography and epithelial cell count by light microscopy. Papillary bleeding index (PBI) was determined in standard stomatologic examination. Results. In Study I results from our previous studies showing no correlation between salivary and plasma TBARS levels were confirmed. This indicates that the local salivary level of TBARS is unlikely to be directly affected by systemic oxidative stress. In Study II higher PBI was associated independently (adjusted for age and sex) tightly with higher TBARS (p < 0.001) and with lower number of epithelial cells in saliva (p < 0.05). Smokers had higher salivary MDA levels (p < 0.003) and lower number of epithelial cells in saliva (p < 0.01). Conclusion. Salivary TBARS are a simple parameter that partially reflects the parodontal status with a potential usefulness in the clinical stomatology. We show herein that salivary MDA is dependent on age and smoking, but there is no correlation between MDA and PBI. Further studies should uncover the main salivary TBARS compound in patients with altered parodontal status and trace the origin of these salivary lipoperoxidation markers.