Evaluation of salivary oxidate stress biomarkers, nitric oxide and C‐reactive protein in patients with oral lichen planus and burning mouth syndrome
Oxidative stress is defined as an imbalance between the production of free radicals and antioxidants, and it was related to various diseases such as atherosclerosis, neurodegenerative diseases, diabetes, and aging among others 2. Presence of oxidative stress in saliva has been also described and was associated with periodontal disease and dental caries 1.
Oral lichen planus (OLP) and burning mouth syndrome (BMS) are chronic diseases of the oral mucosa characterized by persistent pain and/or discomfort that compromises quality of life of patients 3. OLP is an inflammatory disease of unknown origins. Its pathogenesis has yet to be fully understood 4, although oxidative stress would appear to play an important role. In 2007, Sezer et al. 5 observed an increase in oxidative stress, since detected increased peroxidation lipids together with an imbalance in the antioxidative defense system, in patients with cutaneous lichen planus, which suggests that reactive oxygen species (ROS) could be involved in the pathogenesis of LP; recent studies have supported these findings 6. Sunitha and Shanmugam 11 also found an increase in nitric oxide levels in LP patients in comparison with control subjects and concluded that free radicals represent a route in pathogenesis and that excess salivary nitric oxide could be involved physiopathologically in the erosive lesions of lichen planus.
BMS is characterized by a burning sensation that affects the oral mucosa and by the absence of clinical or laboratory data that might otherwise explain this symptom. The pathogenesis of this entity remains unclear and has generated controversy in recent years 3. Its etiopathogenesis is complex and probably involves interactions between local and systemic and/or psychogenic factors 3. Although increases in ROS mechanisms in the pathogenesis of pain have been investigated, no such studies have been conducted among patients with BMS 6. Nor is there much published research into oxidative stress among patients with BMS. Nevertheless, markers associated with the oral mucosa defense system (MUC1 y TLR2) in patients with BMS have been studied, observing increased MUC1 in patients with BMS in comparison with patients with OLP and control subjects, which suggests that MUC1 plays an important role in the appearance and evolution of burning mouth 12.
Overall, research about markers of oxidative stress and inflammation as means of explaining the role that saliva might play in OLP and BMS is scarce and poorly documented. For this reason, this study aimed to evaluate possible presence of oxidative stress in the saliva of patients with OLP and BMS, measuring total antioxidant capacity (TAC), salivary protein oxidation status, and ROS. In addition, biomarkers related with inflammation such as NO, nitrates, nitrites, and C‐reactive protein (CRP) levels were also determined.