Oral ulcers develop when the epithelial lining of the oral mucosa is compromised, often leading to pain, redness, discomfort, and bleeding. While some ulcers are triggered by local trauma, systemic illnesses, or medications, the causes of many remain unclear. This pilot study explores the composition of saliva and the oral microbiome in individuals with atraumatic pre-ulcerous and ulcerous lesions, compared to healthy controls, while accounting for three prevalent risk factors: smoking, stress, and sex. Using samples matched for age, sex, and ethnicity, we examined salivary levels of surfactant protein A (SP-A) and characterized the diversity and abundance of oral microbial populations. The study aimed to identify salivary indicators that could serve as early biomarkers for susceptibility to atraumatic oral ulcers. Our results demonstrate that SP-A levels are notably lower in female smokers than in healthy non-smoking females. Female patients with oral lesions also showed reduced SP-A compared to controls. Microbial composition was strongly influenced by both SP-A concentration and smoking status. Comparing healthy participants with those affected by lesions revealed 16 bacterial species with significant differences, all of which were modulated by SP-A and smoking. LEfSe analysis further highlighted five bacterial species as potential biomarker candidates. These findings suggest that alterations in the oral microbiome and SP-A levels are linked to risk factors for atraumatic oral ulcers. This preliminary work underscores the potential of saliva-based markers to predict ulcer susceptibility and points to possible interactions between innate immune mechanisms and microbial communities in the oral cavity.
