Salivary E-cadherin, Calprotectin, and Matrix Metalloproteinase-9 Levels in Recurrent Aphthous Stomatitis

Inclusion Criteria: * Participants aged 18 years or older * Clinically diagnosed with minor recurrent aphthous stomatitis (RAS) (defined as having a history of at least three RAS episodes within the past year) * Systemically healthy (i.e., without any diagnosed systemic disease) * No history of tobacco use * Presence of at least one active aphthous ulcer at the time of saliva sample collection * No known mental or physical disabilities Exclusion Criteria: * Use of any pharmacological treatment within the past 3 months * Use of antiseptic mouthwash within the past 3 months * Pregnant or lactating individuals, or those currently using oral contraceptives * History of systemic diseases associated with oral ulcerations such as Crohn's disease, ulcerative colitis, celiac disease, or Behçet's disease * History of chemotherapy or radiotherapy * Current or prior use of immunomodulatory drugs, cytotoxic agents, or systemic corticosteroids * Undergoing orthodontic treatment (to avoid misdiagnosis with traumatic ulcers) * Use of removable dental prostheses (to avoid misdiagnosis with traumatic ulcers) * Presence of periodontal disease (CPI score of 3 or 4) * Caries risk not classified as very low (DMFT ≥ 5) * Presence of pathological oral mucosal lesions such as lichen planus, pemphigus vulgaris, or mucous membrane pemphigoid