Patients were requested to perform a mouth rinse (3 min) with distilled water before proceeding with the saliva and epithelial cells collection from 10:00 a.m. to 12:00 p.m. After 10 min, the patient’s saliva (2‒3 mL) was collected in a sterile Falcon tube of 5 mL, under non-stimulatory conditions. The process included swallowing first, followed by a forward head tilt, and spitting out all UWS into the sterile tube through a plastic funnel. The collected UWS was centrifuged at 4000× g for 10 min to filter debris. Saliva was transported to the pathology laboratory and stored at −80 °C.