Background <p>Academic examinations are recognized as significant psychological stressors that can trigger measurable physiological responses. Salivary cortisol serves as a reliable noninvasive biomarker, reflecting the activity of the hypothalamic–pituitary–adrenal (HPA) axis during stress. This study investigated the effects of exam predictability on salivary cortisol levels in dental students from Duhok City.</p> Methods <p>Fifty-three second-year dental students (aged 19–22 years) were enrolled in a repeated-measures study design. Saliva samples were collected in the morning prior to both scheduled (pre-announced) and unscheduled (unannounced examinations concerning the date or time of the assessment) examinations. Cortisol concentrations were quantified using enzyme-linked immunosorbent assay (ELISA). Demographic and lifestyle variables, including body mass index (BMI), sleep duration, and anxiety level, were recorded and analyzed.</p> Results <p>Mean salivary cortisol levels were significantly higher before unscheduled examinations (37.14 ± 24.83 nmol/L) compared to scheduled examinations (23.56 ± 14.27 nmol/L; <i>p</i> = 0.0003). A positive correlation was found between BMI and cortisol concentration prior to scheduled exams (<i>r</i> = 0.3046, <i>p</i> = 0.027). No significant associations were identified with gender, sleep duration, or self-reported anxiety.</p> Conclusion <p>Higher cortisol levels in saliva were observed in association with unscheduled academic exams compared to scheduled exams. These findings indicate a physiological stress response during academic assessment and underscore the possible influence of academic challenges on stress-related biomarkers (salivary cortisol levels) in dental students.</p>