Salivary Alpha-Amylase and Psychosocial Factors in Acute and Chronic Orofacial Pain—An Observational Cross-Sectional Study

Background: Orofacial pain (OFP) is a common clinical problem. It may present as acute or chronic pain and involves different biological and psychosocial factors. Acute OFP is often related to odontogenic causes and short-term nociceptive activation, whereas chronic OFP, particularly temporomandibular disorder (TMD), is frequently associated with stress, depression, and other psychosocial symptoms. Salivary alpha-amylase (sAA) reflects autonomic nervous system activity and has been suggested as a non-invasive biomarker of stress-related pain. However, its role in OFP and its relation to psychosocial burden remains unclear. Objectives: To investigate sAA activity and psychosocial factors in women with acute and chronic OFP compared with pain-free controls. Methods: A total of 144 women were included: 47 with acute OFP, 47 with chronic OFP diagnosed according to diagnostic criteria for TMD, and 50 pain-free controls. Psychological variables were assessed using the Perceived Stress Scale (PSS-14) and the Symptom Checklist-90-Revised short version (SCL-32-R). Unstimulated saliva samples were collected and analysed for sAA activity using a kinetic enzyme assay. Results: Significant group differences in sAA activity were observed (p = 0.038). Patients with acute OFP showed higher sAA activity compared with controls (p < 0.05), whereas no significant differences were found between chronic OFP and controls. Across all participants, a weak positive pooled correlation was observed between sAA activity and current pain intensity (rs = 0.23, p < 0.007). Chronic OFP patients reported higher levels of non-specific physical symptoms and current stress compared with controls (p < 0.01). Within the chronic OFP group, depressive symptoms, perceived stress, and non-specific physical symptoms were strongly correlated. Conclusions: Acute and chronic OFP were associated with different patterns: acute OFP was associated with higher sAA activity than in controls, whereas chronic OFP was associated with higher current stress and non-specific physical symptoms, but not with higher sAA activity. These cross-sectional findings should be interpreted cautiously and do not establish that the observed differences are attributable to pain duration alone.