This observational study evaluates whether resting-state EEG alpha activity can help identify endodontic patients at higher risk of post-operative pain following single-visit root canal treatment. EEG will be recorded before treatment and pain intensity will be self-reported using a Visual Analogue Scale (VAS) during the early post-treatment period.

This observational clinical study is designed to examine the association between resting-state electroencephalography (EEG) alpha activity and the intensity of post-operative pain following single-visit root canal treatment. Participants will be recruited from an endodontic clinic after ethics committee approval. Resting-state EEG will be recorded using a wearable EEG system prior to treatment. Post-operative pain intensity will be assessed using a patient-reported Visual Analogue Scale (VAS) during the early post-treatment period.

Participants will be classified based on baseline alpha activity (e.g., lower versus higher alpha power range). Analyses will evaluate whether baseline EEG alpha measures are associated with subsequent pain ratings and whether differences in alpha activity relate to higher post-operative pain susceptibility. The goal is to determine whether EEG alpha activity may serve as a practical biomarker for post-endodontic pain susceptibility.

Inclusion criteria:

1. Patient's age ranges from 20-40.
2. Vital lower first molar with signs and symptoms of acute irreversible pulpitis and indicated for single visit root canal treatment.
3. Patients that had not received any medicinal therapy after endodontic treatment.
4. Patients who are mentally and physically capable to record pain intensity estimated every 6 hours after endodontic treatment using VAS.

Exclusion criteria:

1. Patient systemic disease or neurogenic disease that contraindicates the use of the EEG or have sensitivity to the electrode material.
2. Cases that root canal treatment could not be finished in a single visit such as teeth with apical periodontitis, pulpal necrosis, chronic apical abscess.
3. Patients who took analgesics within 24 hours after endodontic treatment.

The study population consists of patients seeking dental treatment at the Department of Endodontics, Faculty of Dentistry, Ain Shams University.