The purpose of this study was to evaluate the association between COMT, MAOA, and SLC6A4 genetic polymorphisms and the success of inferior alveolar nerve block (IANB) in patients with symptomatic irreversible pulpitis in mandibular molars. Patients presenting with moderate to severe pain were enrolled. Before anesthesia, pain intensity was assessed using the Heft-Parker Visual Analog Scale (HP-VAS), and pulpal vitality was evaluated using cold and electric pulp tests. All participants received a standardized inferior alveolar nerve block with 4% articaine containing epinephrine. Fifteen minutes after injection, pulpal anesthesia was reassessed using cold and electric pulp tests. Patients who continued to respond to these tests were considered to have unsuccessful pulpal anesthesia and were excluded from the study. Patients with no response to either test were included in the study, and root canal treatment was initiated. Pain experienced during the procedure was assessed using the HP-VAS. Buccal swab samples were collected for genomic DNA isolation, and COMT, MAOA, and SLC6A4 polymorphisms were analyzed using a Real-Time PCR-based TaqMan genotyping assay. The association between genetic polymorphisms and the success of inferior alveolar nerve block was statistically evaluated.

Inclusion Criteria:

Age between 15 and 60 years. American Society of Anesthesiologists (ASA) Physical Status I. Clinical diagnosis of symptomatic irreversible pulpitis in a mandibular molar requiring primary root canal treatment.

Positive response to both the cold test and electric pulp test before treatment.

Presence of pulpal bleeding upon access cavity preparation, confirming pulp vitality.

Periodontal probing depth ≤3 mm. Sufficient coronal tooth structure to allow rubber dam isolation. No use of nonsteroidal anti-inflammatory drugs (NSAIDs) within 12 hours before enrollment.

No known allergy or hypersensitivity to articaine or epinephrine. No history of systemic or genetic disease. Ability and willingness to provide written informed consent.

Exclusion Criteria:

Previous endodontic treatment of the study tooth. Extensive coronal destruction preventing rubber dam isolation. Internal or external root resorption. Periodontal probing depth >3 mm. Pregnancy or breastfeeding. Known allergy or hypersensitivity to articaine or epinephrine. Use of nonsteroidal anti-inflammatory drugs (NSAIDs) within 12 hours before enrollment.

Presence of any systemic or genetic disease. Inability or unwillingness to provide written informed consent.