Association of the SCN9A rs6746030 (R1150W) Polymorphism on Inferior Alveolar Nerve Block Failure in Symptomatic Irreversible Pulpitis.

INTRODUCTION

This study evaluated whether the SCN9A rs6746030 (G>A; R1150W) polymorphism is associated with the clinical success or failure of pulpal anaesthesia following an inferior alveolar nerve block (IANB).

METHODS

In this prospective clinical genetic association study, 320 patients with symptomatic irreversible pulpitis in mandibular molars were recruited. Each patient received a standardized IANB with 2% lidocaine and 1:80000 epinephrine. Anaesthesia was considered successful if the Heft-Parker Visual Analogue Scale (HP-VAS) score was below 54 mm during access cavity preparation/instrumentation; scores of 54 mm or higher were classified as failures. Buccal swab samples were collected for genotyping of rs6746030 using a TaqMan SNP assay. Genotype distributions were compared between the success and failure groups. Statistical analysis included Hardy-Weinberg equilibrium testing, chi-square comparisons, and binary logistic regression with genotype, age and gender as predictors.

RESULTS

Out of 320 patients analysed, 199 experienced failed anaesthesia, while 121 achieved successful outcomes. A significant deviation from Hardy-Weinberg equilibrium was found in the failed anaesthesia group (p < 0.05), suggesting potential genetic influence, while the successful group showed no deviation (p = 0.99). Logistic regression revealed that patients with the AA genotype had significantly lower odds of successful anaesthesia (OR = 0.22; 95% CI: 0.049-0.993). No significant associations were observed for the GA genotype, age, or gender. The model's predictive ability was limited, with an AUC of 0.53.

CONCLUSION

The rs6746030 polymorphism of SCN9A in its AA form is associated with a higher likelihood of IANB failure in mandibular molars with symptomatic irreversible pulpitis.