Anesthetic efficacy of the inferior alveolar nerve block in red-haired women.

INTRODUCTION: The exact reasons for failure of the inferior alveolar nerve (IAN) block are not completely known, but red hair could play a role. The genetic basis for red hair involves specific mutations, red hair color (RHC) alleles, in the melanocortin-1 receptor (MC1R) gene. The purpose of this prospective randomized study was to investigate a possible link between certain variant alleles of the MC1R gene or its phenotypic expression of red hair and the anesthetic efficacy of the IAN block in women.

MATERIALS: One-hundred twenty-four adult female subjects (62 red haired and 62 dark haired) participated in this study. Dental anxiety was determined in each subject using the Corah Dental Anxiety Questionnaire. The subjects were given 2 cartridges of 2% lidocaine with 1:100,000 epinephrine via the IAN block. Pulpal anesthesia was measured in the posterior and anterior teeth in 4-minute cycles for 60 minutes using an electric pulp tester. The MC1R alleles were genotyped for each subject from cheek cells containing DNA collected using buccal swabs.

RESULTS: Women with red hair and women with 2 RHC alleles reported significantly higher levels of dental anxiety compared with women with dark hair or women with 0 RHC alleles. No significant differences in anesthetic success were found between any of the groups for any of the teeth.

CONCLUSIONS: Red hair and the MC1R gene were significantly linked to higher levels of dental anxiety but were unrelated to success rates of the IAN block in women with healthy pulps.