Elsevier

Journal of Endodontics

Volume 38, Issue 12, December 2012, Pages 1564-1569
Journal of Endodontics

Clinical Research
Anesthetic Efficacy of the Inferior Alveolar Nerve Block in Red-haired Women

https://doi.org/10.1016/j.joen.2012.08.014Get rights and content

Abstract

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.

Section snippets

Materials and Methods

One hundred twenty-four adult female subjects participated in this study. The subjects were in good health and were not taking any medications that would alter pain perception. Exclusion criteria were as follows: male, younger than 18 years of age, older than 65 years of age, allergies to local anesthetics or sulfites, pregnancy or nursing, a history of significant medical conditions (American Society of Anesthesiologists class II or higher), taking any medications (eg, over-the-counter

Results

A total of 124 women, 62 with natural red hair and 62 with natural dark hair, were included in the study (Tables 1 and 2). Aside from hair color, the women were also grouped by genotype. For the purposes of this experiment, the alleles strongly linked to the RHC phenotype (D84E, R151C, R160W, D294H, I155T, and R142H) and N29insA were all considered RHC alleles. Table 2 gives the number of red-haired and dark-haired subjects possessing 2 or 0 RHC alleles. A total of 45 women were shown to be

Discussion

Only women were used in this study because recent research has indicated that sex may play a role in the physiology and metabolism involved with pain perception, anesthesia, and analgesia in individuals with red hair and in those with variant alleles in the MC1R gene. Mogil et al (13) found that women with 2 variant MC1R alleles displayed significantly greater analgesia from the kappa opioid pentazocine when compared with red-haired men and nonredheads of both sexes. Delaney et al (14) also

Acknowledgments

The authors thank Elizabeth Hudson and Dr Ronald Gregg of the DNA Core at the Center for Genetics and Molecular Medicine at the University of Louisville for their expertise in genotyping the melanocortin-1 receptor gene.

The authors deny any conflicts of interest related to this study.

References (33)

Cited by (16)

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Supported by an AAE Foundation grant.

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