Paresthesia Following Dental Local Anesthesia in the United States

Background: Local anesthetics (LA) are safe and effective; however, complications associated with their use occur. Paresthesia, defined as persistent anesthesia, numbness or tingling, or a painful neuropathy known as dysesthesia, represent potential complications. Objective: To determine the difference in the incidence of oral paresthesia among the five currently available LAs in the United States (US). Methods: Records of voluntarily reported oral paresthesia involving dental LAs over the period of November 1997 to September 2008 were obtained from the US Food and Drug Administration (FDA) Adverse Event Reporting System (AERS). Exclusions were made if it was known that the dental procedures involved surgery. Chi-Square analysis was used to compare expected frequencies, based on US LA sales data obtained from the research company Strategic Data Marketing, to observed reports of non-surgical oral paresthesia made to the AERS. Results: In all, 248 cases of paresthesia following non-surgical dental procedures were reported. Most (94.5%) of these cases involved mandibular nerve blockade. The lingual nerve was affected in 89.0% of cases, the inferior alveolar nerve in 7.3%, and both were affected simultaneously in 3.7% of cases. Reported cases involving the drugs prilocaine 4% and articaine 4% were 7.4-times and 3.6-times, respectively, greater than expected (÷2, p<0.0001) based on LA usage by US dentists. Conclusions: These data suggest that oral paresthesia is more common following the use of 4% LA formulations. These findings are consistent with a number of similar reports from other countries. Until further studies are available, dental practitioners should consider these results when assessing the risks and benefits of using higher concentration LAs for mandibular block anesthesia.