Effectiveness of 20% Benzocaine as a Topical Anesthetic for Intraoral Injections: MATERIALS AND METHODS

A total of 1080 adult patients participated in this study. They received a total of 2336 injections. Patients included in this retrospective study were participants in 25 independent, cross-over anesthetic research studies conducted at The Ohio State University. All patients were in good health as determined by a written health history and oral questioning. No patient was taking any medication that would alter pain perception. All patients were asymptomatic and volunteered for participation in their respective studies. The Ohio State University Human Subjects Committee approved each study, and written informed consent was obtained from each patient. Patients received either a conventional inferior alveolar nerve block, an infiltration over a maxillary lateral incisor, or a maxillary infiltration over a first molar. A 27-gauge needle was used for each injection.

Prior to 720 injections, topical anesthetic was utilized. The remaining 1616 injections did not receive topical anesthetic. The injection site was dried with gauze and approximately 0.2 mL of topical anesthetic (Hurricaine; Beutlich Pharmaceuticals LP, Waukegan, 111), consisting of 20% benzocaine, was applied using a cotton-tip applicator passively for 60 seconds. Prior to needle insertion, each subject was informed of the pain rating system to be employed. The scale consisted of 4 ratings: 0 = no pain; 1 = mild pain (pain that was recognizable, but not discomforting); 2 = moderate pain (pain that was discomforting, but bearable); and 3 = severe pain (pain that caused considerable discomfort and was difficult to bear). Patients were asked to hold up the appropriate number of fingers, 0-3, for the pain experienced after the 27-gauge needle was inserted 2 mm sub-mucosally. No anesthetic solution was deposited prior to the rating. After the pain rating was noted, the needle was directed toward the injection target site and the injection was completed.

Data were analyzed nonparametrically using a logistic regression model with the generalized estimating equation to correct for each subject receiving multiple injections. A separate model was generated for each of the 3 injection areas (ie, maxillary anterior, maxillary posterior, inferior alveolar nerve block). In each model, the dependent variable was absence of insertion pain (a pain rating of 0) or presence of pain (a pain rating of 1, 2, or 3), and the independent variables were topical anesthetic use and the study (provider). avodart 0.5 mg