Using a Narcotic to Enhance the Numbing Effect of the Local Anesthetic Lidocaine on Inflamed Molar Teeth

Overview

The effectiveness of local anesthetics is reduced if inflammation is present, making it difficult to control pain during such procedures as root canals and wisdom teeth removal. This set of studies will assess the effectiveness of the opioid (synthetic narcotic) fentanyl in enhancing the local anesthetic lidocaine (delivered with epinephrine) when used on inflamed molar teeth. In the first study, a topical anesthetic patch or a placebo will be placed on the gum tissues next to four or five lower posterior teeth. The patch will removed at either 5, 10, or 15 minutes. An electronic test that sends a light electronic impulse into the tooth, lip sensitivity testing ("Is your lip numb?"), and discomfort reports will be started immediately after removal of the patch and repeated every 5 minutes for 30 minutes. An oral surgeon will then remove the patient's wisdom teeth (tooth). In the second and third studies, a topical anesthetic will be placed on the gum tissue. An electronic test that sends a light electronic impulse into the tooth, lip sensitivity testing ("Is your lip numb?"), and discomfort reports will be started and done several times throughout the test. Then two small openings, one on each side of the tooth, will be drilled into the bony tissues surrounding the tooth. A narcotic drug fentanyl or a placebo drug will be delivered through these openings, allowing placement of the drug next to the nerves that are difficult to numb. Lidocaine, along with a small amount of epinephrine, will be delivered. An oral surgeon will then remove the patient's wisdom teeth or tooth (study 2) or do a root canal (study 3). In the fourth study, a topical anesthetic will be placed on the gum tissue. Then two small openings, one on each side of the tooth, will be drilled into the bony tissues surrounding the tooth. A narcotic drug fentanyl or a placebo drug will be delivered through these openings. Lidocaine, along with a small amount of epinephrine, will be delivered at one of three rates (15 patients for each rate). Blood pressure, heart rate, and breathing rate will be taken before the topical anesthetic patch is applied, 2 minutes after, and every 5 minutes for the next 45 minutes. Blood samples will be taken 6 times over the course of 60 minutes. When testing is complete, an oral surgeon will remove the wisdom teeth (tooth). One month later, blood samples will be taken using a different drug delivery method in order to compare results.

The clinical efficacy of local anesthetics is reduced in the presence of inflammation, sometimes limiting the ability to perform necessary therapeutic procedures. Recent studies suggest, however, that opiate receptors are expressed in the dental pulp and oral mucosal tissues and increase in number under conditions of inflammation. The proposed clinical study will assess the therapeutic effectiveness of the opioid, fentanyl, to enhance the profoundness of the local anesthetic lidocaine with 1:100,000 epinephrine when used on inflamed mandibular molar teeth. Delivering lidocaine 2% with 1:100,000 epinephrine intraosseously immediately after delivering fentanyl intraosseously is predicted to increase the success rate of local anesthesia on the inflamed pulpal tissues of mandibular molars. Three different strategies will be studied to assess fentanyl as an adjunct to local anesthesia. The first study will assess the efficacy of individual drugs under normal conditions in patients whose mandibular molars have healthy pulpal tissues. Pulpal anesthesia will be measured by an electronic pulp tester and drugs will be delivered intraosseously. A second study will evaluate local anesthetic success using the same drugs and route of administration in patients whose mandibular molars have inflamed pulpal tissues. Root canal treatment will test for the clinical effectiveness of local anesthesia. A third study will assess systemic side effects using different rates of intraosseous drug delivery. This series of studies may provide a rationale for the adjunctive administration of opioids in clinical conditions where inflammation limits the effectiveness of local anesthetics alone.