Local anesthetics in dentistry: then and now.

Local anesthetics have been in use in dental practice for more than 100 years. The advent of local anesthetics with the development of nerve blockade injection techniques heralded a new era of patient comfort while permitting more-extensive and invasive dental procedures. A brief history and summary of the current local anesthetics available in the United States is provided, and some of the newest techniques for delivering local anesthetics are reviewed. General guidelines for addressing difficulties encountered in anesthetizing patients are also discussed.