Failure of local anesthetics is a common problem in dentistry. A sample of 210 dental practitioners was chosen at random and asked to evaluate the significance of anesthesia failure, comparing different injecting techniques. A standardized questionnaire, including a visual analogue scale for quantitative data, was distributed among the participants. The frequency of failure was indicated by most of the participants at 2% to 5% total. Considerably higher assessments were apparent in endodontics and abscess incisions. Rates of failure were said to be low in infraorbital nerve block, average in infiltration anesthesia and high in mandibular nerve block. These preliminary results indicate that a reliable anesthetic in dental treatment cannot always be provided.