ANESTHETIC EFFICACY OF THE INTRAOSSEOUS INJECTION AFTER AN INFERIOR ALVEOLAR NERVE BLOCK

The purpose of this study was to determine the contribution of the int raosseous (IO) injection to the inferior alveolar nerve (IAN) block in human first molars. Using a repeated-measures design, 40 subjects ran domly received either a combination IAN block + IO injection (on the d istal of the first molar) using 2% lidocaine with 1:100,000 epinephrin e or an IAN block + mock IO injection (gingival penetration only) at t wo successive appointments. The first molar and adjacent teeth, and co ntralateral canine (+/- controls) were blindly tested with an Analytic Technology pulp tester at 2-min cycles for 60 min. An 80 reading was used as the criterion for pulpal anesthesia. One hundred percent of th e subjects had lip numbness with the IAN block. For the first molar, a nesthetic success, defined as achieving an 80 reading within 15 min an d keeping this reading for 60 min, was 42% with the IAN and 90% with t he IAN + IO. Anesthetic failure defined as never achieving two 80 read ings during the 60 min was 32% with the IAN and 0% with the IAN + IO. The onset of anesthesia was immediate with the IO injection. Eighty pe rcent of the subjects sampled had a subjective increase in heart rate with the IO injection. The IO injection and postinjection questionnair e recorded low pain ratings.