I read with great interest the excellent article by Dr. Al Reader and colleagues, "The Anesthetic Efficacy of Articaine in Buccal Infiltration of Mandibular Posterior Teeth" (
JADA 2007;138[8]:1104–12
). It has confirmed my clinical experience, and that of many other clinicians. However, it seems that a thick osseous cortex may inhibit adequate anesthesia with articaine infiltration. It has also been my experience that mandibular infiltration anesthesia with articaine fails when the buccal cortex at the injection site is deemed thick by palpation and visual examination.
Additionally, because the lingual cortex is thicker than the buccal cortex1 (also D.F., unpublished data, 2007), I have found that infiltration anesthesia given from solely the lingual aspect is also ineffective for tooth anesthesia. It may be that mandibular infitration is effective in the mandible where the buccal cortex is thin or, more likely, where there is an alveolar dehiscence or fenestration that allows direct apical contact of the anesthetic.
The cortical thickness, or lack thereof, may explain the longer duration but lack of efficacy of the higher 4 percent concentration of articaine. Additionally, there was a higher success rate in the first molars and premolars as compared with second molars where the thick external oblique ridge occurs.
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