Epinephrine and local anesthesia revisited.

The issue concerning how much and under what circumstances epinephrine vasoconstriction within dental local anesthesia is appropriate has been strenuously debated over the last 50 years. Because relevant human and animal studies are difficult to perform, there are, at present, insufficient data to answer many of our questions.Many of the previous conclusions regarding safety and efficacy were based upon incomplete understanding, bias, and limited scientific and clinical data. Well designed controlled, randomized, and blinded studies are the gold standardwith regard to determining pharmacotherapeutic efficacy and safety. With regard to epinephrine vasoconstriction, many opinions concerning this issue neglect our current understanding of physiology and pharmacology as well as the results of scientific clinical studies. Previous misunderstanding has been woven into much of our current clinical practice and as such reappraisal is warranted, because medical comprehension of the dynamics of physiology and pharmacology have recently undergone dramatic changes. Issues regarding these medications remain and include: 1) the advantages of combining vasoconstriction with local anesthesia, 2) the physiologic workings of the adrenergic nervous system, 3) toxicity issues of vasoconstrictors, 4) insignificant changes in mean arterial (MAP) blood pressure with relatively small amounts of epinephrine, 5) recep-