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The posterior superior alveolar (PSA) injection technique has varied over time with respect to the depth and angle of penetration, the location for deposition of anesthetic agent, and the number of injections necessary to assure adequate anesthesia to the maxillary molars. Of the standard intraoral injections, the PSA carries with it the second highest risk for anesthesia complications. With changes in armamentarium and technique, the complication rates have declined and more often are associated with anatomical considerations with respect to neurovascular compromise and/or anesthetic solution. In this study, the PSA injection technique and complication histories were investigated. Seventeen variations to the technique are reported along with 12 injection complications. A historic injection complication classification system is presented along with a management strategy based upon a review of reported provider experiences and treatment suggestions.

The posterior superior alveolar (PSA) injection technique is commonly used to anesthetize soft and hard tissues of the posterior maxilla. As with all injections, complications arise, including hematoma formation secondary to needle-induced vascular trauma. In an attempt to develop a hemorrhage-free PSA injection technique, 361 infratemporal dissections were completed on human cadaver specimens. Three distribution patterns were identified for the external branch of the PSA artery. Regardless of distribution pattern, an anatomical Triangle of Safety was found superior to the maxillary second molar that was free of neurovascular tissues in more than 99% of individuals. Injection into this area appears to meet anesthetic needs while reducing the risk of hematoma formation. The combination of this anatomical triangle with newer anesthetic agents and computerized delivery systems holds promise for continued improvement of the PSA injection technique.