What is the indication for a PSA nerve block?

• A. When treatment involves two or more maxillary molars and infiltration is contraindicated or has proved ineffective
• B. For any anterior tooth
• C. For mandible anesthesia
• D. For palatal soft tissue only

Answer: (A)

The key idea is when to use the PSA nerve block. The PSA block is chosen when the treatment involves two or more maxillary molars and infiltration is contraindicated or has proven ineffective. This block targets the posterior superior alveolar nerves as they enter the maxilla, providing anesthesia to the maxillary molars and the buccal gingiva with a single injection. It is particularly useful when dense bone, infection, or inflammation makes infiltrations unreliable or when multiple teeth need anesthesia, avoiding the need for several infiltrations or palatal injections. It’s not used for anesthesia of anterior teeth, for mandibular anesthesia, or for just palatal soft tissue.