If a long needle is used for a PSA, what is the proper penetration depth?

In performing a posterior superior alveolar (PSA) nerve block, the goal is to effectively deposit anesthetic near the target area without causing unnecessary trauma to surrounding tissues. Using a long needle, the proper penetration depth is approximately half of the needle's length.

This depth is appropriate because it allows the clinician to reach the PSA nerve while minimizing the risk of penetrating too deeply into the pterygoid muscle or maxillary sinus. At this depth, the anesthetic can diffuse effectively to provide adequate anesthesia to the molar teeth in the targeted area.

Selecting a depth that is too shallow might lead to insufficient anesthesia, while opting for a deeper insertion could increase the risk of complications, such as damaging surrounding structures or causing hematoma formation. Thus, aiming for about half the length of the needle strikes a balance, ensuring effective delivery of the anesthetic agent while maintaining patient safety.