A long needle measuring 1 5/8" is typically used for which type of injection?

A long needle measuring 1 5/8 inches is typically used for a mandibular block injection. This type of injection is necessary to anesthetize the inferior alveolar nerve, which innervates the lower jaw. The longer length of the needle allows the clinician to reach the deeper tissues of the mandible effectively.

In contrast, other types of injections, such as infiltration or periodontal ligament injections, generally require shorter needles since they are performed at or near the surface of the oral tissues. A palatal block also typically involves shorter needles due to the proximity of the target area. Therefore, the use of a long needle is specifically suited for providing adequate anesthesia in the mandibular region, where deeper insertion is essential.