During a nerve block, if the patient's tongue becomes numb, what does this typically indicate?

The presence of numbness in the patient's tongue during a nerve block typically indicates that the mandibular nerve block was successful. This occurs because the mandibular nerve, which is a branch of the trigeminal nerve (V3), innervates not only the lower jaw and teeth but also the anterior two-thirds of the tongue. When the anesthetic effectively blocks this nerve, the sensation in the tongue will diminish, leading to the characteristic numbness.

In contrast, successful anesthesia of the posterior superior alveolar (PSA) nerve primarily numbs the maxillary molars and does not usually affect the tongue. Similarly, the incisal nerve block is more focused on the incisors and adjacent soft tissues, without involvement of the tongue's sensory innervation. Additionally, while some normal reactions to anesthesia can occur, the specific numbness of the tongue is a clear sign of a mandibular nerve block's effectiveness.