What is the likely diagnosis for a patient with ulcerations on the soft palate after local anesthesia for root planing?

The diagnosis of recurrent herpes is strongly supported in this case, particularly because the ulcerations on the soft palate developed following local anesthesia for a dental procedure. Herpes simplex virus can remain dormant in the nervous system and reactivate due to various triggers, including stress from dental treatment or trauma to the soft tissues.

In dental settings, the physical stress of procedures, such as root planing, may induce the reactivation of the herpes virus, leading to painful vesicular lesions and subsequently ulcerations that commonly appear on the soft palate or other mucosal tissues. The timing of the ulcerations, immediately following the dental work, aligns with herpes flare-ups, which often occur after such triggers.

In contrast, recurrent aphthous ulcers typically present as painful, shallow ulcers but are not commonly associated with the timing of dental procedures or preceded by vesicular lesions. Herpangina is a viral infection characterized by fever and ulcerations mainly on the oropharyngeal area, usually affecting children, and does not usually arise in the context of local anesthesia. An allergic reaction, while possible, would more commonly present with localized swelling, itching, or urticaria rather than isolated ulcerations, making recurrent herpes the most likely and fitting diagnosis in this scenario.