Abstract Trismus may represent an external sign of masticatory or lateral pharyngeal abscess that in rare cases is the consequence of pathogen action by micro-organisms introduced in deep tissues after inferior alveolar block. The case presented shows a buccal-masseteric mycotic abscess following restorative procedure involving inferior alveolar anesthesia on the same side. A 49-year-old woman was referred to the Dental Clinic (University of Trieste) complaining of a progressive inability to open her mouth since one week associated to a hemifacial edema in the right parotid region. The symptoms initially started one week before. Infection developed after restorative procedures performed 10 days before on the same side. Based on clinical signs and cultural exam findings, a buccal-masseteric mycotic abscess was found and magnetic resonance (MR) was performed to assess its localization and extension. Initial pharmacological therapy with piperacillin/tazobactam administered intravenously,
