Anatomical considerations for mandibular anesthesia in patients with hemifacial microsomia.

Hemifacial microsomia is a congenital abnormality of the structures derived from the first and second branchial arches. The severity of this disorder is variable and affects the anatomical landmarks essential for establishing the proper pathway for needle insertion prior to deposition of the local anesthetic solution to attain regional mandibular anesthesia preparatory to dental procedures. This paper describes normal anatomical considerations for regional anesthesia in the mandibular arch, deviations in normal anatomy found in patients with hemifacial microsomia, the rationale for suggesting modifications to standard techniques for mandibular anesthesia in patients with this disorder, and presents ways for the dentist to achieve anesthesia (analgesia) on the affected side of the mandibular arch in patients with hemifacial microsomia.