Submasseteric Abscess — MFDS Part 1 MCQ

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ModerateOral Surgery PrinciplesSubmasseteric AbscessMFDS Part 1

A 24-year-old patient presents with marked trismus and a firm swelling over the mandibular ramus. CT demonstrates an abscess between the masseter muscle and the lateral surface of the mandibular ramus. The infection began as pericoronitis. Which tooth is the most likely source?

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Correct answer: B — Mandibular third molar

The correct answer is B, the mandibular third molar. Submasseteric infection is classically odontogenic and most often follows pericoronitis around a partially erupted mandibular third molar. Infection reaches the space between the masseter and lateral mandibular ramus, producing marked trismus and firm swelling over the ramus. A maxillary third molar can rarely be associated with submasseteric infection, particularly following extraction and spread through deeper spaces, but it is not the usual pericoronitis-related source. Mandibular first molars more commonly produce buccal or submandibular space infection according to the relationship of their roots to muscle attachments. Maxillary canines and mandibular premolars have no typical anatomical relationship with the submasseteric space.

Reference: Schwartz RH, Bahadori RS, Willis A. Submasseteric Infection: A Rare, Deep Space Cheek Infection Causing Trismus. Pediatric Emergency Care. 2015;31(11):787–788. https://www.acutedentalproblems.sdcep.org.uk/guidance/management-of-oral-conditions/common-oral-conditions/acute-pericoronitis-including-erupting-teeth-in-children/