Post-Extraction Trismus — MFDS Part 1 MCQ
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Correct answer: A — Postoperative inflammation with protective spasm of the muscles of mastication
The correct answer is A. Early trismus after mandibular third-molar surgery is usually part of the local postoperative inflammatory response. Pain, oedema and irritation of adjacent muscles of mastication produce protective limitation and muscle spasm; the pterygoid muscles may be involved because of their anatomical proximity. This commonly causes a sore, stiff jaw during the first postoperative days and normally improves as inflammation resolves. Mandibular fracture and condylar dislocation are uncommon complications and would usually produce additional findings such as altered occlusion, deformity or abnormal mandibular position. Facial nerve injury causes weakness of facial expression rather than restricted mouth opening. Lingual nerve injury causes altered sensation or taste affecting the tongue and does not itself cause trismus.
Reference: Faculty of Dental Surgery, Royal College of Surgeons of England. Parameters of Care for Patients Undergoing Mandibular Third Molar Surgery, Surgical intervention section, 2021. https://www.rcseng.ac.uk/-/media/Files/RCS/FDS/Guidelines/3rd-molar-guidelines--April-2021-v4.pdf; Ribeiro MS et al. Effect of low-level laser therapy on the post-surgical inflammatory process after third molar removal, 2013. https://pubmed.ncbi.nlm.nih.gov/24195796/