Oral Surgery · patient case question
Which space is involved, and what is the complication to anticipate?
Patient case: Anaesthesia and infection spread in the mandible
Patient: Male, 38 years old
Chief Complaint: “The tooth at the back on the bottom is throbbing and my neck is swollen.”
Background: Untreated caries in tooth #19 for months. No systemic disease. Separately, a restoration is planned on tooth #4.
Vital Signs: BP 132/82 mmHg · HR 102 bpm · T 101.8°F · RR 20
Findings: Tender, indurated swelling BELOW the inferior border of the mandible in the region of #19, with the swelling extending medially. Tooth #19 non-vital with a periapical radiolucency. Mouth opening 30 mm. Tongue position normal, voice normal, swallowing intact at present.
Show answer and explanation
Correct answer: D. The submandibular space, with Ludwig angina if it spreads
- A. The infratemporal space is involved by maxillary third molar infection or a contaminated posterior superior alveolar injection, and produces trismus with retro-maxillary pain.
- B. The buccal space lies lateral to the buccinator and produces cheek swelling. Cavernous sinus thrombosis is a complication of MAXILLARY and midface infection tracking through the valveless facial veins.
- C. The canine space arises from a maxillary canine and produces swelling that obliterates the nasolabial fold.
- D. CORRECT. The apices of the mandibular MOLARS lie BELOW the mylohyoid line, so infection perforating the lingual plate drains into the SUBMANDIBULAR space — producing swelling below the inferior border, exactly as described. The complication to anticipate is LUDWIG ANGINA: bilateral involvement of the submandibular, sublingual and submental spaces, which elevates the tongue and obstructs the airway. It is a rapidly progressive, life-threatening emergency requiring airway protection, intravenous antibiotics and surgical drainage.
Note: The MYLOHYOID LINE decides everything in the mandible. Apices ABOVE it — the premolars and usually the first molar — drain into the SUBLINGUAL space, elevating the floor of the mouth. Apices BELOW it — second and third molars, often the first — drain into the SUBMANDIBULAR space, swelling below the jaw. The warning signs that turn this into an emergency are elevation or protrusion of the TONGUE, a muffled 'hot potato' VOICE, DROOLING or inability to swallow, and any stridor. Assess and document all four at every visit in a spreading infection.