A patient presents with swelling and pain originating from the anterior maxillary teeth. What is the most serious potential complication of an untreated abscess in this region?

The canine space (associated with the maxillary canine and anterior maxillary teeth) communicates superiorly with the infraorbital space and orbital region via the angular vessels and the infraorbital foramen. An untreated abscess from anterior maxillary teeth can spread via the canine space to the infraorbital and orbital spaces, causing periorbital cellulitis or orbital cellulitis — a sight-threatening and potentially life-threatening emergency. The angular vein also connects to the ophthalmic venous system, creating a pathway for cavernous sinus thrombosis. Prompt recognition and treatment (antibiotics, surgical drainage, hospitalization if necessary) are critical.