Life-Threatening Infectious Consequences of Neglected Oral Cavity Diseases: A Comprehensive Review

Background: Untreated dental caries, pulpal gangrene, apical periodontitis, and impacted molar pericoronitis remain prevalent chronic conditions that frequently breach local biological containment when professional intervention is withheld or delayed. Objectives: To evaluate the direct pathophysiological routes, microbiological shifts, and clinical spectrum of life-threatening regional and systemic infections specifically arising from untreated oral diseases. Methods: A narrative synthesis of peer-reviewed clinical studies, prospective trials, and systematic reviews indexed in PubMed addressing severe odontogenic deep neck infections, mediastinal extension, intracranial spreading, and necrotizing fasciitis was conducted. Results: Odontogenic origins account for 34.2% to 49% of all diagnosed deep neck infections. Cortical erosion inferior to the mylohyoid line precipitates Ludwig's angina, leading to tongue elevation and precipitous airway asphyxia. Uncontrolled extension through the pharyngeal and retrovisceral 'danger space' (Space 4) causes descending necrotizing mediastinitis, carrying a mortality rate of 20–40%. Craniomaxillofacial necrotizing fasciitis displays a striking 30.3% mortality rate in diabetic cohorts due to severe microvascular thrombosis. Retrograde propagation via valveless ophthalmic and facial venous plexuses precipitates cavernous sinus thrombosis, orbital cellulitis, and brain abscesses. Microbiological evaluation demonstrates penicillin-resistant strains in 54% of severe cases driven by beta-lactamase-producing anaerobes, rendering delayed antimicrobial monotherapy ineffective without surgical intervention. Conclusions: Abandoning routine and curative dental care directly triggers catastrophic surgical emergencies. Early identification of red-flag symptoms (trismus, dysphagia, stridor), broad-spectrum parenteral coverage, and prompt surgical eradication of the causative dental source are imperative to prevent fatal outcomes and long-term musculoskeletal deformity.