Biomedical Sciences: Anatomy, Physiology, Pathology, Microbiology and Pharmacology in Dental Practice
Anatomy that questions are built on
Know the trigeminal nerve cold: V1 (ophthalmic) supplies the cornea and forehead, V2 the midface, upper teeth and palate, V3 the lower teeth, tongue (via lingual), and muscles of mastication (via mandibular division). The nerve to mylohyoid branches from the inferior alveolar nerve before the mandibular foramen, so a blocked IAN can spare the floor of the mouth. The lingual nerve sits anterior and medial to the IAN and carries taste from the anterior two-thirds of the tongue via chorda tympani. Maxillary posterior roots lie closest to the sinus floor. Odontogenic infections spread along fascial planes: mandibular molars to the submandibular and buccinator spaces, maxillary canines to the canine fossa with a venous route toward the cavernous sinus.
Physiology and pathology
Expect acid–base (anion gap = Na − [Cl + HCO3], normal 8–12), calcium homeostasis (PTH raises serum Ca, vitamin D increases absorption), and wound healing phases. Neoplasia concepts: dysplasia versus carcinoma in situ, route of spread, and the significance of perineural invasion.
Microbiology, immunology, pharmacology
Viridans streptococci dominate early infective endocarditis; anaerobes (Prevotella, Porphyromonas, Fusobacterium) dominate odontogenic abscesses. Master the four hypersensitivity types. For drugs, know NSAID mechanisms and renal/GI risk, antibiotic prophylaxis indications, and local anaesthetic maximum doses.
Traps
- Confusing lingual nerve injury (loss of taste and lingual sensation, no lip numbness) with IAN injury.
- Assuming every penicillin-allergic patient needs clindamycin; current guidance favours alternatives with lower C. difficile risk.
- Mixing up the maximum dose of plain versus vasoconstrictor-containing anaesthetic.
- Swapping Type II (cytotoxic, e.g. drug-induced haemolysis) and Type III (immune complex) hypersensitivity.
Worked example
Lidocaine 2% with 1:100,000 epinephrine for a 60 kg adult: 4.4 mg/kg × 60 = 264 mg; 2% = 20 mg/mL, so 264 ÷ 20 = 13.2 mL ≈ 7 cartridges of 1.8 mL, with a 300 mg absolute ceiling.