Applied Basic Sciences
This domain tests whether you can connect anatomy, physiology, pathology, microbiology, pharmacology and biochemistry to surgical decisions in the mouth and jaws. Questions often hide a basic-science fact inside a clinical scenario.
Core rules
- The lingual nerve lies lingual to the mandibular third molar crown, often close to the lingual plate; the inferior alveolar nerve runs in the mandibular canal, usually buccal to the roots.
- The mandible receives blood mainly from the inferior alveolar artery; the maxilla from maxillary artery branches. The pterygoid venous plexus can spread odontogenic infection.
- Bone healing: hematoma, inflammation, soft callus, hard callus, remodeling. Smoking, diabetes and steroids impair it.
- Odontogenic infections are usually polymicrobial, with viridans streptococci and anaerobes such as Prevotella and Fusobacterium.
- Lidocaine 2% is 20 mg/mL; with epinephrine 1:100,000, maximum is often 7 mg/kg, not exceeding 500 mg; without epinephrine, 4.4 mg/kg.
- Patients with prolonged systemic corticosteroid use may need supplemental steroid coverage for major surgery.
Worked example
A 28-year-old has temporary tongue numbness after surgical removal of 38. The likely cause is lingual nerve traction or compression, not inferior alveolar nerve injury, because inferior alveolar injury would produce lip and chin numbness. Document sensation, avoid immediate re-exploration, and review; most neurapraxic injuries improve.
Traps
Confusing lingual and inferior alveolar nerve deficits; calculating local anesthetic dose from cartridge volume rather than mg/mL; assuming all swelling is bacterial cellulitis; forgetting that epinephrine-containing solutions need caution in uncontrolled hyperthyroidism or pheochromocytoma.