NBDE Part I cheat sheet

Trigeminal nerve exits: ophthalmic (V1) through the superior orbital fissure, maxillary (V2) through the foramen rotundum, mandibular (V3) through the foramen ovale.

Muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid) are all supplied by V3; the lateral pterygoid is the only depressor/protruder of the mandible.

Facial nerve (CN VII) exits the stylomastoid foramen and supplies muscles of facial expression; it supplies none of the muscles of mastication.

The carotid sheath contains the common carotid artery, internal jugular vein, and vagus nerve (CN X).

Lingual nerve carries general sensation from the anterior two-thirds of the tongue; chorda tympani carries taste from that region; taste from the posterior third travels with CN IX.

The middle meningeal artery, a branch of the maxillary artery, enters the cranium through the foramen spinosum and is at risk in temporal bone fracture.

The pterygoid venous plexus communicates with the cavernous sinus via emissary veins, providing a route for spread of odontogenic infection.

The temporomandibular joint is a bilateral ginglymoarthrodial synovial joint whose articular surfaces are covered by fibrocartilage, not hyaline cartilage.

Submandibular and sublingual glands receive parasympathetic secretomotor fibers from the superior salivatory nucleus via chorda tympani and the submandibular ganglion.

Net ATP yield: anaerobic glycolysis of one glucose to two lactate = 2 ATP; complete oxidation to CO2 and water = approximately 30-32 ATP.

Rate-limiting enzyme of glycolysis is phosphofructokinase-1: inhibited by ATP and citrate, activated by AMP and fructose-2,6-bisphosphate.

Michaelis-Menten: v = Vmax[S]/(Km + [S]); Km equals the substrate concentration at half-maximal velocity, and a lower Km means higher enzyme affinity.

Competitive inhibitors increase apparent Km with unchanged Vmax; noncompetitive inhibitors decrease Vmax with unchanged Km.

The oxyhemoglobin dissociation curve shifts right (lower affinity) with increased PCO2, decreased pH, increased temperature, and increased 2,3-BPG.

Renal glucose reabsorption occurs in the proximal convoluted tubule via SGLT2 (sodium-coupled); the renal threshold is approximately 180 mg/dL.

Aldosterone increases sodium reabsorption and potassium secretion in the distal nephron; ADH inserts aquaporin-2 channels in the collecting duct.

Resting membrane potential of about -70 mV is set mainly by potassium leak conductance and maintained by the Na+/K+ ATPase (3 Na+ out, 2 K+ in per ATP).

Vitamin C is required for hydroxylation of proline and lysine in collagen; deficiency impairs cross-linking and produces scurvy.

Gram-positive cell wall: thick peptidoglycan with teichoic acids, no outer membrane; gram-negative wall: thin peptidoglycan plus an outer membrane containing lipopolysaccharide (endotoxin).

Streptococcus mutans is the principal cariogenic organism; glucosyltransferase converts sucrose into glucans that anchor the organism to the acquired pellicle.

Lactobacillus species are associated with progression of caries into dentin; Actinomyces species with root caries.

Aggregatibacter actinomycetemcomitans is linked to aggressive periodontitis; Porphyromonas gingivalis, a black-pigmented anaerobe, is linked to chronic periodontitis.

Type I hypersensitivity is IgE-mediated and mast-cell dependent (anaphylaxis, hay fever); Type IV is T-cell mediated and delayed 48-72 hours (tuberculin reaction, contact dermatitis).

Acute inflammation shows vasodilation, increased vascular permeability, and neutrophil emigration; chronic inflammation shows lymphocytes, plasma cells, and macrophages.

Gram stain sequence: crystal violet, iodine mordant, alcohol decolorizer, safranin counterstain; gram-negative organisms decolorize and stain pink/red.

Autoclave sterilization: 121 degrees Celsius at 15 psi for 15-20 minutes, which destroys bacterial spores.

Squamous cell carcinoma is the most common oral malignancy; leukoplakia is a white patch that cannot be rubbed off and is a potentially malignant lesion.

Universal numbering runs 1-32: tooth 1 is the maxillary right third molar, 16 the maxillary left third molar, 17 the mandibular left third molar, and 32 the mandibular right third molar.

FDI two-digit notation: first digit is the quadrant (1 maxillary right, 2 maxillary left, 3 mandibular left, 4 mandibular right); second digit is the tooth position 1-8 from the midline.

Maxillary first molar usually has three roots (mesiobuccal, distobuccal, palatal) and four canals; mandibular first molar usually has two roots and three canals.

Eruption ages: mandibular central incisor 6-7 years, maxillary central incisor 7-8 years, mandibular first molar about 6 years (first permanent tooth to erupt).

Angle Class I: mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first molar.

Angle Class II: mandibular first molar is distal to its Class I position; Angle Class III: it is mesial to that position.

Canine-protected occlusion is considered ideal in lateral excursion because working-side canine contact discludes the posterior teeth.

Curve of Spee is the anteroposterior curvature of the occlusal plane; curve of Wilson is the mediolateral curvature of the mandibular posterior teeth.

Bennett movement is the lateral bodily shift of the mandible toward the working side; the nonworking condyle moves forward, downward, and medially.