FCPS Part I Dentistry – Comprehensive Study Notes (May 2018 Past Paper)

Radiation Physics & Protection

  • Natural background radiation

    • Main source: cosmic rays arriving from outer space.

    • Significance: forms baseline exposure against which diagnostic/therapeutic doses are compared.

  • Lead–rubber apron

    • Attenuates approximately 96 % of scatter (≈0.25 mm Pb equivalent)\left(\approx 0.25\,\text{mm Pb equivalent}\right) thus mandatory in intra-oral radiography.

  • Dental–medical sources are artificial; contrast with natural sources (cosmic, terrestrial, internal radionuclides).

Oral Pathology & Oral Medicine

  • White/whitish lesions

    • Leukoedema: milky-white mucosal change that disappears on stretching; benign, common in elderly smokers.

    • Frictional keratosis: white striae/keratin at sites of chronic trauma (e.g. broken molar cusp). Reversible after elimination of trauma.

    • Leukoplakia / erythroplakia: true potentially malignant disorders— persist on stretching.

    • Lichen planus: buccal mucosa, saw-toothed rete ridges microscopically; clinically Wickham’s striae.

  • Pigmented lesions

    • Bronze mucosal discoloration → Addison’s disease (↓cortisol – ACTH hyper-secretion stimulates melanocytes).

  • Vascular lesions of tongue

    • Hemangioma: dilated, engorged blood-filled spaces, bluish-red, blanch on pressure.

    • Lymphangioma: translucent vesicular, often causes macroglossia; may appear “frog-egg / tapioca” like.

  • Pyogenic granuloma

    • Reactive lesion most common on attached gingiva in pregnancy & chronic irritation.

  • Talon cusp most frequently affects permanent incisors (especially maxillary lateral).

  • Branchial (cervical) cyst: fluctuating swelling at mandibular angle, enlarges on deglutition, opens intra-orally on relaxation.

Embryology & Development

  • Facial prominences

    • Philtrum of lip/nose: fusion of medial nasal processes.

    • Upper cheek/maxillary region: maxillary prominence derivatives.

  • Mandible develops from 1st (mandibular) pharyngeal arch (Meckel’s cartilage template).

  • Neurulation → formation of neural tube (future CNS).

  • Germ cells originate in the yolk-sac endoderm (3rd week) → migrate to genital ridge.

  • Palatal defects

    • Unilateral cleft palate ⇒ failure of palatal shelves to fuse with each other (secondary palate).

    • Bottle-feeding preference in neonate often due to cleft soft palate.

  • 3rd pharyngeal pouch → thymus + inferior parathyroids.

Head & Neck Anatomy

  • Muscles & Movements

    • Depression of mandible: chiefly lateral pterygoid (with suprahyoids & gravity).

    • Tongue protrusion: genioglossus supplied by XII; injury after submandibular surgery → inability to protrude.

    • Latissimus dorsi: essential for scratching back / climbing.

    • Soft-palate elevation: levator veli palatini (X via pharyngeal plexus).

  • Nerves

    • SCM: spinal accessory (XI).

    • Bitter taste posterior 1⁄3 tongue via glossopharyngeal (IX); not hypoglossal (XII is motor only).

    • Tip of nose – external nasal branch of ophthalmic (V1).

    • External laryngeal (branch of X) supplies cricothyroid; paralysis → loss of high-pitched voice; most commonly injured nerve in thyroidectomy.

    • Glossopharyngeal compression by elongated styloid → Eagle’s syndrome.

  • Circle of Willis

    • Components: anterior & posterior cerebral, internal carotid, anterior & posterior communicating arteries.

    • Middle cerebral artery not part of the circle.

    • Posterior communicating artery contributes arterial flow.

  • Lymphatic drainage

    • Boil on tip of nose → submandibular nodes.

  • Sesamoid cartilage exists in the ala of nose.

  • Cranial N. III (oculomotor) emerges from mid-brain at level of superior colliculus.

  • Foramen cecum: embryologic origin of the thyroid diverticulum.

  • Trachea begins at C6C6 opposite cricoid cartilage.

Oral & Dental Anatomy / Occlusion

  • Hertwig’s epithelial root sheath (HERS) dictates root shape, size, number.

  • Complete anodontia: classical in ectodermal dysplasia.

  • Mandibular 2nd premolar often exhibits Y-shaped occlusal groove.

  • Upper 2nd molar – mesio-lingual cusp occludes with central fossa of lower 2nd molar (ideal intercuspation).

  • Retained primary canine (53) → impaction of permanent canine (13).

Dental Materials

  • Amalgam phases

    • γ\gamma (Ag_3Sn) – strongest, least corrosion.

    • γ1\gamma_1 (Ag_2Hg_3) – adequate strength.

    • γ2\gamma_2 (Sn_7–8Hg) – weakest, prone to creep/corrosion.

    • Adding copper reduces γ2\gamma_2, silver increases overall strength; lower mercury → better marginal seal but ↑ contraction.

  • Flux for soldering Cr-Co alloys: boric acid eliminates chromium oxide film.

  • Suck-back porosity appears in casting of alloys when sprue freezes before button.

  • Zinc oxide–eugenol (ZOE) impression pastes

    • Accelerator: zinc acetate.

    • Cotton fibres ineffective as separating medium.

  • Dental plaster vs stone differ principally in water–powder ratio (stone 0.25 vs plaster 0.50 ml g⁻¹) producing greater strength & density.

  • Heat-cure acrylic cured >100 ∘C100\,^{\circ}\text{C} → porosity in thickest areas (monomer boiling).

  • Imbibition & syneresis characteristic of irreversible hydrocolloid (alginate); store in 100 % humidity to minimise.

  • Elastomer compression set highest in polysulfide rubber; addition silicones least.

  • Quartz (crystalline silica) in porcelain acts as strengthener.

  • Onlay: to support weakened cusps and prevent fracture.

Prosthodontics & Orthodontics

  • Circumferential (supracrestal) gingival fibres responsible for relapse after rotational correction → retain 3-6 months.

  • Reduced occlusal contact area → ↑ marginal fracture of amalgam.

Oral & General Surgery / Medicine

  • Tonsillectomy with tachycardia + hypotension after 2 h → hypovolaemic shock from bleeding.

  • Branchial cyst differential for fluctuant swelling near angle of mandible.

  • Maxillary sinus expands with eruption of secondary dentition; opens into middle meatus via hiatus semilunaris.

  • Eagle’s syndrome: elongated styloid compresses glossopharyngeal nerve.

  • Biopsy fixation: 10 % neutral buffered formalin prevents autolysis & putrefaction by protein cross-linking.

Systemic Pathology

  • Necrosis types

    • Liquefactive: bacterial abscesses, brain infarcts.

    • Fat necrosis: pancreatitis, omentum, breast trauma (most common cause = trauma).

    • Dystrophic calcification: occurs in damaged tissue e.g. tuberculosis lesions.

    • Metastatic calcification favours kidney, gastric mucosa, lungs in hyper-calcaemia.

  • Reversible cell injury hallmark: cellular (hydropic) swelling due to ATP-driven pump failure.

  • Acute appendicitis pain mediators: bradykinin & PGE₂; both produce hyperalgesia and vasodilatation (leucocytosis typical).

  • Most potent intracellular antioxidant: reduced glutathione (GSH).

Pharmacology

  • Pharmacodynamics = “what the drug does to the body” (receptor interaction, dose–response, efficacy).

  • Sulphonamides

    • Competitive inhibition of dihydropteroate synthase → folic-acid blockade (bacteriostatic).

    • Adverse: Stevens–Johnson syndrome, kernicterus (neonates).

  • Vancomycin for hospital MRSA; community-acquired strains often cotrimoxazole sensitive.

  • Paracetamol (acetaminophen) hepatotoxicity antidote: N-acetyl-cysteine replenishes hepatic glutathione.

  • Oxybutynin (anti-muscarinic) for nocturnal enuresis.

  • Half-life concept

    • Steady-state ≈ 4–5 half-lives. t<em>SS=4.5 t</em>1/2t<em>{SS}=4.5\,t</em>{1/2}

    • For t<em>1/2=2 mint<em>{1/2}=2\ \text{min} ⇒ t</em>SS≈9 mint</em>{SS}\approx 9\ \text{min}.

Physiology & Biochemistry

  • Hormones & Stress

    • Main stress hormone: cortisol; catecholamines equally important.

    • Stress increases GH, ADH, catecholamines, cortisol but not insulin.

    • Somatomedin (IGF-1) provides negative feedback and suppresses GH release; GH stimulated by exercise, hypoglycaemia, deep sleep.

  • Growth hormone inhibited by somatomedins; stimulated by exercise.

  • Renal physiology

    • Glucose reabsorbed exclusively in proximal convoluted tubule via SGLT-2.

    • PCT has brush border; distal convoluted tubule lacks.

  • Cardiovascular

    • AV node – slowest conduction (~0.05 m s⁻¹) allowing ventricular filling.

    • Conduction fibres lie in sub-endocardium.

    • Right border of heart formed by right atrium.

  • Respiratory

    • Negative intrapleural pressure chiefly from lymphatic drainage continually removing pleural fluid.

    • Emphysema: destruction of alveolar septa distal to terminal bronchiole.

  • Digestive & Metabolic

    • Protein digestion starts in stomach (pepsin at pH 1–2).

    • Fat absorption primarily in jejunum via micelles; requires bile salts & pancreatic lipase (also essential for fat-soluble vitamins A, D, E, K).

    • Carbohydrate malabsorption most often due to lactase deficiency (absence of intestinal lactase): osmotic diarrhoea.

    • Active vitamin D = 1,25 (OH)2-cholecalciferol1,25\,(OH)_2\text{-cholecalciferol} (calcitriol).

    • Daily protein requirement: ≈50 g\approx50\,\text{g} (0.8 g kg⁻¹ for 70 kg adult).

    • Average male body-fat ≈ 15%15\%.

    • BMI =mass (kg)height (m)2=\dfrac{\text{mass (kg)}}{\text{height (m)}^2}; 100 kg at 1.97 m gives ≈25\approx25 (upper normal).

    • Ketone excess when insulin deficiency (uncontrolled diabetes) promotes lipolysis.

  • Neurophysiology

    • Withdraw reflex via nociceptor A-δ/C fibres.

    • Motor cortex possesses large myelinated Betz cells; lesion causes contralateral paralysis.

    • Primary auditory cortex (Brodmann 41,42) in superior temporal gyrus.

    • Basal ganglia lesions produce choreiform jerky movements.

Microbiology / Immunology / Haematology

  • MRSA = methicillin-resistant Staph. aureus; glycopeptide or TMP-SMX therapy.

  • Transfusion reactions

    • Febrile non-haemolytic = most common early reaction; cytokine mediated.

    • TRALI: acute lung injury within 4 h due to donor anti-leukocyte antibodies.

    • IgA-deficient patient receiving IgA-containing blood → Type I hypersensitivity (anaphylaxis).

  • Sickle-cell anaemia

    • β-globin missense point mutation (Glu→Val at β6).

    • Hb 6 g dL⁻¹ with mild jaundice → haemolytic crisis.

    • Severe anaemia with splenic sequestration in children distinguishes sequestration crisis.

  • Iron deficiency confirmation: ↓serum ferritin (best single test).

  • Platelet & coagulation

    • Vitamin C deficiency → bleeding gums (collagen cross-link failure).

  • Lysozyme in saliva cleaves β-1,4 glycosidic bonds in peptidoglycan → bacteriolysis.

Dental Public Health / Preventive

  • Fluorosis produces diffuse mottling; enamel hypo-plasia presents pits/furrows due to disturbance during matrix formation.

Miscellaneous Anatomy & Histology

  • Superficial fascia = loose areolar + adipose connective tissue.

  • Danger area of scalp: loose areolar layer – emissary veins communicate with intracranial sinuses.

  • Urothelium (transitional epithelium) lines renal pelvis, calyces, ureter, bladder, prostatic & spongy urethra but not membranous urethra.

  • Submandibular gland: mixed acini; mucous acini capped by serous demilunes.

  • Epicardium = visceral layer of serous pericardium (mesothelium + connective tissue).

Biochemistry

  • Phenylalanine → tyrosine → catecholamines, thyroxine; not precursor of melatonin (from tryptophan).

  • Norepinephrine is immediate precursor of epinephrine via PNMT (requires S-adenosyl-methionine).

  • Gluconeogenesis: hepatic/renal synthesis of glucose from non-carbohydrate precursors (lactate, alanine, glycerol).

  • Glycogenesis = storage; glycolysis = catabolism.

Dental Radiology & Colour Science

  • Metamerism: two shades match under one light source but differ under another – critical when selecting tooth shade in operatory vs daylight.

Endodontics / Operative

  • Maxillary 1st molar often has a 4th canal in mesiobuccal root (MB2).

Orthopaedics / Hand Injuries

  • Most disabling hand nerve injury: median nerve (thenar wasting, loss of opposition).

  • Radial nerve injury low in spiral groove: spares ECRL but paralyses anconeus; elbow extension intact via triceps (proximal).

Public Health & Nutrition

  • Soy-bean oil richest in poly-unsaturated fatty acids (linoleic, α-linolenic).

  • Daily protein, fat-soluble vitamin absorption, unsaturated fats – integrate in diet‐counselling.

Haematology & Transfusion Calculations

  • Half-life / steady-state, TRALI timing, transfusion reactions – emphasise patient monitoring within 4 h post-transfusion.

These bullet-point notes encapsulate every fact tested in the FCPS Part I Dentistry (May 2018) past paper, cross-referenced with underlying principles, clinical relevance, and where possible numerical data or formulae for quick recall.