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Jordan Dental Exam practice questions

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Question 1Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which cranial nerve provides the efferent motor innervation to the muscles of mastication?

  1. Hypoglossal nerve
  2. Glossopharyngeal nerve
  3. Facial nerve
  4. Mandibular division of the trigeminal nerve Correct answer.

Explanation

The mandibular division (V3) of the trigeminal nerve carries branchial motor fibers to the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles. The trigeminal nerve also supplies sensation to the face, but only its third division carries motor fibers to these muscles.

Question 2Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Enamel is formed by which cell type during amelogenesis?

  1. Ameloblasts Correct answer.
  2. Fibroblasts of the periodontal ligament
  3. Odontoblasts
  4. Cementoblasts

Explanation

Ameloblasts are the specialized epithelial cells of the inner enamel epithelium that secrete enamel matrix and later mineralize it. Odontoblasts, by contrast, secrete the dentin that lies immediately beneath the enamel.

Question 3Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which immunoglobulin isotype is the principal antibody in saliva and other mucosal secretions?

  1. IgM
  2. IgA Correct answer.
  3. IgG
  4. IgE

Explanation

Secretory IgA, produced as a dimer and stabilized by the secretory component, is the dominant antibody of mucosal surfaces including saliva. It neutralizes pathogens locally without invoking strong inflammatory responses.

Question 4Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which enzyme catalyzes the rate-limiting step of glycolysis?

  1. Phosphofructokinase-1 Correct answer.
  2. Pyruvate kinase
  3. Lactate dehydrogenase
  4. Hexokinase

Explanation

Phosphofructokinase-1 converts fructose-6-phosphate to fructose-1,6-bisphosphate and is the committed, rate-limiting step of glycolysis. It is allosterically regulated by ATP, citrate, AMP, and fructose-2,6-bisphosphate.

Question 5Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

The resting membrane potential of a typical neuron is closest to which value?

  1. +30 mV
  2. −70 mV Correct answer.
  3. −140 mV
  4. 0 mV

Explanation

Resting membrane potential in most neurons is approximately −70 mV, set largely by potassium conductance and the Na+/K+ ATPase. Values near +30 mV correspond to the peak of an action potential, not the resting state.

Question 6Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which vitamin deficiency classically produces megaloblastic anemia with hypersegmented neutrophils?

  1. Vitamin C
  2. Vitamin B12 Correct answer.
  3. Vitamin D
  4. Vitamin K

Explanation

Vitamin B12 deficiency impairs methionine synthase and DNA synthesis, producing megaloblastic changes in rapidly dividing cells. The resulting anemia shows macroovalocytes and hypersegmented neutrophils, often with neurologic signs.

Question 7Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which bacterial species is most strongly associated with chronic periodontitis as a red complex organism?

  1. Streptococcus mutans
  2. Lactobacillus acidophilus
  3. Porphyromonas gingivalis Correct answer.
  4. Staphylococcus aureus

Explanation

Porphyromonas gingivalis is a gram-negative anaerobe of the red complex strongly implicated in chronic periodontitis. It produces gingipains and other virulence factors that degrade host tissues and evade immune defenses.

Question 8Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which cells are the mechanoreceptors that mediate the jaw-jerk (masseter) reflex?

  1. Muscle spindles of the masseter Correct answer.
  2. Ruffini endings in the joint capsule
  3. Free nerve endings in the periodontal ligament
  4. Golgi tendon organs of the temporalis

Explanation

The jaw-jerk reflex is a monosynaptic stretch reflex whose afferent limb arises from muscle spindles within the masseter. Sudden stretch of the mandible activates these spindles, which synapse on trigeminal motor neurons to contract the elevator muscles.

Question 9Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient has a lesion of the hypoglossal nerve. Which clinical finding is expected?

  1. Deviation of the tongue toward the side of the lesion on protrusion Correct answer.
  2. Loss of sensation over the chin
  3. Paralysis of the soft palate
  4. Loss of taste on the posterior tongue

Explanation

The hypoglossal nerve supplies the intrinsic and extrinsic tongue muscles, so unilateral injury weakens the affected side. On protrusion, the intact contralateral genioglossus pushes the tongue toward the weak side, producing deviation to the side of the lesion.

Question 10Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which statement best describes the role of cementum in the periodontium?

  1. It forms the bulk of the crown before eruption
  2. It is highly vascular and contributes to dentin repair
  3. It is avascular and provides attachment for periodontal ligament fibers to the root Correct answer.
  4. It is secreted by odontoblasts throughout life

Explanation

Cementum is a mineralized avascular tissue covering the root surface, and its collagen fibers interdigitate with periodontal ligament Sharpey fibers to anchor the tooth. Because it is avascular, it does not remodel like bone and can accumulate with age.

Question 11Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A drug that inhibits cyclooxygenase-1 in the gastric mucosa most directly predisposes to which adverse effect?

  1. Osteoporosis
  2. Renal stone formation
  3. Hyperkalemia
  4. Gastric mucosal ulceration Correct answer.

Explanation

Gastric mucosal protection depends on COX-1-derived prostaglandins that increase mucus and bicarbonate secretion and maintain mucosal blood flow. Inhibiting COX-1 removes this protection and predisposes to erosions and ulceration.

Question 12Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which feature distinguishes apoptosis from necrosis in a histological section?

  1. Single-cell loss with chromatin condensation and formation of apoptotic bodies Correct answer.
  2. Extensive neutrophilic infiltration of surrounding tissue
  3. Cell swelling with rupture of the plasma membrane
  4. Coagulation of cytoplasmic proteins with preservation of tissue architecture

Explanation

Apoptosis affects individual cells, shows chromatin condensation and nuclear fragmentation, and packages the remnants into membrane-bound apoptotic bodies that are rapidly phagocytosed. Inflammation is minimal because cellular contents are not released.

Question 13Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

In a patient with untreated diabetes mellitus, which finding best reflects osmotic diuresis?

  1. Decreased urine output with hyperkalemia
  2. Increased urine specific gravity with oliguria
  3. Increased urine output with glycosuria Correct answer.
  4. Decreased serum osmolality with hyponatremia

Explanation

When filtered glucose exceeds the renal tubular reabsorption maximum, glucose remains in the tubular fluid and exerts osmotic pressure that retains water. The result is polyuria with glycosuria and subsequent polydipsia.

Question 14Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which component of the bacterial cell wall is the target of beta-lactam antibiotics?

  1. The 30S ribosomal subunit
  2. Peptidoglycan cross-linking by transpeptidases Correct answer.
  3. DNA gyrase
  4. The lipopolysaccharide layer of gram-negative bacteria

Explanation

Beta-lactams acylate penicillin-binding proteins, which are transpeptidases that cross-link peptidoglycan strands. Loss of cross-linking weakens the cell wall and leads to lysis, especially in actively dividing bacteria.

Question 15Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which hormone is released from the posterior pituitary?

  1. Adrenocorticotropic hormone
  2. Thyroid-stimulating hormone
  3. Antidiuretic hormone Correct answer.
  4. Prolactin

Explanation

The posterior pituitary stores and releases antidiuretic hormone and oxytocin, which are synthesized in the hypothalamic supraoptic and paraventricular nuclei. The other listed hormones are anterior pituitary products.

Question 16Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A deficiency of vitamin K most directly impairs the synthesis of which coagulation factors?

  1. Von Willebrand factor
  2. Factors VIII and IX
  3. Fibrinogen and factor V
  4. Factors II, VII, IX, and X Correct answer.

Explanation

Vitamin K is a cofactor for gamma-carboxylation of glutamate residues on factors II, VII, IX, and X, as well as proteins C and S. Without carboxylation these factors cannot bind calcium and phospholipid membranes effectively.

Question 17Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which salivary gland secretion is predominantly mucous and drains via the sublingual duct?

  1. Parotid gland
  2. Sublingual gland Correct answer.
  3. Submandibular gland
  4. Minor palatal glands

Explanation

The sublingual gland produces mainly mucous saliva and drains through several small ducts, including the sublingual ducts of Rivinus. The parotid is purely serous, and the submandibular is mixed but predominantly serous.

Question 18Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

During the cardiac cycle, which event coincides with the first heart sound?

  1. Atrial contraction during late diastole
  2. Closure of the atrioventricular valves at the onset of ventricular systole Correct answer.
  3. Closure of the semilunar valves at the end of ventricular systole
  4. Opening of the atrioventricular valves during rapid filling

Explanation

The first heart sound is produced by closure of the mitral and tricuspid valves as ventricular pressure exceeds atrial pressure at the start of systole. Semilunar valve closure generates the second heart sound.

Question 19Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which mechanism best explains why local anesthetics fail to act in an acidic, inflamed tissue environment?

  1. The charged form cannot cross the neuronal membrane because the proportion of uncharged base is reduced Correct answer.
  2. The acidic environment converts the drug into a permanent agonist of sodium channels
  3. Inflammation increases local blood flow, which enhances drug binding to channels
  4. Acidosis increases sodium channel affinity for the drug

Explanation

Local anesthetics must cross the membrane in their uncharged base form before binding the intracellular side of sodium channels. In acidic tissue the equilibrium shifts toward the protonated, charged form, reducing membrane penetration and efficacy.

Question 20Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which collagen type predominates in the organic matrix of dentin?

  1. Type I Correct answer.
  2. Type IV
  3. Type III
  4. Type II

Explanation

Dentin matrix is composed largely of type I collagen, which provides the scaffold for mineral deposition by odontoblasts. Type II is mainly in cartilage, type III in reticular fibers, and type IV in basement membranes.

Question 21Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with chronic renal failure develops anemia. Which mechanism is most likely responsible?

  1. Impaired iron absorption due to gastric atrophy
  2. Autoimmune destruction of erythrocyte precursors
  3. Reduced erythropoietin production by the kidney Correct answer.
  4. Increased destruction of red cells by splenic macrophages

Explanation

The kidney produces erythropoietin in response to hypoxia, and loss of functioning renal parenchyma reduces this signal. The resulting normocytic normochromic anemia responds to erythropoiesis-stimulating agents.

Question 22Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which statement correctly describes the role of fluoride in caries prevention at the enamel surface?

  1. It directly kills all cariogenic bacteria in the plaque biofilm
  2. It promotes formation of fluorapatite, which is less soluble than hydroxyapatite Correct answer.
  3. It removes the acquired pellicle and exposes fresh enamel
  4. It increases enamel permeability to acids

Explanation

Fluoride incorporated into enamel forms fluorapatite, which has lower solubility than hydroxyapatite and is more resistant to acid demineralization. Topical fluoride also enhances remineralization and reduces bacterial acid production.

Question 23Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which feature best distinguishes type I from type II muscle fibers in a histological preparation?

  1. Type I fibers have more mitochondria and myoglobin and rely on oxidative metabolism Correct answer.
  2. Type II fibers have more mitochondria and are slower to fatigue
  3. Type I fibers contain no myofibrils and appear pale
  4. Type II fibers are exclusively innervated by parasympathetic fibers

Explanation

Type I (slow, red) fibers are rich in mitochondria and myoglobin and depend on oxidative phosphorylation, making them resistant to fatigue. Type II fibers are more glycolytic, faster, and fatigue more readily.

Question 24Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

In a patient taking warfarin, which laboratory test best monitors the anticoagulant effect?

  1. Prothrombin time with international normalized ratio Correct answer.
  2. Bleeding time
  3. Platelet count
  4. Activated partial thromboplastin time

Explanation

Warfarin reduces vitamin K-dependent factors II, VII, IX, and X, and factor VII has the shortest half-life, so the extrinsic pathway is affected first. Prothrombin time with INR is therefore the standard monitoring test.

Question 25Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

Which mechanism explains the analgesic effect of opioid drugs at the level of the dorsal horn?

  1. Presynaptic inhibition of neurotransmitter release from primary afferents and postsynaptic hyperpolarization Correct answer.
  2. Direct blockade of voltage-gated sodium channels in peripheral nociceptors
  3. Inhibition of cyclooxygenase and reduced prostaglandin synthesis
  4. Activation of transient receptor potential vanilloid-1 channels

Explanation

Opioids act on mu receptors in the substantia gelatinosa to inhibit adenylyl cyclase and open potassium channels, reducing presynaptic transmitter release and hyperpolarizing postsynaptic neurons. This dampens nociceptive transmission to higher centers.

Question 26Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

During a histology practical, a section of the periodontal ligament shows a mineralized tissue lining the root surface that lacks canaliculi and receives nutrition mainly from the periodontal ligament. Which tissue is described?

  1. Enamel
  2. Acellular cementum Correct answer.
  3. Dentin
  4. Alveolar bone proper

Explanation

Cementum covers the root surface, is avascular, lacks canaliculi, and is nourished by diffusion from the periodontal ligament. The acellular variety forms slowly and is found on the cervical and middle root.

Question 27Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A student bites into ice cream and feels a brief sharp pain in a maxillary molar. Which nerve fibers are primarily responsible for transmitting this fast, well-localized sensation from the dental pulp?

  1. Sympathetic postganglionic fibers
  2. Thinly myelinated A-delta fibers Correct answer.
  3. Preganglionic parasympathetic fibers
  4. Unmyelinated C fibers

Explanation

Sharp, rapidly conducted pain is carried by thinly myelinated A-delta fibers, which have higher conduction velocity than unmyelinated fibers. C fibers conduct more slowly and produce dull, poorly localized pain.

Question 28Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A 6-year-old child develops painful vesicles on the gingiva and hard palate that rupture to form shallow ulcers, with fever and tender cervical lymph nodes. Which virus is the most likely cause?

  1. Herpes simplex virus type 1 Correct answer.
  2. Epstein-Barr virus
  3. Coxsackievirus A
  4. Human papillomavirus

Explanation

Primary herpetic gingivostomatitis is caused by herpes simplex virus type 1 and presents with fever, vesicles, and shallow ulcers on the gingiva and oral mucosa in young children.

Question 29Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with a salivary gland obstruction has reduced salivary flow. Which electrolyte change in whole saliva is most directly explained by decreased ductal reabsorption of sodium?

  1. Increased salivary sodium concentration Correct answer.
  2. Decreased salivary bicarbonate concentration
  3. Increased salivary potassium concentration
  4. Decreased salivary calcium concentration

Explanation

Salivary ducts reabsorb sodium and secrete potassium and bicarbonate. When flow is reduced and ductal function is impaired, sodium reabsorption falls, so the sodium concentration of the saliva rises.

Question 30Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A biopsy of a chronic periapical lesion shows a dense infiltrate of lymphocytes, plasma cells, and macrophages with granulation tissue. Which process best describes this tissue reaction?

  1. Caseous necrosis with granuloma formation
  2. Chronic inflammation with fibrous repair Correct answer.
  3. Metaplastic ossification
  4. Coagulative necrosis

Explanation

Chronic inflammation is characterized by mononuclear cells, plasma cells, and granulation tissue with fibrosis. Periapical granulomas represent this chronic inflammatory response to persistent infection.

Question 31Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with a history of peptic ulcer disease takes a nonselective NSAID for dental pain. Which mechanism best explains the increased risk of gastric mucosal injury?

  1. Inhibition of lipoxygenase
  2. Blockade of histamine H2 receptors
  3. Inhibition of cyclooxygenase-1 Correct answer.
  4. Stimulation of prostaglandin synthesis

Explanation

Nonselective NSAIDs inhibit cyclooxygenase-1, reducing protective prostaglandins in the gastric mucosa and increasing susceptibility to acid injury.

Question 32Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with a mandibular fracture is evaluated for nerve injury. Which nerve provides sensory innervation to the lower lip and chin and is at risk in this injury?

  1. Lingual nerve
  2. Inferior alveolar nerve Correct answer.
  3. Mylohyoid nerve
  4. Long buccal nerve

Explanation

The inferior alveolar nerve runs within the mandibular canal and supplies sensation to the lower teeth, lower lip, and chin. Mandibular fractures can injure it and cause numbness in that distribution.

Question 33Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with chronic kidney disease has a serum calcium of 7.8 mg/dL. Which compensatory mechanism is most likely to be activated?

  1. Increased parathyroid hormone secretion Correct answer.
  2. Decreased renal phosphate reabsorption
  3. Increased calcitonin secretion
  4. Decreased intestinal calcium absorption

Explanation

Hypocalcemia stimulates parathyroid hormone release, which raises serum calcium by increasing bone resorption, renal calcium reabsorption, and activation of vitamin D.

Question 34Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with a bleeding disorder has a prolonged bleeding time but normal platelet count and normal coagulation studies. Which function is most likely impaired?

  1. Vitamin K-dependent carboxylation
  2. Fibrin cross-linking
  3. Factor VIII activity
  4. Platelet adhesion and aggregation Correct answer.

Explanation

Primary hemostasis, reflected by the bleeding time, depends on platelet adhesion and aggregation. Normal platelet count and coagulation tests point to a functional platelet defect.

Question 35Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A dental student is studying the role of the parotid gland. Which statement best describes its secretory product and duct?

  1. It produces mixed saliva that drains through Bartholin's duct.
  2. It produces mucous saliva that drains through Wharton's duct.
  3. It produces serous saliva that drains through the submandibular duct.
  4. It produces serous saliva that drains through Stensen's duct. Correct answer.

Explanation

The parotid gland is predominantly serous and drains through Stensen's duct, which opens opposite the maxillary second molar.

Question 36Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with diabetes mellitus reports increased thirst and frequent urination. Which mechanism best explains the polyuria?

  1. Osmotic diuresis from glucose in the tubular fluid Correct answer.
  2. Increased aldosterone secretion
  3. Excess ADH secretion
  4. Reduced glomerular filtration rate

Explanation

When filtered glucose exceeds the renal reabsorption threshold, glucose remains in the tubular fluid and exerts an osmotic effect that impairs water reabsorption, producing polyuria.

Question 37Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A tumor is described as well differentiated with slow growth and no metastasis. Which feature best supports a benign rather than malignant classification?

  1. Absence of invasion and metastasis Correct answer.
  2. Presence of tumor giant cells
  3. High mitotic rate
  4. Presence of nuclear pleomorphism

Explanation

Benign tumors remain localized, do not invade surrounding tissues, and do not metastasize. Pleomorphism, high mitotic activity, and giant cells are features of malignancy.

Question 38Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with severe liver disease develops prolonged prothrombin time. Which mechanism best explains this finding?

  1. Increased vitamin K absorption
  2. Excess platelet production
  3. Increased bile excretion
  4. Reduced synthesis of clotting factors Correct answer.

Explanation

The liver synthesizes most coagulation factors, so severe hepatic dysfunction reduces their production and prolongs the prothrombin time.

Question 39Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient with a deep neck infection is treated with an antibiotic that binds to the 30S ribosomal subunit and blocks the initiation complex. Which drug is most consistent with this mechanism?

  1. Metronidazole
  2. Vancomycin
  3. Amoxicillin
  4. Tetracycline Correct answer.

Explanation

Tetracyclines bind the 30S ribosomal subunit and inhibit protein synthesis by blocking aminoacyl-tRNA attachment and the initiation complex.

Question 40Basic and Applied Biomedical Sciences (anatomy, histology, physiology, biochemistry, microbiology, pathology, pharmacology)

A patient has a lesion affecting the mandibular division of the trigeminal nerve. Which finding is most consistent with this lesion?

  1. Loss of vision in the ipsilateral eye
  2. Loss of hearing in the ipsilateral ear
  3. Loss of taste over the anterior tongue
  4. Loss of sensation over the lower lip and chin Correct answer.

Explanation

The mandibular division of the trigeminal nerve supplies sensation to the lower lip, chin, and lower teeth. Taste, vision, and hearing are mediated by other cranial nerves.

Question 41Oral Biology, Oral Pathology and Oral Medicine

Which salivary component is primarily responsible for the acquired pellicle that forms on tooth surfaces within minutes of cleaning?

  1. Precipitation of calcium phosphate from gingival crevicular fluid
  2. Secretion of secretory IgA by plasma cells in the gingiva
  3. Glycoprotein adsorption, especially proline-rich proteins and statherin Correct answer.
  4. Bacterial synthesis of dextran from sucrose by streptococci

Explanation

The acquired pellicle is a thin organic film formed mainly by selective adsorption of salivary glycoproteins such as proline-rich proteins, statherin and cystatins onto hydroxyapatite. It forms within minutes and provides receptors for early bacterial colonizers. Secretory IgA and bacterial glucans contribute to plaque ecology but are not the principal structural source of the pellicle.

Question 42Oral Biology, Oral Pathology and Oral Medicine

A 30-year-old patient reports that a lower first molar is painful to cold fluids, and the pain lingers for several minutes after the stimulus is removed. Which pulp diagnosis best fits this presentation?

  1. Normal pulp
  2. Symptomatic irreversible pulpitis Correct answer.
  3. Reversible pulpitis
  4. Asymptomatic irreversible pulpitis

Explanation

Provoked pain that persists after removal of the stimulus indicates that pulpal inflammation has progressed beyond the reversible stage. Symptomatic irreversible pulpitis is characterized by spontaneous or lingering thermal pain, whereas reversible pulpitis resolves promptly when the stimulus is removed. Asymptomatic irreversible pulpitis lacks spontaneous symptoms, and normal pulp produces only brief, non-lingering sensitivity.

Question 43Oral Biology, Oral Pathology and Oral Medicine

Which epithelial layer of the gingiva is non-keratinized and permits passage of gingival crevicular fluid into the sulcus?

  1. Oral gingival epithelium
  2. Rete pegs of the oral epithelium
  3. Junctional epithelium
  4. Sulcular epithelium Correct answer.

Explanation

The sulcular epithelium lines the gingival sulcus and is thin and non-keratinized, allowing fluid and cells to pass from the connective tissue into the sulcus. The oral gingival epithelium is keratinized for protection, while the junctional epithelium attaches to the tooth via hemidesmosomes. Rete pegs are epithelial extensions into connective tissue, not a separate fluid-permeable lining.

Question 44Oral Biology, Oral Pathology and Oral Medicine

A patient undergoing chemotherapy develops multiple painful ulcers on the buccal mucosa and tongue with a white pseudomembrane. Which condition is most likely?

  1. Oral candidiasis
  2. Oral lichen planus
  3. Recurrent aphthous stomatitis
  4. Chemotherapy-induced oral mucositis Correct answer.

Explanation

Chemotherapy-induced oral mucositis presents as painful, erythematous or ulcerated lesions with pseudomembrane formation, typically appearing 7 to 14 days after cytotoxic therapy. It reflects direct mucosal toxicity and impaired epithelial turnover. Candidiasis and lichen planus have different clinical patterns, and recurrent aphthous ulcers are not temporally tied to chemotherapy.

Question 45Oral Biology, Oral Pathology and Oral Medicine

Which tooth is most commonly affected by dens invaginatus, making it prone to early pulpal infection?

  1. Mandibular first molar
  2. Maxillary central incisor
  3. Maxillary lateral incisor Correct answer.
  4. Mandibular canine

Explanation

Dens invaginatus most frequently affects the maxillary lateral incisor because of an infolding of the enamel organ during development. The invagination can harbor bacteria and communicate with the pulp, leading to infection even without caries. Other teeth may occasionally be involved but are far less common.

Question 46Oral Biology, Oral Pathology and Oral Medicine

Which immunoglobulin is the predominant type in whole saliva and helps inhibit bacterial adhesion to oral surfaces?

  1. IgG
  2. Secretory IgA Correct answer.
  3. IgE
  4. IgM

Explanation

Secretory IgA is the dominant immunoglobulin in whole saliva, produced by plasma cells and transported across the epithelium with a secretory component. It agglutinates bacteria and blocks adhesion to mucosal and tooth surfaces. IgG and IgM are present in smaller amounts, and IgE is associated with allergic responses.

Question 47Oral Biology, Oral Pathology and Oral Medicine

Which microorganism is considered the primary etiologic agent of early childhood caries when transmitted from caregivers?

  1. Streptococcus sanguinis
  2. Actinomyces viscosus
  3. Streptococcus mutans Correct answer.
  4. Veillonella parvula

Explanation

Streptococcus mutans is strongly associated with early childhood caries because it adheres to enamel, produces acid, and synthesizes glucans from sucrose. Vertical transmission from caregivers, often via saliva, is well documented. Streptococcus sanguinis is an early colonizer but is less acidogenic, and Veillonella is a lactate-utilizing organism.

Question 48Oral Biology, Oral Pathology and Oral Medicine

A patient has a white, non-scrapable plaque on the lateral border of the tongue that cannot be wiped off. Which diagnosis should be considered first?

  1. Pseudomembranous candidiasis
  2. Lichen planus
  3. Oral hairy leukoplakia Correct answer.
  4. Chemical burn

Explanation

Oral hairy leukoplakia presents as a white, corrugated, non-removable plaque typically on the lateral border of the tongue and is associated with Epstein-Barr virus, especially in immunocompromised patients. Pseudomembranous candidiasis is removable, leaving an erythematous base. Lichen planus usually shows bilateral striae, and chemical burns have a history of irritant contact.

Question 49Oral Biology, Oral Pathology and Oral Medicine

Which periodontal pathogen is strongly associated with localized aggressive periodontitis in adolescents and demonstrates leukotoxin production?

  1. Tannerella forsythia
  2. Porphyromonas gingivalis
  3. Prevotella intermedia
  4. Aggregatibacter actinomycetemcomitans Correct answer.

Explanation

Aggregatibacter actinomycetemcomitans is a gram-negative capnophilic rod strongly linked to localized aggressive periodontitis in adolescents. Its leukotoxin impairs neutrophil function, contributing to rapid attachment loss. Porphyromonas gingivalis and Tannerella forsythia are more associated with chronic periodontitis, though mixed infection occurs.

Question 50Oral Biology, Oral Pathology and Oral Medicine

A patient reports a burning sensation on the palate after eating spicy food, and examination shows erythema limited to the hard palate. Which condition is most consistent with this presentation?

  1. Burning mouth syndrome
  2. Median rhomboid glossitis
  3. Denture stomatitis Correct answer.
  4. Geographic tongue

Explanation

Denture stomatitis commonly presents as erythema of the palatal mucosa beneath a removable prosthesis, often caused by Candida albicans and chronic trauma. It is usually asymptomatic but may cause burning. Geographic tongue affects the dorsum of the tongue, median rhomboid glossitis is midline on the tongue, and burning mouth syndrome lacks visible mucosal erythema.