Free NBDE Part II Questions and Answers — Questions and Answers

Question 1: Enamel's structural degeneration is brought on by:

Lowered pH (Correct answer)
Increase pH
Neutralize pH
Acidogenic

Correct answer: Lowered pH

Enamel's structural degeneration, or demineralization, is primarily caused by a lowered pH in the oral environment. When cariogenic bacteria metabolize sugars, they produce acids that decrease the pH below the critical level (approximately 5.5 for enamel). This acidic environment causes calcium and phosphate ions to leach out of the enamel, leading to its breakdown and the formation of carious lesions.

Question 2: For remineralization of onset lesions to take place, what must be ample?

Bacteria
Dentin
Fluoride (Correct answer)
Acidogenic

Correct answer: Fluoride

For remineralization of early carious lesions to occur effectively, an ample supply of fluoride is crucial. Fluoride ions incorporate into the demineralized enamel, forming fluorapatite, which is more resistant to acid dissolution than the original hydroxyapatite. It also attracts calcium and phosphate ions from saliva, facilitating the repair process and strengthening the tooth structure.

Question 3: What allows caries to infiltrate the dento-enamel junction?

Enamel caries
Fissure caries
Frank caries (Correct answer)
Pit caries

Correct answer: Frank caries

Frank caries refers to a carious lesion that has progressed beyond the initial stages and has clearly penetrated the enamel, reaching and often spreading along the dento-enamel junction (DEJ). At the DEJ, the caries can spread laterally due to the change in tooth structure, making it a critical point for the progression of the disease into the dentin.

Question 4: What is the most prevalent cariogenic bacterium at the root surface of caries?

Actinomyces viscus (Correct answer)
Veillonella
Streptococcus salivarious
Lactobacilli

Correct answer: Actinomyces viscus

Actinomyces viscus (now often referred to as Actinomyces naeslundii genospecies 2) is widely recognized as a primary etiological agent in root surface caries. Unlike coronal caries, which is often initiated by S. mutans, root surface caries occurs on exposed root surfaces and is strongly associated with the acidogenic and aciduric properties of Actinomyces species, particularly A. viscus.

Question 5: Which three regions of carious dentin can remineralize?

Normal dentin, transparent dentin, and infected dentin
Turbid dentin, infected dentin, and sub-transparent dentin
Normal dentin, sub-transparent dentin, and transparent dentin (Correct answer)
Transparent dentin, turbid dentin, and infected dentin

Correct answer: Normal dentin, sub-transparent dentin, and transparent dentin

Carious dentin can be broadly categorized into an outer infected layer and an inner affected layer. The inner affected dentin, which includes normal dentin, sub-transparent dentin, and transparent dentin, is demineralized but not yet irreversibly infected with bacteria. These layers retain their collagen matrix and are capable of remineralization if the bacterial insult is removed and appropriate conditions are present.

Question 6: Caries can be successfully diagnosed and treated by:

Good patient history, complete clinical evaluation, radiographic analysis, and comprehensive risk assessment (Correct answer)
Good patient history, initial clinical evaluation, radiographic analysis, and quantity of saliva output
Good patient history, visible plaque, blood pressure evaluation, and saliva output
Good patient history, amount of fluoride intake, clinical evaluation, and risk assessment

Correct answer: Good patient history, complete clinical evaluation, radiographic analysis, and comprehensive risk assessment

A thorough diagnosis and effective treatment plan for dental caries require a multi-faceted approach. This includes gathering a good patient history to understand risk factors, performing a complete clinical evaluation to visually and tactilely assess tooth surfaces, utilizing radiographic analysis to detect interproximal or hidden lesions, and conducting a comprehensive risk assessment to tailor preventive and restorative strategies.

Question 7: What type of caries has a sudden start and severe oral decay?

Arrested caries
Rampant caries (Correct answer)
Tubular caries
Carious lesion

Correct answer: Rampant caries

Rampant caries is a severe and rapidly progressing form of tooth decay characterized by a sudden onset and widespread involvement of multiple teeth, often affecting surfaces typically resistant to caries. It is frequently associated with factors like poor oral hygiene, high sugar intake, reduced salivary flow (xerostomia), or drug abuse, leading to extensive destruction of tooth structure.

Question 8: Remineralization is described as being hard, discolored, asymptomatic:

Rampant caries
Arrested caries (Correct answer)
Acute caries
Frank caries

Correct answer: Arrested caries

Arrested caries describes a carious lesion that has stopped progressing and has undergone remineralization. Clinically, these lesions appear hard to the explorer, often discolored (dark brown or black) due to trapped pigments, and are typically asymptomatic because the demineralization process has ceased. This indicates a shift in the oral environment towards health and repair.

Question 9: Beta-blockers, antipsychotics, diuretics, and anticholinergics are a few examples of medications that contribute to the reduction in:

Urine production
Saliva production (Correct answer)
White blood cell production
Tear production

Correct answer: Saliva production

Many medications, including beta-blockers, antipsychotics, diuretics, and anticholinergics, have xerostomia (dry mouth) as a common side effect. These drugs can interfere with the normal functioning of salivary glands, leading to a significant reduction in saliva production. Reduced saliva flow increases the risk of dental caries, periodontal disease, and oral discomfort.

Question 10: To identify dental caries:

Visual and tactical (Correct answer)
Visual only
Tactical only
Visual and tactical if aided by X-ray

Correct answer: Visual and tactical

Identifying dental caries primarily relies on a combination of visual and tactile examination. Visual inspection allows for the detection of color changes, surface irregularities, and cavitation. Tactile examination, using a dental explorer, helps assess the texture and hardness of the tooth surface, distinguishing between demineralized, soft enamel/dentin and sound, hard tooth structure.

Question 11: The restoration alloy and mercury mixture that has a track record for longevity and durability is:

gold
Silver
Enamel
Amalgam (Correct answer)

Correct answer: Amalgam

Dental amalgam is a restorative material composed of a mixture of liquid mercury and a powdered alloy, primarily silver, tin, and copper. It has been used for over 150 years and is well-known for its excellent longevity, durability, strength, and cost-effectiveness, particularly in posterior teeth where chewing forces are high.

Question 12: What components make up cements?

Fluoride and liquid
Zinc, fluoride, and glass
Chemical bonder and water
Powdered oxide or glass, plus a liquid (Correct answer)

Correct answer: Powdered oxide or glass, plus a liquid

Dental cements are typically formed by mixing a powdered component with a liquid component. The powder often consists of metal oxides (like zinc oxide) or finely ground glass particles, while the liquid can be an acid (like phosphoric acid or polyacrylic acid) or eugenol. This combination reacts to form a hardened material used for luting, bases, or temporary restorations.

Question 13: What features do zinc oxide-eugenol have?

Oil-based, low strength, has a calming effect of pulp and acts as temporary cement (Correct answer)
Oil-based, low strength, has a calming effect of pulp and acts as temporary cement
Oil-based, highly acidic, strong and acts as temporary cement
Oil-based, low acidity, low strength and acts as permanent cement

Correct answer: Oil-based, low strength, has a calming effect of pulp and acts as temporary cement

Zinc oxide-eugenol (ZOE) cement is an oil-based material known for its sedative or calming effect on the dental pulp, making it useful for temporary restorations or as a base under other fillings. It exhibits relatively low strength compared to other restorative materials, which is why it is primarily used for temporary applications or as a provisional luting agent.

Question 14: What is the drug uptake process called?

Drug distribution
Absorption (Correct answer)
Drug route
Membrane transference

Correct answer: Absorption

Absorption is the process by which a drug moves from its site of administration into the systemic circulation (bloodstream). This is the first step in pharmacokinetics after drug administration, and its efficiency depends on factors like the drug's chemical properties, formulation, and the route of administration.

Question 15: Website for drug administration includes:

Intramuscular, oral, transdermal, intravenously (Correct answer)
Leg, oral, transdermal, arm
Intramuscular, oral, intra-dermal, intravenously
Intramuscular, oral, transdermal, and intravenously (Correct answer)
Leg, oral, transdermal, and arm

Correct answer: Intramuscular, oral, transdermal, intravenously

The question refers to common routes or sites of drug administration. Intramuscular (injection into muscle), oral (by mouth), transdermal (through the skin), and intravenously (injection into a vein) are all well-established and frequently used routes for administering medications. Each route has distinct advantages and absorption characteristics, influencing how quickly and effectively a drug reaches its target.

Question 16: What is bioavailability?

A measurement of how much and how quickly a drug reaches the epidermis
A measurement of how much and how quickly a drug reaches the circulatory system (Correct answer)
A measurement of how much and how quickly a drug builds-up in the liver
A measurement of how much drug stays in the bloodstream after 30 days

Correct answer: A measurement of how much and how quickly a drug reaches the circulatory system

Bioavailability is a pharmacokinetic term that describes the fraction of an administered dose of unchanged drug that reaches the systemic circulation and the rate at which it does so. It is a crucial parameter for determining drug dosage and understanding how much of the drug is actually available to exert its therapeutic effects. Higher bioavailability means more of the drug reaches its target.

Free NBDE Part II Questions and Answers

Enamel's structural degeneration is brought on by: