Mixed Deck — All NDEB Topics Flashcards

A 68-year-old male patient with a history of hypertension, well-controlled with propranolol, requires a mandibular tooth extraction. After administering a local anesthetic containing 1:100,000 epinephrine, the patient's blood pressure rises sharply, and their heart rate drops. Which of the following best explains this reaction?

Answer: Unopposed alpha-adrenergic stimulation from epinephrine.

Propranolol is a non-selective beta-blocker, meaning it blocks both beta-1 and beta-2 adrenergic receptors. When epinephrine is administered, its beta-2 mediated vasodilatory effects are blocked by propranolol, leaving the alpha-1 mediated vasoconstrictive effects unopposed. This leads to a significant increase in peripheral vascular resistance and blood pressure (hypertension), which in turn triggers a compensatory reflex bradycardia (decreased heart rate).

In a child with Turner tooth (enamel hypoplasia of a permanent tooth), what is the most likely cause?

Answer: Periapical infection of the overlying primary tooth

Turner tooth results from periapical infection or trauma to the primary predecessor tooth disrupting enamel formation of the developing permanent tooth.

Overjet is defined as:

Answer: The horizontal distance between the labial surface of the maxillary incisors and the labial surface of the mandibular incisors

Overjet is the horizontal (sagittal) distance measured from the labial surface of the mandibular central incisor to the labial surface of the maxillary central incisor.

Surface enamel is more highly mineralized than the rest of the enamel because _______:

Answer: crystallites are deposited parallel to the surface.

Explanation: Surface enamel is more highly mineralized than the rest of the enamel because the crystallites are deposited parallel to the surface, resulting in greater mineral density and hardness.

A patient with a known allergy to ester-type local anesthetics requires a maxillary infiltration for a restorative procedure. Which of the following local anesthetic agents would be the safest to use?

Answer: Lidocaine

Lidocaine is an amide-type local anesthetic. Allergies to local anesthetics are more common with the ester class due to their metabolism to para-aminobenzoic acid (PABA). A true allergy to one ester-type anesthetic generally contraindicates the use of all other ester anesthetics (like procaine and tetracaine). While benzocaine is an ester, an allergy to one amide does not rule out the use of another amide, making lidocaine a safe choice in this scenario.

Which of the following occlusal schemes is most frequently recommended for complete dentures to enhance stability during parafunctional movements and accommodate patients with resorbed ridges?

Answer: Lingualized occlusion

Lingualized occlusion is an occlusal scheme where the maxillary lingual cusps articulate with the central fossae of the mandibular teeth. This setup centralizes occlusal forces, minimizes tipping forces, and provides bilateral balance, which is highly advantageous for denture stability, especially in patients with significant ridge resorption. Canine guidance and group function are concepts primarily applied to natural dentition and fixed prosthodontics and can create destabilizing forces in complete dentures.

A 58-year-old male patient with a history of a prosthetic heart valve replacement 2 years ago requires a surgical extraction of a non-restorable tooth. The patient has a documented allergy to penicillin, which manifests as anaphylaxis. According to the most current Canadian guidelines for infective endocarditis prophylaxis, which of the following is the most appropriate antibiotic to prescribe?

Answer: Clindamycin 600mg orally, 1 hour before the procedure

For patients with high-risk cardiac conditions, such as a prosthetic heart valve, who are undergoing a dental procedure involving manipulation of gingival tissue, antibiotic prophylaxis is recommended. Since this patient has a history of an anaphylactic reaction to penicillin, cephalosporins should also be avoided due to potential cross-reactivity. Therefore, Clindamycin 600mg orally is the recommended alternative prophylactic agent. Amoxicillin is contraindicated due to the severe allergy.

Which bacteria is most associated with the initiation of dental caries?

Answer: Streptococcus mutans

Streptococcus mutans is the primary cariogenic bacterium, producing lactic acid and colonizing smooth tooth surfaces to initiate decay.

During an endodontic procedure, a dentist fractures a small file tip in the apical third of a root canal. The dentist successfully seals the canal, and the prognosis is considered good. Which of the following actions best demonstrates the ethical principle of veracity?

Answer: Informing the patient of the incident, discussing the potential prognosis, and documenting the conversation in the chart.

Veracity, or truthfulness, obligates dentists to be honest with patients about all aspects of their treatment, including procedural complications or adverse events. Informing the patient about the separated instrument, discussing the prognosis, and documenting this communication respects the patient's autonomy and upholds the principle of veracity.

What is the optimal fluoride concentration in community water fluoridation recommended by the US Public Health Service?

Answer: 0.7 mg/L

The US Public Health Service recommends 0.7 mg/L as the optimal fluoride concentration for community water fluoridation to prevent caries while minimizing fluorosis.

A patient presents with a deep, isolated 8mm periodontal pocket on the mesial aspect of a mandibular first molar, which has a necrotic pulp. Radiographically, a periapical radiolucency is evident. According to Simon's classification, what is the diagnosis and the correct initial treatment sequence?

Answer: Primary endodontic lesion with secondary periodontal involvement; initiate endodontic therapy first, then re-evaluate periodontal status.

The lesion originates from the necrotic pulp (primary endodontic) and drains coronally through the periodontal ligament space, creating a deep pocket that can subsequently become colonized by plaque and calculus (secondary periodontal involvement). The correct protocol is to address the primary source of infection—the necrotic pulp—by performing root canal therapy first. Periodontal status is then re-evaluated after 2-3 months to determine if the pocket has resolved or if subsequent periodontal therapy is required.

When prescribing codeine, patients should be informed ________:

Answer: to avoid consuming alcohol.

Explanation: Patients should be advised to avoid consuming alcohol while taking codeine because it can enhance the sedative effects of the medication and increase the risk of adverse reactions such as dizziness, drowsiness, and respiratory depression.

A patient presents with a suspected vertical root fracture on an endodontically treated maxillary premolar. A periapical radiograph shows a subtle 'J-shaped' or 'halo-like' radiolucency around the apex. Which imaging modality would be most definitive for confirming the presence and extent of the fracture?

Answer: Cone Beam Computed Tomography (CBCT)

While periapical radiographs may show suggestive signs like a J-shaped lesion, they are often inconclusive for diagnosing vertical root fractures due to the 2D nature of the image. Cone Beam Computed Tomography (CBCT) provides a 3D view, which allows for direct visualization of the fracture line in multiple planes (axial, sagittal, coronal), making it the most accurate and definitive imaging modality for this purpose.

Which behavior management technique involves telling a child what will happen before a procedure to reduce anxiety?

Answer: Tell-Show-Do

Tell-Show-Do involves explaining (tell), demonstrating (show), then performing (do) a procedure to reduce pediatric patient anxiety.

What is the main purpose of a needs assessment in dental public health?

Answer: To identify oral health problems and resources in a community

A community needs assessment identifies the oral health status, disease burden, and existing resources to plan appropriate public health interventions.

Which of the following restorative materials exhibits a coefficient of thermal expansion (CTE) that is most dissimilar to that of natural tooth structure, posing the greatest risk of percolation and marginal gap formation?

Answer: Unfilled acrylic resin

The coefficient of thermal expansion (CTE) measures how much a material expands and contracts with temperature changes. A large mismatch between the restorative material and tooth structure (enamel CTE ≈ 11.4 ppm/°C) can lead to stress, marginal leakage (percolation), and debonding. Unfilled acrylic resin has a very high CTE (70-90 ppm/°C), making it the most dissimilar. Adding inorganic fillers to create composite resins significantly lowers the CTE (to 25-40 ppm/°C), bringing it closer to tooth structure. Amalgam and porcelain also have CTEs that are more compatible than unfilled resin.

Which of the following is the most likely result of an acetaminophen overdose?

Answer: Hepatotoxicity

Explanation: An acetaminophen overdose is most likely to result in hepatotoxicity, which refers to liver damage or toxicity. Acetaminophen is primarily metabolized in the liver, and an overdose can overwhelm the liver's ability to process it, leading to liver damage or failure.

An SNA of 88˚ most likely indicates a maxilla positioned ________:

Answer: anteriorly.

Explanation: An SNA angle of 88˚ indicates that the maxilla is positioned anteriorly relative to the cranial base.

A clinician is preparing a maxillary first molar for a full gold crown. To ensure adequate retention and resistance form, what is the ideal total occlusal convergence (taper) of the axial walls?

Answer: 6-10 degrees

While perfectly parallel walls would offer maximum theoretical retention, they are clinically impossible to create without causing undercuts. A total occlusal convergence (the sum of the taper on opposing walls) of 6 to 10 degrees is widely accepted as the clinical ideal. This taper allows for the restoration to seat completely while providing sufficient parallelism to resist dislodgement from functional forces.

A dentist is restoring a deep Class I occlusal preparation in a mandibular molar using a bulk-fill composite resin. Which factor associated with the cavity's geometry creates the highest polymerization shrinkage stress?

Answer: The high ratio of bonded to unbonded surfaces

The Configuration Factor, or C-Factor, describes the ratio of bonded to unbonded surfaces of a restoration. A Class I preparation is a box with five bonded surfaces (mesial, distal, buccal, lingual, pulpal) and only one unbonded surface (occlusal). This high C-Factor of approximately 5 limits the resin's ability to flow and relieve stress during polymerization, leading to high internal stresses that can cause marginal gaps, debonding, and post-operative sensitivity.