Free NBDE Trivia Questions and Answers — Questions and Answers

Question 1: The palatine bone of the mouth, separates the oral cavity from which body cavity?

Buccal Space
Nasal Cavity (Correct answer)
Mental Space
Submandibular space
Oropharynx

Correct answer: Nasal Cavity

The palatine bone, along with the palatine processes of the maxilla, forms the hard palate, which serves as the roof of the oral cavity. Directly superior to the hard palate lies the nasal cavity. Therefore, the palatine bone acts as a structural barrier, effectively separating the oral cavity from the nasal cavity.

Question 2: Which nerve is responsible for causing elevation of the soft palate during the swallowing process?

Vestibulocochlear nerve
Facial nerve
Hypoglossal nerve
Vagus nerve (Correct answer)
Glossopharyngeal nerve

Correct answer: Vagus nerve

The vagus nerve (Cranial Nerve X) is primarily responsible for the motor innervation of most muscles of the soft palate, including the levator veli palatini. This muscle's contraction elevates the soft palate, which is a critical action during swallowing to seal off the nasopharynx and prevent food or liquid from entering the nasal cavity.

Question 3: While repairing an injury to the temporomandibular joint, the surgeon notes significant amounts of hemorrhage from the artery that courses medial to the neck of the mandibular condyle. What artery is injured?

Internal carotid artery
External carotid artery
Maxillary artery (Correct answer)
Facial artery

Correct answer: Maxillary artery

The maxillary artery is a major branch of the external carotid artery that courses medial to the neck of the mandibular condyle. It supplies numerous structures in the deep face, including the temporomandibular joint (TMJ) region. Significant hemorrhage from this location during TMJ surgery strongly indicates injury to the maxillary artery due to its anatomical proximity.

Question 4: Which vessels supply the buccal gingiva overlying tooth #3?

Anterior superior alveolar vessels
Middle superior alveolar vessels
Posterior superior alveolar vessels (Correct answer)
Inferior alveolar vessels
Greater palatine vessels

Correct answer: Posterior superior alveolar vessels

Tooth #3 refers to the maxillary right first molar. The posterior superior alveolar vessels are responsible for supplying blood to the maxillary molars and premolars, as well as the buccal gingiva in that posterior region. Therefore, these vessels specifically provide the blood supply to the buccal gingiva overlying tooth #3.

Question 5: The blood supply to the periodontal ligament (PDL) comes from the:

Facial artery
Lingual artery
Occipital artery
Ascending pharyngeal artery
Maxillary artery (Correct answer)

Correct answer: Maxillary artery

The periodontal ligament (PDL) receives its essential blood supply primarily from branches of the maxillary artery. These branches, including the superior and inferior alveolar arteries, give off perforating arteries that enter the alveolar bone and supply the PDL from various aspects. This rich vascular network is crucial for the health, nutrition, and function of the PDL.

Question 6: Which of the following molecules is primarily produced when glycogen is degraded?

Glucose 1-Phosphate (Correct answer)
Glucagon
Glycogen phosphorylase
Protein kinase
Glucagon Synthase

Correct answer: Glucose 1-Phosphate

Glycogen degradation, also known as glycogenolysis, is initiated by the enzyme glycogen phosphorylase. This enzyme cleaves glucose units from the non-reducing ends of glycogen chains, releasing them as glucose 1-phosphate. Glucose 1-phosphate is then converted to glucose 6-phosphate, which can enter glycolysis or be dephosphorylated to free glucose.

Question 7: At which location does glycogen synthesis usually occur?

Endoplasmic reticulum
Skeletal muscle
Cytosol (Correct answer)
Extracellularly
Liver

Correct answer: Cytosol

Glycogen synthesis, or glycogenesis, is a metabolic pathway that primarily occurs in the cytoplasm (cytosol) of cells, particularly in the liver and skeletal muscle. The enzymes responsible for this process, such as glycogen synthase and branching enzyme, are located within the cytosol. Glycogen is stored as granules within this cellular compartment.

Question 8: Hemoglobin molecules are essential with oxygen transport. Only one molecule of oxygen may bind to a hemoglobin molecule. (Select the correct choice)

Both statements are true
Both statements are false
The first statement is true, the second is false (Correct answer)
The first statement is false, the second is true

Correct answer: The first statement is true, the second is false

Hemoglobin molecules are indeed crucial for oxygen transport in the blood. However, each hemoglobin molecule is composed of four heme groups, and each heme group can bind one molecule of oxygen. Therefore, a single hemoglobin molecule has the capacity to bind four molecules of oxygen, not just one.

Question 9: The process that converts glucose-6-P to glycogen is known as:

Glycolysis
Gluconeogenesis
Glycogenolysis
Glycogenesis (Correct answer)

Correct answer: Glycogenesis

Glycogenesis is the metabolic pathway responsible for synthesizing glycogen from glucose, serving as the body's primary method of glucose storage. In this process, glucose-6-phosphate is converted to glucose-1-phosphate, which is then activated to UDP-glucose and added to a growing glycogen chain by glycogen synthase. This allows the body to store excess glucose for later energy needs.

Question 10: Which of the following mandibular premolars has a mesial groove, distal groove, and lingual groove on the occlusal surface?

Mandibular first premolar two-cusp type
Mandibular first premolar three-cusp type
Mandibular second premolar two-cusp type
Mandibular second premolar three-cusp type (Correct answer)
Mandibular second premolar with an H-shaped groove pattern

Correct answer: Mandibular second premolar three-cusp type

The mandibular second premolar can present with either two or three cusps. The three-cusp type is uniquely characterized by a distinct Y-shaped groove pattern on its occlusal surface, which includes a mesial groove, a distal groove, and a lingual groove. This specific morphology helps distinguish it from other premolar types.

Question 11: The greater palatine nerve block will anesthetize which of the following structurees?

The maxillary 1st molar
The maxillary 2nd molar
The maxillary 3rd molar
Palatal gingiva/mucosa in area of maxillary 1st premolar (anteriorly) to the posterior portion of the hard palate to the midline (Correct answer)
All maxillary molars

Correct answer: Palatal gingiva/mucosa in area of maxillary 1st premolar (anteriorly) to the posterior portion of the hard palate to the midline

A greater palatine nerve block effectively anesthetizes the posterior portion of the hard palate and the overlying palatal gingiva and mucosa. This includes the area extending from the maxillary first premolar posteriorly to the midline, reaching the junction with the soft palate. The injection targets the greater palatine nerve as it exits the greater palatine foramen.

Question 12: Which of the following occlusal disharmony is the most damaging to the dentition?

Premature tooth contact
Fremitus
Balancing side interferences (Correct answer)
Crepitus
Mandibular deviation

Correct answer: Balancing side interferences

Balancing side interferences, where teeth on the non-working side contact during lateral mandibular movements, are considered the most damaging occlusal disharmony. These interferences create unfavorable leverage on the teeth, leading to excessive and traumatic occlusal forces. This can result in tooth mobility, accelerated wear, periodontal ligament damage, and even temporomandibular joint issues.

Question 13: Which microscopic zone of necrotizing ulcerative gingivitis does the necrotic zone occur?

Zone 1
Zone 2
Zone 3 (Correct answer)
Zone 4
Zone 5

Correct answer: Zone 3

Necrotizing ulcerative gingivitis (NUG) is characterized by distinct microscopic zones of tissue alteration. Zone 3 is specifically identified as the necrotic zone, where there is extensive destruction and necrosis of the gingival connective tissue and epithelial cells. This zone is located superficially to the spirochetal zone and deep to the bacterial zone.

Question 14: Gram-positive bacteria change color when a Gram stain is used because:

The outer cell membrane adsorbs the crystal violet stain
The stain gets trapped in the thick, cross-linked peptidoglycan layer (Correct answer)
The counterstain safranin turns the bacteria red
The acetone or alcohol washes away the cells natural coloring

Correct answer: The stain gets trapped in the thick, cross-linked peptidoglycan layer

Gram-positive bacteria retain the crystal violet-iodine complex during Gram staining because they possess a thick, cross-linked peptidoglycan cell wall. This robust layer traps the stain, preventing it from being washed away by the decolorizer (alcohol or acetone). Consequently, Gram-positive bacteria remain purple, distinguishing them from Gram-negative bacteria.

Question 15: Triclosan is an effective antimicrobial agent which three types of pathogens?

Gram-positive bacteria, gram-negative bacteria, and fungi
Gram-negative bacteria, fungi and viruses
Gram-positive bacteria, gram-negative bacteria, and mycobacteria
Gram-positive bacteria, gram-negative bacteria, and viruses (Correct answer)
Gram-positive bacteria, mycobacteria, and viruses

Correct answer: Gram-positive bacteria, gram-negative bacteria, and viruses

Triclosan is a broad-spectrum antimicrobial agent commonly incorporated into dental products like toothpastes and mouthwashes. It is effective against a wide range of microorganisms, including both Gram-positive and Gram-negative bacteria, as well as certain viruses. Its mechanism involves disrupting bacterial cell membranes and inhibiting enzyme activity.

Question 16: Which of the following is not commonly associated with plaque-induced gingivitis?

Erythema
Edema
Tissue enlargement
Necrotic papilla (Correct answer)
Bleeding

Correct answer: Necrotic papilla

Plaque-induced gingivitis is characterized by inflammatory signs such as erythema (redness), edema (swelling), tissue enlargement, and bleeding on probing. Necrotic papilla, which involves the destruction and ulceration of the interdental papilla, is a distinctive feature of necrotizing ulcerative gingivitis (NUG), not typically associated with simple plaque-induced gingivitis.

Free NBDE Trivia Questions and Answers

The palatine bone of the mouth, separates the oral cavity from which body cavity?