Free NBDE Ultimate Questions and Answers — Questions and Answers

Question 1: A patient presents with a white lesions on his buccal mucosa. The lesion is 4mm x 4mm in size and has been present in the patient's mouth for 4 months. Last week it became ulcerated and prompted the patient to see you. What would appropriate management entail?

Needle biopsy
Incisional biopsy
Continued monitoring
Excisional biopsy (Correct answer)
Exfoliative cytology

Correct answer: Excisional biopsy

A white lesion that has been present for 4 months and recently became ulcerated is suspicious for malignancy or a significant pathology. Given its relatively small size (4x4mm), an excisional biopsy is appropriate to completely remove the lesion for definitive diagnosis and simultaneously treat it if benign. This approach provides the most comprehensive diagnostic and therapeutic benefit for suspicious, small lesions.

Question 2: A patients presents with a mandibular first molar that has a failing root canal. Recurrent decay underneath the crown has caused severe damage to the remaining tooth structure and re-infection of the root canal space. Due to remove the tooth. What nerves would need to be blocked for surgical removal of this tooth?

Inferior alveolar, lingual
Inferior alveolar, lingual, mental
Interior alveolar, lingual, cervical
Inferior alveolar, mental, long buccal
Inferior alveolar, lingual, long buccal (Correct answer)

Correct answer: Inferior alveolar, lingual, long buccal

To extract a mandibular first molar, the inferior alveolar nerve needs to be blocked for pulpal and buccal bone anesthesia. The lingual nerve needs to be blocked for lingual soft tissue anesthesia. Additionally, the long buccal nerve (also known as the buccal nerve) needs to be blocked to anesthetize the buccal soft tissue and periosteum in the molar region, ensuring complete pain control during the procedure.

Question 3: Of the following root fracture possibilities, which has the WORST prognosis?

Mobile vertical fracture (Correct answer)
Coronal horizontal fracture
Mid-root horizontal fracture
Apical horizontal fracture

Correct answer: Mobile vertical fracture

Vertical root fractures, especially when mobile, have the worst prognosis because they often involve the entire length of the root, leading to bacterial contamination of the periodontal ligament and bone. They are difficult to treat and often result in extraction due to irreparable damage and persistent infection. Horizontal fractures generally have a better prognosis, especially if apical or mid-root and non-mobile.

Question 4: You are performing endodontic therapy on an upper first molar, and a file is broken in the distobuccal canal. On radiograph, you discover the fragment is 2.5mm long and is wedged tightly in the apical portion of the root, but not extruding past the foramen. What should you do?

Refer immediately to an endodontist
Perform an apicoectomy
Extract the tooth
Inform the patient, complete the procedure and monitor (Correct answer)

Correct answer: Inform the patient, complete the procedure and monitor

If a file fragment is broken in the apical portion of a canal, is tightly wedged, and not extruded, the best course of action is often to inform the patient, complete the root canal procedure to the level of the fragment, and then monitor the tooth. Attempting to retrieve a tightly wedged, non-extruded fragment can cause more damage (e.g., perforation, further extrusion) and many teeth with retained fragments remain asymptomatic and functional.

Question 5: In adolescents, when minor fractures occur to the permanent teeth, it is prudent to use which type of restoration?

Full coverage crown
Amalgam fillings
Stainless steel crown
Composite resin restorations (Correct answer)

Correct answer: Composite resin restorations

Composite resin restorations are the preferred choice for minor fractures in permanent teeth of adolescents due to their conservative nature and excellent aesthetics. They bond directly to the tooth structure, preserving maximum natural tooth tissue, which is crucial for young permanent teeth that may still have large pulp chambers. Other options like full crowns are more aggressive, and amalgam is less aesthetic.

Question 6: Which instruments are used for finishing and polishing amalgam?

Fine white stone
Plastic finishing strip
Finishing diamonds
Mounted abrasive rubber discs
Steel burs (Correct answer)

Correct answer: Steel burs

Steel burs, specifically multi-bladed finishing burs, are primarily used for the initial contouring and smoothing of amalgam restorations. After using burs to refine the anatomy, a sequence of abrasive rubber points and cups, followed by polishing pastes, is typically employed to achieve a high-gloss finish. The other options are generally used for different restorative materials or different stages of finishing and polishing.

Question 7: An asymptomatic red patch with or without foacl hyperkeratosis found in the floor of the mouth, lateral tongue or retromolar area is significant because:

It is likely a pyogenic granuloma
It is likely an indication of psoriasis
It is likely an indication of Kaposi’s sarcoma
It is likely an erythroplakia (Correct answer)

Correct answer: It is likely an erythroplakia

An asymptomatic red patch (erythroplakia) in high-risk oral areas like the floor of the mouth, lateral tongue, or retromolar area is highly significant because it has a high malignant transformation rate. Unlike benign reactive lesions or conditions associated with systemic diseases, erythroplakia is considered a precancerous lesion. Therefore, it warrants immediate biopsy and further investigation to rule out or diagnose squamous cell carcinoma.

Question 8: Which gland do most acinic cell adenocarcinomas occur?

Sublingual gland
Submandibular gland
Parotid gland (Correct answer)
Von Ebner glands
Minor salivary glands

Correct answer: Parotid gland

Acinic cell adenocarcinomas are malignant tumors that most frequently originate in the parotid gland, which is the largest of the major salivary glands. While these tumors can occur in other salivary glands, the parotid gland is the predominant site for this specific type of salivary gland malignancy. Therefore, any suspicious mass in the parotid region should be thoroughly investigated.

Question 9: Premature loss of a primary maxillary canine would MOST DIRECTLY result in:

A Class II molar relationship bilaterally
A Class III molar relationship bilaterally
Posterior crowding
Upper midline shift towards the affected side (Correct answer)

Correct answer: Upper midline shift towards the affected side

The premature loss of a primary maxillary canine can lead to an upper midline shift towards the affected side. This occurs because the adjacent teeth, particularly the incisors and posterior teeth, tend to drift into the space created by the missing canine. This mesial drift of posterior teeth and distal drift of incisors on the affected side can disrupt the dental arch and cause the upper midline to deviate.

Question 10: Which dental specialty focuses on the diagnosis and surgical treatment of diseases, injuries, and defects of the oral and maxillofacial region?

Orthodontics
Endodontics
Periodontics
Oral and Maxillofacial Surgery (Correct answer)

Correct answer: Oral and Maxillofacial Surgery

Oral and Maxillofacial Surgery is the dental specialty dedicated to the diagnosis, surgical and adjunctive treatment of diseases, injuries, and defects involving both the functional and aesthetic aspects of the hard and soft tissues of the oral and maxillofacial region. This encompasses a wide range of procedures, from complex tooth extractions and dental implant placement to facial trauma repair and reconstructive surgery. The other specialties focus on different aspects of dental care.

Question 11: What is the most appropriate treatment for a non-vital (dead) tooth with an infected pulp?

Dental extraction
Root canal therapy (Correct answer)
Crown placement
Antibiotic regimen

Correct answer: Root canal therapy

Root canal therapy is the most appropriate treatment for a non-vital tooth with an infected pulp because it aims to save the natural tooth. This procedure involves removing the infected or necrotic pulp tissue from within the tooth's root canals, thoroughly cleaning and shaping them, and then sealing them to prevent further bacterial contamination. While extraction is an option, root canal therapy preserves the tooth's function and aesthetics.

Question 12: Which dental material is commonly used for its high strength and durability in posterior restorations?

Amalgam (Correct answer)
Composite resin
Glass ionomer
Zinc oxide eugenol

Correct answer: Amalgam

Amalgam is a dental restorative material widely recognized for its high strength, durability, and longevity, making it an excellent choice for posterior restorations. It can withstand significant occlusal forces and has a proven track record of clinical success in areas where aesthetics are not the primary concern. Its robust properties ensure the restoration can endure the demands of chewing in the back of the mouth.

Question 13: What is the primary cause of enamel erosion?

Bacterial plaque
Acidic foods and drinks (Correct answer)
Poor oral hygiene
Grinding teeth

Correct answer: Acidic foods and drinks

Enamel erosion is primarily caused by the chemical dissolution of tooth enamel due to frequent exposure to acids, rather than bacterial action. Acidic foods and drinks, such as sodas, fruit juices, and citrus fruits, lower the pH in the mouth, leading to the gradual demineralization and irreversible loss of tooth structure. This process weakens the enamel, making teeth more susceptible to sensitivity and decay.

Question 14: Which oral structure is responsible for producing saliva?

Parotid gland (Correct answer)
Submandibular gland
Thyroid gland
Thymus gland

Correct answer: Parotid gland

The parotid gland is the largest of the three major salivary glands and is primarily responsible for producing serous saliva, which is rich in enzymes like amylase. While the submandibular and sublingual glands also contribute to saliva production, the parotid gland secretes a significant portion of the total salivary flow, especially during mastication and eating. Saliva plays a crucial role in digestion, lubrication, and oral health.

Question 15: What is the main function of the periodontal ligament?

Nourishing the tooth pulp
Anchoring the tooth in the jawbone (Correct answer)
Producing saliva
Aiding in speech production

Correct answer: Anchoring the tooth in the jawbone

The periodontal ligament (PDL) is a specialized connective tissue that surrounds the root of the tooth and connects it to the alveolar bone of the jaw. Its main function is to anchor the tooth securely in its socket, acting as a suspensory ligament. The PDL also serves as a shock absorber during chewing, provides sensory feedback, and contains cells vital for tooth and bone maintenance.

Question 16: Which dental specialty focuses on the alignment and positioning of teeth and jaws?

Prosthodontics
Oral and Maxillofacial Surgery
Orthodontics (Correct answer)
Endodontics

Correct answer: Orthodontics

Orthodontics is the dental specialty focused on the diagnosis, prevention, and treatment of dental and facial irregularities, specifically malocclusions (bad bites) and misaligned teeth and jaws. Orthodontists use various appliances, such as braces, aligners, and retainers, to move teeth into their correct positions and improve overall oral health, function, and aesthetics. The other specialties address different aspects of dental care.

Free NBDE Ultimate Questions and Answers

A patient presents with a white lesions on his buccal mucosa.
The lesion is 4mm x 4mm in size and has been present in the patient's mouth for 4 months.
Last week it became ulcerated and prompted the patient to see you.
What would appropriate management entail?