FREE NBDE Ultimate Questions and Answers
What is the most appropriate treatment for a non-vital (dead) tooth with an infected pulp?
Root canal therapy involves removing the infected pulp tissue from a non-vital tooth to save the tooth and alleviate infection.
What is the main function of the periodontal ligament?
The periodontal ligament attaches the tooth root to the surrounding jawbone, providing stability and support.
Premature loss of a primary maxillary canine would MOST DIRECTLY result in:
The premature loss of a primary canine would most directly result in a shift of the midline towards the affected side. The loss of a canine prematurely would not directly impact the molar relationship bilaterally (a, b). It may impact one side’s molar relationship, but this is unlikely. The loss of the canine would not directly impact crowding in the posterior (c). It may have some influence on the position and eruption of the first premolar, however not as directly as it would influence the midline.
Of the following root fracture possibilities, which has the WORST prognosis?
Vertical root fractures present some of the worst problems in diagnosis and treatment. In order to have a good prognosis with a vertical fracture, the tooth segments must not be movable, and the patient must not have any symptoms. All other types of root fractures have fair to poor prognosis and will likely not be helped by endodontic therapy. In most cases, vertical fractures necessitate the complete extraction of the tooth. Coronal horizontal fractures (b) are fractures of the tooth immediately apical to the cemento-enamel junction or within a few millimeters subgingivally. This type of root fracture will most likely necessitate the removal of the coronal fragment (the crown) and the remaining tooth structure is evaluated for restorability. Often it can be root canal treated and restored with a post and crown. Mid-root (c) and apical root fractures (d) both have a more favorable prognosis since the fracture is not connected to the oral environment. Often the body is able to heal each segment once the pieces are repositioned. Additionally, if the coronal portion of the root becomes non-vital, endodontic treatment of that segment will often be sufficient. It is extremely rare that the apical segment would lose vitality and require endodontic therapy.
Which oral structure is responsible for producing saliva?
The parotid gland is one of the major salivary glands responsible for producing saliva.
In adolescents, when minor fractures occur to the permanent teeth, it is prudent to use which type of restoration?
In adolescents, tooth, bone and gingival development are not yet complete. When a permanent tooth is fractured, the nerve may be disturbed. Composite restorations are preferred because they restore esthetics and function, but also allow for a more definitive treatment when development has completed. Full coverage crowns (A) are not generally indicated in this scenario because of the incomplete bone, tooth and gingival development. Additionally, if pulpal problems should arise later, it would be better to complete endodontic therapy and then place a crown on the tooth once the patient is fully grown.Amalgam fillings (B) are not esthetic for anterior teeth. Stainless steel crowns (C) are also unesthetic and not indicated for permanent teeth.
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?
Excisional biopsies are generally warranted for lesions smaller than 1 centimeter in diameter, and may be performed as definitive treatment for such lesions. Also, excisional biopsies remove an additional 2-3mm border of tissue around the lesion itself. This is determined by the suspected diagnosis. If a malignancy is suspected a wider perimeter may be taken. Because this patient exhibits a lesion that has been present for over two weeks and has recently become ulcerated, suspicion of malignancy would be quite high. As the dimensions remain less than 1 centimeter in diameter, an excisional biopsy would serve this patient well. Needle biopsies (A), or aspiration biopsy, are more frequently done to determine if a lesion contains fluid. There is no indication from the description given that this patient’s lesion would warrant a needle biopsy. Incisional biopsies (B) should be done for lesions greater than 1 centimeter in diameter. Continued monitoring (D) would be ill advised at this time since the patient has already had the lesion for 4 months. And with the recent changes, the suspicion of malignancy is high. Cytological investigation (E) may be prudent if there was suspicion of a candidal or viral infection. The presentation of this lesion warrants more definitive action than a cytological smear.
What is the primary cause of enamel erosion?
Enamel erosion is primarily caused by the exposure of teeth to acidic foods, drinks, and other substances.
An asymptomatic red patch with or without foacl hyperkeratosis found in the floor of the mouth, lateral tongue or retromolar area is significant because:
Such a presentation is indicative of an erythroplakia (d). This is the most significant because 90% of such lesions are either carcinoma in situ or invasive squamous cell carcinomas. Pyogenic granulomas (a) do present as red lesions, however are usually correlated with pregnancy or traumatic events. They would also not present as a patch, but as a raised bulbous lesion. Patients with psoriasis (b) may present with red lesions with white patches, however they would more likely present on other skin and mucosal areas. They are not the most clinically significant type of red lesion for the locations listed. Kaposi’s sarcoma (c) is clinically significant due to the presence of the HIV virus and clinical manifestation of AIDS. However, the lesion would most likely present itself on the palate and would also contain red and blue macules or nodules.
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?
In this case, the piece of separated file is located at the apex of the tooth and wedged tightly in the canal. Because of this, it would be extremely difficult to remove the segment without possibly fracturing the root and necessitating extraction. Completing the cleaning and shaping coronal to the separated fragment and obturating well would allow the prognosis to be fair. The patient should always be informed of a separated instrument and should be placed on a monitoring schedule. It is not necessary to refer immediately (a) to an endodontist. This may be required in the future if the patient has symptoms, but not at this stage. Since the procedure and obturation are not yet complete, it would not be prudent to jump into surgical treatment (b) before completing standard therapy. Again, an apicoectomy may be warranted down the line if the patient develops symptoms or pathology around the apex. Extracting the tooth (c) would be extreme at this stage since there are still less invasive ways of treating the tooth in question. Extraction would be the last resort once other options are exhausted.
Which dental specialty focuses on the diagnosis and surgical treatment of diseases, injuries, and defects of the oral and maxillofacial region?
Oral and Maxillofacial Surgery is the dental specialty that deals with the diagnosis and surgical treatment of conditions affecting the oral and facial regions.
Which gland do most acinic cell adenocarcinomas occur?
Around 85% of all acinic cell adenocarcinomas occur in the parotid gland, a logical finding because this is the largest gland and one that is composed entirely of serous elements. Most surveys have shown that this neoplasm makes up 1% to 3% of all parotid tumors, although one study showed it represented 8.6% of all parotid tumors. It is much less common in the submandibular gland, which is the site for only 2.7% to 4% of these tumors. About 9% of all acinic cell adenocarcinomas develop in the oral minor salivary glands, with the buccal mucosa, lips, and palate being the most common site. Overall, around 2% to 6.5% of all minor salivary gland tumors are acinic cell adenocarcinomas.
Which instruments are used for finishing and polishing amalgam?
Steel burs are used for finishing amalgam preparation and restorations (E). In addition, metal finishing strips may be used. Fine white stones (A), plastic finishing strips (B), finishing diamonds (C), and mounted abrasive rubber discs (D) are used for finishing composite restorations
Which dental material is commonly used for its high strength and durability in posterior restorations?
Amalgam is known for its high strength and durability, making it suitable for posterior restorations.
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?
Though the inferior alveolar nerve is the only nerve for mandibular tooth innervation, several other nerves must also be anaesthetized in order to perform a surgical extraction. The lingual nerve innervates the lingual soft tissue of mandibular teeth. And the long buccal nerve anaesthetizes the buccal soft tissue of the molars and second premolar. Since all of these tissues surround the mandibular first molar, they should all be anesthetized for surgical extractions. The mental nerve block (b, d) only provides anaesthesia to the buccal mucous membranes from the mental foramen to the midline. The cervical branches (c) of cranial nerve VII may rarely provide accessory innervation for some mandibular regions. However, it is not standard to anaesthetize those nerves for tooth extractions.
Which dental specialty focuses on the alignment and positioning of teeth and jaws?
Orthodontics is the dental specialty concerned with correcting the alignment and positioning of teeth and jaws for functional and aesthetic purposes.