2024 First AID Questions and Answers fir NBDE Exam (Orthopedics, Pharma, Pedia, Endodontics, Periodontics & Oral and Maxillofacial Surgery and Pain Control) Exam Test Bank Orthodontics What will be detected in the dark zones with application of light continuous force for 4 hours? A. Osteoclasts B. Osteoblasts C. Both osteoblasts and osteoclasts D. Neither osteoblasts nor osteoclasts E. cAMP ---------- Correct Answer --------- The correct answer is E. There is an increase in cAMP level along with cellular differentiation within the periodontal ligament in approximately 4 hours after an application of continuous light force to a tooth. Osteoclasts and osteoblasts remodel the bony socket, which induces tooth movement at approximately the second day after a continuous light force is applied to a tooth. Which of the following is an application of cephalometric radiographs? A. It is the only method to determine the Angle classification. B. It can be used to analyze treatment results. C. It is the only reliable method to determine which teeth to extract. D. It is the only radiograph that determines the status of wisdom teeth. E. It is used to determine the exact inclination and location of an impacted tooth. --------- - Correct Answer --------- The correct answer is B. Superimposition of cephalometric radiographs taken before, during,and after treatment will show changes in jaw and tooth positions that have occurred due to orthodontic therapy and orthognathic surgery.Answer A is incorrect because Angle classification can usually be determined from cast models, photographs, or clinical examination of the patient.Answer C is incorrect because the decision to extract teeth is the result of a comprehensive evaluation of the patient's complete record in combination with clinical presentation of the patient in addition to patient preferences.Answer D is incorrect because the status of the wisdom teeth can usually be determined via Panorex radiogram or orthopantogram. Answer E is incorrect because the exact location of an impacted tooth is best studied through Cone Beam CAT Scans. A flat mandibular plane angle correlates with a long anterior vertical dimension and an anterior open-bite malocclusion because cephalometrically, the mandibular plane angle is measured at the intersection formed by mandibular plane and the sella-nasion line. A. Both the statement and the reason are correct and related. B. Both the statement and the reason are correct but NOT related. C. The statement is correct, but the reason is NOT. D. The statement is NOT correct, but the reason is correct. E. NEITHER the statement NOR the reason is correct. ---------- Correct Answer --------- The correct answer is D. The statement is not correct because a steep mandibular plane angle correlates with a long anterior vertical dimension and an anterior open bite. The reason is also correct. Porion is located: A. In the center of external auditory canal B. Below the external auditory canal C. In front of the external auditory canal D. Behind the external auditory canal E. On the outer upper margin of the external auditory canal ---------- Correct Answer ----- ---- The correct answer is E. Porion is located on the outer upper margin of the external auditory canal. All of the following are indications for removable appliances except: A. Limited tipping movement B. Retention after comprehensive treatment C. Growth modification during mixed dentition D. Close extraction spaces fully ---------- Correct Answer --------- The correct answer is D. Answer D is false because bodily tooth movement is required to close extraction spaces fully for which full orthodontic treatment with fixed appliances is necessary. What will be detected in the dark zones with application of light continuous force for 2 days? A. Osteoclasts B. Osteoblasts C. Both osteoblasts and osteoclasts D. Neither osteoblasts nor osteoclasts E. cAMP ---------- Correct Answer --------- The correct answer is A. Resorption of alveolar bone is represented by the dark areas (known as compression areas of the periodontal ligaments).Osteoclasts are usually found in these areas. Osteoclasts and osteoblasts remodel bony socket, which induces tooth movement at around second day after a continuous light force is applied to a tooth. Osteoblasts are present only on the opposite surface of a root that is undergoing bodily movement and appear on the second day of continuous light force application. Along the tension front, a different type of activity occurs as the fibers are under tension and the bone quickly activates; here, bone is stimulated to begin formation. There is an increase in cAMP levels along with cellular differentiation within the periodontal ligament, in approximately 4 hours after an application of continuous light force to a tooth. What will be detected in the dark zones with application of heavy continuous force for 4 hours? A. Increase in cAMP levels B. Cell differentiation C. Cell death D. Release of prostaglandins and cytokines ---------- Correct Answer --------- The correct answer is C. The amount of force(heavy or light) determines the biological pathway of tooth movement and the formation or lack of formation of a hyalinized zone with undermining resorption. With an application of heavy continuous force, the cell death is observed in the compressed area. Increased cAMP levels are detectable within 4 hours of continuous light force application to the tooth. There is cellular differentiation within periodontal ligament in approximately 4 hours of continuous light force application to the tooth. Few minutes of light continuous force application usually leads to release of prostaglandins and cytokines. Methods employed in orthodontic treatment to align a crowded dentition include: A. Extraction of teeth B. Expansion of arches C. Distalization of teeth D. Interproximal reduction of teeth E. All of the above ---------- Correct Answer --------- The correct answer is E. All of the methods mentioned are employed in orthodontic treatment to align a crowded dentition. The extraction of first premolars to relieve the crowding (in case of severe crowding) is known as serial extraction. For example, palatal arch can be lengthened to make room for proper eruption of teeth with palatal expander. Distalization is a process of tipping a crown of the tooth distally to create space. Interproximal reduction is a process of removing a small portion of tooth enamel interproximally to create space and align teeth. Which of the following will require the most force to move tooth #27? A. Tipping B. Translation C. Root uprighting D. Rotation E. Extrusion F. Intrusion ---------- Correct Answer --------- The correct answer is B. Tooth movement such as translation requires the most force (70-120 gm). Tooth movements in descending order of requiring force are: I. Translation II. Root uprighting III. Tipping, rotation, and extrusion require similar force application IV. Intrusion Below are the indications for using bands instead of brackets, except for: A. Patient with amelogenesis imperfecta B. Teeth with long clinical crowns C. Patient with cuspal interference D. Teeth that will need both lingual and labial attachment ---------- Correct Answer -------- - The correct answer is B. Patients with short clinical crowns have an indication to use a band instead of a bracket. Patients with amelogenesis imperfecta have tooth surface that is incompatible with successful bonding for the placement of brackets. Therefore, the use of bands is indicated. Patients with cuspal interference or who experience heavy masticatory forces require band placement rather than brackets to better resist breakage. Patients with teeth requiring both lingual and labial attachment have an indication for a band placement Which one of the following statements is true about primate space in the primary dentition? A. Primate space is located between canine and first molar in the mandibular arch. B. Primate space is located between canine and first molar in the maxillary arch. C. It should be present in permanent teeth. D. It should be present in permanent teeth and deciduous teeth. ---------- Correct Answer --------- The correct answer is A. Generalized spacing of primary teeth is required for proper alignment of the permanent incisors. The primate space is located between lateral incisor and canine in the maxillary arch, and between the canine and first molar in the primary dentition of the mandibular arch. It should be present in deciduous teeth. The primate space should not be present in permanent teeth, and if there is spacing, then an orthodontic appliance should be placed to close it A 10-year-old girl presents to the office requesting to close her diastema. What is the correct treatment for this patient? A. Perform a frenectomy prior to orthodontic treatment and after maxillary canines erupt. B. Perform a frenectomy prior to orthodontic treatment and before maxillary canines erupt. C. Perform a frenectomy after orthodontic treatment and after maxillary canines erupt. D. Perform a frenectomy after orthodontic treatment and before maxillary canines erupt. E. Do not perform a frenectomy, and proceed with the orthodontic treatment. ---------- Correct Answer --------- The correct answer is C. In this case, a diastema is caused by a low frenum attachment. Teeth should be aligned orthodontically, followed by a frenectomy after maxillary canines erupt, because spaces tend to close as permanent canines erupt. Which one of the following statements is false about headgear? A. Headgear is typically used in skeletal class II. B. Headgear needs to be worn 10 to 14 hours per day to be effective. C. Treatment length is 6 to 18 months. D. Headgear can be used in adult patients. E. All of the above statements are false.