NBDE Exam Part 1
Hemoglobin molecules are essential with oxygen transport. Only one molecule of oxygen may bind to a hemoglobin molecule. (Select the correct choice)
Hemoglobin is a metalloprotein that contains iron, which gets transported by red blood cells. This molecule also carries oxygen to provide energy to mammals and also involved in transport of other gases. Hemoglobins have the capability to bind to four oxygen molecules due to the fact that it contains 4 heme groups. There are two forms regarding hemoglobins. The T form is known as the taute (tense) form and is also known as the low oxygen affinity form; whereas the R form is the high oxygen affinity form that is also known as the relaxed form. REFERENCE: Champe, Pamela, Harvey, Richard, and Ferrier, Denise. Lippincott’s Illustrated Reviews: Biochemistry 4th edition. Copyright 2008.
What salivary gland disorder would you suspect with your patient who suffers from keratoconjunctivits sicca and xerostomia?
Sjogren syndrome. Sjogren syndrome is a chronic, systemic autoimmune disorder that princiapply involves the salivary and lacrimal glands, resulting in xerostomia (dry mouth) and xeropthalmia (dry eyes). The effect on the eye often are called keratoconjuctivits sicca, and the clinical presentation of both xerostomia and xerophthalmia is also sometimes called sicca syndrome. Primary Sjogren syndrome is when there is no other autoimmune disorder present. Secondary Sjogren syndrome is when the patient manifests sicca syndrome in addition to another associated autoimmune disease. Although rheumatoid arthritis is the most common associated disorder with secondary Sjogren syndrome, it would not be originally suspected in this scenario. REFERENCE: Neville BW, Damm DD, Allen CM, Bouquot JE. Oral & Maxillofacial Pathology. 2002. Saunders, Philadelphia, Pensylvania.
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?
The maxillary artery is a branch of the external carotid artery that supplies blood to the deep structures of the face. The artery arises behind the neck of the mandible and courses medially to the neck of the mandibular condyle before passing into the pterygopalatine fossa. The maxillary artery has numerous branches, including the middle meningeal artery, the deep auricular artery, buccal artery, and masseteric artery. Answer A: The internal carotid artery is one of the most important arteries of the body and arises from the bifurcation of the common carotid artery into the internal and external carotid arteries. The internal carotid artery is the principal source of blood to the brain, while the external carotid artery supplies portions of the face, scalp, skull, and meninges. The artery courses laterally along the neck and would be much deeper than the maxillary artery in comparison to the temporomandibular joint. Answer B: The external carotid artery is a major artery of the head and neck that arises from the common carotid artery after it bifurcates to form the internal and external carotid arteries. The external carotid artery courses from the upper border of the thyroid cartilage where it moves anteriorly to course upward toward the head and passes behind the neck of the mandible before dividing into the superficial temporal and maxillary arteries. The external carotid artery is important for supplying blood to many structures of the face including the tongue (via the lingual artery) as well as the muscles of the face via the facial artery. Answer D: The middle meningeal artery is a branch of the maxillary artery and is one of the terminal branches of the external carotid artery. The middle meningeal artery courses superficially along the sphenoid and temporal bones of the skull in order to supply blood to the meninges. The middle meningeal artery is clinically relevant because it is the primary artery injured in an epidural hematoma, leading to blood accumulation between the meninges and the skull. Answer E: The facial artery is also a branch of the external carotid artery and is responsible for supplying blood the structures of the superficial face, including the muscles of facial expression. The facial artery enters the face by passing anterior to the body of the mandible before ascending along the side of the nose towards the eye. The facial artery would be to anterior to be significantly affected during surgery to the temporomandibular joint. REFERENCE: Dhillon, Nripendra. "Chapter 1. Anatomy." CURRENT Diagnosis & Treatment in Otolaryngology—Head & Neck Surgery, 3e. Ed. Anil K. Lalwani. New York, NY: McGraw-Hill, 2012. LeBlond, Richard F., et al. "Chapter 7. The Head and Neck." DeGowin's Diagnostic Examination, 9e. Eds. Richard F. LeBlond, et al. New York, NY: McGraw-Hill, 2009.
Which vessels supply the buccal gingiva overlying tooth #3?
The gingival overlying the first (such as tooth #3), second, and third molars are supplied by gingival branches of the posterior superior alveolar nerve and vessels. The gingiva overlying the central incisors, lateral incisors, and canines are supplied by gingival branches of the anterior superior alveolar vessels (choice A). The gingiva overlying the premolars are supplied by the gingival branches of the middle superior alveolar vessels (choice B). Branches of the inferior alveolar vessels (choice D) supply the vestibular gingival of the mandibular incisors, canines, and premolars. The greater palatine vessels (choice E) supply the palate. REFERENCE: Liebgott B. (2001). The anatomical basis of dental anatomy (2nd ed). St. Louis, MO: Mosby, Inc
Triclosan is an effective antimicrobial agent which three types of pathogens?
Triclosan is an antimicrobial agent that has been found to be effective against gram-positive bacteria, gram-negative bacteria, and viruses. The efficacy against gram-positive bacteria and viruses has been found to be the excellent, and its effectiveness against gram-negative bacteria is deemed “good” because it does not include the full gram-negative spectrum. Triclosan speed of action is categorized as intermediate and it is usually acceptable for hand hygiene, though it’s acceptability varies. Triclosan is NOT effective against fungi or mycobacteria (a, b, c, e). REFERENCE: Miller, Palenik. Infection Control and Management of Hazardous Materials for the Dental Team, 4th Edition. Mosby, 2009. Chapter 10.
Which virus is associated with Forchheimer's sign?
Rubella. Rubella (German Measles) is a mild viral illness that is produced by a togavirus. Oral lesions, known as Forchheimer’s sign, have been reported to be present in about 20% of the cases. These consist of small, discrete, dark-red papules that develop on the soft palate and may extend onto the hard palate. This enanthem arises simultanesouly with the rash, becoming evident in about 6 hours after the first symptoms and not lasting longer than 12 to 14 hours. Palatal petechiae also may occur. REFERENCE: Neville BW, Damm DD, Allen CM, Bouquot JE. Oral & Maxillofacial Pathology. 2002. Saunders, Philadelphia, Pensylvania.
A patients X-rays revealed lesions located on the substantia nigra portion of his brain. Which of the following disease may this patient be diagnosed with?
The substantia nigra is a part of the brain structure that plays a role in movement, addiction, and reward. Usually patients with Parkinson’s disease will have lesions that are located in the substantia nigra and their dopaminergic neurons destroyed. REFERENCE: Costanzo, Linda. S. Physiology: Fifth Edition. Board Review Series. Copyright 2011
Which of the following molecules is primarily produced when glycogen is degraded?
Glycogen is mainly found in the liver and the skeletal muscle. It is primarily used during muscle contractions and as a source of energy for ATP. The synthesis of glycogen occurs in the cytosol and needs energy such as ATP and UTP (uridine triphosphate). Molecules of a-D-glucose are used to synthesize glycogen. The primary product that is produced when glycogen molecule is degraded is glucose 1-phosphate. This usually occurs when there is breakage of glycosidic bonds and free glucose is released. REFERENCE: Champe, Pamela, Harvey, Richard, and Ferrier, Denise. Lippincott’s Illustrated Reviews: Biochemistry 4th edition. Copyright 2008.
A heterotrimeric protein composed of three individual peptide chains describes:
Collagen (c) is an abundant human protein that in monomeric form assumes a left-handed, a-helical tertiary structure. Another way to describe this type of protein is a heterotrimeric protein composed of three individual peptide chains. When collagen monomers interact, they link to form a triple-stranded, right-handed super helical quaternary structure. Hemoglobin (a) is a tetrahedral group of two sets each of a-globin and ?-globin subunits, creating a quaternary structure. It is an oxygen transport protein. Myoglobin (b) is an oxygen storage protein, composed of loops connecting eight a-helices. Elastin (d) is an elastic protein found in connective tissue, and it mainly acts as cross-linked protein with monomers of the elastin molecule tropoelastin. REFERENCE: Baynes, John W. Medical Biochemistry, 3rd Edition. Mosby Ltd., 2009. Chapters 5 & 28.
At which location does glycogen synthesis usually occur?
Glycogen is mainly found in the liver and the skeletal muscle. It is primarily used during muscle contractions and as a source of energy for ATP. The synthesis of glycogen occurs in the cytosol and needs energy such as ATP and UTP (uridine triphosphate). Molecules of a-D-glucose are used to synthesize glycogen. REFERENCE: Champe, Pamela, Harvey, Richard, and Ferrier, Denise. Lippincott’s Illustrated Reviews: Biochemistry 4th edition. Copyright 2008.
The zona glomerulosa is responsible for:
The synthesis of aldosterone is carried out in the zona glomerulosa of the adrenal gland (b). This is the outermost of the three-layered cortex. The inner two layers of the adrenal cortex are the zona fasciculata and zona reticularis; these zones are responsible for the synthesis of cortisol (c), and adrenal androgens (a). The synthesis of ACTH or adrenocorticotropic hormone is done in the pituitary gland. This ACTH then acts on the adrenal glands to stimulate cortisol production by the zona fasciculata and zona reticularis. REFERENCE: Baynes, John W. Medical Biochemistry, 3rd Edition. Mosby Ltd., 2009. Chapter 17.
The greater palatine nerve block will anesthetize which of the following structurees?
Palatal gingiva/mucosa in area of maxillary 1st premolar (anteriorly) to the posterior portion of the hard palate to the midline. The greater palatine nerve is a division of the maxillary division of the trigeminal nerve. This nerve exits the greater palatine foramen and travels anteriorly in the hard palate to innervate the palatal gingiva/mucosa in area of maxillary 1st premolar (anteriorly) to the posterior portion of the hard palate to the midline. The greater palatine nerve does not innervate dentition. REFERENCE: Norton, NS. (2007). Netter’s Head and Neck Anatomy for Dentistry. Philadelphia, PA: Saunders.
What is the most common form of gingival disease?
Gingivitis that is associated with dental plaque formation is the most common form of gingival disease. Gingivitis has been previously characterized by the presence of clinical signs of inflammation that are confined to the gingiva and are associated with teeth showing no attachment loss. Gingivitis also has been observed to affect the gingival of periodontitis-affected teeth that have previously lost attachement but have not received periodontal therapy to stabilize any further attachment loss. REFERENCE: Newman MG, Takei HH, and Carranza FA. (2002). Carranza’s Clinical Periodontology (9th ed). Philadephia, PA: W.B. Saunders Company
Gram-positive bacteria change color when a Gram stain is used because:
Gram-positive bacteria change color to a purplish hue when a Gram stain is used. This is due to the trapping of stain in the thick, cross-linked peptidoglycan layer of the cell wall (b). The outer membrane of the bacteria (a) is not responsible for the color change after Gram staining. The counterstain safranin does NOT turn gram-positive bacteria red (c). It turns gram-negative bacteria red since they so not have a thick peptidoglycan layer to trap the crystal violet stain. The alcohol or acetone used in the third step of the Gram stain procedure removes any non-trapped crystal violet/iodine precipitate, in essence the purplish hue, from the first two steps of the Gram procedure (d). In gram-positive bacteria, the stain remains after this step because of the thick peptidoglycan layer. In gram-negative bacteria, this removes all of the Gram stain and allows the bacteria to be stained by the counterstain safranin. REFERENCE: Murray, Patrick R. Medical Microbiology, 6th Edition. Mosby, 122008. Chapter 2.
Which of the following systematic diseases is not associated with aphthous-like ulcerations?
Irritable bowel syndrome is not associated with apththous-like ulcerations. It is characterized by abdominal pain or discomfort and has no known organic cause. Inflammatory bowel disease, however, is associated with aphthous-like ulcerations. Behcet syndrome (Choice B) is a multisystem disorder that affects the oral cavity in almost all cases. The oral lesions are aphthous-like in appearance, but are often larger and more numerous than those found in healthy individuals. Aphthous-like ulcers are often seen in patients with celiac disease (Choice C). Celiac disease is caused by a reaction to gliadin, a protein found in wheat. IgA deficiency (Choice D) is associated with apthous-like ulcerations. Nutritional deficiencies (Choice E), such as iron, zinc, B1, B2, B6 and B12, are associated with aphthous-like ulcerations. REFERENCE: Neville, B. W. (2009). Oral and Maxillofacial Pathology (3rd Ed.). St. Louis, MO: Saunders, an imprint of Elsevier Inc
Which microscopic zone of necrotizing ulcerative gingivitis does the necrotic zone occur?
The light microscope and the electron microscope have been used to study the relationship of bacteria to the characteristic lesion of NUG. The four zones, which blend with each other and may not be all present in every case: -Zone 1 (choice A): Bacterial zone – the most superficial, consists of varied bacteria, including a few spirochetes of the small, medium, and large types. -Zone 2 (Choice B): Neutrophil-rich zone – contains numerous leukocytes , preponderantly neutrophils, with bacteria, including many spirochetes of various types, between the leukocytes. -Zone 3 (choice C): Necrotic zone – consists of disintegrated tissue cells, fibrillar material, remnants of collagen fibers, and numerous spirochetes of the medium and large types, with few other organisms. -Zone 4 (choice D): Zone of spirochetal infiltration – consists of well-preserved tissue infiltrated with medium and large spirochetes, without other organisms. There is no Zone 5 (choice E). REFERENCE: Newman MG, Takei HH, and Carranza FA. (2002). Carranza’s Clinical Periodontology (9th ed). Philadephia, PA: W.B. Saunders Company
The palatine bone of the mouth, separates the oral cavity from which body cavity?
The palatine bone is an important component of the oral cavity as it is the primary component forming the hard palate on the superior surface of the oral cavity. The palatine bone is important for the oral cavity as it differentiates the oral cavity from the nasal cavity. The palatine bone is not directly connected or involved with the temporomandibular joint. The nasal cavity is an air filled space that lies posterior to the nose and serves as the primary point of air entry into the body. The nasal cavity has numerous functions including cleaning inhaled air of pathogens and dust as well as serving as a drainage point for the paranasal sinuses. Answer A: The buccal space is a fascial space in the head and neck that serves as a potential space in the cheek. A potential space is an area that is not a distinct cavity on its own, but can serve as a conduit for the transmission of fluid or pathogens to different areas of the body. The buccas space is formed by the contours of the masseter muscle, the zygomatic process of the axilla, and the angle of the mouth. It is clinically relevant because a hemorrhage from oral surgery or dental abscess can drain into the buccal space leading to significant swelling and pain. Answer B: The submandibular space is another potential space of the head and neck that is found on the superficial aspect of the mylohyoid muscle. The space forms the region known as the submandibular triangle found in the anterior neck. This is space is clinically relevant because infections, particularly those from mandibular molar tooth abscesses can track within this space and can lead to Ludwig’s angina, pain, swelling, and erythema of the lower jaw and upper neck. Answer C: The mental space is potential space located bilaterally in the chin between the mentalis muscle and the platysma muscle. Along with many of the other spaces of the head and neck, it can be inflamed due to the presence of pus from an odontogenic infection such as a tooth abscess. The mental space is not involved in the formation of the hard palate. Answer E: The oropharynx is an important organ in the body that is part of the digestive system as well as serves as the conducting zone for the respiratory system. The oropharynx lies directly behind the oral cavity and connects with the esophagus after passing through the epiglottis. The pharynx contains many unique structures and muscles that serve to aid swallowing and propulsion of food towards the stomach, as well as other structures such as cilia and mucus secreting cells that serve to clean inhaled air. REFERENCE: Dhillon, Nripendra. "Chapter 1. Anatomy." CURRENT Diagnosis & Treatment in Otolaryngology—Head & Neck Surgery, 3e. Ed. Anil K. Lalwani. New York, NY: McGraw-Hill, 2012 Morton, David A., et al. "Chapter 24. Oral Cavity." The Big Picture: Gross Anatomy. Eds. David A. Morton, et al. New York, NY: McGraw-Hill, 2011.
The process that converts glucose-6-P to glycogen is known as:
Glycogenesis (d) is the formation of glycogen from glucose or glucose-6-P. Glycolysis (a) is the breakdown of glucose into ATP, carbon dioxide and water. Gluconeogenesis (b) is the production of glucose as a fuel for glycolysis via the metabolism of fatty acids in the absence of hepatic glycogen stores. Glycogenolysis (c) is the breakdown of glycogen to produce molecules of glucose for energy production. REFERENCE: Baynes, John W. Medical Biochemistry, 3rd Edition. Mosby Ltd., 2009. Chapter 13.
Which nerve is responsible for causing elevation of the soft palate during the swallowing process?
The vagus nerve (CN X) is an extremely important cranial nerve that serves as the primary parasympathetic innervation to most of the body as well as supplying important motor innervation to the soft palate. The vagus nerve also has motor components that control movement of the cricothyroid muscle, levator veli palatini, palatoglossus, palatopharyngeus muscle, and the superior/middle/inferior pharyngeal constrictors. These muscles are important for elevation of the soft palate during swallowing as well as the initiation of esophageal peristalsis. The vagus nerve provides parasympathetic fibers to all of the body’s vital organs from the neck all the way to the transverse colon. This means that the vagus nerve is the primary parasympathetic controller of the heart, lungs, pancreas, stomach, and bowel. Answer A: The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain. Answer B: The facial nerve (CN VII) is one of the twelve cranial nerves and is primarily responsible for controlling the muscles of facial expression. These muscles are principally located superficially on the face and the nerve does not control deeper muscles, such as those of the soft palate. In addition, the facial nerve also controls salivary excretion, tear formation, and also transmits taste sensation from the anterior two-thirds of the tongue. The facial nerve courses within the parotid gland and injuries to the parotid gland can often sever the nerve. This type of injury would often lead to ipsilateral facial paralysis. Answer C: The hypoglossal nerve (CN XII) is the primary motor nerve supplying the tongue. The nerve is the principal component in controlling tongue movements that are important for swallowing, speech, and food manipulation. The hypoglossal nerve is not involved in innervation of the muscles of the soft palate. The hypoglossal nerve is a purely motor nerve and does not have any sensory or autonomic function. Damage to the hypoglossal nerve leads to loss of motor function of the tongue and leads the tongue to be deviated towards the side of the lesion. Answer E: The glossopharyngeal nerve (CN IX) is a mixed sensory and motor cranial nerve that provides sensory, motor, and autonomic fibers to the oral cavity. The glossopharyngeal nerve courses from the jugular foramen in the base of the skull anteriorly to the oral cavity. The glossopharyngeal nerve provides general sensation to the pharynx, the middle ear, and the posterior one-third of the tongue. REFERENCE: Dhillon, Nripendra. "Chapter 1. Anatomy." CURRENT Diagnosis & Treatment in Otolaryngology—Head & Neck Surgery, 3e. Ed. Anil K. Lalwani. New York, NY: McGraw-Hill, 2012 Waxman, Stephen G. "Chapter 8. Cranial Nerves and Pathways." Clinical Neuroanatomy, 27e. Ed. Stephen G. Waxman. New York, NY: McGraw-Hill, 2013
Which of the following occlusal disharmony is the most damaging to the dentition?
Balancing side interference refers to any contact on the nonworking side. These interferences are damaging to the involved teeth. They can also cause joint pain, and damage muscles and ligaments on the working side. Premature tooth contact (Choice A), sometimes called “deflective” tooth contact, occurs when teeth come into contact before the jaw closes in CR position. Fremitus (Choice B) is the visible or palpable movement of a tooth that is subjected to normal occlusal forces. Fremitus is not necessarily indicative of an unhealthy condition. However, it may indicate a premature CR tooth contact or an interference during lateral excursions (in dentition lacking canine guidance). Crepitus (Choice D) is the crackling noise in the TMJ due to improper movement of the disc and condyle. Crepitus is not a rare occurrence. It is often left untreated unless it is accompanied by pain, trismus, locking of the jaw, or limited jaw opening. Mandibular deviation (Choice E) refers to the direction and movement of the mandible from the first tooth contact (a premature contact) as the jaw is guided from CR into CO. Deviation usually is directed forward and upward. Sometimes there is a lateral component. Small deviations are common and are often recorded as part of a periodontal/occlusal exam. REFERENCE: Woelfel, J.B., Scheid, R.C. (1997). Dental Anatomy: Its Relevance to Dentistry (5th Edition). Baltimore, MD. Williams & Wilkins. Nelson, S.J., Ash, M.M. (2010). Wheeler’s Dental Anatomy, Physiology, and Occlusion (9th Edition). St. Louis, MO. Saunders Elsevier.
The blood supply to the periodontal ligament (PDL) comes from the:
Maxillary artery The blood supply to the PDL arises from the maxillary artery and reaches the PDL via periosteal vessels, transalveolar vessels, and anastomosing vessels from the gingiva. The nerve fibers to the PDL arise from the trigeminal nerve (cranial nerve V), and provide sensory fibers responsible for pain, pressure, and proprioception.
What is the resting membrane potential of a cell that is in state of domancy?
The resting membrane potential of a cell that is inactive is -70 mV. This is usually measured by the diffusion potentials of ions that try to achieve equilibrium potential. REFERENCE: Costanzo, Linda. S. Physiology: Fifth Edition. Board Review Series. Copyright 2011
Which of the following mandibular premolars has a mesial groove, distal groove, and lingual groove on the occlusal surface?
(A) Mandibular first premolars generally have two cusps with mesial and distal grooves and often have a mesiolingual groove in the majority of cases but do not have a lingual groove. (B) Mandibular first premolar three-cusp type teeth do not exist. (C) Mandibular second premolar two-cusp type teeth have a single central groove that is U-shaped. (D) Mandibular second premolar three-cusp type teeth have a mesial, distal, and lingual groove. The groove pattern is Y-shaped and the lingual groove separates the mesiolingual cusp and distolingual cusp. (E) Mandibular second premolars with an H-shaped groove pattern are two-cusp type premolars where the grooves make an H-shaped pattern instead of a U-shaped pattern. REFERENCE: Woelfel's Dental Anatomy: Its Relevance to Dentistry 7th (seventh) Edition by Scheid DDS MEd, Rickne C. . Lippincott Williams & Wilkins. Pg. 221.
What is a common ingredient in soft drinks, gum candy, toothpaste, breath fresheners, dental floss that often causes contact stomatitis?
Flavoring. It is usually cinnamon flavoring that causes these reactions. Mucosal abnormalities secondary to the use of artificially flavored cinnamon products are fairly common, but the range of changes was not widely recognized until the late 1980’s. Cinnamon oil is used as a flavoring agent in confectionery, ice cream, soft drinks, alcoholic beverages, processed meats, gum, candy, toothpaste, breath fresheners, mouthwashes, and even dental floss. Concentrations of the flavoring are up to 100 times that in the natural spice. The reactions are documented most commonly in those products associated with prolonged or frequent contact, such as candy, chewing gum, and toothpaste. REFERENCE: Neville BW, Damm DD, Allen CM, Bouquot JE. Oral & Maxillofacial Pathology. 2002. Saunders, Philadelphia, Pensylvania.
Which of the following is not commonly associated with plaque-induced gingivitis?
The most common form of gingivitis is plaque-induced gingivitis. Common clinical findings in gingivitis include erythema (choice A), edema (choice B), tissue enlargement (choice C), and bleeding (choice E). Necrotic papilla is characteristic of necrotizing periodontal diseases such as acute necrotizing ulcerative gingivitis (ANUG). REFERENCE: Newman MG, Takei HH, and Carranza FA. (2002). Carranza’s Clinical Periodontology (9th ed). Philadephia, PA: W.B. Saunders Company
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