Darby's Comprehensive Review of Dental Hygiene, 9th Edition Chapter 02 PDF

**Blue: Darby\'s Comprehensive Review of Dental Hygiene, 9th Edition** **Chapter 02:** **Histology and Embryology** **Chapter Review - Answers and Rationales** **Darby Question Rationales** Case A Pediatric Questions 1-12 Rationales Rationale -- Question 1 A. Dentin has no nerve innervation....

**Blue: Darby\'s Comprehensive Review of Dental Hygiene, 9th Edition** **Chapter 02:** **Histology and Embryology** **Chapter Review - Answers and Rationales** **Darby Question Rationales** Case A Pediatric Questions 1-12 Rationales Rationale -- Question 1 A. Dentin has no nerve innervation. Nerves associated with dentin are located in the pulp. The pulp and the periodontal ligament have nerve innervation. B. Dentin has no nerve innervation. Nerves associated with dentin are located in the pulp. The pulp has nerve innervation. **C. The pulp and the periodontal ligament have nerve innervation.** D. Cementum has no nerve innervation. E. Cementum and dentin have no nerve innervation. Question 2 A. The free unmyelinated nerve endings of the pulp tissue cannot distinguish between hot or cold. All stimuli are interpreted as a pain perception. B. The free unmyelinated nerve endings of the pulp tissue cannot distinguish between hot or cold. All stimuli are interpreted as a pain perception. C. The free unmyelinated nerve endings of the pulp tissue cannot distinguish the sensation of pressure. All stimuli are interpreted as a pain perception. The encapsulated nerve endings are responsible for registering pressure changes. **D. The free unmyelinated nerve endings of the pulp tissue can sense pain only. It cannot distinguish between hot or cold. It cannot distinguish the sensation of pressure. All stimuli are interpreted as a pain perception. The encapsulated nerve endings are responsible for registering pressure changes** E. The free unmyelinated nerve endings of pulp tissue can sense pain only. It cannot distinguish between hot or cold. It cannot distinguish the sensation of pressure. All stimuli are interpreted as a pain perception. The encapsulated nerve endings are responsible for registering pressure changes. Question 3 A. The permanent molars develop from the extension of the dental lamina B. The permanent molars are nonsuccedaneous and have no primary predecessors C. The permanent molars develop from the extension of the dental lamina **D. Six permanent molars per dental arch develop from a posterior extension of the dental lamina** Question 4 A. Inner enamel epithelial cells give rise to ameloblasts. B. Inner enamel epithelial cells give rise to ameloblasts. **C. The enamel matrix is directly secreted from Tomes process** D. Inner enamel epithelial cells give rise to ameloblasts. Question 5 A. The pink labial mucosa or buccal mucosa meets the redder alveolar mucosa at the mucobuccal fold deep with the vestibular fornix. B. The pink labial mucosa or buccal mucosa meets the redder alveolar mucosa at the mucobuccal fold deep with the vestibular fornix. **C. The pink labial mucosa or buccal mucosa meets the redder alveolar mucosa at the mucobuccal fold deep with the vestibular fornix.** Question 6 A. Inner cells become the pulp B. Preamelobalsts become amelobalsts, secreting enamel **C. Outer cells differentiate into dentin-secreting cells, odontoblasts** D. Cementoblasts secrete cementum Question 7 **A. The eleventh and twelfth week of prenatal development is the fourth stage of** **Odontogenesis the Bell Stage** B. The Initiation Stage is the first stage of odontogenesis C. The ninth and tenth week of prenatal development is the third stage of Odontogenesis the Cap Stage D. The eighth week of prenatal development is the second stage of odontogenesis Is the Bud Stage Question 8 A. Outer linings of the body are derived from Ectoderm during prenatal development B. Internal linings of the body are derived from endoderm during prenatal development C. Peripheral nervous system is derived from the neural crest cells during prenatal development **D.** **Connective tissue is derived from Mesoderm during prenatal development** Question 9 A. Structural unit of dentin B. Structural unit of cells **C. Structural unit of Enamel** D. Structural unit of nails Question 10 A. Interglobular dentin is located in the crown. It is composed of uncalcified spots, which are irregular shapes located a short distance from the dentino-cemental junction. Interglobular dentin is believed to occur from a metabolic disturbance. **B. Bacteria smaller than dentinal tubules enter the tubules and destroy the odontoblastic processes (dentinal fibers) and follow the course to pulp.** C. **Secondary dentin** is dentin formed after the completion of the apical foramen. D. Predentin is located close to the pulp. It is the latest layer of dentin to be formed, and it is composed of newly formed organic matrix that has not been mineralized. Question 11 -------- -------------------------------------------------------- A. an increased number of ameloblasts **B.** **reduction in the quantity of enamel matrix** C. grooves and pitting on the enamel surface D. interference in the metabolic processes of ameloblasts -------- -------------------------------------------------------- Question 12 ------------------------------------------------------------------------------------------------------------------------------- **A. Branchial arch 1 forms two lateral swellings and one medial swelling (tuberculum impar) to form the body of the tongue** B. Branchial arches 2, 3, and part of 4 form the copula to from the base of the tongue C. Branchial arch 4 is the site where the epiglottis is formed D. Thyroid gland develops from an invagination of ectoderm in the area of the foramen cecum of the tongue. ------------------------------------------------------------------------------------------------------------------------------- **Case B Adolescent Rationales 13- 25** Question 13 A. Gingiva contains circular fiber or circumferential fibers that envelop each tooth separately within the free gingiva. B. Attached gingiva is composed of orthokeratinized stratified squamous epithelium. Epithelium is not vascularized and depends on the underlying connective tissue for nourishment; the epithelium interfaces with underlying connective tissue to enhance this nourishment. Epithelial extensions into connective tissue are called ridges or rete pegs. This rete peg arrangement produces the clinical appearance of stippling. C. The epithelium interfaces with underlying connective tissue to enhance nourishment. Connective tissue papillae are the connective tissue extensions into overlying epithelium. D. Fibroblasts are present in gingival connective tissue; they produce various types of fibers and synthesize intercellular ground substance. **E. Correct answer is All of the above; therefore, see rationales for A, B, C, and D combined.** Question 14 **A. Attached gingiva is composed of keratinized (orthokeratinized) stratified squamous epithelium.** B. Attached gingiva is composed of keratinized (orthokeratinized) stratified squamous epithelium; nonkeratinized stratified squamous epithelium is found in the lining mucosa of the oral cavity---lips, cheeks, floor of mouth, soft palate, alveolar mucosa, and ventral surface (underside) of tongue. C. Attached gingiva is composed of keratinized (orthokeratinized) stratified squamous epithelium; keratinized simple squamous epithelium is not found in the oral cavity. D. Attached gingiva is composed of keratinized (orthokeratinized) stratified squamous epithelium; pseudostratified columnar epithelium is not found in the oral cavity; pseudostratified columnar epithelium is found in the respiratory tract. E. Attached gingiva is composed of keratinized (orthokeratinized) stratified squamous epithelium; nonkeratinized simple squamous epithelium is not found in the oral cavity. Question 15 A. The palatine process is not associated with lip formation. **B. Cleft lip occurs when the maxillary process fails to fuse with the globular process. The maxillary process forms the sides of the lip, and the globular process (medial nasal process) forms the center or philtrum of the lip. A cleft lip can occur on one side (e.g., the right maxillary process fails to fuse with the globular process), or on both sides (e.g., the right and left maxillary processes fail to fuse with the globular process).** C. The lateral nasal process is not associated with lip formation. D. The mandibular process is not associated with lip formation. E. The globular process (medial nasal process) is between the right and left maxillary processes. The right and left maxillary processes do not fuse with each other. Question 16 A. The stomodeum is the primitive mouth. **B. The first branchial arch gives rise to a large portion of the face and the intraoral structures. The mandible is derived from the first branchial arch.** C. The lower border of the frontal process gives rise to the nasal processes. D. The second and third branchial arches play a role in tongue development. Question 17 A. The second branchial arch does not give rise to the anterior portion of the tongue. It is associated with the formation of the posterior or base of the tongue. B. The maxillary process is not associated with tongue development. **C. The mandibular process gives rise to the body of the tongue. Maxillary processes arise from the superolateral border of the first branchial arch. Once this occurs, the rest of the first branchial arch is referred to as the *mandibular process*. From the mandibular process (first branchial arch), two lateral swellings and one medial swelling (tuberculum impar) merge to form the body of the tongue.** D. The globular process (medial nasal process) does not give rise to the anterior portion of the tongue. E. Rathke's pouch is not associated with tongue development. Question 18 **A. The nasal septum is a vertical groove on the midline of the upper lip** B. The submandibular can also be palpated, but not in the midline of the neck. C. On each side of the nose, inferior to the apex is a nostril. D. The parotid salivary gland is not in the midline. Question 19 A. Continuous replacement of cells is not a characteristic of simple squamous epithelium. **B. Continuous replace of cells is a characteristic of stratified squamous epithelium. The cells of the basal layer constantly under mitosis, and the surface cells slough off as new cells move to the surface.** C. Continuous replacement of cells is not a characteristic of pseudo-stratified columnar tissue. D. Continuous replacement of cells is not a characteristic of stratified transitional epithelium. Question 20 A. The first and second premolars are components of the same lateral palatine process; therefore, there are no lines of fusion between them. B. The central incisors arise from the same premaxillary process; therefore, there are no lines of fusion between them. **C. A cleft of the alveolar ridge results from the lack of fusion of the premaxilla, which forms the anterior portion of the palate and gives rise to the maxillary incisors, and of the lateral palatine processes (palatal shelves), which give rise to the posterior two thirds of the hard palate and contain the maxillary canines and posterior teeth. The lines of fusion, therefore, fall between the laterals and the canine teeth.** D. The canine and the first premolar are both components of the same lateral palatine process; therefore, there are no lines of fusion between them. Question 21 A. Primary teeth is a child's first set of teeth B. Secondary dentition is adult teeth C. Tertiary is a term to describe reparative dentin **D. A mixed dentition is one with primary and secondary teeth** Question 22 A. Cells within interphase engage in growth, metabolism, organelle replacement, and substance production, including chromatin and centrosome replication. **B. within interphase engage in growth, metabolism, organelle replacement, and substance production, including chromatin and centrosome replication.** C. within interphase engage in growth, metabolism, organelle replacement, and substance production, including chromatin and centrosome replication. D. within interphase engage in growth, metabolism, organelle replacement, and substance production, including chromatin and centrosome replication. Question 23 **A. Facial skeleton is derived from Meckel's cartilage** B. Neck Skeleton forms the hyoid bone C. Connective tissue components D. Tooth development Question 24 A. 22, 45 incorrect haploid and diploid numbers B. 21, 44 incorrect haploid and diploid numbers C. 20, 43 incorrect haploid and diploid numbers **D. 23, 46 haploid and diploid numbers** Question 25 **A.** **Each tooth is the product of Epithelium, Ectomesenchyme** B. Each tooth is the product of Epithelium, Ectomesenchyme C. Each tooth is the product of Epithelium, Ectomesenchyme D. Each tooth is the product of Epithelium, Ectomesenchyme **Case C ~~Adolescent~~ Rationales 26 - 38** Question 26 A. Nonkeratinized simple squamous epithelium B. Keratinized simple squamous epithelium C. Orthokeratinized stratified squamous epithelium D. Pseudostratified columnar epithelium E. Nonkeratinized stratified squamous epithelium Question 27 A. Loose connective tissue **B. Dense connective tissue** C. Mixed connective tissue D**.** Cannot be determined Question 28 **A. Attached gingiva** B. Sulcular epithelium C. Alveolar mucosa D**.** Soft palate Question 29 A. gingiva - The outer surface of the free gingiva, the papillae and the attached gingiva function mainly as protective tissues and the epithelium is mainly keratinized.  Therefore, the description of the tissue on the outer surface of the free gingiva, the papillae and the attached gingiva is stratified squamous keratinized epithelium. The inner surface of the free gingival margin extending apically (sulcus) is nonkeratinized.  Therefore, the sulcular epithelium is described as stratified squamous. The gingival connective tissue consists of a dense network of collagen fibers.  Collagen fibers function to provide firmness to the gingiva and to attach the gingiva to the underlying cementum and alveolar bone.  The connective tissue of the gingiva is also rich in blood, lymphatic vessels, nerves, and many cells specific to inflammation and vascularity **B. crown is not a supporting structure of the periodontium, it is an anatomical structure of the tooth** C. periodontal ligament is a supporting structure of the periodontium D. alveolar bone is a supporting structure of the periodontium Question 30 **A. enamel is the substance that covers the anatomic crown of the tooth, it is the hardest substance in the body. It is created by cells known as ameloblasts.** B. lymphatic tissues are present in the connective tissue of the gingiva and is also rich in blood, nerves, and many cells specific to inflammation and vascularity. C. collagen fibers function to provide firmness to the gingiva and to attach the gingiva to the underlying cementum and alveolar bone.  The connective tissue of the gingiva is also rich in blood, lymphatic vessels, nerves, and many cells specific to inflammation and vascularity. D. blood cells are present in the connective tissue of the gingiva and is also rich in lymphatic vessels, nerves, and many cells specific to inflammation and vascularity. Question 31 A. periodontal ligament **B. free gingiva surrounds the tooth and creates a cuff or collar of gingiva** C. attached gingiva extends apically from the free gingiva to eventually merge with the alveolar mucosa D. oral mucosa eventually merge with the alveolar mucosa. The attached gingiva is firmly bound to the underlying cementum and bone with collagen fibers of the connective tissue Question 32 A. loosely attached gingiva measuring \>3 mm indicates an unhealthy periodontium **B. firm attached gingiva is healthy gingiva and will have a snug, firm attachment to the underlying supporting structures. The gingival margin follows a scalloped-like course across the dentition due to the interdental papillae, which fill the interdental spaces beneath the tooth contacts** C. purple colored gingiva as opposed to healthy gingiva will appear coral pink in color (with the exception of normal pigmentation seen in dark-skinned individuals) indicating a lack of inflammation (inflammation would indicate unhealthy gingiva). D. inflamed gingiva is influenced by many local factors.  Some specific local factors are plaque, bacteria and calculus.  These local factors, in part, contribute to the gingiva\'s inflammatory response.  Proper oral hygiene can control many of these local factors so that the disease process is never initiated or is reversed in cases where initiation has taken place Questions 33 A. the smaller the tooth the larger the papilla B. the larger the tooth the smaller the papilla C. the larger the tooth the larger the papilla **D. tooth size does not relate to papilla size** Question 34 A. Spongy bone is between the cortical plates **B. Cortical plates make up the inner and outer dense surfaces of the alveolar bone** C. Cementum is the substance that covers the root of the tooth. It is very thin and not as hard as the enamel but has a similar hardness to bone. Cells known as cementoblasts from cementum D. Oblique fibers are periodontal fibers, these fibers allow for movement of the tooth Question 35 A. Trabecular bone is between the cortical plates B. Dentin is not as hard as enamel, but it makes up the major portion of the tooth. It is created by cells known as odontoblasts. **C.** **Lamina Dura is a thin dense bone where the periodontal ligament is attached** D. Cancellous bone is between the cortical plates Question 36 **A. Periodontal fibers attach the root of the tooth to the cementum and bone. a series of periodontal fibers that make up the periodontal ligament and allow for minor movement of the tooth in the socket without damage to the tooth or the underlying structures.  These fibers are classified apical, oblique, horizontal, alveolar crest and interradicular fibers.** B. Attached gingiva is a part of keratinized gingiva which aids in Increase resistance to external injury and contribute in stabilization of gingival margin. C. Cementum is the substance that covers the root of the tooth. It is very thin and not as hard as the enamel but has a similar hardness to bone. Cells known as cementoblasts from cementum. D. Interradicular bone is alveolar bone that forms sockets around multirooted teeth Question 37 A. Molars are the most posterior teeth in the mouth. There are 12 molars in the permanent dentition and eight in the primary dentition. B. Lateral Incisors are present in both dentitions. One is present in each quadrant. C. Central Incisors are present in both dentitions. One is present in each quadrant. D. **Premolars are not present in the primary dentition. There are eight premolars in the permanent dentition.** Question 38 A. Cementum is the substance that covers the root of the tooth. It is very thin and not as hard as the enamel but has a similar hardness to bone. Cells known as cementoblasts from cementum. B. **Enamel** **is the substance that covers the anatomic crown of the tooth, it is the hardest substance in the body. It is created by cells known as ameloblasts.** C. Dentin is not as hard as enamel, but it makes up the major portion of the tooth. It is created by cells known as odontoblasts. D. Dentinal Tubules are microscopic tubes in dentin. Case D **Geriatric Rationales 38 - 50** Question 39 **A. Cells are attached to other cells by a desmosome attachment.** B. Cells attach to noncellular surfaces by a hemidesmosome attachment. C. A gap junction is the attachment mechanism that contains a channel between the two adjoining cells. This type of attachment is not found in the basal layer of stratified squamous epithelium. It is more commonly found in muscle tissue. D. A tight junction is when the two adjoining cells have fused cell membranes that limit movement. This type of attachment is not found in the basal layer of stratified squamous epithelium. It is more commonly found in some duct tissue. Question 40 A. Endosteum is a thinner, more delicate connective tissue membrane that covers the inner surface of compact bone, trabeculae, and lines Haversian canals and Volkmann's canals. It does not cover bundle bone. Bundle bone is bone adjacent to the periodontal ligament. B. Bundle bone is bone adjacent to the periodontal ligament, but the bundle bone is localized within the alveolar bone proper. It is not adjacent to the fat marrow. C. Bundle bone is located within the alveolar bone proper. It is not adjacent to the fat marrow and does not contain one end of the Sharpey's fibers. **D. Bundle bone is adjacent to the periodontal ligament. It contains one end of the Sharpey's fibers.** Question 41 A. Osteocytes are found in the lacuna of bone. These cells are entrapped osteoblasts. The cells in the resorption areas of Howship's lacuna are osteoclasts. **B. Howship's lacunae are found in areas of resorbed bone. The bone-resorbing cells (osteoclasts) are found in these hollowed out depressions that the osteoclasts created.** C. Cementocytes are found in the lacuna of cementum. D. Cementoclasts are cementum-resorbing cells. The cells in the resorption areas of Howship's lacuna are osteoclasts, bone-resorbing cells. Question 42 A. Lamellae are closely apposed sheets of bone tissue in compact bone. Enamel lamellae are faults or cracks in the enamel filled with organic material. They are partially calcified vertical sheets of enamel matrix. **B. The space occupied by a cementocyte is called a lacuna, meaning "little space."** C. Canaliculi are the canals that house the cytoplasmic extensions of osteocytes. D. A cementicle is a calcified body of cementum found within the periodontal ligament space. Question 43 A. Both cellular cementum and bone contain cells. **B. Cementum is different from bone in that cementum contains no blood vessels; bone is a vascular tissue.** C. Both cementum and bone have similar organic to inorganic composition. D. Cementum does not resorb more readily than bone. Because of the presence of the outer less-calcified layer of cementoid tissue covering the cemental surface, bone resorbs more readily than cementum. Question 44 A. Cellular cementum is the portion of cementum that contains cementocytes and is capable of remodeling itself. B. Acellular cementum is the portion of cementum that does not contain cementocytes and is not capable of remodeling itself. **C. Cementoid is the outer less-calcified layer of cemental tissue. It is the layer of organic matrix that was most recently laid down. This cementoid layer results in cementum resorbing less readily than bone.** D. Cementicles are the calcified bodies of cementum found in the periodontal ligament space. Question 45 A. Enamel pearls are spherical enamel formations on the root surface that are thought to result from the differentiation of Hertwig\'s epithelial root sheath cells into ameloblasts. B. Denticles are calcified bodies found within the pulp chamber. **C. The Rests of Malassez are remnants of Hertwig's epithelial root sheath that remain in the periodontal ligament space following root formation. They are the source of cyst formation.** D. Cementicles are calcified bodies of cementum found in the periodontal ligament space. Question 46 **A. It is this inorganic substance in a crystalline formation of mainly calcium hydroxyapatite that gives bone its hardness** B. Bone matrix is initially formed as osteoid, which later undergoes mineralization. C. Mature bone contains osteocytes, which are entrapped mature osteoblasts, contain a cell body which is surrounded by mature bone. D. The cytoplasmic processes of the osteocyte radiate outward in all directions in the bone and are located in tubular canals of matrix, or canaliculi. Question 47 A. The Osteoblast are bone forming cells B. The Cementoblasts are cementum forming cells C. The Odontoblasts are dentin producing cells D. **The Fibroblasts of the periodontal ligament is responsible for the production of the fibrous matrix and ground substance; they build and produce new fibers which remodel existing fibers.** **Question 48** **A. dental follicle is the tooth germ and three embryological structures the enamel organ, dental papilla, and dental sac** B. Herwig's epithelial root sheath function to shape the root by inducing dentin formation C. stratum intermedium supports future production of enamel D. central cells of dental papilla produce future dentin and pulp for the inner part of the tooth Question 49 A. Tonsils are drained by the upper deep cervical nodes B. Base of the tongue is drained by the upper deep cervical nodes C. Third Molars are drained by the upper deep cervical nodes **D. Soft Palate is drained by the retropharyngeal nodes** Question 50 **A. Increased collagen fibers are present as teeth age** **B. True denticles are small calcified bodies formed during tooth development** **C. False denticles form when components of the pulp start to degenerate** **D. Diffuse calcifications occur in diseased pulp**