Embryology and Histology: Dental 2024-2025 Questions and Answers, Exams of Nursing

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Embryology And Histology

Dental 2024-2025. Questions

& Correct Answers. Graded A+

___________ is the term used to refer to a developmental anomaly characterized by teeth that are smaller than normal. - ANSMesiodens A mesiodens is a supernumerary (extra) maxillary central incisor located in the midline. Succedaneous teeth include all of the permanent teeth except the molars ___________ is the term used to refer to dentin formed by odontoblasts before the formation of the apical foramen. - ANSPrimary dentin Primary dentin accounts for the vast majority of dentin in the tooth and is the most abundant material of the tooth overall. Primary dentin is formed first and the dentin formed before apex formation. ___________ is the term used to refer to primitive oral cavity found in the embryo.

• ANSStomodeum The stomodeum arises from the rupture of the oropharyngeal membrane during the fourth week of development. As a result of periodontal disease, the patient's "gums" have receded apically, making the tooth appear much longer. What will be longest, if measured? - ANSClinical crown The more that the gums recede apically, the longer the clinical crown will appear. The length of the anatomic crown will not be affected by changes in gum position. There is no such thing

as a clinical root. The _________ stage of tooth development is characterized by specialization of the cells of the enamel organ (into ameloblasts) and dental papilla (into odontoblasts). - ANSBell The bell stage is characterized by specialization of the cells of the enamel organ (into ameloblasts) and dental papilla (into odontoblasts). This is in preparation for the appositional stage when these specialized cells lay down organic tooth matrix. The ________________ is the embryonic layer responsible for dentin formation. - ANSMesoderm The mesodem gives rise to the dental papilla that forms both dentin and pulp. Ectodermal cells form the enamel organ and are responsible for enamel formation. Endodermal cells form the digestive system. The periodontal ligament (PDL) is classified into groups by the structures to which the fibers of the PDL extend. - ANSTrue The PDL consists of numerous groups of fibers, including the periodontal fiber group (extending from alveolar bone to cementum), the transseptal fiber group (extending between adjacent teeth above the crest of the bone), and the gingival fiber group (extending from the cementum into the gingival tissues). The term that means "associated with the root of the tooth" is: - ANSRadicular The term radicular is used to indicate that a structure has something to do with the root of the tooth. Radicular dentin, for example, is dentin located in the root of the tooth. Coronal

dentin, on the other hand, is dentin located in the crown of the tooth. The term used to describe projections of the dentin- forming cells that extend from the enamel into the pulp is: - ANSOdontoblastic processes Odontoblasts lay down dentin matrix starting at the future dentinoenamel junction of the tooth before receding inward toward the pulp. In doing so, they leave a cellular projection known as an odontoblastic process in each newly formed dentinal tubule. The upper lip and philtrum forms at the junction of the following structures... - ANSMaxillary processes Medial nasal processes The philtrum is a midline depression of the upper lip formed by the right and left medial nasal processes. The upper lip is formed when the right and left maxillary processes fuse with the philtrum bilaterally. Failure of these structures to fuse results in a cleft lip. What is the result when odontoblasts stray past the DEJ? - ANSEnamel spindles Enamel spindles can be seen under high magnification as extensions of odontoblasts that stray over the junction between enamel and dentin. What is the term given to embryonic structures that are the origin of the sense organs? - ANSPlacodes The placodes (otic, nasal, and lens) are the earliest sites for the development of the sense organs on the embryo. Which embryonic structure gives rise to the primary palate? - ANSIntermaxillary segment The intermaxillary segment, which forms the primary palate, develops from the

medial nasal processes, which also form the nose. The primary palate fuses with the secondary palate to form the hard palate. Which of the following components of the tooth is the least mineralized? - ANSCementum Enamel is the most mineralized tooth substance at 96%. Dentin is about 70% mineral, and cementum is the softest and least mineralized at about 65%. Which structure of the tooth germ gives rise to the cementum?

• ANSDental sac Cementoblasts form from cells of the dental sac that line the newly formed root dentin beyond the end of the enamel organ. Which term is used to describe a congenitally missing tooth? - ANSAnodontia Anodontia refers to congenitally missing teeth. These are often third molars, maxillary lateral incisors or 2nd premolars. Supernumerary teeth are extra teeth, and microdontial and macrodontia are anomalies of tooth size. Which type of cell produces dentin? - ANSOdontoblast Odontoblasts are dentin-producing cells that line the pulp and continue producing dentin throughout life. Odontoclast cells resorb tooth structure in preparation for exfoliation. Ameloblasts form enamel, and cementoblasts form cementum.