DADH

DADH The fibers which continue bone to ligament are A.Sharpeys fibers B. Tomes fibersC.Ray fibers D.All of the above

.Ans: A. Sharpeys fibres Ref: Orbans Oral Histology, 12/E, p. 172Explanation: Sharpeys Fibres Collagen fibres are embedded into cementum on one side of the periodontal space and into alveolar bone on the other. These embedded fibres are termed as Sharpeys fibres Sharpeys fibres in the primary acellular cementum is completely mineralized but those in the cellular cementum and bone are partially mineralized Few Sharpeys fibres pass uninterrupted through the bone of the alveolar process and continue as principal fibres of the adjacent periodontal ligament. They are termed as Transalveolar fibres These fibres pass through bone only when alveolar process consists of compact bone entirely without Haversian systems The embedded Sharpeys fibres calcify to a certain degree and they are associated with non collagenous proteins like osteopontin and bone sialoprotein They are derived from dental follicle

Tooth eruption is due to A.Osteoclastic activity B. Proliferation of cells at crypt C.Exfoliation of primary tooth D.Eruptive forcesAns: D. Eruptive forces Ref: Orbans Oral Histology, 12/E, p. 288Explanation: Tooth eruption is the axial or occlusal movement of the tooth from its developmental position within the jaw to its functional position in the occlusal position. Eruptive force is responsible for the eruption of tooth. Eruptive force is derived from bone remodeling, root growth, vascular pressure, ligament traction. There is a good deal of evidence that the eruptive force resides in the dental follicleperiodontal ligament complex. Disturbances during calcification of dentin causes A.Cementicles B. Dentin dysplasia C.Interglobular dentin D.NoneAns: C. Interglobular dentin Ref: Orbans Oral Histology, 12/E, p. 93Explanation: Interglobular Dentin Interglobular dentin is the area of unmineralized or hypomineralised dentin which persists within the normally mineralized dentin Sometimes mineralization of dentin begins in small globular areas that fail to fuse resulting in the formation of irregular areas of hypocalcified matrix called Interglobular dentin It is found along the incremental lines especially in the crown of teeth in the Circumpulpal dentin Dentinal tubules pass without deviation through interglobular areas Peritubular dentin are absent from dentinal tubules passing through interglobular dentin as interglobular dentin remains uncalcified In dry ground sections a small amount of interglobular dentin may be lost and a space results which appears black in transmitted light. Hence it as also called interglobular space or globular dentin. This layer shows a high amount of sulphur It is frequently seen in vitamin D deficiency or exposure to high level of fluoride during Dentinogenesis. Cementicles Cementicles are round lamellated cemental bodies that lie free in the periodontal ligament space Found along the root and more common in aged persons Dentin Dysplasia Rootless teethTypes 1. Radicular Both dentitions are affected Normal eruption pattern Complete obliteration of pulp chambers deciduous teeth Crescent shaped pulpal remnants permanent teeth Show lava flowing around the boulders 2. Coronal Clinical appearance is normal for permanent teeth Blue gray opalescent appearance for deciduous teeth Obliteration of pulp chambers deciduous teeth Large pulp chamberspermanent teeth thistle tube in shape

Ankylosis is due to deposition of A.Bone B. Cementum C.Bone and Cementum D.DentinAns: A. Bone Ref: Orbans Oral Histology, 12/E, p. 158Explanation: Fusion of cementum and alveolar bone with obliteration of periodontal ligament is termed as Ankylosis It may develop after chronic periapical inflammation, tooth replantation, occlusal trauma, and around embedded teeth Ankylosis results in resorption of root and its gradual replacement by bone tissue As the periodontal ligament is replaced by bone, proprioception is lost It may be seen in case of gingival recession and loss of attachment The cementum become permeable to organic substances, inorganic ions and bacteria Cemental caries can develop The layer present on tooth immediately after eruption of teeth A.Primary cuticle B. Secondary cuticleC.Operculum D.Enamel cuticleAns: D. Enamel cuticle Ref: Orbans Oral Histology, 12/E, p. 54Explanation: Enamel Cuticle/Nasmyths Membrane/Primary Cuticle A non mineralized electron dense structure less membrane seen on the crown of the tooth, adhering firmly to its surface It is formed by an accumulation of basal lamina material produced by the junctional epithelium of the dentogingival junction It is mostly seen in newly erupted teeth and is lost due to mastication It is about 0.5 1.5 mm thick Enamel cuticle is made of 2 cuticles Primary cuticle Secondary cuticle Primary Enamel Cuticle is the last product of the enamel forming ameloblasts and it becomes mineralized Secondary Enamel Cuticle: It covers the primary cuticle and is a product of the reduced enamel epithelium and is not mineralized. It is also known as Dental cuticle and it is structurally described as basal lamina PDL around mandibular canine is thinned in old patients due to A.Deposition of cementum B. Deposition of cementum & bone C.Deposition of bone only D.Deposition of dentinAns: A. Deposition of cementum Ref: Orbans Oral Histology, 12/E, p. 148Explanation: Cementum is known to form throughout life and thus it leads to the decrease in the width of the periodontal ligament space around the teeth.Odontoblasts are derived from A.Undifferentiated mesenchymal cells B. HistocytesC.Macrophages D.LymphocytesAns: A. Undifferentiated mesenchymal cells Ref: Orbans Oral Histology, 12/E, p. 35Explanation: Undifferentiated mesenchymal cells are the primary cells in pulp which differentiate to become odontoblasts, fibroblasts or macrophages when need arises. Odontoblasts are present next to predentin layer, derived from ectomesenchymal cells and are known to produce dentin matrix. Blood supply of PDL is through A.Net like vessels near the cementum B. Net like vessels near the boneC.The vessels which do not anastamose with capillaries in sulcus area D.The vessels which comes from the Apical ForamenAns: B. Net like vessels near the bone Ref: Orbans Oral Histology, 12/E, p. 175Explanation: The arterioles and capillaries of the microcirculation ramify in the periodontal ligament, forming a rich network of arcades that is more evident in the half of the PDL space adjacent to bone than that adjacent to cementum. Blood supply of PDL is through A.Net like vessels near the cementum B. Net like vessels near the boneC.The vessels which do not anastamose with capillaries in sulcus area D.The vessels which comes from the Apical ForamenAns: B. Net like vessels near the bone Ref: Orbans Oral Histology, 12/E, p. 175Explanation: The arterioles and capillaries of the microcirculation ramify in the periodontal ligament, forming a rich network of arcades that is more evident in the half of the PDL space adjacent to bone than that adjacent to cementum Main function of Pulp is A.Dentin formation B. Nutrition C.Sensory D.Enamel formationAns: A. Dentin formation Ref: Orbans Oral Histology, 12/E, p. 126Explanation: The primary function of pulp is to interact with epithelial cells, which leads to differentiation of dental lamina cells and thus induce differentiation of odontoblast in order to form dentin.. Where does the mandibular permanent tooth bud lie in relation to deciduous tooth A.Superiorly and Lingually B. Superiorly and Buccally C.Interiorly and Buccally D.Inferiorly and LinguallyAns: D. Inferiorly and Lingually Ref: Orbans Oral Histology, 12/E, p. 294Explanation: Mandibular permanent tooth lies inferiorly and lingually in relation to deciduous tooth. Permanent mandibular incisors usually do not move to the apical position and thus erupts lingually to the still functioning deciduous tooth. Bifurcated roots are most common in the following A.Maxillary Canine B. Mandibular CanineC.Mandibular Incisor D.Maxillary IncisorAns: B. Mandibular Canine Ref: Wheelers Dental Anatomy, 8/E, p. 209Explanation: Mandibular canine shows the cusp tip in line with the center of the root, from mesial or distal aspect, sometimes may become lingual. A variation in the form of mandibular canine which is not uncommon is bifurcated root. If the pulp of a single rooted canal is triangular in cross section with the base of the triangle located facially and apex located lingually with the Mesial arm longer than the distal, the tooth is most likely A.Maxillary Central Incisor B. Maxillary Lateral Incisor C.Maxillary Canine D.Mandibular Central IncisorAns: A. Mandibular Central Incisor Ref: Wheelers Dental Anatomy, 8/E, p. 341Explanation: Maxillary central incisor has the pulp of a single rooted canal is triangular in cross section with the base of the triangle located facially and apex located lingually with the Mesial arm longer than the distal. All other teeth in the given option show oval or round or elliptical shape of root in cross section.

Dystrophic calcification is seen most commonly in which of the following oral tissues A.Enamel B. Pulp C.Dentin D.Periodontal ligamentAns: B. Pulp Ref: Orbans Oral Histology, 12/E, p. 129Explanation: Diffuse calcifications are classified as dystrophic calcifications, surround blood vessels and arefound most commonly in root canals. These are the calcific deposits in the pulp tissue following the collagenous bundles or blood vessels..26. Non-Keratinized epithelium is found over A.Attached gingiva B. Free gingiva C.Interdental papillae D.Gingival sulcusAns: D. Gingival sulcus Ref: Orbans Oral Histology, 12/E, p. 240 Explanation: Gingival sulcus is lined by non keratinized stratified squamous epithelium. It lacks epithelial ridges and forms a smooth interface with the lamina propria Anatomic form of roots of teeth is determined by A.Hertwigs sheath B. Periodontal ligament C.Hammock ligament D.Dental lamina.Ans: A. Hertwigs sheath Ref: Orbans Oral Histology, 12/E, p. 30Explanation: The enamel organ plays an important role in root development by forming Hertwigs epithelial root sheath, which molds the shape of the root and initiates radicular dentin formation. It consists of outer and inner enamel epithelium The last primary tooth to be replaced by a permanent successor is A.Maxillary canine B. Mandibular canine C.Maxillary 1st molar D.Mandibular 2nd molarAns: A. Maxillary canine Ref: Wheelers, 8/E, p. 32Explanation: Order of Eruption Deciduous Dentition 1. Mandibular central incisor 2. Mandibular lateral incisor 3. Maxillary central incisor 4. Maxillary lateral incisor 5. Mandibular first molar 6. Maxillary first molar 7. Mandibular canine 8. Maxillary canine 9. Mandibular second molar 10. Maxillary second molarPermanent Dentition 1. Mandibular first molar 2. Maxillary first molar 3. Mandibular central incisor 4. Mandibular lateral incisor 5. Maxillary central incisor 6. Maxillary lateral incisor 7. Mandibular canine 8. Mandibular first premolar 9. Maxillary first premolar 10. Mandibular second premolar 11. Maxillary second premolar 12. Maxillary canine 13. Mandibular second molar 14. Maxillary second molar 15. Mandibular third molar 16. Maxillary third molar The enamel has no capacity of self-repair because A.It has only a small percent of organic content B. Its formative cells are lost once it is completely formed C.It is essentially a keratin tissue and has no blood vessels D.It has no direct connection with th active cells of the dental pulp.Ans: B. Its formative cells are lost once it is completely formed Ref: Orbans Oral Histology, 12/E, pp. 1, 2Explanation: The enamel present in the fully formed crown has no viable cells, as the cells forming it the ameloblasts degenerates, once enamel formation is over. Therefore all the enamel is formed before eruption. This is of clinical importance as enamel lost, after tooth has erupted, due to wear and tear or due to dental caries, cannot be formed againAging of pulp is evidenced by increase in A.Increased cellular elements B. Increased fibrous elements and decrease in cellular elements C.Non-calcified areas within pulp D.Cellular elementsAns: B. Increased fibrous elements and decrease in cellular elements Ref: Orbans Oral Histology, 12/E, p. 128Explanation: In aging, pulp shows decreased number of cells and increased fibrous accumulation. Cells decrease in number and as well as size. Fibers accumulate in more diffuse bundles throughout the pulp chamber. The increase in collagen fibres is more apparent than actual, being attributable to decrease in the size of pulp chamber The formation of the dental lamina is initiated by A.Forebrain B. Rathkes pouchC.Neural crest cells D.OdontoblastsAns: C. Neural crest cells Ref: Orbans Oral Histology, 12/E, p. 24Explanation: Development of toot results from interaction of the epithelium derived from the first arch and ectomesenchymal cells derived from the neural crest cells. Certain areas of oral ectoderm proliferate rapidly leading to the formation of primary epithelial band that has invaded the underlying ectomesenchyme along each of the horse shoe shaped future dental arches, which is called as dental lamina.35. Non-keratinized epithelium is found over A.Attached gingiva B. Free gingiva C.Interdental papilla D.Gingival sulcusAns: D. Gingival sulcus Ref: Orbans Oral Histology, 12/E, p. 240Explanation: Gingival sulcus is lined by non keratinized stratified squamous epithelium. It lacks epithelial ridges and forms a smooth interface with the lamina propria.