Which of the following is correct: A. Each rod is formed by 4 ameloblasts B. Each ameloblast contributes to 4 different rods C. Head of the rod is formed by one ameloblasts, and tail is formed by three other ameloblasts D. All of the above
Enamel can act in a sense like a: A.Permeable membrane B. Impermeable membrane C. Semipermeable membrane D. Infrapermeable membrane
Dark bonds that are present in enamel rods at intervals of 4 μms are: A. Neonantal bands B. Cross striations C. Striae of Retzius D. Hunter-Schregar bands
The average width of enamel rods is: A. 10mm B. 5mm C. 2mm D. 0.5mm
The shallow furrows on the enamel surface, where stria of Retzius end are known as: A. Cracks B. Pellicle C. perikymata D. Enamel lamellae
The key hole, pattern appearance in the cross section is feature of: A. Aprismatic enamel B. Prismatic enamel C. Intertubular dentin D. Intratubular dentin
The class of low molecular weight calcium binding proteins seen predominantly in developing enamel are: A. Enamelin B. Amelogenin C. Tuftelin D. Ameloplakin
Metalloprotienases are used in which stage of the amelogenesis: A. Organising B. Formative/ Secretory C. Protective D. Desmolytic
Nutritional supply of the ameloblasts during most of their life cycle is from the: A. Dental pulp B. Odontoblastic processes C. Dental sac D. Reduced dental organ
Neonatal line is also referred to as: A. Retzius line B. Line of cross striations C. Incremental lines D. Line of enamel tufts
Among the following the structure that is most calcified is: A. Enamel lamella B. Enamel rod C. Enamel spindle D. Enamel tuft
Synthesis of enamel matrix proteins occurs in the: A. Outer enamel epithelium B. Ameloblast C. Stratum intermedium D. Stratum granulosum
Enamel is laid down: A. Mainly by odontoblasts B. Mainly by ameloblasts C. Only on odontoblasts D. Only by ameloblasts
The striking difference between enamel and other mineralized tissues is: A. Presence of high percentage of organic matrix B. Presence of incremental lines C. Enamel has high reparative capacity D. Most of organic component is lost during mineralization
Formation of dentin by odontoblasts begins in: A. Morphogenic stage B. Organizing stage C. Desmolytic stage D. Formative stage
Chronological hypoplasia is: A. Hypoplasia of local origin B. Hypoplasia of systemic origin C. Hypoplasia of hereditary origin D. None of the above
Dentino enamel junction is: A. Non-scalloped B. Straight C. Scalloped and the convexities are directed towards dentin D. Scalloped and the convexities are directed towards enamel
True about direction of enamel rods: A. They originate at right angle to dentin surface B. They are almost vertical near the incisal edge (or) cusp tip areas C. In the cervical third of deciduous crowns they are almost horizontal in direction D. In cervical region of permanent teeth, they deviate in apical direction E. All of the above
The diameter of the rod is: A. 4 μ m B. 9 μ m C. 7 μ m D. 2 μ m
Inorganic content of enamel is about: A. 35% B. 50% C. 4% D. 96%
Calcification in enamel starts at: A. Enamel matrix B. Root C. CEJ D. DEJ
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 the active cells of the dental pulp
The formative cells of which of the following dental tissues disappear once tissue is formed: A. Enamel B. Dentin C. Periodontal ligament D. Cementum
On microscopic examination enamel rods have: A. Key hole appearance in cross section B. Paddle appearance in cross section C. Lanullate appearance in cross-section D. None of the above
All are true about the striae of retzius except: A. Constitute the rest lines with in the enamel rods B. Have high inorganic content C. They are areas of increased porosity D. Allow the movement of water and small ions
Ionic exchange between enamel surface and environment: A. Does not take place once enamel surface and invironment B. Stops after 2 years of eruption C. Continues till adult life D. Continues through out life
Incremental lines of retzius are seen in: A. Enamel B. Dentin C. Cementum D. Pulp
Blunt cell processes seen on the developing ameloblasts are celled as: A. Tomes fibres B. Tomes layer C. Tomes processes D. Odontoblastic processes
Following is not an external manifestation of enamel: A. Enamel tufts B. Enamel lamella C. Incremental lines of enamel D. Enamel cuticle
Hunter Schreger band are: A. Dark and light bands of enamel seen in longitudinal ground section B. Dark and light bands of enamel seen in horizontal ground section C. Dark and light brands of dentin seen in longitudinal section D. Dark and light bands of dentin seen in horizontal
The percentage of inorganic matter in fully developed enamel is about: A. 66% B. 76% C. 86% D. 96%
Non acidic, nonionic protein which helps in enamel mineralization: A. Tuftelin B. Sheathlin C. Enamelin D. Amelogenin
Which of the following is correct about enamel crystals: A. Same as dentin crystals B. Contains organic portion in the center C. Roughly texagonal in shape D. Their diameter is about 5 microns in size
Maximum amount of phosphate is seen in: A. Bone B. Enamel C. Gingiva D. Dentin
Neonatal lines are seen in: A. Enamel of deciduous incisiors B. Enamel of permanent incisors C. Enamel of premolars D. Dentin of all teeth, as if is formed first
Narled enamel is seen in: A. Proximal surface of tooth B. Cervical region of tooth C. Cusp tips of tooth D. All of the above
The thickness of prismless enamel in deciduous teeth is: A. 25 μ m B. 50 μ m C. 75 μ m D. 100 μ m
Enamel rods at the cervical area at the occlusal edge and incisal lip in permanent teeth are: A. Straight B. Shallow C. Bent D. Curved
Incremental lines of Retzius appear: A. As lines in the enamel running at right angles to the enamel surface B. As lines in the dentin running at right angles to the dentino-enamel junction C. In enamel and follow the apposition pattern D. In dentin and follow the appositional pattern
Enamel spindles are formed by: A. Cracks B. Ameloblasts C. Odontoblasts D. Hypocalcified rods
The small ridges, perikymata, seen on facial surfaces of canines are the result of: A. Hyperplasia B. Hypoplacification C. Normal development D. Interstitial development
Ameloblasts is: A. A cell from which tooth enamel is formed: B. A tissue from which tooth erupts C. A tumour of the jaw D. Pertaining to dentin
Shape of enamel rod is: A. Key hole or paddle shaped B. Square C. Round D. None of the above
Moth eaten appearance of enamel is seen in: A. Odontodysplasia B. Amelogenisis stage C. Desmolytic stage D. Mottled enamel
Hertwig’s root sheath is formed from: A. Stratum inter medium B. Stellate reticulum C. Outer enamel epithelium D. Cervical loop
Thin leaf like structures that extend from enamel surface in to DEJ are: A. Enamel spindles B. Enamel lamella C. Enamel tufts D. Perikymata
Which of the following statement is correct: A. In cross sections enamel rods appear hexagonal and resembles fish scales B. The bodies of rods are near occlusal and incisal surfaces, where as the tails point cervically C. The apatite crystals are parallel to bodies and deviate 65° from the tails D. All of the above
Length of enamel rods is: A. Greater than the thickness of enamel B. Less than the thickness of enamel C. Equal to the thickness of enimal D. None of the above
Specific gravity of enamel is: A. 2.8 B. 3.8 C. 4.8 D. 2.3
The type of fibrous element in enamel is: A. Tono filament B. Keratin like fibre C. Collagen fibre D. Vimentin filament
Which of the following tissues have no reparative capacity: A. Enamel B. Dentin C. Cementum D. Periodontal ligament
Which of the following structures is not of ectodermal origin: A. Hunter schreger bands B. Enamel spindles C. Enamel tufts D. Enamel lamellae
Neonatal lines are found in all of the following except: A. Enamel of primary incisors B. Enamel of permanent canines C. Enamel and dentin of permanent first molars D. Dentin of permanent mandibular incisors
Approximately how many enamel rods will be present in a maxillary molar: A. 5 million B. 7 million C. 9 million D. 12 million
All are true regarding the enamel spindles except: A. Produced by ameloblasts B. Found in the region of cusps C. Surrounded by inter prismatic enamel D. Terminate as rounded process
Interwining of the enamel rods at the cusp timps and the incisal edges of a tooth is called: A. Enamel spindles B. Gnarled enamel C. Incremental lies of woven D. Incremental lines of retzius
Ratio of diameter of enamel rods in the DEJ to the enamel surface is: A. 1:4 B. 1:1 C. 1:2 D. 2:1
Enamel tufts are: A. Thin tuft like structure extending from enamel surface of dentin enamel junction B. Tuft like structure arising from dentin-enamel junction towards enamel surface C. Odontoblastic processes extending into enamel D. None of the above
The enamel of the posterior teeth is thickest at: A. Cervical third of buccal surface B. Middle third of buccal surface C. Middle third of lingual surface D. Occlusal surface
Perikymata are the external surface manifestations of: A. Enamel rods B. Incremental lines of retzius C. Nasmyth’s membrane D. Pellicle
