ENAMEL

1.Which of the following structures is not of ectodermal origin: : 1.Which of the following structures is not of ectodermal origin: Hunter-schreger bands Enamel spindles Enamel tufts Enamellamellae

2.The formative cells of which of the following dental tissues disappear once tissue is formed : 2.The formative cells of which of the following dental tissues disappear once tissue is formed Enamel Dentin Periodontal ligament Cementum

3.Which of the following tissues have no reparative capacity : : 3.Which of the following tissues have no reparative capacity : Enamel Dentin Cementum Periodontal ligament

4.The enamel has no capacity of self -repair because : 4.The enamel has no capacity of self -repair because It has only a small percent of organic content Its formative cells are lost once it is completely formed It is essentially a keratin tissue and has no blood vessels It has no direct connection with the active cells of the dental pulp

5.The type of fibrous element in enamel is : : 5.The type of fibrous element in enamel is : Tomes filament Keratin like fibre Collagen fibre Vimentin filament

6.Calcification in enamel starts at : : 6.Calcification in enamel starts at : Enamel matrix Root CEJ DEJ

7.Specific gravity of enamel is : : 7.Specific gravity of enamel is : 2.8 3.8 4.8 23

8.Inorganic content of enamel is about : 8.Inorganic content of enamel is about 3% 2% 4% 96%

9.Length of enamel rods is : 9.Length of enamel rods is Greater than the thickness of enamel Less than the thickness of enamel Equal to the thickness of the enamel Less than the thickness of enamel Equal to the thickness of enamel None of the above

10.The diameter of the rod is : 10.The diameter of the rod is 4 um 9 um 7 um 2 um

11.Which of the following statement is correct : 11.Which of the following statement is correct In cross sections enamel rods appear hexagonal and resembles fish scales The bodies of rods are near occlusal and incisal surfaces, where as the tails point cervically The appatite crystals are parallel to bodies and deviate 65° from the tails. All of the above

12.True about direction of enamel rods : 12.True about direction of enamel rods They originate at right angle to dentin surface They are almost vertical near the incisal edge (or) cusp tip areas In the cervical third of deciduous crowns they are almost horizontal in direction In cervical region of permanent teeth, they deviate in apical direction All of the above

13.Thin leaf like structures that extend from enamel surface in to DEJ are : 13.Thin leaf like structures that extend from enamel surface in to DEJ are Enamel spindles Enamellamella Enamel tufts Perikymata

14.Dentino enamel junction is : 14.Dentino enamel junction is Non-scalloped Straight Scalloped and the convexities are directed towards dentin Scalloped and the convexities are directed toward enamel

15.Hertwig's root sheath is formed from : 15.Hertwig's root sheath is formed from Stratum inter medium Stellate reticulum Outer enamel epithelium Cervical loop

16.Perikymata are the external surface manifestations of : 16.Perikymata are the external surface manifestations of Enamel rods Incremental lines of retzius Nasmyth's membrane Pellicle

17.The percentage of inorganic matter in fully developed enamel is about : 17.The percentage of inorganic matter in fully developed enamel is about 66% 76% 86% 96%

18.The enamel of the posterior teeth is thickest at : 18.The enamel of the posterior teeth is thickest at Cervical third of buccal surface Middle third of buccal surface Middle third of lingual surface Occlusal surface

19.Enamel tufts are : 19.Enamel tufts are Thin tuft like structure extending from enamel surface to dentin-enamel junction Tuft like structure arising from dentin­enamel junction towards enamel surface Odontoblastic processes extending into enamel None of the above

20.Following is not an external manifestation of enamel : 20.Following is not an external manifestation of enamel Enamel tufts Enamellamella Incremental lines of enamel Enamel cuticle

21.Ratio of diameter of enamel rods in the DEJ to the enamel surface is : 21.Ratio of diameter of enamel rods in the DEJ to the enamel surface is 1:4 1:1 1:2 2:1

22.Interwining of the enamel rods at the cusp tips and the incisal edges of a tooth is called : 22.Interwining of the enamel rods at the cusp tips and the incisal edges of a tooth is called Enamel spindles Gnarled enamel Incremental lines of woven Incremental lines of retzius

23.Incremental lines of retzius are seen in : 23.Incremental lines of retzius are seen in Enamel Dentin Cementum Pulp

24.All are true regarding the enamel spindles except : 24.All are true regarding the enamel spindles except Produced by ameloblasts Found in the region of cusps Surrounded by inter prismatic enamel Terminate as rounded process

25.Neonatal lines are found in all of the following except : 25.Neonatal lines are found in all of the following except Enamel of primary incisors Enamel of permanent canines Enamel and dentin of permanent first molars Dentin of permanent mandibular incisors