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151. Acid-etching of surface enamel to create a surface for better binding with dental

materials most commonly

a. preferentially removes centers of rods
b. dissolves hydroxyapatite crystals more readily in a direction perpendicular to their

long axis

c. shows little correlation with key-hole-shaped rods
d. bears no resemblance to rod structure
e. preferentially removes peripheries of rods
 

152. Ameloblasts are derived from
 

a. dental papilla
b. outer dental epithelium
c. inner dental epithelium
d. dental sac
e. ectomesenchymal cells

 
153. Which one of the following activities of the dental organ continues for the longest time

with the development of any tooth?

a. morphogenic
b. organizing
c. formative
d. maturational
e. protective

 
154. The formation of cementum results when the dental organ
 

a. adheres to dentin
b. becomes discontinuous over dentin
c. is in its secretory stage
d. is in its protective stage
e. forms an epithelial diaphragm

 
155. The periodontal ligament develops from
 

a. pulpal tissue
b. dental papilla
c. dental sac
d. outer dental epithelium
e. inner dental epithelium