541. During shedding which of the following is wrong:
A. The pulp plays an active role.
B. The pulp plays a passive role.
C. The pulp appears histologically normal till the end of the process.
D. The neural elements remain in the pulp until shedding is completed.
542. Which of the following is true about ankylosis?
A. Is a union of the tooth with the periodontal ligament.
B. The active eruption of an ankylosed tooth continues.
C. Is a bony union between the alveolar bone and the roots of teeth.
D. Ankylosed teeth do not show Howship’s lacunae on the root.
543. Shedding is predominantly the:
A. Physiologic loss of impacted teeth.
B. Pathologic loss of non-vital primary teeth.
C. Physiologic loss of permanent teeth.
D. Physiologic loss of primary teeth.
544.Ameloblasts having ruffled borders are:
A. Secretory ameloblasts.
C. Protective ameloblasts.
D. Transitional ameloblasts.
545.Which of the following is not a feature of enamel?
A. Contour lines of Owen.
B. Cross striations.
C. Prism sheath.
546. Maturativeameloblasts are characterized by having:
A. A distally positioned nucleus.
B. A highly basophilic cytoplasm.
C. A highly-developed Golgi complex.
D.A distal cell membrane with many infoldings.
547. Which of the following does not occur during maturation of enamel?
A. Influx of calcium and phosphorus.
B. Growth of hydroxyapatite crystals.
C. Increase in organic content.
D.Decrease in the water content.
548. Incremental lines are a result of variation in:
D. Rhythmic apposition.
549. The prismatic structure of enamel is due to:
A.Variation in the density of organic material.
B.Variation in crystal orientation.
C.A rhythmic pattern of apposition.
D. The periodic change in prism direction.
550. The prismless layer of enamel:
A. Is found only in primary teeth.
B. Does not contain prism & prism sheaths.
C. Is found near the amelo-dentinal junction.
D. Contains no hydroxyapatite.
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