441. Preameloblasts differentiate into ameloblasts:
A. After the differentiation of odontoblasts.
B. Before the differentiation of odontoblasts.
C. During the differentiation of odontoblasts.
D. During & after the differentiation of odontoblasts.

442. During the early stages of tooth development three transitory structures may be seen, these structures are:
A. Enamel knot, enamel organ & enamel niche.
B. Enamel knot, enamel cord & enamel niche.
C. Enamel knot, enamel organ & enamel epithelium.
D. Enamel niche, enamel organ & enamel knot.

443. The epithelial rests in the periodontal ligament are derived from:
A. Dental pulp.
B. Epithelial root sheath of Hertwing’s.
C. Vestibular lamina.
D. Dental sac.

444. Appositional stage is confined to:
A. Cap stage.
B. Bud stage.
C. Bell stage.
D. Dental lamina.

445.Concresense usually occurs with:
A. Permanent maxillary molars.
B. Permanent maxillary premolars.
C. Permanent mandibular premolars.
D. Permanent mandibular premolars.

446. Supernumerary roots occur mainly with:
A. Permanent third molars.
B. Permanent second molars.
C. Permanent first molars.
D. Permanent second premolars.

447 Enamel pearls occur in:
A. Apical third of molars roots.
B. Furcation area of molars.
C. Cervical third of molars roots.
D. Furcation area of premolars.

448. The process of differentiation of mesenchymal cells into
Odontoblasts is called:
A. Initiation.
B. Induction.
C.Apposition.
D.Morphodifferentiation.

449. The epithelial root sheath of Hertwing’s is composed of:
A.Outer enamel epithelium & inner enamel epithelium.
B. Inner enamel epithelium & stratum intermedium.
C. Outer enamel epithelium & stellate reticulum.
D. Stellate reticulum & stratum intermedium.

450. Inner dental epithelium:
A. Consists of a single layer of cuboidal epithelial cells.
B. Consists of a single layer of columnar epithelial cells.
C. Consists of a single layer of polyhedral epithelial cells.
D. Consists of a single layer of polygonal epithelial cells.

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