tooth development Flashcards
Concrescence is:
a- An extra root or accessory roots in a formed tooth.
b- Distorted root or roots in a formed tooth.
c- A union of root structure of two or more teeth through cementum only.
d- A spherical projection on the cemental root surface.
C
What structure is formed in the crown first?
a- Enamel.
b- Cementum.
c- Pulp.
d- Dentine.
D
Which of the following induces the dental papilla cells to be differentiated into
odontoblasts?
a- Stratum intermedium.
b- Reduced enamel epithelium.
c- Inner enamel epithelium.
d- Outer enamel epithelium.
C
No basal lamina is found between the cells of the:
a- Stratum intermedium and inner enamel epithelium.
b- Outer enamel epithelium and the dental sac.
c- Inner layer of Hertwig’s sheath and the dental papilla.
d- Inner enamel epithelium and the dental papilla.
A
Which of the following is not a functional activity of the enamel organ:
a- Inducing the differentiation of Odontoblasts.
b- Secretion of enamel matrix.
c- Maturation of enamel.
d- Formation of cementum.
D
Which of the following is not derived from the dental organ:
a- Stellate reticulum.
b- Hertwig’s epithelial root sheath.
c- Odontoblasts.
d- Ameloblasts.
C
The stratum intermedium:
a- Induces dentin formation.
b- Is separated from the stellate reticulum by a basal lamina.
c- Develops in cap stage.
d- Is important for enamel maturation.
D
The dental organ
a- Develops from cells in the dental follicle.
b- Is a completely connective tissue structure.
c- Is a completely epithelial structure.
d- Is highly vascular, as ameloblasts require an enriched environment.
C
The enamel cord
a- Is an extension of the dental lamina.
b-Is an extension of the outer dental epithelium.
c- Is an extension of successional dental lamina
d-Extends from the stratum intermedium to the stellate reticulum.
D
Dental follicle cells
a- Differentiate into the ameloblast layer.
b- Differentiate into the odontoblast layer.
c- Are found within the dental organ.
d- Migrate to dentin surface of the root and differentiate into the cementoblast.
D
All of the following is the functions of The Stellate Reticulum except:
a- Keep Space for The enamel development.
b- Act as a reservoir for nutritive materials.
c- Act as a cushioned to protect ameloblasts.
d- Secretes alkaline phosphatase enzyme.
D
The epithelial root sheath of Hertwig disintegrates:
a- After odontoblastic differentiation & before dentin matrix formation.
b- After odontoblastic differentiation & dentin matrix deposition.
c- Before odontoblastic differentiation.
d- After cementum formation.
B
All of the following is a function of dental sac except:
a- Nutrition of enamel organ.
b- Formation of cementum.
c- Formation of periodontal ligament.
d- Formation of supporting alveolar bone.
D
The lateral dental lamina gives rise to:
a- Deciduous teeth .
b- Permanent successors.
c- Permanent molars.
d- Vestibular lamina.
A
The stratum intermedium:
a- Lies between outer enamel epithelium & stellate reticulum.
b- Is a transient structure.
c- Is rich in mucopolysaccharides.
d- Plays important role in enamel calcification.
D
The down growth of an epithelial thickening buccal to the dental lamina is
known as:
a- Vestibular lamina.
b- Linguo-alveolar Sulcus.
c- Lateral dental lamina.
d- Successional dental lamina.
A
The dental lamina is induced to proliferate into a tooth bud by the:
a- Basement membrane.
b- Nerve endings.
c- Ecto-mesenchyme.
d- Oral epithelium.
C
Calcified tissues of the tooth are derived from:
a- Ectoderm only.
b- Endoderm only.
c- Mesoderm only.
d- Ectoderm & Mesoderm.
D
A layer of cells that seems to be essential to enamel formation but does not actually secrete the enamel is:
a- Outer dental epithelium.
b- Stratum intermedium.
c- Reduced dental epithelium.
d- Vestibular lamina.
B
The stimulus that initiates the actual formation of enamel matrix seems to be:
a- Reduction of stellate reticulum.
b- Influence of increased vascularization of the dental sac.
c- Disappearance of the cell free zone of dental papilla.
d- Presence of predentin.
D
The number of roots that are formed is determined by the:
a- Number of root sheaths developed by the enamel organ.
b- Number of medial ingrowths at the epithelial diaphragm.
c- Number of root sheaths developed by the dental sac.
d- Thickness of the cervical loop.
B
Which of the following is the first process to occur in the sequence of tooth
development:
a- Deposition of the first layer of enamel.
b- Deposition of the first layer of dentin.
c- Elongation of the inner dental epithelial cells.
d- Differentiation of odontoblasts.
C
All of the following are involved in the formation of a tooth except:
a- Epithelial root sheath
b- Successional lamina.
c- Dental lamina.
d- Vestibular lamina.
D
The dental lamina initiating the permanent molars develops:
a- As successional lamina.
b- As a distal extension of the dental lamina.
c- As lateral dental lamina.
d- As vestibular lamina.
A
The cell rests of Malassez are derivatives of:
a- Cervical ameloblasts.
b- Outer enamel epithelium.
c- Dental papilla.
d- Root sheath.
D
The embryo’s stomodeum is lined by:
a- Ectoderm.
b- Endoderm.
c- Mesoderm.
d- Ectomesenchyme.
A
By the 6th week of tooth development, the oral epithelium is:
a- 2-3 layers thickness.
b- 3-4 layers thickness.
c- 4-5 layers thickness.
d- 2-5 layers thickness.
A
The vestibular lamina gives rise to:
a- The alveolodental sulcus.
b- The alveolobuccal sulcus.
c- The alveololingual sulcus.
d- The alveologingival sulcus.
B
The ectomesenchymal cell condensation just beneath the enamel organ is
called:
a- Dental sac.
b- Dental follicle.
c- pulp.
d- Dental papilla.
D
The cells of the tooth bud have:
a- High RNA content only.
b- Low glycogen content only.
c- Increased oxidative enzyme activity only.
d- All of the above.
D
Regulatory genes play a significant role in tooth development, they:
a- Control the tooth position.
b- Control the tooth number.
c- Determine the tooth shape.
d- a & b.
D
Initiation of dental lamina is induced by:
a- Neural crest cell.
b- Endoderm.
c- Ectoderm.
d- Mesoderm.
A
Primordium for the permanent dentition appears as an extension of dental
lamina into the ectomesenchyme:
a- Lingual to the developing primary tooth germ.
b- Labial to the developing primary tooth germ.
c- Mesial to the developing primary tooth germ.
d- Distal to the developing primary tooth germ.
A
The region where the inner and outer enamel epithelium meets at the rim of
the enamel organ is known as:
a- Zone of Flection.
b- Cervical loop.
c- Epithelial Diaphragm.
d- Root Sheath of Hertwing’s
B
Which the followings is not a function of the stellate reticulum
a- Protection of the underlying dental tissues.
a function of stellate reticulum:
b- Maintenance of tooth shape.
c- Support the production of enamel.
d- Control the position & number of tooth germs.
D
The epithelial pearls are derived from:
a- Dental lamina.
b- Dental pulp.
c- Dental sac.
d- Dental organ.
A
Odontoblasts start their secretory activity:
a- Before enamel matrix production.
b- After enamel matrix production.
c- During enamel matrix production.
d- During & after enamel matrix production.
A
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.
A
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.
B
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.
B
Appositional stage is confined to:
a- Cap stage. b- Bud stage.
c- Bell stage. d- Dental lamina.
C
Concresense usually occurs with:
a- Permanent maxillary molars.
b- Permanent maxillary premolars.
c- Permanent mandibular premolars.
d- Permanent mandibular premolars.
A
Supernumerary roots occur mainly with:
a- Permanent third molars.
b- Permanent second molars.
c- Permanent first molars.
d- Permanent second premolars.
A
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.
B
The process of differentiation of mesenchymal cells into
Odontoblasts is called
Induction
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.
A
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.
B
Determination of the initial position of the first cusp of the tooth during
crown pattern formation may be achieved by:
a- The enamel knot. b- The enamel cord.
c- Both enamel knot and cord. d- None of the above.
A
