Tooth development Flashcards
What structure is formed in the crown first?
Dentine
What induces the dental papilla cells to be differentiated into odontoblasts?
Inner enamel epithelium.
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
6- 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
What does the stratum intermedium do?
Is important for enamel maturation.
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
What is the enamel cord?
Extends from the stratum intermedium to the stellate reticulum.
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
After odontoblastic differentiation & dentin matrix deposition.
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 what?
Deciduous teeth
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
What is the stimulus that initiates the actual formation of the enamel matrix?
Influence of increased vascularization of the dental sac.
The number of roots that are formed is determined by what?
Number of medial ingrowths at the epithelial diaphragm.
The vestibular lamina gives rise to: a- The alveolodental sulcus. b- The alveolobuccal sulcus. c- The alveololingual sulcus. d- The alveologingival sulcus.
B
How do Regulatory genes play a significant role in tooth development?
They control the tooth position and the tooth number
When do Preameloblasts differentiate into ameloblasts?
After the differentiation of odontoblasts
The process of differentiation of mesenchymal cells into
Odontoblasts is called?
Induction
Before enamel formation begins:
a- Enamel knot disappears and enamel cord remains.
b- Enamel knot remains and enamel cord disappear.
c- Both knot and cord disappear.
d- Both knot and cord remain.
C
Concerning the stratum intermedium, one of the following statements is incorrect:
a- It is composed of 2-3 layers of squamous epithelial cells.
b- It is differentiated between the inner enamel epithelium and stellate reticulum.
c- It is connected to each other and to the cells of stratum intermedium by desmosomes.
d- It is essential for enamel formation as it contains acid phosphatase enzyme.
B
Which one of the following functions of the inner dental epithelium is wrong?
a- It exerts an organizing influence on the undifferentiated cells of the dental
papilla to differentiate into ameloblasts.
b- It shares in the transport of the nutritive materials.
c- It determines the future incisal or occlusal crown pattern.
d- It lays down enamel matrix and helps in its mineralization.
A
The epithelial root sheath of Hertwig can’t be seen as a continuous layer in the developing root because:
a- The rapid epithelial sheath proliferation.
b- The dentin formation.
c- The rapid epithelial sheath destruction after dentin formation.
d- All of the above.
C
Epithelial rests of Malassez are:
a- Epithelial strands and may undergo degeneration only.
b- Epithelial remnants of the epithelial root sheath of Hertwig only.
c- Network or isolated islands in the P.L. only,
d- All of the above.
D
If Hertwig’s epithelial root sheath does not disintegrate:
a- No cementum will be formed on the radicular dentin.
b- It is likely that some of the enamel will be resorbed.
c- The apical end of the junctional epithelium will lie occlusal to the
cemento-enamel junction.
d- Predentine will form on the outer surface of the radicular dentin.
A
The reduced enamel epithelium is derived from:
a- Maturative ameloblasts and stratum intermedium.
b- Stratum intermedium, stellate reticulum and outer dental epithelium.
c- Stratum intermedium, stellate reticulum and inner epithelium.
d- Protective ameloblasts, stratum intermedium, stellate reticulum and outer dental epithelium.
D
Which of the following indicates the major components of a tooth germ?
a- The dental lamina, the stellate reticulum and the stratum intermedium.
b- The dental organ, the dental papilla and the dental sac.
c- The dental pulp, the dental sac and the dental lamina.
d- The cervical loop, Hertwig’s sheath and the inner enamel epithelium.
B
Which of the following is not true of Hertwig’s epithelial root sheath?
a- It lacks a stellate reticulum.
b- It is derived from stomodeal ectoderm.
c- Its remnants form epithelial rests.
d- It remains intact until a layer of cementum has been formed.
D
Which of the following contain blood vessels? a- Cartilage. b- Enamel. c- Dental lamina. d- Dental sac.
D
The development of the root begins when what event occurs?
The crown is completely formed
The epithelial component of the tooth germ is known as what?
The enamel organ
Which of the following is not part of the tooth germ? a- Dental papilla. b- Dental follicle. c- Dental lamina. d- Enamel organ.
C
The reduced enamel epithelium:
a- Lacks cells derived from the stellate reticulum.
b- Contains protective ameloblasts.
c- Overlies immature enamel which has not yet reached its full thickness.
d- Does not cover enamel located at the cervical end of the crown.
B
Which of the following is a component of tooth germ? a- Lateral dental lamina. b- Successional lamina. c- Vestibular lamina. d- Dental sac.
D
