1. What is the first sign of tooth development, and when is it seen?

The dental lamina is the first sign of tooth development, and it is first seen during the 6th embryonic week.

2. Oral epithelium is an example of what type of epithelial arrangement?

Stratified squamous epithelium

3. The enamel organ comes from what germ layer?

Ectoderm

4. What are the stages of the enamel organ and what general changes are taking

place? Bud stage – Localized thickening begins in dental lamina and a

bloblike cluster of cells bulges into connective tissue deep

to the dental lamina Cap stage – The deep part of bud begins to develop a depression on

the surface and dental papillae is seen condensing

beneath it, three layers are present. Bell stage – The deep surface of the organ begins to take on the shape

of the future tooth, four layers are present.

5. What is ectodermal dysplasia, and what is the significance of the origin of the

enamel organ in relation to this pathologic condition? Aside from enamel, what other structures develop abnormally from this condition?

Ectodermal dysplasia is the developmental problem affecting structures that arise from ectoderm. The significance of the origin of

the enamel organ is that any developmental problems that affects

ectodermally derived structures will affect enamel. Other structures affected are hair, nails, sweat glands, sebaceous glands and salivary

glands.

6. What are the four layers of the enamel organ as seen in bell stage, and what is

their function? a. Outer Enamel Epithelium:

Protects enamel organ and later aids in nourishment

b. Inner Enamel Epithelium: Forms ameloblasts which then form enamel

c. Stellate recticulum:

Protects IEE and helps in nourishment d. Stratum intermedium:

Nourishment of ameloblasts; provides proteins and receives secretion from ameloblasts

7. Define and describe the roles of the following:

a. Successional lamina:

It is a budding off of the dental lamina; develops the enamel

organs of the 20 succedaneous permanent teeth. b. Vestibular lamina:

It is the thickening of oral tisses facial to dental lamina; splits and forms the vestibular or mucobuccal mucolabial fold.

c. Dental papilla:

It is the mesodermal condensation of cells next to IEE, and eventually forms dentine and pulp.

d. Dental sac:

It surrounds part of the OEE and part of the dental papillae, and eventually forms periodontal ligament, cementum and part of

the alveolar bone.