Exam 2 - Oral histology and Embryology

pulp, dentin, cementum

what are the dental tissues that are specialized forms of connective tissue?

enamel organ

The epithelial component of the dental tissue is what?

mesenchyme and oral epithelium

each tooth in the mouth is a product of what two tissues that interact during tooth development?

7th week

what does tooth development begin?

mesenchyme

derived from neural crest cells and forms the dental papilla

oral epithelium

derived from ectoderm and forms the enamel organ

morphodifferentiation and cytodifferentiation

tooth development involves what 2 processes?

morphodifferentiation

shaping of the tooth

Cytodifferentiation

cells differentiate into specific tissue forming cells

ameloblasts

enameling forming cell

cementoblasts

cementum forming cell

odontoblasts

dentin forming cells

Fibroblasts

pulp forming cells

shaping the tooth within morpho differentiation

oral epithelium and the underlying mesenchyme are responsible for _____________________

initiation stage

small condensed areas of mesenchyme

bud stage, cap stage, bell stage, apposition and maturation

what are the stages in morpho differentiation?

extensive proliferation of the dental lamina into buds. The condensed areas of mesenchymal cells are continuous with the oral epithelium.

describe the bud stage

dental lamina

the connection between the mesenchyme and oral epithelium is referred to as the________________ (stalk)

9-10 weeks. The epithelial tissue gains a concave surface. A portion of the mesenchyme deep to the buds has condensed into a mass within the concavity.

describe the cap stage

dental papilla

The inner mas of mesenchyme is now considered what?

dentin and pulp for the inner portion of the tooth

the dental papilla helps form what?

dental follicle

the area around the structure is called what?

cementum, PDL, and alveolar bone

what is formed from the dental follicle?

enamel organ, dental papilla, and the dental follicle

what are the tooth germs?

11-12 weeks, morpho and cytodifferentiation

describe the bell stage

OEE, IEE, stellate reticulum, stratum intermedium

what are the organized layer of the enamel organ?

inner and outer cells

the dental papilla during the bell stage will divide into what?

pulp

what will the inner cells form?

odontoblasts or dentin

what will the outer cells form?

successional lamina

permanent tooth that will succeed the primary tooth; appears as an extension.

collagen

During the bell stage, the dental follicle increases in what fiber?

all of the cells that have differentiated begin to secrete their matrixes appositionally

describe the apposition stage

the tissues fully mineralize- many inductions occur

describe the maturation stage

dentin

what is the first dental tissue produced?

four

During cytodifferentiation, epithelial components become the enamel organ which is organized into how many layers?

OEE

the outer cuboidal cells of the enamel organ

IEE

the innermost, tall, columnar cells of the enamel organ on the concave side

ameloblasts.

IEE cells with become future ______________

stratum intermedium

compressed cells that lie on top of the IEE

stellate reticulum

starshaped cells that fill the bulk of the enamel organ

subdivided

During cytodifferentiation the mesenchymal components become _______________

dental follicle (sac)

surrounds the developing tooth germ and provides cells that will form the cementum, PDL, and alveolar bone.

dental papilla.

condensed mesenchyme located on the concavity side of the enamel organ. outer cells will change into dentin forming cells

pulp

the center of the dental papilla will become the __________

interactions between cells

series of sequential cellular interactions between epithelial and mesenchymal components of the tooth germ

1st interaction

between the oral epithelium and the mesenchyme. The mesenchyme instructs the epithelium to grow down into the mesenchyme to shape the tooth

2nd interaction

given by the cells if the IEE (preameloblasts) to the outer cells of the dental papilla to differentiate into odontoblast to begin the deposition of dentin

3rd interaction

as soon as odontoblasts begin to deposit dentin, preameloblast (IEE) become true secreting ameloblasts and begin the deposition of enamel

4th interaction

occurs with the development of root dentin and cementum

Dentogenesis

preameloblasts induce differentiation of odontoblasts from the dental papilla

columnar epithelium

during dentogenesis, odontoblasts condense to form a ___________________

predentin

odontoblasts produce ________________appositionally on their outer surface

odontoblasts

what produces a fibrous CT matrix?

by the deposition of hydroxyapatite crystals into the matrix

how is dentinal tissue calcified?

at the crown (cusp tips or incisal edge)

where does dentin formation begin first?

no, continues throughout life when needed

Does dentin ever stop producing?

odontoblastic cell process

what odontoblast has a long cell extension called the ____________________________

incremental lines (lines of Von Ebner)

daily cycles of secretion and mineralization from the odontoblast creates_______________

amelogenesis

production of enamel

protein

ameloblasts produces an enamel matrix with what components?

deposition of hydroxyapetite crystals

the enamel matrix is calcified immediately by what?

tomes process

the ameloblasts secretion process is called______________

no vital cells

when the tooth emerges into the oral cavity, the enamel has ______________________associated with the tissue.

cervical loop

the structure responsible for root development is the _____________________

Hertwig's epithelial root sheath

what grows downward from the cervical loop?

Odontoblasts

the inner root sheath induces formation of ________________from the dental papilla to form dentin

Epithelial rests of Malassez

the sheath breaks down to form the ____________________

dental follicle (sac)

the cells of the _________________ contact newly formed root dentin

cementoblasts

when the cells of the dental follicle contact root dentin, it induces differentiation of __________________ from the dental follicle to begin secretion of cementoid.

over

as a result, the apposition of cementum ____________the dentin occurs.

central

the _______________ cells of the dental papilla are forming into the pulp

PDL

the dental follicle cells begin to form the _______________

process involves forming collagen fibers that are immediately organized into the fiber bundles of the PDL

How is the PDL formed?

the outer portion of the cementum and the surrounding alveolar bone to support the tooth.

Where do the ends of the fibers insert into?

the tooth sockets or alveoli of the alveolar bone surrounding the PDL.

The mesenchyme if the dental follicle beings to mineralize to form what?

enamel

hardest calcified tissue is the human body due to its high content of inorganic matter

96%

what percent of enamel is inorganic?

1%

what percent of enamel is organic?

3%

what percent of enamel is water?

its brittle

what is a disadvantage of enamel?

appositional stage

when does amelogenesis begin?

deposition of dentin

IEE becomes secretory ameloblast shortly after what?

mineralization

when the deposition of enamel occurs what happens immediately?

hexagonal

what is the cross section of the ameloblasts?

tomes process

shovel shaped secretory process on surface of ameloblasts

secrete and resorb

ameloblasts can ___________

hydroxyapatite crystals

are long and narrow

4x

hydroxyapatite crystals are __________as large than other crystals.

enamel prisms (rods)

tightly packed masses of crystals

hyper mineralized

enamel prisms are__________

from DEJ to outer edge of enamel

how do prisms run?

in rows causing a keyhole shape; interlocked

how are prisms stacked?

4 um

what is the diameter of a prism?

prism sheath (interprismatic region)

separates adjacent prisms in head region (outline)

perpendicular

prisms are ____________ to the outer surface of enamel

Striae of Retzius, perikymata, neonatal lines

what are the different incremental lines?

striae of retizus

hypo mineralized layers that result from interrupted production of calcium by some physiological processes. (rests)

perikymata

Grooves evident on teeth associated with the lines of Retzius in enamel

neonatal lines

more pronounced striae of retizus

Hunter-Schreger bands

dark and light bands: results from zigzagging