Board Exam (CDCA-WREB-CITA)

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Epithelium (ectoderm) forms

the lamina (layer)

The tooth germ grows from the

lamina into the underlying tissue (mesoderm)

The dental papilla forms the

Dentin and pulp

The dental sac forms the

Cementum, PDL, and lamina dura

Lamina dura is

bundle bone that lies adjacent to the periodontal ligament, lining the tooth socket. The lamina dura surrounds the tooth socket and provides the attachment surface with which the Sharpey's fibers of the periodontal ligament perforate. On an x-ray a lamina dura will appear as a radiopaque line surrounding the tooth root

Basal Lamina

1. the layer of the basement membrane lying next to the basal surface of the adjoining cell layer, comprising two layers, the electron-lucent lamina lucida and the electron-dense lamina densa.
2. sometimes, the entire basement membrane.

Basement Membrane

(a thin sheet of fibers underlying the epithelium) separates the enamel from the dental papilla...which becomes the DEJ. REE (reduced enamel epithelium) protects the tooth until it erupts.

Hertwigs Root Sheath

An elongation of the cervical loop, which helps determine the shape, size, and number of roots and which influences the formation of dentin during the developmental stages of a tooth

The Rests of Malassez

Epithelial remnants of Hertwigs in the periodontal membrane; sometimes develops into a dental cyst

Stomodeum

Becomes the oral cavity and nasal cavity; results from invagination of the ectoderm at the cephalic end of the embryo

Buccopharynge al membrane

When the ectoderm meets the endoderm

Separates the primitive mouth from the foregut

When does the buccopharyngeal membrane rupture?

4th week in utero

Anterior lobe of hypophysis

The developing pituitary gland

When does the anterior lobe of hypophysis develop?

3rd week in utero

Rathke’s pouch

The pit that is formed by the formation of the anterior lobe of hypophysis

Frontal process

Large bulb in cephalic portion caused by fore brain

Frontal processes

Gives rise to the nasal septum, upper part of the face, and anterior part of the roof of the mouth

Arch I

Mandible and large part of maxilla

Arches II, III, IV

Join with I to make the tongue

Mesenchymal cells

Embyronic cells

2 Maxillary processes

Form the upper part of the cheeks, side of the upper lip and the palate

2 Mandibular processes

Lower part of the cheeks, lower lips, lower jaw, part of the tongue

Nasal septum

Results from an ingrowth of the medial nasal process into the stomodeum; divides the right and left nasal chambers

Globular Process

Develops from the medial nasal process; extends below the olfactory pits; lies between the right and left maxillary processes; forms the philtrum

Cleft lip

The partial or complete failure of the maxillary process to merge with the globular process; can be unilateral or bilateral

When is cleft lip apparent?

2nd month in utero

Mascrotomia

Failure of the sides of the mouth to close during embryonic development

When does the palate start to develop?

Near the end of the 2nd month in utero

Three growths in the stomodeum that form the palate

Right lateral palatine process, left lateral palatine process, premaxillary area

Palate

The fusion of the right and left maxillary process with premaxillary process forming a Y-shaped closure

When is fusion of the palate completed?

By the 12th week in utero

Cleft Palate

Failure of the fusion of the lateral palatine processes with each other or with the premaxillary process

When is cleft palate apparent?

By the 12th week or 3rd month in utero

3 anterior swellings that form the tongue

Tuberculum impar (middle); right lateral lingual swelling, left lateral lingual swelling

Posterior swelling that help form the tongue

Copula

When does the tongue begin to develop?

4th week in utero

Where does the body of the tongue develop from?

1st branchial arch

Where does the base of the tongue develop from?

2nd, 3rd, 4th branchial arches

When is the tongue recognizable

By the end of the 2nd month in utero

Thyroid gland

Originates from the foramen cecum, a depression posterior to the circumvallate papillae on the tongue

When is the thyroid gland apparent?

About 17 days in utero

Thyroglossal duct

Duct that thyroid gland uses to travel to the throat

What happens in the first (mandibular) branchial arch

Formation of bones, muscles, and nerves of the face

What happens in the second (hyoid) branchial arch?

Formation of the styloid process, stapes of the ears, stylohyoid ligament

What happens in the forth, fifth, and sixth branchial arches?

Formation of the structure of the lower throat, thyroid cartilage, muscles and nerves of the pharynx and larynx

Hard and soft palates

Formed from two separate embryonic structures; primary and secondary

In what week of prenatal development do the teeth develop?

When the embryo is 5-6 weeks old

Where does tooth development begin?

In the anterior mandibular region then in the anterior maxillary region

Embryology

Study of prenatal development in the stages before birth

Histology

Study of the structure and function of the tissues on a microscopic level

Earliest signs of tooth development

Found in the anterior mandibular region, when the embryo is 5 to 6 weeks old

At birth there are ____ in various stages of development

44 teeth

Life cycle of a tooth:

Growth

Calcification

Eruption

Bud stage

Formation of tooth begins

Cap stage

Cells of the developing tooth increase

Bell stage

Different tissues of the tooth form and its shape is established

Fissure

Fault along a developmental groove on the occlusal surface caused by incomplete or imperfect joining of the lobes during the formation of the tooth

Pit

Results when two developmental groove cross each other, forming a deep area that is too small for the bristle of a toothbrush to clean

Enamel

Hardest material of the tooth body

Pulp

Made up of nerves and blood vessels, and arteries of the body through a small opening at the tip of the root known as "Apical Foramen"

Alveolar crest

Is the highest point of the alveolar ridge

Which period of prenatal development is the most critical?

Embryonic period

Name the process for the laying down or adding of bone

Deposition

Name the process of bone loss or removal

Resorption

What is the first sign of tooth development?

Formation of the primary dental lamina

Dental lamina grows down into underlying ___________ in ___ maxillary and ____ mandibular spots

Mesenchyme, 10, 10

What are the spots of dental lamina that grow into the underlying mesenchyme?

tooth buds/germ

Small clumps of cells with the ability to form tooth tissues

Tooth buds/germ

How many embryonic tissues make up tooth germ? What are they?

2: ectoderm and ectomesenchyme

Tissue from the dental lamina;

Is from oral epithelium

Ectoderm forms;

Skin, lining of oral/nasal cavity, enamel, salivary glands, nerves

Ectomesenchyme

Tissue from neural crest cells; Underlies ectoderm; it is a specialized connective tissue

Parts of the tooth germ

Enamel organ, dental papilla, dental sac

Enamel organ

Forms enamel; from ectoderm

Dental papilla

Forms dentin + pulp; from mesenchyme

Dental sac

Forms cementum, PDL, lamina dura; from mesenchyme

Stages of enamel organ development; morphodifferentiation

Bud stage (1st)

Cap stage (2nd)

Bell stage (3rd)

Bud Stage includes the formation of the tooth ____, ________ _______develops, appearance of ____________, then a budding off from the dental lamina.

Bud, enamel organ, mesenchyme

Stage of enamel organ development in which the dental papilla if formed, enamel organ has 2 layers, and the vestibular lamina appears

Cap stage (2nd)

Stage of enamel organ development which includes formation of hard tissues, four layered enamel organ, form of crown is determined, and the bud of the permanent tooth forms; there is also morpho- and cytodifferentiation

Bell stage (3rd)

Four layers of the Enamel Organ

OuterStellate Reticulum (SR)
Enamel Epithelium (OEE)
Stratum Intermedium (SI)
Inner Enamel Epithelium (IEE)

What layer of the enamel organ has cuboidal cells, protective function, direct connection with basal layer of epithelium, and organizes a network of capillaries that will bring nutrition to the ameloblasts?

Enamal Epithelium (OEE)

What layer of the enamel organ consists of a loose network of epithelial cells resembling connective tissue cells, makes up the bulk of the enamel organ, transmits nutrients to SI,and acts as a cushion for the IEE?

stellate reticulum

What layer of the enamel organ is made up of packed, flattened epithelial cells and helps provide nourishment for the IEE?

stratum intermedium

What layer of the enamel organ has a single layer of columnar epithelial cells, is next to the dental papilla separated by a basement membrane (future DEJ), and is continuous with the OEE? What layer of cells will become ameloblasts and is responsible for actual enamel formation?

Inner enamel Epithelium (IEE)

Future area of the CEJ
An area where the OEE and IEE meet at the most apical edge

cervical loop

The end of the cervical loop is where the _______ begins

root sheath (HERS)

T/F Enamel forms before dentin

FALSE;Dentin forms before enamel

Tooth formation starts at the _______ and _______ as well as along the ____.

incisal edge and cusp tips, DEJ

______ forms first then tooth formation progresses ________ to form the ____.

Crown;downward, root

Stages of Eruption

1: pre-eruptive
2: pre-functional (active) or passive eruptive
3: post-eruptive/functional (active)

stage of eruption that begins when the crown is formed; from developmental position and root formation to functional occlusion

pre-functional (active)

stage of eruption that exhibits occlusal wear and attrition; added cementum at apex of root

post-eruptive/functional (active)

stage of eruption that looks like the tooth erupts, but in reality the gingiva recedes instead

passive eruption

Causes for Exfoliation/Eruption

1: increase in permanent tooth size
2: attached PDL fibers are lost
3: increased masticatory forces or muscle growth
4: facial growth of arches and alveolar processes

What happens with premature loss of a deciduous tooth?

normal jaw growth may not take place: 1 side develops differently

Why does one side of the jaw develop differently when a primary tooth is prematurely lost?

chewing only on 1 side; chewing side stimulates bone growth only on that side

Problems with mixed dentition

retained root tips;
permanent tooth impactions,
midline diastimas,
submerged/impacted primary teeth
ectopic eruption

Retained root tips most commonly occur in primary ______. What teeth replace them?

molars;premolars

The inner part of the JE is attached to the tooth via the ______ lamina by _________.

basal;hemidesmosomes