Head and neck exam 3

From the point of fertilization to two weeks of gestation

Ovum

Develops into teeth, skin, fingernails, eye tissues.

Ectoderm

Develops into muscle, blood vessels, lymph, connective tissues, bone, cartilage

Mesoderm

Develops into respiratory epithelium, digestive system, liver, pancreas

Endoderm

From week 3-8 of gestation

Embryo

From week 9 through week 36 of gestation

Fetus

6 ridges of tissue, _________ _____ are present in the neck region.

Pharyngeal arches

U shaped bars of tissues containing a wire of tissue (cartilage, artery, nerve, muscle). The first is the ______ arch, second is the _____ arch, third is through arch VI.

Mandibular, hyoid arches

The external depression between arches is called..

Pharyngeal grooves

The internal surface of the depressions are called..

Pharyngeal pouches

Pharyngeal arches wrap around the hollow tube of the developing ________.

Digestive tract

The primitive digestive tract is divided into the ______, _____, and _____.

Foregut, midgut, and hindgut

________ is the primitive oral cavity, and ectodermal depression in front of the foregut.

Stomodeum

_____________________ is between the tongue and palatine tonsil area and when it breaks the connection between the OC and digestive tract is made

Buccal pharyngeal membrane

Facial development from an anterior view at 3 weeks shows...

Frontal prominence, stomodeum, mandible and maxilla process developing from the 1st pharyngeal arch.

Nasal pits form on the _______________ and they create medial and lateral halves.

Frontal prominence

The two medial halves grow together to form the ______

Lip

If there is an error when these two medial halves join it can cause a ___________.

Cleft lip

Created by the right and left maxillary processes and the medial nasal process

Development of the palate

The medial nasal process is an area of tissue that will be the area for the maxillary centrals and laterals as well as the incisive foramen is called the.....

Primary palate/premaxilla

The right and left maxillary processes grow inward towards each other at this point called...

Palatal shelves

Fluid filled sac that develops on midline of palate

Median palatine cyst

Fluid filled sac that develops where palatal shelves and primary palate together (btw max laterals and canine), typically is removed to prevent shifting of dentition

Globilomaxillary cyst

Occurs during weeks 7-11 of development, if it occurs early the entire palate can be open, the closer to week 11 it will only affect soft palate or uvula. More likely in males, hereditary and can be caused by use of alcohol, tobacco, and drugs

Cleft palate

Triangular median swelling, located on the midline on floor of primitive pharynx in embryo, does not form any portion of mature tongue

Tuberculum Impar

2 oval distal tongue buds on each side of the tuberculum impar, the two swellings over grow and encompass the disappearing tuberculum impar to form the anterior ⅔ of the tongue

Lateral tongue swelling

Posterior to lateral tongue swellings becomes the poster third of the tongue

Copula

Posterior to the copula and becomes the epiglottis

Epiglottic swelling

Fusion of lateral tongue swellings and copula, line forms inverted V shaped groove and becomes border between base of tongue and its body

Sulcus terminalis

Located at pit depression at the center of sulcus terminalis, starting point of the thyroid development

Foramen cecum

First sign of tooth development in embryo is during the _________.

6th week

Embryonic oral stratified squamous epithelium begins to thicken and grows _________.

Downwards

Begins at midline and develops posteriorly creating a "U" shaped thickening known as ____________.

Dental lamina

The enamel organ leads to the formation of _________.

Tooth enamel

The enamel consists of 4 layers?

Outer Enamel epithelium (OEE), Inner Enamel Epithelium (IEE), Stellate reticulum (SR), and Stratum intermedium (SI)

Three stages of enamel organ development

Bud stage, cap stage, and bell stage.

The Bud stage consists of three layers of cells

Superficial, basal, and dental lamina.

Buds grow and stretch out from dental lamina, bud begins to ______ and it enters the next stage

Concave

Cap stage now consists of what 3 components

OEE, IEE, and Stellate reticulum.

The outer most part of Cap, direct continuation of basal layer, cells are low columnar or cuboidal

Outer Enamel Epithelium (OEE)

Outlines the concaved portion of the Cap, identical to the cell of OEE but named due to location.

Inner enamel epithelium (IEE)

All the cells between the OEE and IEE

Stellate reticulum

A 4th component now exists alongside OEE,IEE, and SR

Bell stage

What stage does the outline of the tooth begin to form

Bell stage

Comprised of several layers of flattened squamous cells between IEE and SR

Stellate intermedium

During the bell stage, the IEE cells differentiate into ________ to form enamel.

Ameloblasts

Protects and guides the gingiva onto the tooth.

OEE

Differentiate into ameloblasts to create enamel

IEE

Protects IEE and nourishes SI

Stellate Reticulum

Produce protein and probably nourishes the IEE

Stellate Intermedium

Only found on primary teeth and is found on the lingual side of each tooth as an extension of dental lamina. Will go through each development stage and will become permanent incisors, canines and premolars

Successional lamina

Thickened oral epithelium on the buccal direction which will split and become the vestibule

Vestibular Lamina

Condensed cells under the bell which will differentiate into dentin and pulp

Dental papilla

Couple rows of flat cells at the bottom of the papilla which turn into cementum and periodontal ligament

Dental sac/follicle

-Differentiates into the dentin and pulp

And will determine shape of tooth crown

Dental papilla

(DP) Cells of the IEE elongate and change to __________ during bell stage

Ameloblast

Cells at the edge of the DP change to ___________ and move to the center of the DP and secrete dentin matrix

Odontoblasts

_____________ secrete enamel matrix thereby creating the DEJ and move towards the OEE cells

Ameloblast

Dentin and enamel both start to make _________ crystal and calcify

Hydroxyapatite

Dental papilla formation occurs in all teeth, primary or permanent

TRUE

If a primary tooth bud does not form can a primary or permanent tooth form?

No both will be congenitally missing

White hard 96 % inorganic, jewel like hydroxyapatite crystal is the molecule Ca (10)(PO4)6-(OH)2

Enamel composition

Outer organic component of enamel

Rod sheath

4 microns wide and extends to the surface

Enamel rod

Column of rods are __________ from DEJ to surface of tooth

Perpendicular

Rods are ______ shaped with the upper end being more wide the the bottom

Keyhole

Ameloblasts lay down the matrix and deposit millions of hydroxyapatite crystals within a few days, starts at the cusp tip and develops downwards toward CEJ

MIneralization stage

Crystals grow in size until tightly packed together

Maturation stage

Development of the rod which creates a microscopic brown line is called, these can be seen clinically on the facial surfaces of anterior teeth, Aka imbrication lines

Striae of retzius

As the ameloblasts move towards the OEE the SR and SI become.....

Squished

When the ameloblasts reach the OEE it signals them to_________

Cease enamel formation

Ameloblast lay down a protective layer over the enamel called....

Primary enamel cuticle or nasmyths membrane

The OEE and Ameloblasts are squeezed together and is termed

Reduced enamel epithelium (REE)

Reduced enamel epithelium fuses with the oral epithelium producing the _______________ which will hold the gingiva to the tooth

Secondary enamel cuticle or epithelium attachment

Cracks in enamel caused by trauma or developmental issues, Hairline cracks from dentin to enamel

Lamellae

Area of hypo calcified enamel at DEJ

Enamel tuft

An odontoplast process trapped between the enamel rods

Spindle

Normal Density but the enamel is thin, yellow or gray

Hypoplastic enamel

Not enough crystals, or loosely packed aka soft teeth

Hypocalcified enamel

Hard yellow 70 % inorganic, harder than bone but not as hard as enamel

Dentin

Extends from the DEJ to pulp, each houses an odontoblast process

Dentinal tubules

Surrounds the immediate tubules

Peritubular dentin

Everything else in dental composition

Intertubular dentin

For primary dentin, __________ begin to secrete dentin at the DEJ and migrate toward the pulp

Odontoblast

At the time of tooth eruption the dentin that exists is known as _____________.

Primary dentin

Layer of dentin closest to pulp

Secondary dentin

Is secondary dentin created by the same odontoblast as primary dentin

Yes

Forms in response to trauma and in that immediate area, can be occlusal, mechanical, or chemical trauma

Reparative dentin

Entrapped areas of poorly calcified spots

Interglobular dentin

Empty dentinal tubules that allow bacteria access to the pulp leads to rapid decay

Dead Tracts

When dentinal tubules are filled with dentin material due to trauma or decay

Sclerotic dentin

Develops from the dental papilla

pulp

Nerves of the pulp are mostly _____ and only transmit pain signals

sensory

_______ nerves can cause constriction of blood vessels within the pulp

autonomic

what begins at the cervical loop (where the OEE and IEE meet

Root formation

The two layers at the root OEE and IEE fuse and create the

Hertwig's epithelial root sheath (hers)

The heartwig's epithelial root sheath and the epithelial diaphragm determines ______

Shape and number or roots

The epithelial diaphragm grows apically and ______ with single rooted teeth.

Evenly

Two rooted teeth occur when the epithelium diaphragm grows inward at two opposite areas and meet in the ________.

Middle

3 rooted teeth occur when the epithelium diaphragm has 3 areas that grow ______.

Inward