Anatomy - Week 6 PP Flashcards
Odontogenesis
is the process of tooth development
Developmental disturbances
Developmental disturbances can occur within each stage of odontogenesis, affecting the physiologic process taking place
- These developmental disturbances can have
ramifications that may affect the clinical treatment
of a patient
When Does Tooth Development Begin?
Begins in the 7th week of embryonic development
- Continues until the late teens
◦ Exfoliation of primary dentitions
◦ Development and eruption of the permanent teeth
Tooth Tissues
All the tissues of the tooth are specialized forms of
connective tissue, except enamel * Each tooth is the product of two tissues that
interact during tooth development –ectoderm and
mesoderm (mesenchyme) ◦ Enamel - ectoderm
◦ Cementum - mesenchyme
◦ Dentin - mesenchyme
◦ Pulp - mesenchyme
5 Main Processes that Occur
- Induction - one group of cells directs the development of another group of cells.
- Proliferation - results in an increase of the number of cells
- Differentiation - when one cell begins to look different from another – cells become more
specialized. (specialized to do specific function - to do a their job) - Morphogenesis – causes a tissue or organ to develop its shape (cells are specialized to cause organ/tissue to change shape)
- Maturation – creates mature form (cells become mature)
6 Stages of Tooth Development
- Initiation (6-7th week) – ectoderm gives rise to the oral epithelium and then to the dental lamina with its dental placodes
- Bud stage (8th week) —growth of the dental placode into a bud shape that penetrates the
growing ectomesenchyme - Cap stage (9th-10th week)—future shape of the tooth becomes evident; cells specialize to form the enamel organ
- Bell stage (11th -12th week) —differentiation of the enamel organ into a bell shape with 4 cell types and the dental papilla into two cell types.
- Apposition (various times - happen back and forth, not necessarily 5th) — dental tissues secreted in successive layers as a matrix
- Maturation (various times - happen back and forth, not necessarily 6th) — dental tissue types fully mineralize to their mature form
Epithelial components (ectoderm)
- Enamel Organ - tooth germ becomes organized, develops into 4 layers
- proliferation, differentiation, & morphogenesis
- Bell Stage
Outer Enamel Epithelium (OEE) *
*Covers enamel organ
*Cuboidal cells
* One cell layer thick
* Outlines the shape of the
developing enamel *Organizes capillaries
(provides nutrition)
* Protects enamel orga
Stellate Reticulum (SR) (star shaped)
*Between OEE and IEE
*Star-shaped
*Many layers *Protects/Cushions
*Nourishes
Stratum intermedium (SI)
*Between SR and IEE
*Flat epithelial cell * 2-3 layers thick
*Lie on top of the IEE
*Helps ameloblast
formation
*Nourishes IEE
Inner Enamel Epithelium (IEE)
*The concave lining of the
enamel organ
*Cuboidal cells
*Become columnar cells
*One layer thick
*Becomes ameloblasts
*Nourishes
Mesenchymal Components - The Dental Sac
Dental sac (follicle)—surrounds the developing
tooth germ and provides cells that will form the
periodontal ligament, which, in turn, will produce
the cementum and the alveolar bone proper
The Bell Stage Layers of the Enamel Organ
Outer Enamel Epithilum (OEE)
Stellate Reticulum (SR)
Stratum Intermedium (SI)
Inner Enamel Epithelium (IEE)
Mesenchymal Components - The Dental Papilla
Dental papilla—condensed ectomesenchyme
located on the concave side of the enamel organ; peripheral cells facing the IEE will differentiate
into odontoblasts, dentin-forming cells
◦ The center of the dental papilla will become the dental
pulp
Enamel & Dentin Formation
-Apposition and maturation stages
* Induction, proliferation and maturation
* Begins at the dentino-enamel junction (DEJ)