Tooth development Flashcards
Where is enamel derived from?
The ectoderm
Where are the tooths supporting structures derived from?
The ectomesenchyme
What is the ectomesenchyme?
Part of the neural crest that develops alongside the primitive nervous system.
What is phase 1 of development called?
Initiation
What occurs in stage 1 of development?
Development of the epithelium covering the primitive mouth.
What structures are present during phase 1?
Maxillary process
Stomodaeum
Mandibular process
What does the stomodaeum form?
The anterior part of the face
What occurs at 7 weeks from the primary epithelial band?
Jaw subdivides into the
Vestibular lamina: Forms the buccal area and the sulcus.
Dental lamina: Eventually at a later stage forms the enamel organ.
What is stage 2 of development called?
Morphogenesis:
The bud stage. 8-10 weeks
The cap stage 11 weeks
What occurs at stage 2/the bud stage of development?
The dental lamina thickens to form the enamel organ.
Ectomesenchyme cells reorganise to form the dental papilla (which forms tooth supporting structures i.e. dentine and pulp.)
What occurs at stage 2/the cap stage of development?
External and internal enamel epithelia develop.
Both meet at the cervical loop.
What is stage 3 of tooth development called?
Cytodifferentiation/ the bell stage.
What occurs in stage 3?
Defined tooth shape starts to form.
Vascularisation from both sides.
Stellate reticulum forms.
What is the purpose of the stellate reticulum?
Provides support for the tissues during enamel formation.
When do permanent teeth start to germ? What occurs at this stage.
Week 12
Lingual extension of the dental lamina.
When does the first permeant molar develop?
Week 16.
What is stage 4 of tooth formation called?
Matrix secretion/ the late bell stage
What occurs during this stage?
Crown shape is well defined.
Dentine is well established.
Enamel formation begins.
At stage 4; What structure differentiates into odontoblasts?
The dental papilla.
What triggers the start of enamel formation by ameloblasts (from the inner enamel epithelium)?
The start of dentine formation.
Briefly describe the 2 stages of enamel formation.
Matrix secretion.
Maturation by removal of the organic material.
When does stage 5, root formation, occur?
Once the crown has been formed.
What is root shape determined by?
Apical growth of the cervical loop. Called Hertwig’s epithelial root sheath.
what induces the formation of root dentine?
HERS
When does HERS break down?
Once the initial layer of root dentine is formed.
What are debris of malassez?
Remnants of the HERS.
What can debris of malassez lead to the formation of?
Cysts.
Where do mesenchymal cells arise from?
The dental follicle.
What is formed once the mesenchymal cells come into contact with dentine?
Differentiates into cementoblasts which form cementum.
What is the origin of the dental lamina/enamel organ?
Ectoderm.
What is the origin of the dental papilla?
Neural crest
What is the origin of the dental follicle?
Neural crest.
What type of tissue is the enamel organ?
Epithelium
What type of tissue is the dental papilla?
Ectomesenchyme
What type of tissue is the dental follicle?
Ectomesenchyme
