Tooth and jaw development Flashcards
What happens to a tooth as it begins to erupt
The root start to grow with very open apical ends
Why can we not see anything on an xray before the snow capped peaks even though the tooth started developing before that?
As there is no mineral involved in early development of a tooth
Name the 3 main developmental processes of tooth formation
- Determination of position and morphology
- Initiation
- Control
What is the aim of the determination process of tooth development
To map out where teeth will grow in the mouth and which teeth will grow where
How is tooth development controlled
Via ectodermal and mesenchymal interactions
What can interactions between ectodermal and mesenchymal tissue lead to
can up or downregulate:
1. Proliferation
2. Differentiation
What happens if ectodermal/ mesenchymal interactions affects proliferation?
Morphogenesis occurs
What is morphogenesis?
Formation of crown and root shape
What happens if ectodermal/ mesenchymal interactions affects differentiation?
Histodifferentation occurs which leads to tissue formation
What is histodifferentiation
The formation of distinct cell populations
Name the 3 morphogenic field
- Incisor field
- Canine field
- Molar field
What does the ectomesencyme control
What type of tissue will form where and the morphology of the tooth
State the initial stage of tooth development
The primary epithelial band splits into vestibular lamina and dental lamina
List the stages of tooth formation once the dental lamina has formed
- Bud stage
- Cap stage
- Bell stage early
- Bell stage late
- Root development
What is significant about the late bell stage
It marks the point at which the first mineral deposited out the cusp of the tooth
thus the Tooth is first visible at this point on an x ray
What does the primary epithelial band determine
It maps out where the upper and lower dental arches
As the tooth buds continue to develop what else is happening at the same time?
A plate of bone is forming below the tooth germ- this is the lateral plate of the mandible/ maxilla
Where and hoes does the bone of the jaw form
The bone of the jaw forms denovo within the mesenchyme
eventually a second medial plate of bone ill develop to form a trough where the tooth germ is contained
What is bone formation in the mesenchyme called?
Intramembranous bone formation
Name the cartilage found on the mandible
Meckel’s cartridge
As the jaw is developing what is happening to the actual tooth?
- Its enamel organ has started to grow into the beginnings of the cap stage
- Indications of histogenesis starting
- Ectomesenchyme has also proliferated to from a dense condensation in and around the enamel organ
What does the cap shape mark out?
Marks out where the primary cusps of the tooth will form
What is the part enclosed by the enamel organ called
Dental papilla
What is the part surrounded by the enamel organ called
Dental follicle
What does the dental papilla eventually form
Dentine and pulp of the tooth
What does the dental follicle eventually forming
The periodontal ligament and cementum
Possible some of the alveolar bone
Describe the later cap stage
- Beginnings of the socket are evident (bone surrounds tooth germ)
- Enamel organ has grown
- Further histogenesis
- Inner and outer enamel epithelium has formed
- Down growth lingually of a breach of the dental lamina
What is the inner enamel epithelium
A distinct inner layer of columnar cells
What is the other enamel epithelium
More cuboidal cells forming the other envelope
in the later stage what is the bulk of the enamel organ made up of
Consists of loose, stellate reticulum
Describe the enamel organ in the later cap stage
- Bulk made up loose stellate reticulum
- Transitionary structure found
Name the elements of the transitionary structure
Enamel knot
enamel sputum
What is the significance of the enamel knot
May have an important role in interacting with the mesenchyme is cuspal initiation and initial control
What is the significance of the enamel septum
May be a site where cell division is occurring to provide more cells for the stellate reticulum as it enlarges
