histology and properties of teeth Flashcards
What components make up teeth?
enamel, dentine, pulp then bone is around it (alveolar then normal bone)
a) Give the percentage of enamel in comparison to water and mineral in enamel!!! as percentage by weight followed by pecentage by volume:
B)What is the significance of the percentage of mineral in enamel in thin tooth sections (4-10 micrometers)
a) weight=95% -9- vol= 86%
b) Because enamel is highly mineralised, it is completely removed during tissue processing whereas the protein components of dentine (~30% by volume??) remain and can be visualized using histological stains.
Give the percentage of 2) organic matrix 3) mineral in dentine!!! B)What is the significance of the percentage of protein in dentine in thin tooth sections (4-10 micrometers) incomparison to water as well
2) weight=20%- +10Vol=30%
3) weight=70%- /2Vol=45%
The volume is the same % by weight for bone
B) protein components of dentine (~30% by volume??) remain and can be visualized using histological stains unlike enamel whichis mostly mineral
Give the percentage of
3) mineral
in bone!!!
in comparison to water and mineral
3) weight=45%- Vol=23%
Give the percentage of 1) water 2) organic matrix 3) mineral in cementum!!!
1) weight=12%- *3 Vol=36%
2) weight=27%- +4 Vol=31%
3) weight=61%- /2 Vol=33%
What is the mineral content by weight of :
1) enamel
2) dentine
3) cementum
1) 95
2) 70
3) 61
Put these in order of hardness:
enamel, dentine, bone, cementum
enamel, dentine, cementum, bone
If hit with a hard blow to the side what would the following do: 1) enamel 2) dentine 3) cementum B) Which would cope the best?
1) crack- as brittle like glass
2) spring back into shape - as resilient like a balloon
3) bare through- as tought like a mountain backpack
B) dentine
1)Put these in order of non-living to living:
enamel, dentine and cementum
explain your middle choice
2) What is the significance of this to dentine?
enamel- non-living
cementum- living at start then may die in maturity
dentine- living
2) IS the only one that requires nourishment which it receives from odontoblasts
State what cell types forms the following:
1) enamel
2) dentine
3) cementum
1) Ameloblast
2) Odontoblast
3) cementoblast
State what cell types provide nutrition to the following:
1) enamel
2) dentine
3) cementum
1) TRICK_ none
2) odontoblasts (same thing that forms it
3) none or cementocytes
1) Which of the following is sensitive:
2) Why is this essential?
dentine- feels pain
2) pain must be felt so tertairy dentine can be formed to protect pulp form pain causing external stimuli that can be weak or severe
What are the 2 types of tertairy dentine ?
2) Why are they different
1) tertariy reactionary dentine and tertairy reparative dentine
2) orginal odontoblasts from reactionary and ths stimulus is weak, newly recruited odontoblasts (i.e. progenitor cells have had to be recruited and proliferated to form more odontoblasts) form reparative and the injury is severe
Which of the following are able to repair themselves:
enamel, dentine and cementum
dentine (tertariy reactionary dentine and tertairy reparative dentine) and cementum
1) What is the difference between primmary and secondary dentine?
2) WHat is the clinical signifcance of this?
primmary is the only dentine present until completion of the root, after that it is the furthest dentine from the pulp
secondary dentine is closer to the pulp and is formed after completion of roots, in time it reduces the size of the pulp chamber and root canal
2) Older people have smaller roots , so thinner drill used to remove root
What mineral forms enamel?
calcium hydroxyapatite
1) What does one ameloblast form?
2) What structure do these rods take?
1) enamel prism (or rod)
2) they run from the enamel-dentine junction to the crown surface along a curve (you will see lots of little curved Hunter-schreger bands in section- that change )in the vertical plane section while interacting across their length with each other though undulating up and down this is known as decussation. SO if you shaved off some enamel you would see a wave this is the decussation
What is decussation
a weird way to cross one another, enamel rods do this as they run in a curve in the vertical plane but across there length they undulate up an down
You will see nerve endings between odontoblasts. What are the nerve endings function?
The dentine-pulp complex is able to sense changes in the dentine such as tooth wear or progressing caries. There are three different theories how the nerves in the dental pulp could be involved in this process.
Why can pulp stones be present in teeth?
1) teeth have suffered injury
2) age-related, older pulp is less vascular and more often mineralised in the form of pulp stones
How do blood vessels and nerves enter the pulp?
apical foramen and accessory canal
What type of tissue is present in pulp and what is made from?
2) What cells are present in pulp?
1) fibrous connective tissue
2) odontoblasts, fibroblasts, undifferentiated cells and defence cells
Describe the stages of formation of tertiary reparative dentine?
1) intense stimulus/severe injury
2) release of growth factors and signalling molecules
3) odontoblasts upregulated (increase in amount) and progenitor cells are proliferated and recruited to form reparative dentine
What cell types foes the pulp contain?
odontoblasts, fibroblasts, undifferentiated cells and defence cells
What is fissure sealant placed into? why?
occlusal fissures
frequent site of carries as you cannot get a toothbrush bristle in
How is dentine structured?
curved shaped dentinal tubules
What are the tooth supporting structures?
gingiva, periodontal ligament, alveolar bone, cementum
What is the function of tooth supporting structures?
attach teeth to jaw
support teeth during chewing as loads creater lateral and horizontal movement