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
What are the 2 types of gingiva?
a) What is it attached to?
b) Is it keratinized?
1) free gingiva , a) nothing, it is movable (runs upwards ftom free gingival croove to gingival margin)
b) both
2) attached gingiva a) attached to underlying bone
c) keratinized
3) junctional epithelium -possible
What is keratin?
protein formed by damadged epithelial cells
1) where is the junctional epithelium of gingiva in a healthy mouth?
2) What property does it have that has an immunological role?
3) What does it attach to?
1) apex of cemento-enamel junction
2) junction between cells is less tight= leaky to allow crevicular fluid to flow into gingival sulcus (crevice) with immune defence cells
3) enamel
1) Why does healthy gingiva appear pale pink compared ot other areas of the mouth?
2) What is the function of this protein?
1) high content of keratin
2) protects tissue from damage due to abrasive forces during mastication
What is the cause of the enamel space in a demineralised section of gingiva between 2 teeth?
95% mineral so enamel dissolved
What of the gingiva attaches to:
1) enamel
2) cementum?
1) epithelium
2) connectve tissue
What types of connective tissue is periodontal ligament?
dense
Describe the following about periodontal ligament:
1) rate of cell turnover
1) rate of cell tunrover
Describe the following about periodontal ligament: 1) rate of cell turnover 2) vascular supply 3) innervation B) What is the significance of A.2? C) What is the significance of A.3?
A1) high 2)rich 3)rich B) heals quickly C) sensory and pain responce
What cells types are contained within the periodonal ligament and what are there funciton
cementoblasts- form cementum
fibroblasts- form fibres
osteoblasts- form bone
Describe the structure of the periodontal ligamen:
collagen fibres organised into groups=bundles
- the pinciple fibres ( the bundles) are embedded in the alveolar bone and cementum- they are called sharpey fibres
What is the name given to principle fibres of pdl?
sharpeys fibres
What is the function of sharpey fibres?
resist intrusion of tooth during mastication (pushing into mandible
What do cementum and alveolar bone have in common?
attached to either side of pdl, both are mineralised
1) Where is cellular cementum found?
2) Where is acellular cementum found?
3) When does cementum stop growing?
1) around apex of ttoh
2) covering roots
3) TRICK_ grows slowly and accumulates throughout of your life- otherwise what would be the function of those cementoblasts in the pdl
1) Where is cellular cementum found?
2) Where is acellular cementum found?
3) When does cementum stop growing?
1) around apex of ttoh
2) covering roots
3) TRICK_ grows slowly and accumulates throughout of your life- otherwise what would be the function of those cementoblasts in the pdl
What larger bones is the alveolar bone a part of?
maxilla and mandible
Why is the alveolar resorbed?
What cell is responsible?
no stimulus from functional teeth
osteoclasts
1) Describe the difference in appearance of alveolar bone and normal bone in a section?
2) What is alveolar bone called in a radiograph?
alveolar bone is a bit more fibery
2) lamina dura
1) Describe the difference in appearance of alveolar bone and normal bone in a section?
2) What is alveolar bone called in a radiograph?
alveolar bone is a bit more fibery
2) lamina dura
WHat are the sizes of pockets in:
1) moderate periodontal disease
2) severe periodontal disease
1) 4-5.5mm
2) +6
What is the difference between overjet and overbite?
overjet is vertical overlap
overbite is horizontal overlap, you have both at once
What is perikymata?
2) Do they remain a feature of your tooth throughout your life?
outward aspect of internal growth increments;
the normal transverse wave like grooves or lines on the external surface of the tooth.
2) no they can be lost through tooth wear
What is linear enamel hypoplasia?
2) What can cause it?
3) What is the neonatal line?
the disruption to enamel formation = deep grooves on the surface of the tooth
2) poor nutrition “stressful environment” during tooth development
3) a line or enamel formed during physiological change at birth used to identify prenatal and postnatal enamel
What are mamelons?
2) What does this have in common with pulp horns?
elavations in the cutting edge of newly emerged anterior teeth that correspond to their developmental lobes.
2) pulp horns also correspond to developmental lobes
What is the difference between
1) enamel thickness
2) Scalloping at the enamel-dentine junction (EDJ)
between a primary molar and a permanent molar
3) orientation of enamel rods
4) height of pulp horn
1) Primary teeth have thinner enamel than permanent teeth.
2) Primary teeth form faster and therefore show less scalloping at the EDJ.
3) enamel rods only point upwards in primmary teeth while permanent also have enamel in cervical thrid of teeth that point downwards
4) pulp horn higher is primmary teeth
Name three major functions of teeth.
Mechanical break-down of food: cutting, tearing, crushing, grinding
First step in digestion of food
Involved in speech (e.g. production of ‘f’ and ‘ch’ sounds)
Giving confidence (Tooth aesthetics)
1) What are the cells that form enamel called?
2) What is the process of enamel formation called?
Amelogenesis
3) Once enamel is destroyed, can it be replaced or regenerated?
1) Ameloblasts
2) Amelogenesis
3) No, because ameloblasts cannot regenerate and are lost as the tooth erupts into oral cavity.
1) What is the main organic component of dentine?
2) What cells produce dentine?
1) collagen fibres (type 1)
2) odontoblasts
Why is the enamel-dentine junction scalloped?
To provide a greater surface area for tight interlocking of enamel and dentine.
define odontogenesis:
formation and developement of teeth
Name a difference between ameloblasts and odontoblasts.
hint: devrived from what cell type?
Ameloblasts are derived from dental epithelial cells whereas odontoblasts are derived from the dental mesenchymal cells.
What is predentine?
Predentine is the protein-containing dentine matrix secreted by odontoblasts that subsequently mineralises to form dentine.
What structure does the root canal terminate at?
apical foramen
Is dentine harder or softer than bone?
Harder. Dentine (~70%) has more mineral content than bone (~40%).
Is dentine harder or softer than enamel?
Softer. Dentine (~70%) has less mineral content than enamel (~95%).
What name is given to dentine in which the dentinal tubules have become occluded with calcified material?
Sclerotic dentine
- reduces pulp permeability
- form of protection from caries
- increases with age
What cell type contributes to the majority of the dental pulp?
What is this cells function?
fibroblasts
Form and maintain the pulp matrix including collagen fibres and ground substance.
What cell types eliminates dead cells in pulp?
macrophages
Cementum is avascular. True or False?
True. Cementum is a hard tissue that surrounds the tooth roots and is part of the periodontal tissues that anchor the teeth in their sockets. Blood vessels are present in the periodontal ligament but not in cementum.
What types of collagen form the fibres of the periodontal ligament?
Mainly type I (70%) and type III (30%) collagen
Cementum is harder than compact bone. True or False?
True. Cementum (~55%) has more mineral content than bone
Cementum is harder than compact bone. True or False?
True. Cementum (~55%) has more mineral content than bone
Name two functions of the periodontal ligament (PDL).
Tooth attachment
Protection against mastication forces (‘shock-absorber’)- pushing in
