GUMES Oral Bio Flashcards
which layer of the teeth does not contain collagen
enamel
what is the enamel
the hard mineralised coating of the crown that is brittle but resistant to abrasion
is enamel vascular
no it is not
what changes can enamel go through
it is unable to regenerate but it can undergo mineralisation changes
what does translucent mean
allows light to pass through
what is amelogenesis
enamel development
what is the enamel developed from
the ectoderm
which cells form enamel
ameloblasts
what are the stages of enamel formation
secretory and maturation stage
how many ameloblasts form a single rod
four
what is the rate of amelogenesis
4 microns per day
when do primary epithelial bands appear
at 6 weeks of pregnancy
what does the primary epithelial band divide into
dental lamina and vestibular lamina
what does the dental lamina form
the enamel
what are the enamel prisms
tightly packed masses of hydroxyapatite crystals
how is the enamel rod arranged to the amelocemental junction
perpendicular
how thick is enamel
2.5mm
where is enamel the thickest
cusps and incisal edge
where is enamel the thinnest
the cervical margin
how does the enamel of deciduous teeth compare to the enamel of permanent teeth
it is thinner
what percentage of weight of enamel is hydroxyapatite
95%
what percentage of volume of enamel is hydroxyapatite
90%
what percentage of enamel is water weight
4%
what percentage of enamel is water by volume
5-10%
what percentage of enamel is organic matrix by weight
1%
what percentage of enamel is organic matric by volume
1-2%
what is dentine
calcified tissue that surrounds pulp
what does dentine do
provide support for enamel as it is not as brittle
why is dentine permeable
due to the presence of tubules
are there cells in dentine
no, only the cell processes that extend from the pulp
is dentine vascular
no
how much of organic matric is ground substance in dentine
10%
how much of organic matrix is type one collagen in dentine
90%
how much of dentine by weight is hydroxyapatite
70%
how much of dentine by volume is hydroxyapatite
50%
how much of dentine by weight is water
10%
how much of dentine by volume is water
20%
how much of dentine by weight is organic matrix
20%
how much of dentine by volume is organic matrix
30%
what forms the walll of each dentinal tubule
intratubular dentine
describe the shape of dentinal tubules
s
what is found within dentinal tubules
odontoblast processes
nerve terminals
dendritic cells
extra cellulular fluid from the pulp
what is the pulp made up of
odontoblasts fibroblasts and defence cells
describe the pulp
centre of the tooth that is innervated, vascular and containing lymphatics
where is pulp contained
within the pulp chamber
what is dentine formed from
the dental papilla
what is pulp formed from
the dental papilla
if pulp is exposed and there are senses like cold, hot or pressure, are they generated as seperate senses
no it is all generated as pain
what are the four primary functions of pulp
- form dentine
- provide nutritents and moisturise the surrounding tissues
- protective role through reparative dentine
- sensory role as it transmits sensivity
what is cementum
calcified substance covering the root dentine
what forms cementum
cementocytes
where are cementocytes found
in lacunae
is cementum vascular
no
where does cementum receives its nutrition from
the periodontal ligament
what does cementum contain
collagen matrix
is cementum regenerated
continuously
which form of cementum is formed first
acellular
which form of cementum is formed later
cellular
where is cellular cementum found
apical root and furcation regions
which type of cementum contains extrinsic fibres
acellular
how are the extrinsic fibres orientated
perpendicularly
what produces the extrinsic fibres
periodontal ligament fibroblasts
what are sharpey’s fibres
terminal ends of principle fibres that attach tooth to the alveolar bone
which cementum has sharpeys fibres
cellular
how do the intrinsic fibres of cementum lie
parallel to the surface
does cellular cementum attach tooth to the bone
no
what is the periodontal ligament
fibrous connective tissue that joints the cementum to the alveolar bone
how thick is the PDL
0.2mm
what are the features of PDL
cellular
vascular
innervated
what does the organic matrix of periodontal ligament contain
proteoglycans
glycoproteins
GAGs
what are the cells of the periodontal ligament
fibroblasts
cementoblasts
osteoclasts
cementoclasts
epithelial cells
defence cells
what is present in the PDL to register pain and pressure
nerve endings
what do the mechanoreceptors in the PDL do
allow the jaw to relax when biting down on hard objects
what do nociceptors in the PDL do
respond to potentially damaging stimuli by causing perception of pain
what are the two PDL fibres
true periodontal ligament and gingival ligament
function of true PDL
adhere tooth to bone
where is gingival PDL
above the alveolar crest which is the portiono f alveolar bone extending beyond the periphery of the socket
describe the gland types in salivary glands
compound tubuloacinar
when is the bicarbonate concentration of saliva high
at high flow rate
what are the ions found in saliva
fluoride
calcium
phosphate
thiocyanate
bicarbonate
how does bicarbonate enter the saliva
partially from the blood carbon dioxide and through action of carbonic anhydrase
what is the buffering capacity of saliva
6.7
how many ml of saliva is in the mouth at any one time
1.1ml over an area of 200 cm squared, making it 50-100 micrometres thick
what is clearance
the rate at which substances are removed from the mouth
how do plaque microorganisms generate acid
metabolising fermentable carbohydrates
can alternative sweeteners be metabolised by plaque bacteria
no
what are the types of sweeteners
bulk caloric
low caloric
non caloric
what is xerostomia
this is when salivay flow rate falls below 50% of normal levels
what can cause xerostomia
sjogrens syndrome
salivary stones blocking ducts
side effect to drugs
what can saliva substitutes be based on
mucin or cellulose
what does pressure on the PDL lead to
saliva secretion from the ipsilateral galnds
what is the primary secretion of salivary glands produced by
acinar
what is the secondary secretion of salivary glands produced by
ducts
at what angle to enamel rods deposite to the ameloblast
right angles
what is sulcular fluid
the crevicular fluid, the fluid from the epithelium lining the gingival crevice
what is the sulcus
the gingival crevice
which cells are found in the pulp
proteoglycans
odontoblasts
fibroblasts
lymphocytes
what are the functions of the periodontium
retain the tooth in socket
resist masticatory loads
defensive barrier, protect tissues against threats from the oral environment
what are the periodontal fibres
- alveolar crest
- horizontal
- interadicular
- oblique
- trans septal group
- apical
where are interadicular fibres found
bifurcation region
where is transeptal found
horizontally above the alveolar crest fibres
functions of oral fluids
- cleansing
- mucosal protection
- buffering
- antimicrobial
what is the main buffering system in saliva
the carbonic acid, bicarbonate system is the most important buffer in stimulated saliva due to its higher concentration
when are phosphates important buffers
at rest
when does the main buffering action of proteins occur
at pH lower than 5
