histopathology of caries Flashcards
what things leave in early carious lesion
calcium
phosphate
carbonate
what helps remineralization
saliva
calcium
phosphate
carbonate
fluoride
pH control
does enamel erupt fully mineralized? y/n
yes
enamel breakdown by % by weight
95% mineral, 5% water
enamel consist of what
hydroxyapatite
enamel is derived from what
ectodermal component
enamel is formed by what
ameloblast (lost as tooth erupts)
is enamel vascular and cellular
it is avascular and acellular, cannot be regenerated
enamel structure organization
rods (prism) and interrod enamel (interprismatic substance)
enamel is build from closely packed and long, ribbon like and separated by neighbor by what spaces
carbanatoapatite crystals
tiny intercrystalline spaces
crystal dimensions (width and thickness) and what symmetry
60-70nm in width, 25-30 nm in thickness
hexagonal symmetry
hydroxyapatite formula
Ca10(PO4)6(OH)2
what else does enamel consist of
carbonate, sodium, fluoride
hydroxyapatite knoop hardness number
430 KHN
enamel knoop harndess number
370 KHN
ranking of hardness
enamel > dentin = cementum > bone
dentin derived from what original
mesenchymal
what quality of dentin prevents fracture of enamel
elastic
Dentin breakdown
70% inorganic (HA in form of small plates)
20% oranic (90% collage (type I, III, V), proteins and lipids)
10% water
critical pH of enamel
5.5
critical pH of dentin
6.2
critical pH of enamel changes to what w fluoroapatite
4.5
what was used to show dentin is permeable
H2O2
what is the protected area
area on tooth surface where dental plaque is allowed to accumulate undisturbed by mechanical forces days and weeks
1 week change
increase porosity 20-100um deep (microscopically)
dissolution of outer enamel surface
increase in intercrystalline spaces
2 week change
enamel changes visible after air-drying
further increase in enamel porosity
3-4 weeks
whitish opaque change
chalky change visible w/o air drying
subsurface lesion starts to form
extensive loss of mineral beneath the outer surface
white spot lesion surface zone mineral loss
<5% mineral loss
white spot lesion surface body of lesion mineral loss
5-30% mineral loss
white spot lesion dark zone mineral loss
2-4% mineral loss
white spot lesion translucent zone mineral loss
1% mineral loss
relative protection against dissolution of outer enamel what dimension
10-50um
what protein is rich in the saliva that helps prevent breakdown
proline
white spot to cavitation timeline
1-2 week ultrastructural
3-4 weeks white spot
then cavitation
what does sclerotic dentin do
make dentinal tubules smaller so acid cant enter (defense mechanism)
reactive dentin helps protect
pulp
what shape is the smooth surface enamel lesion
board area of origina, conical or pointed extension towards DEJ
V shape from external enamel to DEJ
what is an integral part of the pulpodentinal organ
odontoblast
what is teh most common defense mechanism
tubular sclerosis, which is deposition of mineral along and within the dentinal tubules, resulting in gradual occlusion
outer lesion
bacteria penetrated, most of structure lost to demineralization produced by bacterial acids
turbid inner lesion
no bacteria present
lost peritubular dentin and the intertubular dentin mostly demineralized
transparent inner lesion
retains peritubular dentin and the tubule may be partially filled w minerals (whitlockite crystals)
sub transparent inner lesion
presents granular-shapped crystals and normal dentin is found beneath
what does the inner lesion consist of
turbid, transparent, sub-transparent
when may varying inflammatory reactions be seen in the subodontoblastic regions
when demineralization approaches the pulp between 0.5-1mm
for pulp reactions, the inflammatory cell reactions are the result of what
bacterial byproducts
if bacteria invade the pulp, acute inflammatory response is created with what
neutrophil leukocyte accumulation
composition of root surface
70% inorganic
20% organic
10% water
do early lesions on root surfaces appear as white spots
no
root surface caries factors
root exposed
poor oral hygiene
xerostomia
salivary gland hypofunction
dietary habits
location (plaque retentive areas)
