enamel/dentine caries Flashcards
what is caries?
progressive destruction of tooth structure initiated by microbial activity at tooth surface
what are the requirements for caries?
plaque bacteria
time
carbohydrate substrate
susceptible tooth
what are examples of NCTSL?
erosion
abrasion
attrition
abfraction
what units is the enamel structure made up of?
prism
describe the prism unit
core: tightly packed hydroxyapatite
intercrystaline spaces
sheath: less well packed crystals, pores/spaces containing water and organic material
what does the sheath component of the prism allow?
diffusion of acid
where does demineralisation begin?
prism sheath
how does enamel caries begin?
white spot lesion
describe the zones of an enamel caries lesion
translucent zone
dark zone
body of lesion
surface zone
what occurs at the translucent zone?
1st carious change
few large pores, loss of prism periphery
quinolone fills periphery
what occurs at dark zone?
dark brown with quinolone
consists of small and large pores
demineralisation and remineralisation occuring
what occurs in the body of the lesion?
largest and centre of the lesion
more porous
enamel relatively translucent
striae of retzius more obvious
what occurs at the surface zone?
relatively intact
highly mineralised- high fluoride content
forms and reforms during caries process
what are defence responses shown by dentine?
reactionary/tertiary dentine
translucent/sclerotic zone- blocks tubules
if progression is rapid, what occurs?
no sclerosis
odontoblasts die
reparative, tertiary dentine
what are the zones of dentine caries?
advancing front
zone of bacterial penetration
zone of destruction
what occurs at advancing front?
zone of demineralise dentine
acid demineralisation
no bacteria
what occurs in zone of bacterial penetration?q
bacteria in tubules
lateral spread via branched tubules
lactobacilli present
what occurs in the zone of destruction?
mixed bacterial population
proteolytic enzymes
destroys organic matrix
what occurs in outer/superficial zone
highly infected
irreversibly demineralised dentine
degradation of collagen matrix
what occurs in inner, deeper zones
reversibly attacked dentine
minimally infected
potential for repair
