1cumulative microevents that happen at tooth surface
pH fluctiations
fluctuating mineral loss or gain from that pH fluc
clinical WSL due to mineral loss
2enamel inorg/org by WEIGHT
96 inorg
4 water/org
3enamel inorg/org by VOLUME
86 inorg
2 org
12 water
4why is enamel translucent
hydroxyapatite crystals tightly packed > glass like appearance
5what affects tooth color
thickness of enamel
6can enamel repair or undergo cell remodel
no
7striae of retzius
incremental lines of enamel from amelogenesis
8striae of retzius location
from DEJ to tooth outer surface
9when do striae of retzius appear
rest periods in amelogenesis, where ameloblastic activity slows in consistent intervals
10striae of retzius at tooth outer surface
perikymara, grooves that are separated by ridges
11enamel lamellae
hypomineralized structures from surface to various depths; can sometimes cross DEJ and enter dentin
12enamel lamellae occurs due to
incomplete maturation of groups of prisms
13enamel lamellae can act as
permeable channels for bact; can be entry for dentinal caries
14enamel spindle
entrapped extensions of odontoblasts
15how do enamel spindles form
before enamel formation begins; odontoblast processes cross into dentin, enter enamel, get trapped within ameloblast layer after amelogenesis starts
16are enamel spindles hyper or hypo mineralized
HYPO! less calcium and phosphorus
17enamel spindles serve as
pain receptors! why some people have hypersensitivity with shallow preps
18enamel tuft
HYPOmineralized structures from DEJ to enamel
19where do enamel tufts appear
on inner third of enamel as mineralization faults/defects
20what do enamel tufts contain
hypocalcified enamel rods, inter-rod substances with more prot
21enamel tufts can become
passage for bacteria to dentinal tubules and pulp
22how are enamel crystals packed
rod and interrod; rish shape of head R and tail IR
rods extend thru all of enamel
crystal long axis follow rod
thus perpendicular sectioning shows hexagonal rod
23where is crystal packing looser
rod periphery
24what is the fundamental microstructural element of tooth
enamel rod
25what is the periprismatic sheath
intercrystalline spaces separating each crystal; junction of IR and R
26intercrystalline spaces;periprismatic sheath fillde with
water and organic mats of dev origin
27what are micropores/pores
network of diffusion pathways formed by intercrystalline spaces
29gradual worsening of dissolution of rods corresponds to
looser packing of crystals at rod periphery
30** how is the extermal microsurface involved in the carious process from the very beginning
partial dissolution of individual crystals with enlargement of intercrystalline diffusion pathways
31clinical stage where changes seen without air drying
white stain lesion
32**relative protection of outermost enamel is due to
dynamic chemical processes; especially fluoride conc in oral fluid
33proline-rich proteins in saliva function
prevent spontaneous and selective precipitation of CaPO
inhibit demin
34is caries genetic or enviro dz?
both!
genetics: tooth morph, enamel, saliva
enviro: infeciton, biofilm, fermentable carb
35subsurface demineralization
inc intl enamel porosity > loss of translucency > more opaque
36direct surface erosion
irregular surface > diffuse reflection of light
37what direction does carious dissolution follow
direction of rods
38where is the highest degree of tissue porosity observed
along the central traverse
39what kind of solid is enamel
microporous
40what is the most common defense reaction of teeth
tubular sclerosis; deposition of mins along and within dentin tubules
41what accelerates tubular sclerosis
tooth wear or caries
42tubular sclerosis requires a
vital odontoblast
43why do obturated dentinal tubules look translucent
mineral in tubules make tissue more homogenous
44progressive destruction of occlusal surface initiated by
local process in:
deepest part of open groove-fossa
along entrance to deep, narrow fissure
45**occlusal carious lesions appear as
truncated cones; base of cone toward DEJ
46caries on O surface most often initiated in
fossae; where 2+ grooves meet
47**how many dimensions does the caries process occur in
three dimensions
48enamel lesion is cone shape because
enamel demineralization follows direction of rods
49**O enamel breakdown is the result of
demin of one or more initially established foci