Fluoride and caries Flashcards
in 1930 fluoride levels in drinking water was noted for what
fluorosis was related to F in drinking water and F was associated with reduced caries rates
what is the ideal concentration of F to maximize caries benefits and minimize fluorosis
F at 1 ppm! reduced caries by 50%!
what lays down enamel
ameloblasts
what happens during secretory stage of ameloblasts
ameloblasts lay down protein matrix and rods begin to form
what happens during pre eruptive stage (maturation stage) of ameloblasts
maturation stage= ameloblasts fill in crystal structure with mineral
during the secretory stage high levels of F can do what
high levels of F during secretory stage causes pitting and disturbances in form
what happens during the maturation stage when moderately high levels of F are present
maturation stage + high levels of F = chalky whiteness and weakness of enamel causing possible fracture and stain after eruption
how much F is incorporated into the enamel during the pre eruptive stage
very little F put into enamel during maturation stage
before tooth eruption does F water provide a benefit?
NO benefit of F water before tooth eruption
in order for benefits to continue what must happen
fluoridation must continue throughout life
will people benefit from fluoridation after teeth have erupted?
YES
What has impacted reduced caries rate in addition to F water?
topical products like toothpaste!
what are the effects of water fluoridation?
water fluoridation = topical effects
what increases fluorosis
INGESTION of F
topical products or systemic supplements which one provides a lower risk
TOPICAL products = lower risks
who do we systemically supplement with F
HIGH risk children, but policies are not in line with evidence
Enamel composition
87% HA
11% water
2% organic
what do newly formed crystals in a young tooth usually have?
Impurities such as carbonate, sodium, other ions
what is post eruptive enamel maturation
the replacement of carbonate with phosphate, replacement of sodium w calcium, and replacement of hydroxyl with F through the bathing of saliva that has been exposed to F
what does post eruptive maturation do to enamel
makes HA less soluble and this enamel stronger
what teeth are more susceptible to caries?
young teeth, post eruptive maturation strengthens teeth over time
when does HA crystals dissolve?
when pH drops below 5.5
the lower the pH the more demineralization occurs
What does F ions do?
F prevents dissolving of Ca ions, under acidic conditions HA dissolves and reprecipitates as F-HA
what is less soluble thus stronger? HA or F-HA
F-HA is stronger and less soluble
what does the pH needs to remain above for F-HA to form when HA dissolves from subsurface
F-HA needs pH above 4.5!! and F must be available
when pH rises above 5.5 what happens
F ions enhance remineralization of enamel and dentin
presence of F at ____ levels in solution is more ____ than ____ concentrations incorporated into enamel
presence of F at low levels in solution is more beneficial than high concentrations incorporated into enamel
outer enamel (surface) has more what and less what?
surface enamel has more F-HA and less carbonate
does F diffuse well into the body of a lesion?
NO F will react with outer layers first to form F-HA
what happens during demineralization?
subsurface HA is dissolved while surface F-HA is formed leaving a demineralized subsurface and a thin enamel shell
white spot lesions usually have what compared to surrounding enamel areas?
white spot lesions have very HIGH F concentrations
areas covered by plaque have what
plaque covered enamel has HIGH F levels
worn areas from abrasion and erosion have what levels of F
worn areas= low levels of F
when does F-Ha form on the surfaces of enamel
when topical F concentrations are 50 ppm or lower
what happens when topical F concentrations are 100 ppm or higher?
CaF2 precipitates, acid helps with deposition of CaF bc Ca ions are available
what happens on the surface, in crevices, and in plaque to F
spherical globules precipitate
what 3 factors increase CaF2 deposition
INC concentration of F
INC exposure time
low pH
what protects from CaF2 deposition
limit rinsing or covering with varnish
what prevents teeth from dissolving
supersaturation of saliva with Ca and P
why don’t HA crystal continue to grow?
Bc salivary pellicle proteins coat the enamel such as Tyrosine proteins, statherin, and proline proteins
what prevents spontaneous precipitation in salivary ducts?
salivary pellicle proteins
what does plaque do
Prevents access of saliva to enamel surface
what leads to calculus formation
high concentrations of Ca and P
when can fluorosis occur
During TEETH DEVELOPMENT
F concentration on teeth highest where
F highest on tooth surface decent on topical exposure
is exposure during tooth development a major determinant of F levels in enamel?
NO!!
what is fluorosis
Fluorosis is an increase in enamel porosity that appears chalky white
when does brown discoloration occur to teeth
post eruptively due to staining and browning of exposed proteins
Fluorosis severity and incidence is correlated with what
amount of F exposure
is there a threshold which will cause now fluorosis below that threshold?
NO low levels of F a certain level of fluorosis occurs
what is seen as attractive by most?
mild fluorosis
what teeth have the greatest risk of fluorosis and when?
Upper central incisors from 15-30 months
How does F play a role in antimicrobial effects?
F binds to sites that would normally bind to OH and inhibits enzymes and regulatory proteins
Do bacteria develop resistance to F?
NOO bacterial resistance to F
What does F do to enolase to prevent acid production?
F inhibits enolase
when is F most effective against glycolysis
at low pH
how does F affect the ecology of biofilms?
reduces enrichment of acid tolerant species
does F have affect bacteria at normal pH?
No! F has no inhibitory effects at higher pH
what is the most productive way to distribute F?
Community based water Fluoridation
Self applied F
topical, high freq low concentration and systemic supplements
professionally applied
low freq, high concentration topical
when is optimum benefit of F observed?
during acid challenge
Toothpaste F concentration
1000 ppm F (.1 or .15%)
NaF2 and SnF2 have equal or different effectiveness and concentrations of F
both are equally effective and equally concentrated with F
what is not compatible with chalk based formulas?
NaF2 need silica based for NaF2
what is compatible with chalk based formulas?
MFP
Rx toothpaste has what concentration of F
5000 ppm
is there a relationship between amount of toothpaste and caries
NO. amount doesn’t matter concentration is the important
what is important with toothpaste and brushing?
Frequency! twice a day best!
rinse or no rinse better?
NO RINSE best!
safe amounts for preschool children?
pea sized dab
OTC F rinse concentration and effectiveness
.02% F (200 ppm)
25% reduction in caries
