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Transcript of Aquafresh Science Academy Fluoride Slides
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Caries Formation and the Effects of Various Fluorides in Treatment
©iStockphoto.com ©iStockphoto.com/Günay Mutlu
©iStockphoto.com/Nina Shannon
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Learning objectives
To summarise the caries formation process and
fluoride mode of action
To discuss the different types of fluoride available
and their relative efficacies
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Caries development process
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©iStockphoto.comPeter Nguyen
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The five stages of caries development1,2
1. Collins WJN, et al. A Handbook for Dental Hygienists. 3rd edition. Oxford: Wright, 1992.2. Clarkson BH, et al. Caries Res 1991;25:166-173.
3. Collapse of surface layer to form cavityIrreversible
lesion
Possible
formation of
apical abscess
Reversiblelesion1. Initial subsurface
demineralization
Initial subsurface demineralization
Extension of demineralized
zone towards dentine
Collapse of surface layer to form
cavity
Extension of caries lesion into dentine
Extension of caries into pulp
11
22
33
44
55
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The five stages of caries development
[Insert animation ‘Caries development’]
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Caries sites
Pit-and-fissure caries develop
initially in the fissures of the
teeth, but can spread into the
dentine
Smooth-surface caries are
most common on interdentalsurfaces, but can occur on any
smooth surface of the tooth
Root caries attack the
cementum and dentine, which
becomes exposed asgums recede
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Caries lesions
Figure 1. Sectioned, extracted
tooth with three caries lesions
Figure 2. A single caries lesion
showing bacterial invasion in
dentinal tubules
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Demineralization and remineralization
Tooth enamel is involved in continuous demineralization
and remineralization in the oral environment
The progression or reversal of caries depends upon the
balance of demineralization and remineralization
Demineralization RemineralizationLow pH
Salivary [Ca2+]
Salivary [PO43-]
Salivary [F-]
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The natural demineralization and
remineralization process
Cyclical changes in the oral environment result in
alternating periods of demineralization and
remineralization at the tooth-plaque interface1
1. Gao XJ, et al. J Dent Res 2001;80:1834-1839.
Adapted from Aoba T. Oral Dis 2004;10:249-257.
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The natural demineralization and
remineralization process
[Insert animation ‘The action of demineralization and
remineralization in the mouth’]
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Fluoride mode of action
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Sources of fluoride
Topical agents
Fluoridated water
Other ingested sources
©iStockphoto.com/Adam Gryko
©iStockphoto.com/ Wolfgang Amri
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Fluoride effect on remineralization
and demineralization of enamel
1. Silverstone LM. Clinical uses of fluoride 1985;153-175.
2. Featherstone JD, et al. J Dent Res 1990;69:620-625.3. Aoba T. Crit Rev Oral Biol Med 1997;8:136-153.
4. Briner WW & Francis MD. Arch Oral Biol 1962 7:541-550.
Reduce demineralization2,3 Inhibit acid generationfrom plaque bacteria4
Promote remineralization1
F-
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Fluoride inhibits demineralization:
Formation of FAP
Fluoride prevents demineralization through formationof fluorohydroxyapatite (FAP)
[Insert animation ‘Fluoride prevents
demineralization: The formation of FAP’]
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Fluoride inhibits demineralization:
Helps prevent mineral loss
Fluoride prevents demineralization through inhibitionof mineral loss from enamel
[Insert animation ‘Fluoride prevents demineralization
min loss’]
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Fluoride promotes remineralization:
Formation of a fluoride reservoir
Fluoride promotes remineralization through formationof a fluoride reservoir
[Insert animation ‘Fluoride promotes remineralization:Formation of a fluoride reservoir’]
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Fluoride promotes remineralization:
Creation of supersaturated solutions
Fluoride promotes remineralization through creationof supersaturated solutions
[Insert animation ‘Fluoride promotesremineralization: Creation of supersaturatedsolutions’]
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Fluoride inhibits plaque bacteria in vitro1-4
At low pH, fluoride combines with hydrogen ions anddiffuses into oral bacteria as hydrogen fluoride (HF)
Inside the cell HF dissociates, acidifying the cell and
releasing fluoride ions
Fluoride ions inhibit glycolysis
As fluoride is trapped inside the cell this becomes a
cumulative process
1. Hamilton IR, et al. Fluoride in dentistry. Copenhagen: Munksgaard; 1996. p23-51.
2. Whitford GM, et al. Infect Immun 1977;18:680-687.3. Van Loveren C. J Dent Res 1990;69:676-681.
4. ten Cate JM. Acta Odontol Scand 1999 57:325-329.
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Types of fluoride
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Types of fluoride overview
1. Twetman S, et al. Acta Odontologica Scandinavica 2003;61;6:347-355.2. Volpe AR, et al. Am J Dent. 1993;6:S13-S42.
3. Sullivan RJ, et al. J Clin Dent. 1995;6:135-138.
The use of fluoride dentifriceshas reduced the incidence of
caries by 9.7%–24.9%1
Sodium fluoride (NaF) and
sodium monofluorophosphate(MFP) are the most common
sources of fluoride in
dentifrices
– These can be used alone or in
combination
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Fluoride formulation factors
and mode of action
Not all fluoride toothpastesare the same
– Different fluoride source, pH
and choice of formulation
can affect fluoride uptake1,2
Fluoride needs to be
deposited and slowly
released to be effective
following brushing3
– The amount of fluoridereleased into saliva and
adsorbed by enamel during
the period after brushing
is critical
1. Friberger P. Scand J Dent Res 1975:83;339-344.2. White DJ, et al. Caries Res 1986;20:332-336.
3. ten Cate JM. Eur J Oral Sci 1997;105:461-465.
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Factors that influence fluoride delivery
Fluoride source (NaF, MFP, stannous fluoride) – For example, MFP requires activation by hydrolysis by salivary
phosphatase to release active F-
Fluoride concentration in formulation
Formulation properties – pH will drive different fluoride modes of action
– Ingredients such as divalent cations (eg, Ca2+) can reduce the
amount of available fluoride
– Ingredients such as high levels of phosphates can reduce
fluoride uptake
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NaF vs MFP: Supporting studies
Fluoride ions are freely available in NaF whereas MFPrequires hydrolysis by salivary phosphatase to release
free fluoride, the biologically active species1,2
In vitro, in situ , animal and clinical studies all support that
NaF has superior anti-caries efficacy to MFP in an
equivalent silica base formulation
– A calcium carbonate-based MFP formulation contains abrasive
particles which are thought to complement or enhance fluoride efficacy2
– Meta-analysis of 12 clinical studies: 6.8% clinically and statistically
significant greater benefit with NaF vs MFP3
– Study in adolescents: 7% greater benefit with NaF than MFP4
1. Newby CS, et al. J Clin Dent 2006;17:94-99.
2. Lynch RJ, et al. Int Dent J 2005;55:175-178.3. Bowen WH. J Royal Soc Med 1995;88:505-507.
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Comparison of fluoride performance in dentifrices
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Comparison of marketed NaF and MFP in an
in situ caries model1
ResultsSurface hardness recovery and fluoride uptake weresignificantly ( p<0.001) greater with NaF (1100ppm F) thanMFP (1100ppm F) after 14 days of treatment
1. Zero DT, et al. Caries Res 2007;41:268-334.
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Efficacy of marketed NaF and MFP
dentifrices in an in situ caries model1
Results
Remineralization potential and fluoride uptake were significantly greater for a
dentifrice containing 1350ppm F NaF/silica base than for a dentifrice
containing 1000ppm F MFP/450ppm F NaF/dicalcium phosphate base
1. Zero DT, et al. Presented at the 85th General Session & Exhibition of the InternationalAssociation for Dental Research (IADR), New Orleans, USA, 2007.
Data expressed as least square mean ± S.D. n=39
*p<0.01 compared with 1000ppm F MFP/450ppm NaF
*
* *
*
S f i h d h d
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Surface microhardness changes and
fluoride uptake with marketed NaF and MFP
in an in vitro caries cycling model1
1. Newby EE, et al. 54th ORCA Congress. July 2007. Caries Res 2007;41:328 (abs 173).
ResultsAt least 25% greater surface microhardness was observed with NaF than withMFP after 20 days of treatment ( p<0.05), as a result of improvedremineralization and increased fluoride uptake
NaF in silica base A gave greater surface microhardness and fluoride uptakeafter 20 days of treatment ( p<0.05) than NaF in silica base B
All dentifrices tested contained 1100ppm F
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NaF (1100ppm F/silica base) showed greater efficacy with regard tosurface hardness recovery and fluoride uptake than MFP (1100ppm
F/dicalcium phosphate base) in an in situ caries model1
A second in situ study similarly demonstrated that NaF (1350ppm F)
in a silica base provided greater remineralization potential and
fluoride uptake than a combination of MFP (1000ppm F) and NaF
(450ppm F) in a dicalcium phosphate base2
This in situ evidence is supported by data from an vitro study.3 Taken
together, these results suggest:
– NaF in silica base provides superior anti-caries potential to MFP formulations
– Different formulations of NaF in silica base have different remineralization
potentials and fluoride uptake
1. Zero DT, et al. Caries Res 2007;41:268-334.
2. Zero DT, et al. Presented at the 85th General Session & Exhibition of the International
Association for Dental Research (IADR), New Orleans, USA, 2007.
3. Newby EE, et al. 54th ORCA Congress. July 2007. Caries Res 2007;41:328 (abs 173).
Conclusions from in situ and in vitro studies
comparing NaF with MFP1–3
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Dental caries is a progressive disease characterised by
demineralization (dissolution) and destruction of enamel and dentine
Fluoride can reduce caries by preventing demineralization and
promoting remineralization of tooth surfaces and can also inhibit
plaque acid production
Four fluoride sources are used routinely in dentifrices: sodium fluoride(NaF); sodium monofluorophosphate (MFP); amine fluoride (AmF) and
stannous fluoride (SnF2)
While investigations continue to reveal the relative benefits and mode
of action of these different fluoride sources, there is a strong set of
data which indicates that NaF is a superior anti-caries agent to MFP
Optimizing the base formulation can increase fluoride bioactivity
without altering the fluoride level, with the potential to enhance anti-
caries efficacy
Summary
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