aquafresh science academy fluoride slides

8/14/2019 Aquafresh Science Academy Fluoride Slides

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Caries Formation and the Effects of Various Fluorides in Treatment

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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



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



The five stages of caries development

[Insert animation ‘Caries development’]



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



Caries lesions

Figure 1. Sectioned, extracted

tooth with three caries lesions

Figure 2. A single caries lesion

showing bacterial invasion in

dentinal tubules



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-]



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.



The natural demineralization and

remineralization process

[Insert animation ‘The action of demineralization and

remineralization in the mouth’]



Fluoride mode of action



Sources of fluoride

Topical agents

Fluoridated water

Other ingested sources

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©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-



Fluoride inhibits demineralization:

Formation of FAP

Fluoride prevents demineralization through formationof fluorohydroxyapatite (FAP)

[Insert animation ‘Fluoride prevents

demineralization: The formation of FAP’]



Fluoride inhibits demineralization:

Helps prevent mineral loss

Fluoride prevents demineralization through inhibitionof mineral loss from enamel

[Insert animation ‘Fluoride prevents demineralization

min loss’]



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’]



Fluoride promotes remineralization:

Creation of supersaturated solutions

Fluoride promotes remineralization through creationof supersaturated solutions

[Insert animation ‘Fluoride promotesremineralization: Creation of supersaturatedsolutions’]



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.



Types of fluoride



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



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.



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



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.



Comparison of fluoride performance in dentifrices



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.



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



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



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



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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