Fluoride Action Topical References

8/2/2019 Fluoride Action Topical References

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Commun ity D en t O ra l E pid em io /1 99 9 Feb~27(1):62-71A re-examination of the pre-eruptive and post-eruptivemechanism of the anti-caries effects of fluoride: is there anyanti-caries benefit from swallowing fluoride?Limeback H

Faculty of Dentistry, University of Toronto, Ontario, Canada. [email protected] belief that fluoridated water reduces caries incidence by half stems from years of fluoridation studieswhere the caries rates of people in various fluoridated and non-fluoridated communities were compared.By their nature, the water fluoridation trials were not able to distinguish between the topical effects of thefluoride in the water and the systemic effects of the fluoride that is inevitably swallowed and incorporatedinto developing teeth. Some attempts have been made to estimate the contribution of systemic fluoride tothe control of dental caries but researchers are discovering that the topical effects 'of fluoride are likely tomask any benefits that ingesting fluoride might have. In this updated review of the pre-eruptive vs.post-eruptive benefits of fluoride in the prevention of dental caries, a re-examination of the literature,which is often cited to support the notion that swallowing fluoride, either in water or in pill form, wasdone in recognition of the mounting evidence for the topical mechanism as being the primary mechanismfor the prevention of dental caries. Maximum benefits from exposing newly erupted teeth to topicalfluoride in the oral cavity may have been seriously under-estimated. This has obvious implications for theuse of systemic fluorides to prevent dental caries and forces everyone working in the field to examinemore closely the risks and benefits of fluoride in all its delivery forms.

Commun ity D en tis try a nd O ra l E pid em io lo gy 1999 Feb~27( 1):62-71

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CDC,... . . . _ _ . . . . . . . .-- ,October 22, 1999/ Vol. 48/ No. 41~ Fluoridation of Drinking Water~ to Prevent Dental Caries941 Progress Toward PoliomyelitisEradication ~ Nepal, 1996-1999944 Update: West Nile VirusEncephalitis .....New York, 199995S Notice to Readers, M ORB ID ITY AND M ORTAL ITYWEEKLY REPORT

Achievements in Public Health, 190~1999Fluoridation of Drinking Water to Prevent Dental Caries

Fluoridation of community drinking water is a major factor responsible for thedecline in dental caries (tooth decay) during the second half of the 20th century. Thehistory of water fluoridation is a classic example of clinical observation leadingto epidemiologic investigation and community-based public health intervention.Although other fluoride-containing products are available, water fluoridation remainsthe most equitable and cost-effective method of delivering fluoride to all members of,most communities, regardless of age, educatlonal attainment, or income level.

Biologic Mechanism 'P~ ~ ?36.Fluoride's caries-preventive properties initially were attributed to changes in

enamel during tooth development because of the association between fluoride andcosmetic changes in enamel and a beliefthat fluoride incorporated into enamel during _/tooth development would result in a more acid-resistant mineral. However, laboratory .Ifand epidemiologic research suggests that fluoride prevents dental caries predomI-nately after eruption of the tooth into the mouth, and its actions primarily are topicalfor both adults and children (1) .These mechanisms include 1) inhibition of demIner-alization, 2) enhancement of remineralization, and 3) inhibition of bacterial activity Indental plaque (1 ).Enamel and dentin are composed of mineral crystals (prim~rily calcium andphosphate) embedded in an organic protein/lipid matrix. Dental mineral is dissolvedreadily by acid produced by cariogenic bacteria' when they metabolize fermentablecarbohydrates. Fluoride .present in solution at low levels, which becomes concen-trated in dental plaque, can substantially inhibit-dissolution of tooth mineral by acid.Fluoride enhances remlnerallzation by adsorbing to the tooth surface and attractingcalcium Ions present in saliva. Fluoride also acts to bring t,he calcium and phosphateions together and is Included in the chemical reaction that, takes place, producing a .crystal surface that is much less soluble in acid than the original tooth mineral (1)., ,/'

Fluoride 'from topical sources such as, fh,ioridated drinking water is taken up by "cariogenic bacteria when they produce acid.,Once inside the cells"fluoride interfereswith enzyme activity of the bacteria and the control of int(8cellularpH. This reduces'bacterial acid production, which directly reduces the dissolution rate of tooth mineral(19). ' ' .References", 1. Featherstone JD. Prevention and reversal of dental caries: role of low level fluoride. Com-munity Dent Oral Epidemiol 1999;27:31-40. ,19. Sheiiis RP, D~c~orth RM. Studies on the cariostatic mechanisms of fluoride. Int Den't J1994;44(3 suppl 1):263-73.

U .S . D EPARTMENT OF,H EA LTH & HUMAN S ER VIC ES

Reported by D ivisio n o f O ral H ealthN ational C enter for C hronic D isease P revention and H ealth Prom o tion, CDC3-3d


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C0 VERTHE JOURNAL OF'THE AMERICAN DENTAL ASSOCIATION

S TOR VTHE SCIENCE AND PRACTICEOF CARIES PREVENTION.JOHND.B. FEATHERSTONE. M.SCPH.D.

A B S T RAe TBackground and Overview. Dentalcaries is a bacterially based disease. Whenit progresses, acid produced by bacterialaction on dietary fermentable carbohy-drates diffuses into the tooth and dis-solves the carbonated hydroxyapatite min-eral-a process called demineralization.Pathological factors including acidogenicbacteria (mutans streptococci and lacto-bacilli), salivary dysfunction, and dietarycarbohydrates are related to caries pro-gression. Protective factors-whichinclude salivary calcium, phosphate andproteins, salivary flow,fluoride in saliva,and antibacterial components or agents-can balance, prevent or reverse dentalcaries.

HOW FLUORIDECOMBATS THECARIES PROCESS P SigThe ability of fluoride to pre-vent and arrest caries has beenresearched extensively. FhlO-ride has three principal topicalmechanisms of action:- inhibiting bacterial metabo- . /lism after diffusing into the ~bacteria as the hydrogen fluo-ride, or HF, molecule when the'plaque is acidified;- inhibiting demineralizationwhen fluoride is present at thecrystal surfaces during an acidchallenge;- enhancing remineralizationand thereby forming a low-solubility veneer similar to theacid-resistant mineral fluorap-atite, or FAP, on the remineral-ized crystals.Inhibiting bacterialmetabolism. f' s1l?

In summary, fluoride fromtopical sources is converted par-tiully to HF by the acid that thebacteria produce and diffusesinto the cell, thereby inhibiting('ssential enzyme activity.JADA, Vol. 131, July 2000 887

Conclusions. Caries progression orreversal is determined by the balancebetween protective and pathological fac-tors. Fluoride, the key agent in battlingcaries, works primarily via topical mech-anisms: inhibition of demineralization,enhancement of remineralization andinhibition ofbacterial enzymes.Clinical Implications. Fluoride in drink-ing water and in fluoride-containingproducts reduces caries via these topicalmechanisms. Antibacterial therapy mustbe used to combat a high bacterial chal-lenge. For practical caries managementand prevention or reversal of dentalcaries, the sum ofthe preventive factorsmust outweigh the pathological factors.

Inhibiting demineraliza-tion. p g c ? O _ Only when fluorideis concentrated into a new crys-tal surface during remineraliza-tion is it sufficient to beneficial-ly alter enamel solubility. Thefluoride incorporated devei"OP-'mentally-that is, systemicallyinto the normal tooth mineral-is insufficient to have a measur-able effeCt on acid solubility.t-"

p e a ' l lIn summary, fluoride presentin the water phase at low levelsamong the enamel or dentincrystals adsorbs to these crystalsurfaces and can markedlyinhibit dissolution of tooth min-eral by acid.2136 Fluoride thatacts in this way comes from theplaque fluid via topical sourcessuch as drinking water and . /fluoride products. Fluoride Jt : .incorporated during tootll.


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Prevention and reversal of dentalc a r i e s : r o l e o f l o w l e v e l f l u o r i d eFeatherstone JOB:Prevention and reversal of dental caries: role of low level fluo-ride. Community Dent Oral Epidemiol1999i 27: 31-40. C Munksgaard, 1999Abstract - Dental caries is a bacterially based disease that progresses when acidproduced by bacterial action on dietary fennentable carbohydrates diffuses intothe tooth and dissolves the mineral, that is, demineralization. Pathological factorsincluding acidogen1c bacteria (mutans streptococci and lactobacilli), salivary dys-fwlction, and dietary carbohydrates are related to caries progression. Protectivefactors which include salivary calcium. phosphate and proteins, salivary flow, andfluoride in saliva can balance, prevent or reverse dental canes. Fluoride worksprimarily via topical mechanisms whiCh include (1) inhibition of demineralizationat the crystal surfaces inside the tooth, (2) enhancement of remineralization atthe crystal surfaces (the resulting remineralized layer is very resistant to acid at-tack), and (3) inhibition of bacterial enzymes. Fluoride in drinking water and influoride-containing products reduces tooth decay via these mechanisms. Low butslightly elevated levels of fluoride in saliva and plaque provided from thesesources help prevent and reverse caries by inhibiting demineralization and enhanc-ing remlnerallzation, The level of fluoride incorporated into dental mineral bysystemic ingestion is insufficient to playa significant role in caries prevention. TheeffeCtof systemically ingested fluoride on caries is minimal. Fluoride "supple-ments" can be best used as a topical delivery system by sucking or chewing tabletsor lozenges prior to ingestion.

Copyrlgh/ 0Mil llk sg4 l lrd 1999COMMUNITYD~NTISTRYANOURALEPIDEMIOLOGY

IS SN O JO I-$ 66 1

John D. B. FeatherstoneU niv ersity o f C al ifo rn ia a t S an F ra nc isc o, S anF ra nc is co , USA

K ey w ord s: c arb on ate d a patite ; d en ta l c arie s;fluoride; rernineralization .John D . B . F eatherstone, D epartm ent ofR es to ra ti ve D en tis try , B ox 0 75 8, U n iv ers ity o fC a li fo rn ia a t Sa n F ra nc is co , 7 0 7 Pama ss usAvenue, Sa n F ra nc is co , CA 94143, USATel: +14154760456Fax: + 1 415 476 0858E-mai l : [email protected] ccepted w ithou t peer review 9 N ovem ber1998

The role of low levels of fluoride insaliva and plaque fluidStudies by Zero and co-workersshowed that a 0.05%sodium fluoride mouthrinse(225 ppm F) used for 1 min could give elevatedfluoride levels in saliva for 2-4 hours and in plaquefor much longer times (52),

Bacterial CellpH7 H++ F- ~_ HF

pH 4.5 H++F- ~ HFFig. 6.Schematic representation of fluoride entering a bacteri-al cell in the fonn of HF at lower pH values, dissociating,and thereby providing H+ and F- ions inside the cell. .36

Recent clinical studies(conducted in the late 1980s) which investigatedpossible caries risk factors in 7-12-year-old chil-dren in the United States (55, 56) reported meanbaseline fluoride concentrations in saliva of 0.02-0.04 ppm in both fluoridated and non-fluoridateddrinking water areas with the fluoride concentra-tion being related to caries status rather than drink-ing water concentration (56). Subsequent similarstudies in the 1990s again reported no differencesbetween mean salivary fluoride levels in 7-12-year-old children living in fluoridated and non-fluori-dated communities, with means about 0.05 ppm Fin each (57, 58). '.po.,3e. 37. Again, as described above, theconcentration of fluoride in dental enamel and den-tin provided by fluoridation of drinking water orby natural fluoride levels at about 1 ppm is insuf-ficient to provide protection against caries. Themechanism of action of fluoride in the drinkingwater is therefore as a topical delivery system. Therole of systemically incorporated fluoride is of very

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~ Pub:\led I'uh\lcd Qn':IH' mm9DOther Formats: I Citation II MIDLINEILinks: I Related o\rticles II CO to publisher site JCaries Res 2000 Jan;34(l ):20-25

Caries Prevalence after Cessation of Water Fluoridation in LaSalud, Cuba.Kunzel W, Fischer TDepartment of Preventive Dentistry, Dental School ofErfurt, Friedrich Schiller University of Jena,Germany.[Record supplied by publisher]In the past, caries has usually increased after cessation of water fluoridation. More recently an oppositetrend could be observed: DMFT remaining stable or even decreasing further. The aim of the presentstudy conducted in La Salud (Province ofHabana) in March 1997 was to analyse the current caries trendunder the special climatic and nutritional conditions of the subtropical sugar island Cuba, following thecessation, in 1990, of water fluoridation (0.8 ppm F). Diagnostic evaluations were carried out using thesame methods as in 1973 and 1982. Boys and girls aged 6-13 years (N =414), lifelong residents in LaSalud, were examined. Between 1973 and 1982 the mean DMFT had decreased by 71.4%, the meanDMFS by 73.3% and the percentage of caries-free children had increased from 26.3 to 61.6%. In 1997,following the cessation of drinking water fluoridation, in contrast to an expected rise in caries prevalence,DMFT and DMFS values remained at a low level for the 6- to 9-year-olds and appeared to decrease forthe 101l1-year-olds (from 1.1 to 0.8) and DMFS (from 1.5 to 1.2). In the 12/13-year-olds, there was asignificant decrease (DMFT from 2.1 to 1.1; DMFS from 3.1 to 1.5), while the percentage of caries-freechildren of this age group had increased from 4.8 (1973) and 33.3 (1982) up to 55.2%. A possibleexplanation for this unexpected finding and for the good oral health status of the children in La Salud isthe effect of the school mouthrinsing programme, which has involved fortnightly mouthrinses with 0.2%NaF solutions (i.e. 15 times/year) since 1990.

Caries Research 2000 January;34(1):20-2SAuthors W. Kunzel, T. Fisher2 Tables, 40 References

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Fluoride Action Topical References