fluoride pit and fissure sealants a review

International Journal of Paediatric Dentistry 2000; 10: 90-98

Fluoride pit and fissure sealants: a review

TONIA L. MORPHIS*^ K. JACK TOUMBA* & NICK A. LYGIDAKIS^* Department of Child Dental Health, Leeds Dental Institute, Leeds, UK, 1; PaediatricDentistry Center IKA, Community Health System, Nikea Health Authority, Athens, Greece

Summary. There are two methods of fluoride incorporation into fissure sealants. In thefirst method, fluoride is added to the unpolymerized resin in the form of a solublefluoride salt that releases fluoride ions by dissolution, following sealant application. Inthe second method, an organic fluoride compound is chemically bound to the resin andthe fluoride is released by exchange with other ions (anion exchange system). This reportreviews the literature on the effectiveness of all the fluoride-releasing sealants-commercial and experimental-that have been prepared using either the former or thelatter method of fluoride incorporation. There is evidence for equal retention rates toconventional sealants and for ex vivo fluoride release and reduced enameldemineralization. However, further research is necessary to ensure the clinicallongevity of fluoride sealant retention and to establish the objective of greater cariesinhibition through the fluoride released in saliva and enamel.

Introduction

The addition of fluoride to fissure sealatits wasconsidered more than 25 years ago [1] and efforts tocombine the two continue today [2,3]. Kadoma et al.[4] stated that the properties a fluoride containingsealant should have in order to replace a conven-tional one, are: (a) better or at least comparableretention rates with the conventional sealant, (b)constant fluoride release for a prolonged period oftime and (c) function as a reservoir of fluoride ion toprovide fluoride to enamel and promote fluorapatiteformation in enamel. The aim of this paper is toreview and discuss the literature on the effectivenessof fluoride releasing sealants-commercial andexperimental - that have been prepared using eitherone of two methods of fluoride incorporation. Glass-ionomer cements prepared to be used as fissuresealants are excluded from this review.

Methods of fluoride incorporation in fissure sealants

Two methods of fluoride incorporation into pit andfissure sealants are used. In the first, fluoride is

Correspondence: Dr N. A. Lygidakis, 2 PapadiamantopoulouSt., Athens 11528, Greece. E-mail: [email protected]

added to unpolymerized resin in the form of asoluble fluoride salt. After the sealant is applied tothe tooth, the salt dissolves and fluoride ions arereleased. In the second method an organic fluoridecompound is chemically bound to the resin. Thefluoride is released by exchange with other ions [5,6].

According to the National Institute of DentalResearch [7] the former method has been ques-tioned, because fluoride release resulting from thedissolution of a soluble salt might weaken thesealant in situ and thereby might reduce itsusefulness as a preventive agent. In the lattermethod (anion exchange systems), however, fluorideconstitutes only a small amount of the totalstructure, and is replaced rather than lost. Thus,there should not be any significant decrease in thestrength of the sealant [7].

Method 1: soluble fluoride salts added tounpolymerized resins (see Tables 1 and 2)Lee et al. [1] were the first to formulate apolyurethane fluoride-containing sealant materialthat would release fluoride on the enamel surface foran extended period of 24 h-30 days. A number ofevaluation tests were carried out ex vivo on severalfluoride salts: NaF, acidulated NaF and Na2PO3F.

90 I 2000 IAPD and BSPD

Flouride pit and fissure sealants 91

Table 1. Ex vivo studies on fluoride pit and fissure sealants containing soluble fluoride salts

Authors Formulation Studied properties Findings

Lee et al.(1971) [1]

Swartz et al.(1976) [8]

El-Mehdawietal.(\9%5)[9]

Cooley et al.(1990) [10]

Jensen et al.(1990) [11]

Hicks & Flaitz(1992) [12]

Park et al.(1993) [13]

NaaPOjF, NaF orNaF plus KH2PO4

added to polyurethane

2-5% NaF added toa BIS-GMA resin

0-05%, 0-2%, 2%NaF added to

Nuva-Seal

FluroShieldvs. Helioseal

FluroShieldvs. PrismaShield


and Ketac-Fil


and Delton

-enamel acid solubility-fluoride uptake in enamel

-fluoride release

-enamel acid solubility-fluoride uptake in enamel

-physical properties-fluoride release

fluoride release

fissure penetration-microleakage

-fluoride release

Fluoride effect on size anddepth of artificial caries

lesions.

Caries initiation andprogression in the enamel-restorative interface site in

Class V restorations.

-shear bond strength-scanning electron microscopy

-microleakage

Polyurethane + Na2 PO3F reduced enamel acidsolubility, increased fluoride uptake in enamel

and released fluoride up to 1 month

-reduced enamel acid solubility, increased enamelfluoride uptake

-physical properties remained the same-great fluoride release during the first 1-2 days

-decreased fluoride release over the 3-week study period-increased fluoride release with the highest salt concentration

-no significant difference in fissure penetration-FluroShield allowed microleakage

-fluoride release with FluroShield over the 7-day studyperiod ('burst effect' during the first 2 days)

Lesion depth 3-fold higher with the conventional sealant(PrismaShield).

FluroShield and Ketac-Fil showed less lesionsthan PrismaShield

-significantly higher shear bond strength inFluroShield and PrismaShield than in Delton-better adaptation to the etched enamel with

FluroShield and PrismaShield than with Delton-no significant difference in microleakage among

the 3 FSs

Loyola Rodriguez FluroShieldand Garcia-Godoy vs. HelioSeal(1996) [2] and Teethmate-F

Rock et at.(1996) [3]

FluroShieldvs. Baseline

antibacterial ability againststrains of Mutans streptococci

fluoride release

inhibition of S. mutans and S. sobrinus only fromTeethmate-F

-fluoride release twice as great for FluroShieldthan for baseline

-25% of the total fluoride release occurred in thefirst 2 weeks

Although the greatest fluoride uptake into pow-dered enamel was observed in the acidulated NaFsolutions, Na2PO3F was selected because F~ releaserate in water was more rapid and enamel deminer-alization was less than with other fluoride saltstested. In the in vivo part ofthe same study the ultraviolet-cured fluoride releasing polyurethane sealantwas eflective in reducing the incidence of cariouslesions in molar teeth of albino rats [1].

Swartz et al. [8] conducted an ex vivo study to testthe feasibility of imparting anticariogenic propertiesto ultraviolet polymerized pit and fissure sealants

(Nuva-Seal [LD Chaulk Co., Milford, DE], Epox-ylite 9075 [Lee Pharmaceuticals, El Monte, CA] andtwo experimental formulations) by adding 2-5%NaF. They found that reductions in enamelsolubility were achieved by the addition of NaF inthe range of 2-5% in three ofthe sealants, althoughNuva-Seal required the addition of 5% of NaFbefore maximum efl"ect was attained. The resultsalso indicated that, under the test conditions, thephysical properties of the resins (tensile strength,water absorption, hardness and resistance to tooth-brush abrasion) were not grossly impaired by the

I 2000 IAPD and BSPD, International Journal of Paediatric Dentistry 10: 90-98

92 Tonia L. Morphis, K. Jack Toumba & Nick A. Lygidakis

Table 2. Clinical studies on both types fluoride pit and fissure sealants

Authors

Jensen et al.(1990) [5]

Rock et al.(1996) [3]

do-Rego & de-Araujo(1996) [14]

Lygidakis & Oulis(1999) [15]

Morphis & Toumba(1998) [16]

Kuba et al.(1992) [30]

FS formulation

FluroShield vs.PrismaShield

FluroShield

FluroShield vs.Delton Plus

FluroShield vs.Delton

Delton Plus vs.Delton and

fluoride-glassformulation

MF-MMA andphosphate ester

monomer

(method 2)

Number ofsealants

294

344

153

446

104

70

Study period(years)

1

3

2

4

1

1

Complete retention(%)

86,9 FluroShield80 0 PrismaShield

70

91,35 FluroShield93,14 Delton Plus*

76 5 FluroShield88,8 Delton

67 74 Delton Plus70 Delton

61,29 fluoride-glassformulation

96

*Satisfactory retention, according to the criteria of Ryge [17]

addition of fluoride salts nor was enamel-resin bondstrength or microleakage. However, the greatestamount of fluoride was released during the first dayor two, after which the amount rapidly diminished.

Based on the previous study, El-Mehdawi et al.[9] studied, ex vivo, the ability of an ultravioletpolymerized fissure sealant (Nuva-Seal) to releasefiuoride throughout a 3-week period by addingseveral concentrations of NaF to the sealant. Thereleased fluoride ions were determined using aspecific fluoride ion electrode. It was concludedthat Nuva-Seal did have the ability to releasefluoride over a 3-week period when 005, 0-5 or2-0% NaF was added to it. The quantity of fluorideions increased when the concentration of thefluoride salt in the sealant increased [9].

More recently, a commercially available sealantwith fluoride was marketed that purportedly re-leases fiuoride [10]. This product (FluroShield; LDChaulk/Dentsplay, Milford, USA) is a visible light-cured resin containing 2% NaF and 50% by weightinorganic filler. Cooley et al. [10] compared in an exvivo study, FluroShield with a nonfluoride sealant(HelioSeal; Vivadent Inc., Tonawanda, USA) inorder to evaluate its abiUty to penetrate fissures,resist microleakage and release fluoride. They foundno significant difi"erence between the two sealants in

ability to penetrate fissures, but FluroShield wasfound to have significantly more leakage. Allspecimens of the FluroShield released fiuoride overthe 7-day test period; there was a 'burst efiect' inwhich larger amounts of fiuoride were released onthe first and the second day and then the releasetapered ofi'. Fluoride release decreased by approxi-mately one-half for each of the first 3 days.

Jensen et al. [11] conducted an ex vivo study in 10pairs of human extracted molars, in order tocompare the size and depth of artificial carieslesions when using FluroShield or its nonfluoridecontaining analogue PrismaShield (LD Chaulk/Densply). Lesion depth was found to be over 3-foldhigher in specimens that contained the conventionalsealant compared with specimens that contained thefluoride-releasing sealant. However, because thedata was obtained from a laboratory model, theresults could not directly predict clinical cariesreduction through the use of FluroShield.

Hicks & Flaitz [12] in another ex vivo study used40 sectioned human extracted premolar teeth inorder to determine the efiects of FluroShield oninitiation and progression of caries-like lesionsaround class V restorations, in comparison toPrismaShield and a GIC material, Ketac-Fil(Espe-Premier, Norristown, USA). Surface lesion

2000 IAPD and BSPD, International Journal of Paediatric Dentistry 10: 90-98


depths were significantly reduced in both Fluro-Shield and Ketac-Fil groups when compared withPrismaShield; the GIC material provided the great-est caries protection to the enamel-restorativeinterface and had the least number of wall lesions,while the conventional sealant group had thegreatest number of wall lesions.

In a clinical study, Jensen et al. [5] evaluated theretention and salivary fiuoride release of Fluro-Shield compared to its nonfiuoride-containinganalogue PrismaShield (Chaulk/Densply, Mildford,DE, USA, 19963). One hundred and forty-sevenpairs of sound permanent molars in 82 childrenaged 6-9 years of age were sealed using the twosealant types and samples of whole unstimulatedsaliva, as well as site-specific saliva samples werecollected from 20 randomly selected subjects andanalysed for fiuoride content. There was nosignificant difi"erence in retention between the twosealants at 6 and at 12 months. Complete retentionfor FluroShield-sealed molars was 86 9% and forPrismaShield-sealed molars it was 800%, at 12months. However, fiuoride release was significantlyincreased, when compared to the baseline values,only at the 30 min postsealant sampling interval [5].

Park et al. [13] compared FluroShield, Prisma-Shield and Delton Pit and Fissure Sealant (Johnsonand Johnson, New Brunswick, USA) to each otherthrough shear bond, scanning electron microscope(SE]VI) and microleakage evaluation. No significantdifi'erences in microleakage were noted among thethree sealants, while SEM analysis revealed thatboth Prismashield and FluroShield adapted to theetched enamel surface in a more complete fashionthan the unfilled sealant Delton. Prismashield andFluroShield exhibited significantly higher meanshear bond strength values than Delton.

In one of the most recent studies, LoyolaRodriguez & Garcia-Godoy [2] estimated theantibacterial activity (by using agar plates infectedwith several strains of Streptococcus mutans and S.sobrinus) and the fiuoride release, of FluroShield,Helioseal and a new fiuoride containing sealantTeethmate-FTM (Kuraray Co., Osaka, Japan,batch no. 0761). Teethmate-F was the onlymaterial that showed inhibition activity againstall strains of Mutans streptococci tested; there wasno significant difi'erence in the inhibition betweenstrains of 5. mutans and S. sobrinus. AlsoTeethmate-F exhibited higher fiuoride release thanFluroShield during the 7-day study period. These

materials showed their highest concentration offiuoride release during 2 days after setting. Releasethen decreased to approximately 50% (below 0-1p.p.m. F~) at 7 days [2].

Rock et al. [3] had similar results to those ofLoyola Rodriguez & Garcia-Godoy [2], regardingfiuoride release, ex vivo, from FluroShield incomparison to a GIC material Baseline (De Trey,Dentsply, Weybridge, UK). Approximately one-quarter of the total fiuoride release took place in thefirst 2 weeks, after which time the rate graduallyslowed down. Rock et al. found 70% completeretention of FluroShield applied to contralateralcaries-free first permanent molars in 86 childrenaged 7-8 years, after 3 years follow-up. do-Rego &de Araujo [14] found that 91-35% of FluroShieldsealants and 93-14% of Delton Plus (Johnson andJohnson Dental) sealants were intact-the difi'erencebeing statistically insignificant-after 2 years follow-up. However their technique was more rigorousbecause the authors performed minimal enamelreduction (invasive technique) under completeisolation with rubber dam.

More recently, Lygidakis & Oulis [15] evaluatedthe retention rate and the caries increment difi'er-ences between FluroShield and Delton. The sealantswere applied in a half-mouth design to all fourcaries-free first permanent molars of 112 childrenaged 7-8 years. At 4 years follow-up the completeretention for FluroShield was 76-5% and for Delton88-8%, the difi'erence being statistically significant.However, it is important to note that sealant lossand caries increments were similar in both groups.

In one of the latest clinical studies Morphis &Toumba [16] evaluated the retention rates of threedifi'erent sealants: a conventional sealant Delton, itsrecently marketed fiuoride containing analogueDelton Plus, and an experimental fiuoride-contain-ing sealant which was prepared by adding fiuoride-glass powder to Delton. The sealants were appliedto 104 permanent molars in a randomized way inchildren aged 616 years. Results showed nosignificant difi'erence in retention among the threesealants after a year of follow-up.

Method 2: organic fluoride compounds chemicallybound to the resin (anion exchange systems) (seeTables 2 and 3)In order to avoid the problem of possible dissolu-tion of fiuoride salts incorporated into sealant



Table 3. Ex vivo studies on fluoride pit and fissure sealants using anion exchange systems

Authors FS formulation Studied properties Findings

Rawls & Querens(1980) [19]

Querens et al.(1981) [20]

Querens & Rawls(1982) [21]

Rawls & Zimmerman(1983) [18]

Zimmerman et al.(1984) [22]

Kadoma et al.(1982) [25]

Kojima et al.(1982) [26]

acrylic monomer plust-BAEMA/HF

(fluoride monomer)


(fluoride monomer)

FR-16(16% t-BAEMA/HF)


(fluoride monomer)

Delton with 3% addedt-BAEMA/HF

vs. Delton

MF-MMA copolymer

MF-MMA copolymerincorporated into a

conventional FS (MMA+ MF-MMA) vs.conventional FS

hydrophilicity

-colour stability-toxicity

-mutagenicity

toxicity-mutagenicity

-remineralizationproperties in artificial

carious lesions

-fluoride release-colour stability

-hardness

fluoride release

adhesive tensilestrength

-hydrophobic resin matrix-hydrophilic F~ exchange sitesresulting in deteriorated physical

properties

-poor colour stability-toxic and mutagenic one of the

components (GMA)

-low toxicity level-non mutagenic

-promotion of remineralization-inhibition of demineralization

fluoride FS revealed:-acceptable fluoride release for 9 months

-colour stability and hardness notsignificantly altered

-constant rate of fluoride release-adjustable fluoride release by varying

copolymer composition

adhesive tensile strength minimallyaffected by the addition of MF-MMA

Kadoma et al.(1983) [4]

Tanaka et al.(1983, 1987) [27, 28]

Yoshida et al.(1988) [29]

MF-MMA copolymer

MF-MMA copolymeradded to conventional

experimental FSvs. experimental FS

FS containing MF-MMAcopolymer plus phosphate

ester monomer

-fluoride release-fluorapatite formation

in enamel

-enamel fluoride uptake4 weeks after FS

application inpremolars

fluoride release

constant fluoride release for 84 daysacquired fluoride by enamel present as

fluorapatite

fluoride FS revealed:statistically significant enamel

fluoride uptake

very small amount of fluoride released atleast for the 4-month study-period with

gradual decrease with time

materials Rawls & Zimmerman [18] incorporatedfluoride ions as a mobile charge in an acrylic anion-exchange resin. In these resins the fluoride contain-ing monomer was t-butyl-amino-ethylmethacrylatehydrogen fluoride (t-BAEJVIA: HF), which copoly-merized readily with other acrylic monomers. Thusthe organic portion of the fluoride salt wascovalently bound into the insoluble polymer net-work structure of the resin. An ion from salivadiffused into the resin, exchanged with fluoride ion,which then diffused out and was released [18].

The possibility of making fluoride-releasing sea-lants with organic resin was explored at an earlystage and became one of the major focuses of effort[19]. The initial results demonstrated that the materialwas too hydrophilic so that the physical propertiesdeteriorated. In addition, colour stability was poorand one of the components, glycidyl methacrylate(GMA), proved to be both toxic and mutagenic [20].Reformulation of this 'flrst generation' resin wasaccomplished by replacing GMA with EGDMA(ethylene glycol dimethacrylate). The properties were



much improved and the 'second generation' resin wasneither toxic nor mutagenic [21].

As a first step towards this end it was determinedthat the fluoride monomer could be dissolved in acommercial sealant (Delton) without significantlychanging its rate and degree of polymerization; apotential for 1-year fluoride release (0-03 mg/g/day)with 10% polymer loading was found ex vivo, whilephysical properties remained similar to the sealantalone [22]. Based on these results new formulations('third generation resins') were devised by the sameauthors that were less hydrophilic [23]. Evaluationof these materials is currently in progress.

Kadoma et al. [24] conducted other studies withthe aim of developing fluoride-releasing sealantmaterials. Copolymers were obtained by the copo-lymerization of methacryloyl fluoride (MF) withmethyl methacrylate (MMA), which proved to be ofpotential value as long lasting topical fluoridematerials. The fluoride in the copolymers waspresent as acid fluoride covalently bonded tocarbonyl groups, and fluoride ions were slowlyreleased by hydrolysis in aqueous solution [25]. Therate of release was adjustable by varying thecopolymer composition [25].

On the basis of the above results, a MF-MMAcopolymer with appropriate composition was in-corporated into a powder of a modified commercialsealant [26]. The adhesive tensile strength of thesealant to etched enamel was found to be minimallyaifected by the addition of the copolymer [26].

Release of fluoride from the same sealant placedin a phosphate buflfer solution showed that the rateof decrease of fluoride content was almost constantfor 84 days. It was also found that human enamelfluoride uptake significantly increased with time [4].Similar results were obtained, in vivo, 4 weeks afterexperimental sealant application to caries-free pre-molars that were scheduled to be extracted fororthodontic reasons [27,28].

Yoshida et al. [29] studied a sealant containingMF-MMA copolymer and phosphate ester mono-mer. Very small amounts of fluoride were releasedfrom the sealant over a 4-month period, ex vivo, withgradual decrease over time. Kuba et al. [30]conducted an in vivo study, using the same materialon 35 partially erupted molars in 24 subjects, aged5-13 years. The molars had either sound structure orchalky, demineralized enamel margins next to thefissures. An air polishing device (Quick Jet; Dent-craft Inc., USA) was used as a prophylaxis agent; a

rotating fine needle point at low speed and GK-101solution was also used for sound teeth, while anultrasonic root canal filing device (Enack; OsadaCo., Tokyo, Japan) and GK-101 solution was usedadditionally for teeth with early caries. The authorsattempted to apply the visible light-cured fluoridereleasing material without acid etching. Completeretention of the fissure sealants was 96%, but theobservation period was only 12 months [30].

Discussion

Two common methods of fluoride incorporationinto fissure sealant materials exist: (a) the 'anionexchange system' (organic fluoride compound che-mically bound to the resin) and (b) the addition of afluoride salt to unpolymerized resin. Research of theanion exchange system-sealants is in progress but todate no commercial product is available. Fluro-Shield and Delton Plus are examples of the secondtype of fluoride fissure sealants that contain sodiumfluoride and release fluoride ions as the saltdissolves. In addition, Helioseal-F is anotherfluoride sealant that contains fluoride in the formof 20% fluorosilicate glass [31].

To replace a conventional sealant, a fluoridesealant should have better or at least comparableretention rates with it [32]. Two out of the threestudies mentioned above [5,16] have showed nosignificant difl'erence in retention between the twotypes of sealants. However, the study period in bothwas only 12 months. According to Dennison et al.[33] this is not a study design problem because themost critical period for sealant failure is at baselineand during the 6 months following application.However, a longer follow-up period would givemore confidence about the results. The longestrecent trial [15] on the retention of fluoride fissuresealants was 48 months. This showed a lower fullretention rate for a fluoride sealant (FluroShield)compared to a conventional one (Delton) despitethe fact that total sealant loss and caries incrementwas similar in both groups. It should be mentioned,however, that all the children examined participatedin a regular biannual programme, including topicalfluoride gel (NaF) application. The latter has beenassociated with surface deterioration and weightloss of filled sealants, and this finding may explainthe decreased full retention of FluroShield [34].

According to Ripa [35] in order to have acariostatic efl"ect a fluoride device should be retained



in the mouth and release a constant amount offluoride for at least 6 months. Most of the abovementioned studies investigated the fluoride releaseof fluoride flssure sealants for only a week [2,10] andonly one study investigated fluoride release for 6months [3]. The problem with the release of fluoridein all these studies was that there was a 'burst effect'in which great amounts of fluoride were releasedduring the first days and then, especially after thesecond week, the release slowed down. The longeststudy showed detectable but very low levels offluoride throughout the experimental period of 6months [3]. Results from the only in vivo study onfluoride release showed that the levels of fluoride inwhole saliva, as well as saliva sampled from theimmediate environment of the sealed tooth, re-turned to baseline levels within 24 h [5].

The mechanism of fluoride release from fluorideflssure sealants remains speculative. For example,release might occur from the insoluble sealantmaterial as a result of porosity. It might also occurbecause the fluoride ion or the fluoride-glass is nottightly bound to the polymerized resin molecules.Release in fluoride-glass containing sealants [16]may also be due to fluoride-glass grains depositingon the surface of the resin. Fluoride may havebeen released in several ex vivo systems that havebeen studied from the unpolymerized air-inhibitedlayer on the surface of the specimens [9,10].Unpolymerized resin probably would not be ofbenefit to the enamel, in the clinical situationbecause it contacts the enamel only minimally andalso would be worn away almost immediately aftersealant placement.

Under laboratory conditions most of the mea-surements [2,3,9,10] have been made in distilledwater and not saliva, and fluoride release occursonly in one direction, from the sealant-specimeninto water. In the mouth, it is probable that some ofthe fluoride release is available for ionic substitutionof the mineral phase of the enamel. Release offluoride from fluoride materials into artiflcial hu-man saliva [36] has been shown to be signiflcantlyless than into water [37]. It has been suggested thatcomponents from human saliva form a coating onthe surface of the material that impedes fluoriderelease [38]. Thus, in addition to determining thefluoride ion release from sealants ex vivo, long-termin vivo studies are necessary in order to evaluate thefactors of concentration, rate and duration offluoride release.

Another important although difficult question ishow much fluoride release is required from a fissuresealant in order to be clinically effective and for howlong would the effect last? No in vivo studies havedetermined the minimal amounts of fluoride thatshould be released from a fluoride material in salivaand plaque fluid in order to enhance remineraliza-tion. Jensen et al. [11] showed in an artificial cariesstudy that FluroShield reduced the amount ofenamel demineralization adjacent to it significantlymore than PrismaShield that contains no fluoride.Hicks & Flaitz [12] came to the same conclusionsregarding the depth of artificial caries lesions.

Summary and conclusions

Despite the above evidence for equal retention rates,ex vivo fluoride release and reduced enamel demi-neralization, any statement for additional benefits offluoride over nonfluoride fissure sealants should bemade with caution. It is obvious that further long-term clinical trials are necessary to determine thatthe clinical longevity of the sealant retention is notadversely affected by the presence of fluoride andthat the objective of greater caries inhibition throughthe fluoride released in saliva and incorporated inenamel can be achieved in the clinical situation.Excellent clinical caries reductions are achieved bycorrect use of inert sealants and firm evidence thatthe properties of a resin will not be compromised byfluoride incorporation is presently lacking.

Resume. II existe deux methodes d'incorporation defluor dans les produits de scellement de sillon. Dansla premiere methode, le fluor est ajoute a la resinenon polymerisee sous la forme d'un sel de fluorsoluble qui libere les ions fluorures par dissolution,apres l'application du scellement de sillon. Dans laseconde methode, un composant fluore organiqueest lie chimiquement a la resine et le fluor est liberepar echange avec d'autres ions ('systeme d'echanged'anion'). Une revue de litterature est effectuee surl'efficacite de tous les produits de scellement desillon liberant du fluor-commerciaux et experimen-taux-qui ont ete prepares en utilisant l'une oul'autre des methodes d'incorporation. II y a al'evidence, des taux de retention egaux pour lesproduits conventionnels de scellement de sillons,une liberation ex vivo du fluor, et une demineralisa-tion amelaire reduite. Cependant, des recherchesfutures sont necessaires pour assurer une longevite



clinique de la retention du scellement des sillonsfluore et pour obtenir une plus grande inhibition descaries par le fluor libere dans la salive et I'email.

Zusammenfassung. Es gibt 2 Methoden um Fluorideden Fissurenversiegler beizugefugen bei der erstenMethode wird den unpolymerisierten Kunststofif,Iosbares Fluoride-Salz beigefugt, dieses befreitFluorid- lonen bei der Auflosung, nach dem Auffra-gen des Versieglers. Bei der zweiten Methode wirdein organisches Fluorid chemisch mit dem Kunstoffverbunden und das Fluorid wird durch einenlonenaustasch wirksam (Inion Exchange System).Ein Literatubersicht iiber den 2 erwahnten Metho-den. Es ist erwiesen, dass die Retentionraten dieserVersiegler gleich ist wie bei den konventialenVersiegler, trotzdem sind bezuglich der Langzeitre-tention, der Fluoridmangel im Speichel und demSchmelz weitere Untersuchungen notig.

Resumen. Hay dos metodos de incorporacion de fliiora los selladores de fisuras. En el primer metodo, elfluor se aflade a la resina no polimerizada en la formade una sal soluble de fluor que libera iones fliior pordisolucion, tras la aplicacion del sellador. En elsegundo metodo, un compuesto organico de fliior seune quimicamente a la resina y el fliior se libera porintercambio con otros iones (sistema de intercambioionico). Se hace una revision de la literatura sobre alefectividad de todos los selladores liberadores defliiorcomerciales y experimentales-que han sidopreparados usando tanto el metodo anterior como elultimo metodo de incorporacion de fliior Hayevidencia de porcentajes de retencion iguales a losselladores convencionales, de la liberacion de fliior envivo y de la reduccion en la desmineralizacion delesmalte. Sin embargo son necessarias investigacionesposteriores para asegurar la longevidad clinica de laretencion del sellador con fliior y demostrar elobjetivo de una mayor inhibion de la caries medianteel fliior liberado en la saliva y el esmalte.

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fluoride pit and fissure sealants a review

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