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FLUORIDE RELEASING MATERIALS

Presenter – Dr. Nikhil Saran (Ist year PG)

Department of conservative and endodontics

Sri Sai college of dental surgery, vikarabad

E-mail:- sarannikhil@gmail.com

Vaishno devi mandir, Kattra (J.K.)

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CONTENTS

Significance and relevance of topic. Fluorides

1. Introduction .2. History.3. Availability.4. Sources.5. Application and optimal intake values.

a) Systemicb) Topicalc) Self applied

6. Absorption.7. Excretion .8. Storage.9. Mechanism of action. cont.

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CONT.

Fluoride releasing material and their effects. 1. Restoration failure and its sequelae.2. Secondary caries and its feature 3. Diagnosis of secondary caries.4. Factors influencing F- release.5. F- recharge.6. Plaque and fluoride.7. Mechanism of action(in relation to material).8. Antimicrobial and F-releasing materials9. Fluoride and adjacent tooth. 10. Review of various F-releasing restorative

materials

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RELEVANCE TODAY AND THEN…. (21ST VS PAST)

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RELEVANCE TODAY AND THEN. (21ST VS PAST)

Dental caries most prevailing pre historic infectious diseases exist in developed, developing and under developed counties

Once restored Secondary account for 60% Irrespective of material type

Other reason for restoration failure Material failure, Tooth fracture or defect, Endodontic involvement, Prosthetic abutment use, Technical errors, and Deterioration of aesthetic quality with tooth-colored restoratives.

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Secondary caries and the past.

Proper condensation of gold restoration .

Secondary expansion of amalgam and resiliency of dentine came into play.

With the development of silicate --------------------------------------------------------------------------------------------------------------------------the story continues.

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FLUORIDES

Fluorine word is derived from the Russian word "flor" ---------- "flois" meaning destruction in Greek and from Latin word "fluor" that means to flow since it was used as a flux.

Fluorine (F) most reactive nonmetal

Most electronegative element

It combines with all elements, except oxygen and the noble gases, to form fluorides.

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HISTORY

Sir James Crichton Browne in 1802 first to propose possible connection in dental health and fluoride.

1901 Dr.Fredrick Mckay of Colorado (U.S.A) discovered certain stains.

‘Shoe Leathery Survey’ by Dr.Trendley H.Dean.

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AVAILABILITY OF FLUORIDE

13th trace elements the earth's crust.

Highly reactive anion, atomic weight of 19, atomic number of 9.

Found in biosphere, lithosphere, hydrosphere, atmosphere and in all living organisms.

Chemically exist in the form of fluorides, chiefly as:1. Fluorspar (CaF2)

2. Fluorapatite (Ca10(PO4)6F2)

3. Cryolite (Na3AlF6)

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SOURCES OF FLUORIDE

Water.

Present in all ground water.(except in certain region)

Also derived from plants, marine animals and even dust particles.

Fluoride content varies in different types of food, like:

a) Tea -97 ppm. b) Certain types of fishes -84.5 ppm. c) Potatoes -6.4 ppm.

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FLUORIDE  APPLICATION

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OPTIMUM FLUORIDE INTAKE

Depending upon the mean maximum daily temperature:

Cold climate 1.2 ppm Summer season or temperate climate 0.7

ppm

Calculation of Optimum Level of Fluoride

ppm fluoride = 0.34/E E = -0.038 + 0.0062 X temp, in °F

(E is estimated water intake)

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TOPICAL FLUORIDE APPLICATION

Topical fluoride- Three methods. 1.First method- Application of fluoride solution. 2.Second method- Use of a concentrated

fluoride rinse.

3.Third method- Tray  technique, Usually 8% SnF2 (19,360 ppm) and 2% NaF (9,040 ppm) is used.

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SELF APPLIED TOPICAL FLOURIDE

Concentration ranges from 1,000- 1,500 ppm of fluoride.

Sodium fluoride, sodium monofluorphosphate are added but not the stannous fluoride.

Frequent source of fluoride in low concentration can inhibit demineralization and enhance remineralization.

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ABSORPTION OF FLUORIDE

Readily absorbed into the body.

Stomach, through passive absorption.

Can also occur from the lungs by inhalation.

The solubility of inorganic fluorides in the diet and its calcium content.

Bone deposition of fluoride occurs to the extent of 50% in growing children but only 10% in adults

Fluoride is not protein-bound and occurs as free ion in the plasma . The volume of distribution is 0.5–0.7 litre/kg

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EXCRETION OF FLUORIDE Urine, feces and sweat.

It occurs in traces in milk, saliva, hair and tears.

Urinary fluoride level is regarded as one of the best indices of fluoride intake.

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STORAGE OF FLUORIDE

Fluoride is stored in the hard tissues of the body.

Fluoride uptake depends upon the amount ingested and absorbed.

The duration of fluoride exposure and the type, region and metabolic activity of the tissue decide its storage factor.

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FLUORIDE TOXICITYCHRONIC TOXICITY

Chronic fluorosis: 1. Skeletal fluorosis and 2. Dental fluorosis.

Skeletal fluorosis –1. Joint stiffness and osteosclerosis (milder forms),2. Calcification of ligaments, muscle wasting, osteoporosis, and neurologic deficits

(severe forms).

Symptomatic after about 10 years of fluoride exposure at least 10 mg/day.

Dental fluorosis- 1. Diffuse opacities on the enamel surfaces of the teeth. 2. Noteworthy because of cosmetic concern

May be associated with increased porosity. porosity may stained or coalesce into discrete pits.

Dental fluorosis occurs as a result of high fluoride ingestion in early

life, primarily during the maturation phases of enamel development

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ACUTE TOXICITY

Highly concentrated fluoride ingestion can have toxic effect as

Toxic dose- 8 mg F per kilogram body weight could result in toxic effects.

Acute lethal dose- 32 mg to 64 mg F per kilogram body weight could result in death.

Toxic effects on ingestion 5 mg to 8 mg per kilogram body wt

nausea vomiting diarrhea

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TREATMENT OF ACUTE FLUORIDE TOXICITY

Treatment ranges from

1. Prevention of further absorption by ingestion of milk

2. 5% calcium gluconate

3. Supplemental oxygen therapy

4. Gastric levage.

5. Activated charcoal ingestion.

6. Blood-plasma dialysis

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Possible formation of apical abscess

Reversible lesion1. Initial subsurface

demineralizationInitial subsurface demineralizationInitial subsurface demineralization

Extension of demineralizedzone towards dentine

Extension of demineralizedzone towards dentine

Collapse of surface layer to form cavity

Collapse of surface layer to form cavity

Extension of caries lesion into dentineExtension of caries lesion into dentine

Extension of caries into pulpExtension of caries into pulp

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Mechanism of caries development

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MECHANISM OF ACTION OF FLUORIDES

Increase in enamel resistance OR reduction in enamel solubility.

Increase in post eruptive maturation.

Remineralization of incipient lesions.

Interference with plaque microorganism.

Modification in tooth morphology.

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INCREASED ENAMEL RESISTANCE OR REDUCTION IN ENAMEL SOLUBILITY

Dental caries involve dissolution of enamel from acid produced by bacteria plaque. As lactic acid , propionic acid, formic acid.

Fluoride forma the fluorapatite, which is less soluble mineral.

This reduced solubility is the cause of the caries prevention.

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INCREASE IN POST ERUPTIVE MATURATION.

In this case fluoride help in increased Remineralization rate of the hypomineralized.

Both the mineral and the organic material are deposited from saliva.

Fluoride help to Remineralization of the demineralized area.

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REMINERALIZATION OF INCIPIENT LESIONS.Fluoride is provide from 1.Saliva2.tooth mineral dissolved during demineralization

Fluoride help by accelerating the growth of the enamel crystal.

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INTERFERENCE WITH PLAQUE MICROORGANISM.

High concentration of fluoride is bactericidal 200 ppm or more.

Low concentration it is bacteriostatic.

Fluoride in plaque inhibit bacterial enzyme, causing acid metabolism.

Fluoride mainly interact with the bacterial cell well in aerobic and anaerobic condition their by causing the disruption of the matabolism.

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MODIFICATION IN TOOTH MORPHOLOGY

Studies shows that during tooth development fluoride cause the slightly smaller tooth and with shallow fissures

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Fluoride releasing restorative material

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DemineralizationDemineralization RemineralizationRemineralizationLow pH

Salivary [Ca2+]

Salivary [PO43-]

Salivary [F-]

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RESTORATION FAILURE AND ITS SQUELAE2˚ IS THE CAUSE OF 50% TO 60% OF RESTORATIONS FAILURE.

Restorations life varies as per restorative material.

Amalgams have max. service period. Restoration fails, increases the size of the

cavity by 0.52 mm.

When no caries is present by 0.25 mm.

This implies that the replaced restoration width will be larger by 0.5 to 1.04 mm.

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SECONDARY CARIES

Secondary is defined as caries detected at the margins of an existing restoration. It may have an inactive arrested lesion, an active incipient lesion, or a frankly cavitated lesion.

Only when marginal gaps are greater than or equal to 250 micron can secondary caries be identified clinical and microscopically.

• cont.

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SECONDARY CARIES HAS CERTAIN FEATURES.

Interproximal margins (>90% of failed amalgams, >60% of failed composite resins).

Secondary caries is seen as a white spot (active), or a brown spot (inactive) lesion.

A high proportion of secondary caries is located along the cervical and amalgam restorations impart color changes due to corrosion.

Tran-illumination may be helpful with tooth-colored restorative materials.

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DIAGNOSIS

Diagnosis of secondary caries is dependent on following features.

1. visual inspection, 2. tactile sensation with judicious explorer usage,

and 3. radiographic interpretation.

Whenever a restorative material is placed, there is a possibility for a microspace (gap) to be formed between the restorative material and the cavosurface enamel, dentin, and cementum.

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SECONDARY CARIES AND MATERIALS

The ability of a material to resist secondary caries development is dependent on

1. complete removal of carious tissue.

2. formation of an intimate cavosurface restorative interface with minimal to no microspace, and

3. release of caries protective agents (fluoride, metal ions, antimicrobials, acidic ions) to the adjacent cavosurface and outer tooth surface.

Cont.

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PREVENTION IS BETTER THEN CURE.

fluoride regimen implementation (rinses, gels, fluoridated toothpastes);

Antimicrobials (chlorhexidine);

fluoride-releasing restorative material; Dietary review.

Recaldent and ACP-CCP rigime

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BREAK THROUGH Silicate cement restorations- no secondary caries . Today, there are several fluoride-containing dental

restoratives available in the market including 1. Varnishes2. Sealents3. glass-ionomers, 4. resinmodified glass-ionomer cements, 5. polyacid-modified composites (compomers), composites 6. and amalgams. and many more….

Different matrices and setting mechanisms of the products shows their fluoride release capability.

Antibacterial and cariostatic properties is associated with the amount of fluoride released.

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………CONT.

Fluoride may be released from dental restorative materials as part of the setting reaction.

It can also be added to the formulation with the specific intention of fluoride release.

Fluoride releasing components have included1. Fluoroaluminosilicate glasses (FAG), 2. Stannous fluoride (Snf2), 3. Organic amine fluorides (CAFH) and 4. Ytterbium fluoride (ybf2).

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Type of fluorides

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FACTORS INFLUENCING THE RELEASE OF FLUORIDES

The release of fluoride is a complex process. It can be affected by several intrinsic variables,

such as 1. formulation and fillers . 2. composition and pH-value of saliva, 3. plaque and4. pellicle formation.

It was shown that factor like1. powder–liquid ratio of two-phase-systems, 2. mixing procedure, 3. curing time and 4. the amount of exposed area 5. different storage media affected the fluoride release.

Cont.

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CONT.

The highest release is found in acidic and demineralizing–remineralizing regimes and lowest in saliva.

In acidic media it increases because decrease in pH increases the dissolution of the material, leading to fluoride release

Adhesives or bonding agents when applied increases short and long term fluoride release.

Bleaching and brushing does not affect the fluoride release.

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FLUORIDE RECHARGE

“Recharging” is to maintain level of fluoride release.

FROSTEN et al. found the phenomenon in GIC

Fluoride reservoir ►►permeability of filling material.

Glass-ionomers is best fluoride reservoir then others. Because of loosely bound water.

Exogenous sources of fluoride act as reservoir,1. fluoridated dentifrices,2. mouth rinses 3. high-dose fluoride gels and 4. Varnishes.

In oral environment saliva and plaque has a role in fluoride uptake.

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PLAQUE AND FLUORIDES

Plaque is ≡ caries development,

But this organic film may act as a fluoride reservoir.

Only small concentrations of fluoride in plaque, saliva, or calcifying fluids are necessary to shift the equilibrium.

Remineralization begins with only 0.03 ppm fluoride.

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ANTIMICROBIAL ACTIVITY OF FLUORIDE

Dental plaque fluoride, releases hydrogen fluoride from the plaque into the bacteria.

Hydrogen fluoride inside the bacteria acidifies the bacterial cytoplasm and leads to release of fluoride ions.

Bacterial metabolism enzymes as1. enolase, 2. acid phosphatase, 3. pyrophosphatase, 4. pyrophosphorylase,5. peroxidase, 6. catalase, 7. adenosine triphosphatase.

Increased plaque fluoride --------decreases --------adherence of bacteria to hydroxyapatite, which results in reduced plaque formation.

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FLUORIDE UPTAKE OF ADJACENT TOOTHSTRUCTURE

Tooth surfaces act as a reservoir for fluoride.

Tooth-bound fluoride increases enamel resistance to lesion formation.

Because of microstructure and porosities fluoride uptake is higher for dentin and cementum than for enamel.

Adhesive hybrid layer, may hamper fluoride uptake.

fluoride incorporated in dental hard tissues is of minor importance compared to the fluoride concentration in a fluid-filled micro gap between the restoration and the tooth structures.

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FLUORIDE-RELEASING MATERIALS(CARIES-PREVENTIVE MECHANISMS OF

FLUORIDE RELEASING MATERIALS)

Formation of fluorapatite

Enhancement of Remineralization .

Interference of ionic bonding during pellicle and plaque formation.

Inhibition of microbial growth and metabolism

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HO MUCH IS ENOUGH?

Minimum inhibitory concentration is 100-200μm/ml of sodium fluoride – bacteriostatic for s. mutants

30 times over the above value is bacteriocidal

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CLASSIFICATION

On the bases of similarity in 1. Physical properties 2. Mechanical properties3. Setting properties

They are classified as Resin composites Compomer Resin modified glass ionomers Traditional glass ionomers

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COMPARISON OF VARIOUS F CONTANING RESTORATIVE

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REVIEW OF VARIOUS FLUORIDE RELEASING MATERIALS

1. Glass-ionomers,2. Resinmodified glass-ionomer cements, 3. Polyacid-modified composites (compomers)4. Giomer,5. Composites,6. Amalgams.7. Polycarboxylates8. Sealents9. Varnishes10. silicates

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HISTORY OF DEVELOPMENT OF F RELEASING MATERIALS

1935 joseph H. SCHLESINGER- "Neutralization of acids exuding from silicious cements“ .

1949 Herbert RAUTER- "Improvement in dental cement" (contains uranium and fluoride)

1971 Joseph C. MUHLER- additions of either 1. stannous fluoride, 2. stannous fluorozirconate, 3. Indium fluorozirconate, 4. Zirconium hexafluorogermanate,

1979 Werner SCHMITT et al.- "Light curable acrylic dental composition with calcium fluoride pigment"

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CONT….

1985 Henry R. RAWLS- "Fluoride interpolymeric resin“

1997 British Technology Group ltd., of London- "Introducing fluoride into glass“

1998 Shoji AKAHANE- Dental filling resin contaning fluoride“

2001 Fred RUEGGEBERG- "Fluoride-releasing amalgam dental restorative material"

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GLASS IONOMER CEMENTS Glass ionomer (polyalkenoate) cements are based on an ion-

leachable glass, which releases fluoride in the setting process with polyacids

Positive aspects glass ionomer cements1. chemical adhesion to tooth 2. Resistance to microleakage.3. Good marginal integrity.4. Dimensional stability .5. Coefficient of thermal expansion = tooth structure 6. biocompatibility.7. Fluoride release.8. Rechargeability 9. Less shrinkage than resins upon setting

Negative characteristics of this material include 1. Early moisture sensitivity (requiring protection )2. Poor abrasion resistance. and3. Only average aesthetics.

Cont.

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CONT.

The rapid initial release of fluoride is considered to be that of ‘loosely-bound’ fluoride in the cement matrix.

The slower rate occurs with the release of fluoride from the glass particles.

Re-charging of glass ionomers has been referred to as the ‘reservoir effect’.

High initial fluoride release rate may be positively correlated with a high recharging ability.

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CONT. Remineralisation of root dentine adjacent to GIC

restoration has been reported.

Remineralisation of carious lesions has been reported in dentine adjacent to glass ionomer restorations.

The effect of the glass ionomer was most pronounced in the first week of application.

Levels of fluoride in plaque adjacent to glass ionomer restorations have been found to be higher then other.

A reduction in the acidogenicity of S. mutans has also been found in relation to glass ionomer

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F RELEASE FROM RM-GICS

Resin modified glass ionomer cement materials introduce a polymerisation component to the basic glass ionomer cement setting chemistry

Highest during the first 24h (5–35 g/cm2, depending on the storage media)

Having a potential for releasing F in equivalent amounts as conventional GICs.

Recharging of RM-GICs - After onetime refluoridation

➔ Increased F release for 24h➔ Rapid return to near pre-exposure levels within

several days. RM-GICs may exhibit a reduced subsequent F

release when compared with GICs

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POLYACID-MODIFIED RESIN COMPOSITES(COMPOMERS)

Compomers have been developed in an attempt to combine the therapeutic properties of the conventional glass ionomer materials with the more aesthetic resin composites.

features are common with the glass ionomer cement chemistry, most notably the release of fluoride.

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The advantages of compomers include;1. ease of placement, 2. no mixing,3. easy to polish, 4. good aesthetics,5. excellent handling, 6. less susceptibility to dehydration, and7. radiopacity.

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Disadvantages of compomers include;1. limited clinical experience2. few long-term clinical trials 3. requirement for a bonding agent like composites4. more marginal staining and chipping5. wear more than composites6. enormous variation in products makes longevity

difficult to predict7. weaker physical properties than composites and 8. clinical significance of fluoride release undetermined

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CONT.

The maximum fluoride release from the compomer occurs within the first day.

It is unlikely that the fluoride release has a significant effect on recurrent caries prevention.

This is compounded by observations that recharging of fluoride from topical regimes is minimal.

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COMPOMER IN NUTSHELL

No initial F ‘burst’ effect, but levels of F release

remain relatively constant over time

Long-term release of F from compomers was followed and measured up to 3 years

Compomers don’t recharge from F treatment as much as GICs

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GIOMER

Unlike compomers, fluoro-alumino-silicate glass particles react with polyacrylic acid prior to inclusion into the resin matrix.

pre-reacted glass-ionomers(PRG) helps to form a stable phase of glass-ionomer fillers in the restorative

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Include pre-reacted glass-ionomers(PRG) to form astable phase of glass-ionomer fillers in the restorative

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CONT.

F released from giomers- 1. Less information is available currently2. - No initial ‘burst’ effect could be observed3. - Amounts of F leached from giomers

☺slightly > Composites & Compomers ☹ < GICs

F recharging ability- F release from materials was greatly reduced

➔ Only recharge superficial part- GICs > Giomers- PRG in Giomers is surrounded with resin matrix

➔ Porosity of Giomers is lower than GICs

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F-CONTAINING RESIN COMPOSITE MATERIALS

Recently, ‘fluoride-releasing’ resin composite materials have been introduced which may liberate fluoride through passive leaching from suitably selected filler particles or from the addition of fluoridated monomers.

Ytterbium fluoride (YbF2) filler or organic amine fluorides may be present.

The amounts of fluoride released decreased sharply after 24 hours and gradually reached a plateau.

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•Fluoride recharging on exposure to a 1,000 ppm NaF solution was successful.

•Incorporation of fluoride into resin composite materials has not shown any beneficial effect in reducing the demineralisation of carious lesions in roots when compared to glass ionomer cements.

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COMPOSITES IN NUT SHELL

F levels leached from composites- Much < from GICs or RM-GICs- Somewhat < from Compomers

Long-term F release of resin composites is reported to last for up to 5 years

Recharging effect may simply be the release of surface-retained F

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SMART COMPOSITES Active dental polymers contaning bioactive amorphous

calcium phosphate (ACP) filler capable of responding to environmental pH changes by

releasing calcium and phosphate ions and thus become adaptable to the surroundings.

Also called as intelligent composites.

This class of composite was introduced as the product Ariston pHc in 1998.

Ariston is an ion releasing composite material. It releases functional ions like fluoride, hydroxyl, and calcium ions as the pH drops in the area immediately adjacent to the restorative materials

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AMALGAM

Although fluoride is not a component of silver amalgam composition, it may be added in the hope and expectation of caries inhibition, principally as SnF2. Such materials are termed ‘fluoride-releasing’ amalgams.

The caries inhibition was greater than that in non-fluoridated amalgam and composite groups as well as a fluoridated composite.

Development of secondary caries adjacent to amalgam restorations may be related to marginal integrity.

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FISSURE SEALANT The fluoride release from F containing pit and fissure

sealants maximum on the first day.

This decreases sharply on the second day and then decreased slowly for the remaining period.

Fluoride-releasing sealants 1. ProSeal, 2. GC Fuji Triage

showed a significant reduction in wall lesion frequency when compared with a nonfluoride-containing sealant

3. Delton

The mean outer lesion depths in enamel adjacent to fluoride-releasing sealants were significantly reduced when compared with those in enamel adjacent to a nonfluoride-containing sealant.

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VARNISHES

All thought they are used in the restorative regime but can be used for the recharge of the fluoride releasing restorative material.

Also the patient those are most sustainable for the caries can also be varnished.

Fluoride varnishes significantly reduces the S.mutans count in plaque after 24hr.

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SILICATE CEMENTS

First F-releasing material Not much used presently because,1. Poor bonding2. High solubility3. Poor mechanical properties4. Do not survive well in oral environment.

Incidence of secondary caries is rare.

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SUMMARY 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

Optimizing the base formulation can increase fluoride bioactivity without altering the fluoride level, with the potential to enhance anti-caries efficacy

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REFERENCES:-

John Hicks et al. DCNA 2002;46;247-276

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Thank you for bearing me on toes.