CONTENTS

Fluorides

1. Introduction .

2. History.

3. Availability.

4. Sources.

5. Application and optimal intake values.

a) Systemic

b) Topical

c) Self applied

6. Absorption.

7. Excretion .

8. Storage.

9. Mechanism of action.

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 materials

9. Fluoride and adjacent tooth.

10. Review of various F-releasing restorative materials

Introduction

Dental caries is one of the most common and per historic diseases occurring in human beings, and it is prevalent in developed, developing, and underdeveloped countries. But once restored, the principal reason for restoration failure is secondary caries in both the permanent and primary dentitions. Secondary caries accounts for approximately 60% of all reasons for restoration replacement, regardless of restorative material type. Other reasons include

o material failure,

o tooth fracture or defect,

o endodontic involvement,

o prosthetic abutment use,

o Technical errors, and deterioration of aesthetic quality with tooth-colored

restoratives.

But, in the modern era after understand the effect of fluoride and its preventing action on dental caries as such, which gave a whole new out look to the restoration of carious or any defective tooth without any fear of secondary’s. But again the complex material brings the complex understanding of its judicious use and technique. So, my presentation titled “fluoride relishing material” will fall under following heading :

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.

FLUORIDES are the ultimate weapon in caries prevention But again the complex material brings the complex understanding of its judicious use and technique.

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.

Fluorides history

Fluorine word is derived from the Russian word "flor" ----------à "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.

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.

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)

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.

Fluoride  Application

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)

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.

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.

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

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.

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.

Fluoride toxicitychronic toxicity

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

Acute toxicity

Highly concentrated fluoride ingestion can have toxic effect. 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

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

Mechanism Of Action of fluorides

1. Increase in enamel resistance OR reduction in enamel solubility.2. Increase in post eruptive maturation.3. Remineralization of incipient lesions.4. Interference with plaque microorganism.5. Modification in tooth morphology.

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 forms the fluorapatite, which is less soluble mineral.

This reduced solubility is the cause of the caries prevention.

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.

Remineralization of incipient lesions.

Fluoride help to Remineralization of the demineralized area.

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.

Modification in tooth morphology

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

Restoration failure and its squelae

2˚ 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.

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.

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.

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.

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.

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

Fluoride releasing restorative material

Today, there are several fluoride-containing dental restoratives available in the market including

1. Varnishes

2. Sealents

3. 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.

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 included

1. Fluoroaluminosilicate glasses (FAG),

2. Stannous fluoride (Snf2),

3. Organic amine fluorides (CAFH) and

4. Ytterbium fluoride (ybf2).

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 and

4. pellicle formation.

It was shown that factor like

1. 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.

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.

Fluoride recharge

“Recharging” is to maintain level of fluoride release.

FROSTEN et al. found the phenomenon in GIC and called it “topping up effect”

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.

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.

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 as

1. 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.

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.

Fluoride-releasing materials (Caries-preventive mechanisms)

Formation of fluorapatite

Enhancement of Remineralization .

Interference of ionic bonding during pellicle and plaque formation.

Inhibition of microbial growth and metabolism

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

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. Polycarboxylates

8. Sealents

9. Varnishes

10. silicates

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"

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"

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 cements

1. 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. and

3. Only average aesthetics.

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.

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

Glass ionomer in nutshell

Commercial products

Ketac-fil >>>>>>3M ESPE

Fuji II>>>>>>>>GC America

Ketac-molar>>> 3M ESPE

Fuji IX>>>>>>> GC America

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

Commercial products

Photac-fil>>>>>>>3M ESPE

Fuji II LC>>>>>>>GC America

Vetremer>>>>>>> 3M ESPE

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.

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, and

7. radiopacity.

Disadvantages of compomers include;

1. limited clinical experience

2. few long-term clinical trials

3. requirement for a bonding agent like composites

4. more marginal staining and chipping

5. wear more than composites

6. enormous variation in products makes longevity difficult to predict

7. weaker physical properties than composites and

8. clinical significance of fluoride release undetermined

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.

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

Commercial products

Dyract AP>>>>>caulk dentsply

Hytac>>>>>>>>3M ESPE

Compoglass>>>Ivoclar vivadent

F 2000>>>>>>>3M ESPE

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

F released from giomers-

1. Less information is available currently

2. - No initial ‘burst’ effect could be observed

3. - 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

F-containing resin composite materials

Composite resins have also been formulated to release fluoride. As early as 1970s, some composite resins incorporated fluorides and were shown to release fluorides.

à The release of fluoride from composite resins demonstrated a reduction in 2° caries initiation and even remineralization of adjacent demineralized enamel when examined in vitro. Studies have detected a fluoride release of 200-300µg/mm2 from composites to completely inhibit in situ secondary caries.

à Donly and Gomez (1994) have also demonstrated the remineralizing effects of a fluoride-releasing composite.

à Although fluoride-releasing composites have consistently demonstrated recurrent caries inhibition at enamel margins, there are still conflicting results regarding caries inhibition at dentin margins (Donly 1994).

à As with GICs, there may be a “Synergistic effect” between fluoride-releasing composites and fluoride rinses or fluoridated dentifrices.

à i.e when exposed to external fluoride, the materials surface undergoes an increase in fluoride, which is subsequently released.

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.

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

Commercial products

Haliomolar>>>>>Caulk Dentsply

Tetric>>>>>>>>>Ivoclar Vivadent

Solitaire>>>>>>>Heraeus Kulzer

Surefil>>>>>>>> Caulk Dentsply

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

Amalgam

Fluoride containing amalgams have been shown to have anticaries properties that is sufficient to inhibit the development of caries in cavity walls.

Studies have shown that the concentration of fluoride in the saliva by fluoride-releasing amalgams is sufficient to enhance remineralization.

Therefore, fluoride releasing amalgam restorations may have a favourable effect on initial demineralization in the mouth.

Tviet and Lindh (1980) found that the greatest concentration of fluoride i.e. about 4000µg/mL in enamel surfaces exposed to fluoride-containing amalgams were found in the outer 0.05µm of the tissue.

In dentin, the greatest concentrations, i.e. about 9000µg/ml were found at a depth of 11.5µm.

Most of the fluoride-releasing amalgams like other fluoride containing dental restorative materials show an initial release that is significant. However, this release of fluoride decreases to minor amounts after 1 week.

One study found salivary fluoride concentrations at more than 20 times baseline concentration for the first few days after placement of restorations. The release declined exponentially to baseline levels after 30 days. One In- vivo study has shown that fluoride released from amalgams loaded with soluble fluoride salts was detectable within the first month and thereafter fluorable was not released in measurable amounts. Another in vitro study showed fluoride release can continue as long as 2 years (but at a much lower rate than that for GIC).

Disadvantage – The leaching of fluoride makes the amalgam more susceptible corrosion.

Fissure sealant

In 1984, Roberts, Shern and Kennedy evaluated an autopolymerizing pit and fissure sealant as a vehicle for the slow release of fluoride.

à Sodium fluoride was added to the sealant at several concentration (upto concentrations of 2.5%).

à The fluoride release was measured to be 0.3µg/mL for a period from 31 days to 90 days at the highest concentration (i.e. 2.5%).

à However, when the authors considered the dilution factor due to average salivary flow, they concluded that this level of release would be below any known level of physiologic significance.

à In the late 1980s, a fluoride-containing sealant was introduced to the dental materials market place. The product was evaluate in vitro. It was found to release fluoride over a 7 day evaluation period, beginning at a level of 3.5µg/mL on the 1st day and declining to a level by 0.41µg/mL on the last 2 days.

à This same product was clinically compared to a conventional glass-ionomer sealant.

à It was found that retention of the fluoride releasing resin was much higher and caries incidence was much lower than the glass ionomer (Rock and others, 1996).

à What could not be resolved in this study was whether this lower incidence of caries was due to fluoride release or the greater retention of the resin.

In another, in vitro study (Jensen et al, 1990) a fluoride releasing pit and fissure sealant was found to reduce the amount of enamel demineralization adjacent to the material, compared with conventional pit and fissure sealants.

à Seppa and Forss (1991) found that fissures sealed with a glass ionomer sealant were more resistant to demineralization than were unsealed controls.

They suggested that the result may be the combined effect of fluoride release and residual materials in the bottom of the fissures.

Fluoride-releasing sealants

1. ProSeal,

2. GC Fuji Triage

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

1. 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.

LINERS /BASES AND CAVITY VARNISHES

There are currently half dozen or more fluoride releasing liners on the market.

à Some have been found to significantly reduce lesion areas under amalgam restorations.

à Most of these liners / bases have been found to have a “Burst effect” in the release of fluoride.

à Most studies have shown that the largest proportion of total fluoride release occurs during the first days or weeks, followed by dramatic reductions in the rate of release.

à Long term release of fluoride varied over a range of 0µg/mL to 7 µg/mL.

Glass ionomer cements have also been used as a liner material under amalgam restorations.

à They have been shown to continue releasing measurable amount of fluoride in the range of 0.3µg/mL to 1.1µg/mL after 1 year.

à Certain in vitro studies have also shown glass ionomer cements to reduce recurrent caries when placed under amalgam.

à A light cured and a chemically cured glass ionomer cement liner were found to have a similar effect in inhibiting demineralization.

Both demonstrated significantly less demineralization than a non-fluoride-releasing control liner (Souto and Donly, 1994).

ZINC POLYCARBOXYLATE CEMENT

The powder of zinc polycarboxylate cements contains small quantities of stannous fluoride.

à The stannous fluoride :

1) Modifies the setting time

2) Enhances manipulative properties.

3) Increases strength.

à However, the fluoride released from this cement is only a fraction (15-20%) of the amount released from (zinc silicophosphate) and glass ionomer cements.

à There are not many studies done further regarding the amount/rate of fluoride release for these cements.

Silicate cements

First F-releasing material

Not much used presently because,

1. Poor bonding

2. High solubility

3. Poor mechanical properties

4. Do not survive well in oral environment.

Incidence of secondary caries is rare.

CONCLUSION

From the above, it can be concluded that:

1) All fluoride-containing materials release fluoride in an initial burst and then reduce exponentially to a much lower steady-state level of release.

2) The steady state release of fluoride is reached after approximately 30 days for most materials.

3) Caries inhibition and remineralization potential have been shown in vitro by all of these materials when release levels have been equal to or exceeding approx. 1µg/mL/

4) There are few clinical studies that appear to support the proposition that low levels

of fluoride release can inhibit in vivo demineralization and caries formation.

5) The ultimate goal of correlating fluoride release with actual caries inhibition

reduction is an objective than can be met by completing clinical studies on

materials that release fluoride.

References:-

1. Philips dental materials 10th ed. 2. Mosby dental materials 5th ed.3. Sumit fundamental of operative dentistry 2nd ed.4. Review on fluoride releasing material DCNA 2007