FLUORIDES IN OPERATIVE DENTISTRY

Dr. Abina Rashid

INTRODUCTION The word fluoride has been derived from the word ‘ floris ’

meaning destruction in Greek and from Latin word ‘ Flour’ that means to flow since it was used as a flux.

Fluoride is the most electronegative element . Highly reactive ion with atomic no. of 9 and atomic wt. of 19

HISTORY In 1901, Dr. Frederick McKay found permanent stains on the teeth of

the local inhabitants of Colorado Spring, USA which were known as COLORADO STAINS

IN 1902, Dr. J M Eager – denti di chiaie 1916 , Dr. Green Vardmin Black – an imperfection of the enamel of

the teeth 1931, Churchill – fluoride at the level of 13.7ppm 1933 Trendley Dean – shoe leather survey 1942, Dean et al reported that the 1ppm of fluoride in the drinking

water resulted in 60% caries reduction. 1945 first artificial fluoridation plant was started in Grand Rapidis,

USA 1969 WHO advocated 1ppm of fluoride in community water supplies. 1960 acidulated phosphate fluoride introduced by Brudevolt First fluoride varnish developed in 1964 by Schimdt

SOURCES OF FLUORIDE

Water , naturally or artificially fluoridated is the single most important source of fluoride

Fish contain a large amount of about 87.5ppm Tea contains average of 97ppm The average daily intake from water containing 1ppm fluoride

is about 1.5 mg.

MECHANISM OF ACTION

1. increased enamel resistance or reduction in the solubility. 2. increased rate of post eruptive maturation 3. remineralization of the incipient lesions 4. interference of the plaque micro organisms 5. modifications in the tooth morphology.

FLUORIDE DELIVERY SYSTEMS

TOPICAL FLUORIDES : Professionally applied Self applied SYSTEMIC FLUORIDES Dietary fluorides Fluoridated water

TOPICAL FLUORIDES CLINICAL RECOMMENDATIONS FOR THE USE OF PROFESSIONALLY

APPLIED TOPICAL FLUORIDE Caries active individuals In children shortly after tooth eruption Patients with reduced salivary flow Those receiving radiation of head and neck Patients with fixed or removable appliances. After periodontal surgery when roots of teeth have been exposed Patients with eating disorders

PROFESSIONALLY APPLIED TOPICAL FLUORIDES Bibby in 1942 was the first to demonstrate that repeated

application of sodium or potassium fluoride in children significantly reduced their caries experience.

Topical fluoride application has become an established caries preventive procedure in dental office . Three agents currently in use are;

Neutral sodium fluoride Acidulated phosphate fluoride Stannous fluoride

RATIONALE FOR USING TOPICAL FLUORIDE AGENTS

To speed the rate and increase the concentration of fluoride acquisition above the level which occurs naturally

Best time to apply topical fluoride is soon after eruption. White spot is porous and accumulates fluoride at a much

higher concentration than the adjacent sound enamel

NEUTRAL SODIUM FLUORIDE Sodium fluoride was the first fluoride compound to be used for

topical application A minimum of four applications with 2% NaF solution gives a

caries reduction of about 30%

METHOD OF PREPARATION OF 2% NEUTRAL SODIUM FLUORIDE

Dissolve 20gms of sodium fluoride in 1 litre of distilled water. Fluoride ion of the solution can react with silica of glass

forming silicon fluoride , reducing the availability of free active fluorides for anticarious action

METHOD OF APPLICATION ( KNUTSON TECHNIQUE)

In the first appointment teeth are cleaned with slurry of pumice.

Isolated with cotton rolls by quadrant of half mouth 2% NaF applied on the teeth with cotton applicator till teeth

are visibly wet. Allowed to dry for 4 minutes

Instruct patient not to avoid eating and drinking for 30 minutes.

Second , third and fourth appointments are scheduled at intervals of 1 week

Recommend for ages 3, 7 , 11 and 13 .

ADVANTAGES

No need to prepare fresh solution for each patient Taste is well accepted by patient Does not cause discoloration of teeth Non irritating to gingiva

8 % STANNOUS FLUORIDE

METHOD OF PREPARATION ‘0’ no. gelatin capsules priorly filled with 0.8g powdered SnF2

is dissolved in water in plastic container and the solution is shaken briefly

Solution is prepared just before each application.

TECHNIQUE OF APPLICATION ( MUHLER’S TECHNIQUE)

Thorough prophylaxis is done Isolate each quadrant and dry the teeth Apply freshly prepared 8% stannous fluoride with cotton

applicators Repeat every 15 to 30 seconds to keep the teeth moist for 4

minutes Instruct the patient not to eat or drink for 30 minutes Repeat application every 6 months or more frequently if caries

susceptible

ACIDULATED PHOSPHATE FLUORIDE ( APF )

METHOD OF PREPARATION Dissolve 20gms of NaF in 1 litre of 0.1 M phosphoric acid . To this add 50% hydrofluoric acid to adjust pH at 3 and fluoride

concentration at 1.23%. This is called as Brudevolt solution For APF gel, methylcellulose or hydroxyethyl cellulose is added

TECHNIQUE OF APPLICATION ( BRUDEVOLT TECHNIQUE) Paint- on technique of solution and tray technique for gel Biannual application Oral prophylaxis Complete Isolation and thorough drying of teeth APF solution applied with cotton applicators. Keep the teeth moist for 4 minutes. Flossing to ensure wetting of interproximal areas

FOR GEL APPICATION Fill the U/L trays with APF gel usually less than < 5 ml Insert the trays simultaneously into the mouth and ask the

patient to bite Gels thins out and flows under the biting forces and

penetrates between the teeth.

FLUORIDE FOAM AND VARNISH To minimize the fluoride over dosage. Small amount of fluoride is necessary 1gm of foam / mouth The surfactant lowers the surface tension thus facilitates

penetration into the interproximal surfaces Increasing the time of contact between the enamel surface

and topical fluoride agents favours the deposition of more permanently bound florapatatite and florhydroxyapatite. This is possible by incorporating the fluoride compound dircectly into varnish like coating material

DURAPHAT

Is the first fluoride varnish developed in Germany , is a viscous yellowish material, containing 22,600 ppm fluoride as NaF in a neutral colophonium base.

Caries reduction of between 30 – 40 % in the permanent dentition and 7- 44% in the primary dentition

FLOURPROTECTOR

Is a clear polyurethane based product containing 7000 ppm of fluoride from an inorganic compound, difluorosilane at concentration of 2% by weight equivalent to 0.32% fluoride

TECHNIQUE OF VARNISH APPICATION Thorough prophylaxis and dry the teeth 0.3 – 0.5ml of varnish equivalent to 6.9 – 11.5 mg of fluoride is

required to cover the full dentition. First done on the lower arch and then upper arch starting from

the interproximal areas. Patient s made to sit with open mouth for 4 minutes before

spitting to let varnish set on the teeth. Patient is instructed not to rinse or drink anything for 1 hour

and not to eat anything solids till the next morning

SELF APPLIED TOPICAL FLUORIDES

Self applied topical systems presently include fluoride dentifrices, gels, and rinses.

All of these systems are intended for daily use and contain generally comparable amounts of fluoride.

These preparations expose the dentition to about 0.5- 3.4 mgs fluoride each time they are used.

DENTIFRICES The first clinical trial of a fluoride dentifrices was initiated by Bibby

in 1942. The active agent was sodium fluoride added to conventional

dentifrice containing dicalcium phosphate as the abrasive. Contain 1000 to 1500 ppm fluoride either as sodium fluoride or

sodium monofluorophosphate. The Food and Drug ministration in 1973 approved a NaF dentifrice

formulated with calcium pyrophosphate abrasive system with conc. Of 0.188 to 0.254% an d available fluoride conc. Of 650ppm.

FLUORIDE MOUTHRINSES

In 1975, the Council on Dental Therapeutics of the American Dental Association accepted neutral NaF and APF mouthrinses as effective caries preventive agents.

NaF conc. Of 0.2% ( 900ppm fluoride) for weekly use. Or 0.05% ( 225 ppm fluoride) for daily use. Forcefully swish 10ml of liquid around the mouth for 60

seconds before expectorating.

SLOW RELEASE FLUORIDE DEVICES Two types: the copolymer membrane type and the glass bead

type. COPOLYMER MEMBRANE TYPE; Developed by Cowser et al in 1976. Membrane controlled reservoir type having inner core of

HEMA/ MMA copolymer ( 50:50) containing NaF Surrounded by 30:50 HEMA/MMA copolymer membrane . 8mm in length, 3mm wide, and 2mm in thickness.

GLASS DEVICE The original device was modified to a kidney shaped device,

6mm long, 2.5mm in width, 2.5mm in depth. A new modification was introduced to facilitate attachment,

handling and replacement. This new device is shaped in the form of a disc that is placed

within a plastic basket

TOXICITY OF FLUORIDES

The toxic effects of fluoride can be acute , due to a single ingestion of a large amount of fluoride or chronic, due to long term ingestion of smaller amounts.

The effects of chronic fluoride toxicity on enamel is dental fluorosis.

DENTAL FLUOROSIS Caused by excessive intake of fluoride during tooth

development. Ingestion of water with a fluoride content of two to three times

greater than the recommended amounts causes fluorosis.

MODIFIED FLUOROSIS INDEX (1942) Normal (0) : smooth, glossy, pale white color enamel. Questionable(0.5) : white flecks to occasional white spots. Very mild (1) : small, opaque, paper white areas involving approx. 25%

of tooth structure. Mild(2) : more extensive opaque white areas less than 50% of the tooth Moderate (3) : all enamel surfaces are affected. Brown stain is a

disfiguring feature Severe ( 4) : hypoplasia is so marked that the general form of the tooth

is affected. Brown stains are widespread and teeth present a corroded like apearance

THYLSTRUP AND FEJERSKOV INDEX (1978)

TF 0 : Normal translucency. TF 1 : thin white opaque lines. In some cases, snow capping of cusps or incisal

edges. TF2 : opaque white lines are more pronounced, merge to form small cloudy areas

. snow capping is common. TF3: merging of the white lines, cloudy areas of opacity spread over many parts . TF4 : Entire surface appears chalky white. TF5 : the entire surface is opaque, and there are round pits less than 2mm in

diameter. TF6 : the small pits merge to form bands of less than 2mm in vertical height. TF7: loss of outermost enamel and less than half of the surface is involved. The

remaining enamel is opaque. TF8 : loss of outermost enamel that involves more than half of the enamel. TF 9 : loss of the major part of enamel resulting in change of anatomic shape of

the tooth.

MANAGEMENT OF FLUOROSIS IN- OFFICE VITAL BLEACHING Requires excellent rubber dam isolation. The anterior teeth and sometimes the first premolars are isolated

with a heavy rubber dam to provide max. retraction. Most commonly used bleaching agent is 30%- 35% hydrogen

peroxide. Other additives like metallic ion producing materials or alkalinizing

agents are used to speed up the oxidation reaction. The bleaching agent is placed on the teeth and patient is

instructed to note any sensations of burning of lips or gingiva.

A light source is used to generate heat that accelerates the oxidation reaction of hydrogen peroxide.

On completion of the treatment teeth are rinsed , rubber dam removed patient is cautioned about the post operative sensitivity.

Nonsteroidal analgesic or anti-inflammatory drugs may be prescribed.

Tretment is renedered weekly for 2-6 treatments with each treatment lasting for about 45 minutes.

DENTIST PRESCRIBED , HOME APPLIED TECHNIQUE An alginate impression of the arch being treated is made and

poured in stone. Night-guard is formed on the cast using a vacuum forming

machine. The night-guard is trimmed with scissors or no.11 BP Blade in

horse shoe shape Night guard is inserted into the mouth of the patient to check

for adaptation , rough edges and blanching if tissues.

10%-15% carbamide peroxide is generally recommended. It degrades into 3% hydrogen peroxide ( active ingredient) and 7%

urea . Carbopol is added because it thickens the bleaching solution and

extents the oxidation process. A thin bead of material is extruded into the night guard along the

facial aspects corresponding to the area of each tooth to be bleached. After insertion, excess material is wiped from the soft tissues with a

soft bristled tooth brush. The patient is informed not to drink liquids or rinse during the

treatment and to remove the nightguard before meals and oral hygiene.

MICROABRASION In 1984, McClosky reported the use of 18% HCl swabbed on the

teeth for removal of superficial fluorosis stains. In 1986, Croll and Cauanaugh modified the technique to include

the use of pumice with HCl to form a paste applied with a tongue blade.

The procedure involves surface dissolution of enamel by the acid along with the abrasiveness of pumice to remove surface stains or defects.

Croll further modified the technique by reducing the conc. Of acid to 11% and increasing the abrasiveness of the paste using silicon carbide particles instead of pumice.

This product is marketed as Prema compound ( Prime Dental Products Co. ) or Opalustre ( Ultradent ).

A rubber dam is applied to protect the soft tissues from the acid in the Prema paste.

Protective glasses should be worn by the patient to shied the eyes from splatter.

The Prema paste is applied on the defective area of the tooth with a special rubber cup that has fluted edges.

A 10X gear reduction hand piece is recommended for application of Prema compound to reduce the possibility of removing too much tooth structure and to prevent splatter.

MACROABRASION It uses a 12 fluted composite finishing bur or a fine grit

finishing diamond in a high speed hand piece. Use light , intermittent pressure to monitor removal of tooth

structure carefully to avoid irreversible damage to tooth structure.

Air water spray is recommended. After removal of the tooth structure, a 30 fluted composite

finishing bur is used. Final polishing is done with a abrasive rubber point.

CONCLUSION Cariostatic effects of fluoride have been known to us for more

than half a century. Fluoride rinses, lacquers and the use of fluoride tooth pastes cause the elevation of fluoride levels in the oral fluids at which level the dynamic pattern of mineralization and demineralization be affected.

It is now possible to individually design fluoride therapies, thereby minimizing the risk of overdosing. Such knowledge combined with an analysis of the cost/ benefit relationship of various treatments, will also prove useful in the developing countries where caries is on the rise.