Outline of Today’s lecture 1. Introduction 2. Distribution of Fluoride 3. Fluoride functions 4. Sources of Fluoride 5. Clinical significance of Fluoride

Objectives Mention the normal fluoride level Discuss the systemic effects of fluoride on the developing dentition Discuss the clinical significance of fluoride Identify the symptoms of fluoride toxicity

What is fluoride? Fluoride is the ionic form of the element fluorine. It is negatively charged and will not remain as a free element. Fluoride has a high affinity for calcium. –It is, therefore, very compatible with teeth and bone.

Introduction Fluorides are a large group of chemical compounds formed when fluorine combines with other elements. Fluorides are found everywhere-in soil, air, and water, as well as in plant and animal life. Fluoridation is one of the most effective and economical methods of protecting the tooth against decay, and is one of the greatest achievements in the history of public health.

The hardest substances in the body are bones and teeth. When the teeth are forming, the minerals needed are brought to the jaw and deposited in the teeth buds by blood stream. When one of these minerals, fluoride, is in adequate supply, it is incorporated into the enamel of the tooth, and the resulting mineral structure is stronger than it would be without the fluoride. It is important, then, to get fluoride to the teeth when they are mineralizing.

That means from birth, when the primary teeth are forming, right through the development of the adult molars and even later. Fluoride is found in few foods but in varying quantities in water. The addition of fluoride to toothpaste is now very common and is important in those areas where the water supply is low in fluoride. It supports bone mineralization and protects teeth against dental decay (caries). Very large amounts of fluoride can cause mottling and crumbling of teeth, and changes to the bones, a condition called fluorosis.

Fluorosis Dental Caries

There are tow basic ways to get fluoride: Systemic fluoride: swallow it-as with supplements, or fluorinated water. Topical fluoride: as with daily toothpastes, mouth-rinses, or gel treatment at the dentist’s office.

SYSTEMIC FLUORIDE: Fluoride taken internally is systemic fluoride-it is incorporated into the system as building blocks, and some of it will return to the mouth in saliva. There are several ways of getting into the teeth systemically. In the western world, the drinking water contains fluoride that has been adjusted to a therapeutic level; the effect then is both systemic and topical. Where this is not possible, daily fluoride supplements are available as liquids solutions, in tablet form, and in a preparation that combine fluoride with other vitamins and minerals..

TOPICAL FLUORIDE: There is another way to get fluoride to your teeth. In a topical solution-gel, paste or liquid-the fluoride can be wiped, painted or swished around the tooth surface. 1-Topical Fluoride Treatment: These are applied by a dentist following a professional cleaning. Most preparations have a pleasant taste and the treatment takes only a few minutes.

2-Fluoride Toothpaste’s Daily use of fluoride toothpaste is an excellent way to replenish the fluoride reservoir, even if a child is going to the dentist for routine fluoride application. 3-Fluoride Mouth rinses: The use of these rinses must be under guidance of the dentist.

TOPICAL FLUORIDE:

Activity of Fluoride Activity of Fluoride 1. F luoride prevents demineralization. 2. F luoride enhances remineralization. 3. F luoride alters the action of plaque bacteria. 4. F luoride aids in posteruptive maturation of enamel. 5. F luoride reduces enamel solubility.

Clinical Significance : A-Increased Levels Of Fluoride (Fluorine): Fluorosis (>4 ppm In Water). Osteosclerosis. Exostoses of Spine And Ganuvalgum. Excess Ingestion From Swallowing Fluoridated Toothpaste. B-Decreased Levels Of Fluoride: Marginal to deficient dietary intake from deficiency in geochemical environment. Dental caries. Skeletal changes, especially in long bones.

Symptoms of Fluoride Toxicity: Salivation And Thirst (Salty-Soapy). Hypoglycemia. Central Nervous System Depression. Renal Failure.

Normal (Value) Range: Lethal Dose: 50 – 500 mg/kg body weight; 50 – 500 mg/kg body weight; 5-10 g sodium fluoride g sodium fluoride – 0.2 µg/mlPlasma 0.02 – 1.1 µg/mlUrine RDI (recommended daily intake): Men : 4 mg/d Women : 3 mg/d

The Electrochemical Circuit for an Ion Selective Electrode measurement. An ISE (with its own internal reference electrode - more details later) is immersed in an aqueous solution containing the ions to be measured, together with a separate, external reference electrode. (NB: this external reference can be completely separate or incorporated in the body of the ISE to form a Combination Electrode.) The electrochemical circuit is completed by connecting the electrodes to a sensitive milli-volt meter using special low-noise cables and connectors. A potential difference is developed across the ISE membrane when the target ions diffuse through from the high concentration side to the lower concentration side (a detailed description follows later).

Principle of Operation of the Fluoride ISE. In the case of the fluoride ISE, the ion-selective membrane is a single crystal of Lanthanum Fluoride (LaF3) doped with Europium Fluoride (EuF2) which produces holes in the crystal lattice through which F ions can pass. When immersed in a fluoride solution and connected via a voltmeter to an AgCl/KCl external reference electrode immersed in the same solution, the negative F ions in the solution pass through the crystal membrane by normal diffusion from high concentration to low concentration until there is an equilibrium between the force of diffusion and the reverse electrostatic force due to repulsion between particles of similar charge.

On the other side of the membrane there is a corresponding build-up of positive ions. The build up of negative F ions on the inside of the membrane is compensated for by Cl ions in the internal reference solution becoming neutralized by combining with the Ag/AgCl wire, and electrons are thus forced through the external wire to the voltage measuring device (ion meter or computer interface). The other terminal of the voltmeter is connected to the Ag/ AgCl wire of the external reference electrode. Here, the influx of electrons causes Ag ions in the filling solution to accept electrons and deposit on the silver wire and, consequently, Cl ions to flow out into the sample solution.

Conclusion Fluoride is essential!!! An important mineral for human health Must meet adequate daily intake in order to maintain a healthy teeth A very exciting area for research