Reactions, advantages, methods of delivery fluoride Reactions, advantages, methods of delivery

Session outline Fluoride reactions in oral environment Advantages of use of fluoride Methods of distribution Fluorosis

Fluoride reactions in oral environment Formation of fluorohydroxyapatite Formation of calcium fluoride

Fluoride concentration in solution is low Less than around 50ppm Fluoride reactions in oral environment Formation of fluorohydroxyapatite When Fluoride concentration in solution is low Less than around 50ppm In the acidic environment Ca10(PO4)6(OH)2+F- +H+ Ca10(PO4)6(OH) F+H2O

Fluoride reactions in oral environment Fluorohydroxyapatite Will be situated in outermost layers of enamel Will form integral part of the tissue Its formation is slow, unable to keep pace with normal wear of the tooth structure

Fluoride reactions in oral environment Fluorohydroxyapatite In approximal areas the fluoride content of the surface enamel increases over lifetime On smooth enamel surface the fluoride content is reduced by wear and abrasion

Fluoride reactions in oral environment Fluorohydroxyapatite Conditions Oral fluids, saliva, plaque fluid should be supersaturated in respect to fluoroapatite pH above 4.5

Fluoride reactions in oral environment Formation of calcium fluoride When concentration of fluoride in the solution is above 100ppm Happens when topical fluoride treatment is performed The higher fluoride concentration more calcium fluoride is formed Ca10(PO4)6(OH)2+20F- +8H+ 10 CaF2 + 6 HPO4 2- + 2 H2O

Fluoride reactions in oral environment Formation of calcium fluoride Low pH considerably increase dissolution of hydroxyapatites Thus provides Ca 2+ presence also formation of calcium fluoride is increased

Fluoride reactions in oral environment the role of calcium fluoride Calcium fluoride precipitates on sound enamel surfaces On plaque other inaccessible stagnation area CaF will slowly dissolve Has preventive effect maintaining good concentration of fluoride in the near surroundings

Fluoride preventive action against caries Formation of fluorohydroxyapatites which are more acid resistant Formation of calcium fluoride which provides reservoir of fluoride ions fluoride ions provide remineralization have anti plaque effect

Fluoride reactions in oral environment crystal dissolution All minerals have fixed solubility in water Dissolution is relatively fast at first Slows as ions making up the crystal accumulate in solution Solution is saturated with respect to the mineral Slow exchange of ions between crystal and solution occurs

Fluoride reactions in oral environment crystal dissolution Ca2(PO4)3OH 5Ca 2+ +3PO4 3- +OH – PO4 3- , OH – , Ca 2+ ions accumulate in solution Dissolution slows and stops as the solution becomes saturated with ions

Why the dissolution of the ion is increased in acid? If acid is added PO43- ions , OH– ions combine with H+ to form HPO42- ions and H2O Thereby removing a portion of PO4 3- ions and OH- ions from the solution The solution is then unsaturated and more hydroxyapatites dissolve until saturation is re-established

Fluoride reactions in oral environment Critical pH The point at which the solution becomes just saturated with respect to the mineral For hydroxyapatites is 5.5 For fluorohydroxyapatites is 4.5

Fluoride preventive action against caries remineralization Demineralization Under normal conditions oral fluids are supersaturated with respect to both hydroxyapatite and fluoroapatite As pH is lowered below pH critical the supersaturated status is reduced and replaced by unsaturated

Fluoride preventive action against caries remineralization Because pH critical for hydroxyapatites is 5.5 the solution becomes unsaturated with respect to it faster than with fluoroapatites(pH critical 4.5) Between these two pH Hydroxyapatites dissolve in oral fluids-because fluids are unsaturated with respect to it Fluoroapatites are formating on the surface of enamel

Fluoride preventive action against caries remineralization Demineralization occurs in subsurface region Formation of fluoroapatites occurs on surface The formation of fluoroapatites is responsible for the maintenance of integrity of surface layer For less soluble mineral creation

Fluoride preventive action against caries Anti plaque action Competitive inhibition of saliva proteins adhesion to the enamel surface Thanks to the characteristic of F- ion which is very active Has potential for binding Ca ion on the surface of enamel Thus inhibits adhesion of acidic proteins to the enamel Becouse the formation of the plaque on the base of pellicle is specific F- (special bacteria bind with special proteins on the tooth structure) can alter the plaque composition

Fluoride preventive action against caries Anti plaque action Fluoride ion easly gets into the bacterial cell As the active agent has the potential to block enzyme enolase which hydrolizes corbohydrates Thus blockege of metabolism of bacteria has antimicrobial action

Fluoride preventive action against caries Anti plaque action Fluoride ion has also the potential of blockege of formation the extracellular policarbohydrates They create the reservoir of the carbohydrates for bacteria They are crucial for survival in periodes of time when bacteria can not obtain the energy from saliva They are also the very important component of plaque composition

Fluoride methods of delivery Systemic Topical Primary mode of action of fluoride is the result of its activity in the oral cavity and is little benefit from swallowing it.

Fluoride methods of delivery Systemic Water Supplements Milk Salt

Fluoride methods of delivery Topical Toothpaste Gels Varnishes Paint-on applications Mouthrinses

Fluoride methods of delivery Systemic administration Water can contain 1mgF/l mining 1ppm Provides widespread penetration into the population without individual effort Is effective and save Coutries with water fluoridation USA, Canada, UK, Brazil, Australia, New Zealand, Ireland Most effective and cheapes way to provide fluoride supplementation

Fluoride methods of delivery Systemic administration Salt The salt consumption is variable between families Resulting in the risk of fluorosis when consuption is in large amounts

Fluoride methods of delivery Systemic administration Milk Administration of fluoride by milk has an advatage over water fluoridation that can be targeted directly at segments of population deemed to be at risk In school intervations

Fluoride methods of delivery Systemic administration Fluoride supplementation with drugs Floride concentration in drinking water 6 months -3 years 3-6 years 6-16 years Less than 0.3 ppm 0.25mg 0.5mg 1mg 0.3-0.6ppm 0mg More than 0.6ppm

Role of fluoride incorporated during development for tooth structure Fluoride ions become incorporated into the mineral tooth structure if they are present in the environment They create fluoroapatites which are more resistant minerals toward pH drops they activate the process of formation apatites They also help in formation shallow fissures thus the tooth is much easer to clean

Fluoride methods of delivery Self-applied methods Fluoride toothpaste Gels Mouthrinses

Fluoride methods of delivery self-applied methods Toothpaste The fluoride concentration is between 525-1450ppm Mouthrinses 0.2% NaF typically 10ml for 1min

Fluoride methods of delivery proffesional delivery methods Gels, foams Contain higher concentration of fluoride 5000-12300ppm Applicated in the dental office Usually twice a year It is recommended to sit up the patient, and prevent swallowing, with suction

Fluoride methods of delivery proffesional-applied methods Varnish Appication twice a year Provide high uptake of the fluoride ion into the enamel p.e. Duraphat 22 600ppm Clinician applies a thin layer of the varnish directly on the teeth Application time is several minutes Patients are to avoid eating for several hours and than avoid brushing until next morning

Fluoride consisting materials Materials in which fluoride is the integral part of the material: glassionomers In which fluoride is added for anti-caries action : resin-modified glasionomers, compomers, composites(Tetric Ceram, Tetric Flow)

Fluoride consisting materials Can be the reservoir for fluoride in the oral cavity environment They can increase remineralization Decrease demineralization Fluoride secretion can occure for 8 years

Fluoride consisting materials Glassionomers Can be placed on demineralized(afected) dentin in after preparation and studies show mineralization and even hipermineralization of that dentin

Fluoride consisting materials We use GI when strong anti-caries effect is to be achived during for ex. Atraumatic restorative techniques RMGi we use when slow liberation of the low fluoride is needed for anticaries action composites,compomers for its better chemical and phisical resitance and liberation of fluoreide is less important