Dental structure (Enamel) The enamel is the most highly mineralized tissue in the body consisting of 95% hydroxyapatite (HAP) 4.5% water 0.5% organic matrix.
Dental structure (Enamel) Enamel is the visibl white part of the crown. It contains calcium phosphate, fluorine, protein and water. Thanks to this combination, the enamel optimally protects the interior of each tooth from temperature differences, bacteria and acids, as well as from the pressure required to chew food.
Mineralization• It is the change of physical stat of a substance from liquid and semi-liquid status to solid status through deposition of minerals (calcium and phosphate) .
Hydroxyapatite Crystals Samson Chemical formula is Ca10 (Po4). X2 Hydroxyapatite Crystal has one longitudinal axis C and three transversal axis a1, a2, a3 the two axis a1,a2 are perpendicular with the axis C with an angle of 120 between theses two axiss
Enamel rod StructureEnamel. A, Its rod structure as seen in ground sections with thelight microscope.B, Electron micrography shows that enamel consists of amass of crystallites organized into rod and interrodenamel.
GOALS OF FLUORIDE (F) ADMINISTRATION1. Do no harm 3. Arrest active decay F Fluorosis or toxicity2. Prevent decay on in tact dental surfaces 4. Remineralize decalcified teeth F F
TEXT Do not harm the patient1. Probable toxic dose (PTD): • PTD is 5 mg F/kg body weight. For a 20 kg 5 to 6 year old this would be 100 mg for a 10 kg 2 year old, 50 mg. F content of dental products or treatments may exceed these values for young children. For example, a gel tray containing 5 ml of APF contains 61.5mg F (F is absorbed more quickly when in acidic form.), 100ml of 0.2 or 0.4% F mouth rinse contains 91 or 97mg F and a tube of fluoridated toothpaste contains as much as 230mg F.
POTENTIAL HARMProbable toxic dose: 5 mg F / kg body weight 61.5 mg F/ 91-97 mg F/ ACT 5 ml container of F mouthrinse Topical F, 12,300 ppm F pH= 3.5 20 kg 6 year old, PTD= 100 mg F Symptoms: 1. Vomiting 2. Excess salivary and mucous discharge 230 mg F/ 3. Cold wet skin tube 4. Convulsion at 10 kg 2 year old toothpaste higher dose PTD = 50 mg F
TEXT Do not harm the patient1. Probable toxic dose (PTD): Sub-lethal toxic symptoms are manifested quickly after the dose and consists of 1. vomiting 2. excessive salivation 3. tearing 4. mucous discharge, 5. cold wet skin 6. convulsions
POTENTIAL HARMA serious systemic Counter Measures:consequence is binding of Fto Ca which needed for 1. Emeticsheart function. 2. 1% calcium chloride 3. Calcium gluconate F 4. milk F F Ca F Ca Divalent cations like Ca cause Ca Ca precipitation, of F and prevent absorbtion in the F intestine. F Ca Ca F Ca Ca F F F Ca F F Ca Ca Ca
TEXT Do Not Harm the Patient2. Fluorosis: Fluorosis occurs when teeth are developing. The most critical ages are from 0 to 6 years. After 8 years, risk of fluorosis is essentially past. During the critical ages F intake in excess of 0.1mg/kg body weight/day can lead to fluorosis. This is roughly 1mg/day for a 1 to 2 year old or 1.5 to 2 mg for a 5 year old.
POTENTIAL HARM DMFT FLUOROSIS 10 9 severe 8 moderate 7 6 mild 5 4 slight 3 2 0.0 0.5 1.0 2.0 3.0 4.0 PPM F IN DRINKING WATER F in excess of 0.1mg/ kg body weight = fluorosis
FLUOROSIS F F Enamel prism Excess F affects mineralization of developing teeth Up to age 6 is the critical age for fluorosis. After age 8, risk is past.
TEXT Do Not Harm the Patient2. Fluorosis: Remember that all forms of F intake comprise the daily consumption. This includes 1. water intake (up to 1.5mg/day) 2. Foods (0.3 to 1.0mg) and especially significant in young children 3. Swallowed toothpaste. Children under 2 years swallow 50% of toothpaste during tooth brushing and at 5years, 25%, both of which may amount to 1mg F/day.
FLUOROSIS Daily F intake of a 20 kg 4 year olds with different water F Maxium safe dose for a 2 year old = 1 mg F / day 1 2 3 4 mg F 0.5 ppm water F 1.2 ppm water F supplements toothpaste Maxium safe dose fluids food for a 5 year old = 2 mg F / day DW Banting JADAF in excess of 0.1mg/ kg bodyweight = fluorosis 123:86,1991
FLUOROSIS 5 year olds swallow 25% of toothpaste Children under 2 years swallow 50% of toothpaste 1 to 3 grams “pea” size amount (0.5g) is Toothpaste = 1 mg F / recommenred for fluorosis gram (1000 ppmF) susceptible children.
Prevention of Caries: 1st theory1st theory :Deposition of fluorapatite (FHA) in sound tooth structure: •Caries protection results from FHA being more acid resistant than pure hydroxyapatite (HA). •Deposition takes place when F replaces hydroxyl groups in HA. •This can occur pre- or post-eruption at neutral pH, or post- eruptively at neutral or acidic pH. At low pH, HA dissolves, then re-precipitates as new crystals which are larger and more acid- resistant due to higher FHA and lower magnesium and carbonate content.
Prevention of Caries: 1st theoryDeposition of fluorapatite (FHA) in sound tooth structure:Deposition of FHA is accomplished both by1. systemic intake of F during tooth development2. topical F administration after eruption. Professional topical F treatments with concentrated acidulated phosphate fluoride (APF) gels (2.72% APF gel contains 12,300 ppm F), is the most efficient way to accomplish this, especially when applied to newly erupted teeth (i.e., age 2 for primary molars; age 6 to 8 for permanent first molars and anterior teeth; age 11 to 14 for permanent premolars and second molars).
MECHANISMS OF F PROTECTION DEPOSITIONSaliva (S) F F F F F Plaque (P) F F F F FF FTooth (T) Topical F is the best Theory: method for Increase FHA deposition. levels maximally in intact dental surfaces.
DEPOSITION OF F F FHA is more acid resistant than HA F FF F FHANeutral pH remineralizationH+ PO4 H+ F PO4 F FHA F HA F CO3 Ca Ca pH 5.0 Mg F H+ Mg and CO3 P do not H+ reprecipitate CaFHA
DEPOSITION OF F Best F uptake is late pre-eruption Surface and early post-eruption F build-up of F F F F F F F F F F F F Mature Drinking Permanent Primary enamel water teeth teeth F F Ename F F F 3000 900 l fluid F F F No F 2000 600 Young enamelThis has better F uptake due tomore porosity Maximal F levels of in outer 5 microns
DEPOSITION OF F Fluoride uptake is higher in a decalcified PPM Fluoride area 3000 2000 1000 5 um 3000 ppm F 1500 ppm F outer 2 microns = 6000 ppm fluoride (max. uptake) F F F F Ca Ca Ca Ca CaAs fluoride reacts strongly with calcium itdoes not penetrate far into the tooth.
DEPOSITION OF F: FMaxium uptake cannot be exceeded.(3000 to 4000 ppm Fin outer 5 um) The F-rich surface can be abraded away.
Prevention of CariesBioavailability of F: A second theory of caries prevention asserts thatF in the vicinity of carious activity (in enamel fluid) preventsdissolution of HA crystals. Although this mechanism requires onlylow levels of F (less than 100ppm to as low as 1ppm), F must bepresent when the acid challenge takes place and therefore must besupplied continually.Examples of topical applications which ensure bioavailability arefluoridated drinking water and fluoridated dentifrices. A major sourceof bioavailable F is residual F in plaque and pellicle. F in plaqueminerals such as CaF2 or calculus or in protein complexes is releasedduring bacterial acid production.
MECHANISMS OF F PROTECTIONBIOAVAILABILITY Water fluoridation is an example of a source. S SUGAR F P F ACID T F Theory: Provide continual low level of F to enamel fluid. The benefit occurs at the time of decalcification.
BIOAVAILABILITY OF F Decalcification of enamel crystals: SUGAR S Low level of F F saliva H+ S S plaque F F H+Decalcifying HA F Plaque and Fcrystals H+ enamel fluid H+ F H+ Intact HA crystals J Arends. JDR 69(SI):601,199 0
BIOAVAILABILITY OF F F from plaque J Arends. JDR fluid 69(SI):601,199 0 ACID F F F F H+ F F F F F F H+ F F F F Protection from dissolution Loosely-bound F will eventually F Stable FHA become stable Loosely bound or FHA. F adsorbed F
BIOAVAILABILITY OF F H+ FHA with no F F H+ H+ H+ F F H+ F F PO4 F F F PO4 F H+ H+ H+ F Ca H+ Ca Protection only H+ where is F Incomplete protection J Arends. JDR 69(SI):601,199 0
BIOAVAILABILITY OF F Effect on bacteria: F H+ S S F F F H+ H+ F H+ H+ F MS F H+ F The presence of H+ fluoride at the time of glycolytic activity will also inhibit of plaque acidogenesis.
SOURCES OF BIOAVAILABLE F1. saliva AC T 2. Fluoridated water 3. Home care products Topical F 4. RESIDUAL F F F F F F S ppm F in saliva after drinking P 0.08 F F F F T 0.02 CaF2 precipitates in Calcium plaque during topical 1 3 5 h Fluoride F treatment
BIOAVAILABILITY VERSUS DEPOSITION OF FRodent studies: LESIONS (mean) 30 No FHA MS plus 8 DEPOSITION FHA F F 5 No FHA sugar BIOAVAILABILITY 10 ppm F added to Larson RH. Caries drinking water Res 10:321, 1976
BIOAVAILABILITY OF F Research evidence: Add F: F calcium loss F 5 HA 4 3 pH 5.0 2 1 pH 0 phosphate 0.05 0.1 1 5 calcium F ppm in solutionJM Ten Cate. JDR69(SI):614,1990
Prevention of CariesSummary of preventive F procedures and recommendations:The older view of caries prevention was that FHA deposition in non-cariousdental surfaces should be maximized by systemic F administration duringtooth development, and post-eruptively by topical F treatments.It was believed that increased FHA provided increased protection againstcaries.Although implementation of high FHA deposition has proved beneficial, itdoes not afford as much protection as bioavailable F. Moreover, the highdoses of F required, systemically or topically (which often becomessystemic intake) are partly responsible for the increasing incidence offluorosis.
Prevention of CariesSummary of preventive F procedures and recommendations:Current clinical recommendations for preventive F measures are1) to determine total F intake per day from all sources in order to assessover or under F exposure2) determine caries risk3) institute a regimen commensurate with individual caries risk status whichemphasizes bioavailability of post-eruptive topical F (e.g. regular use of Fdentifrice and other home products if indicated)4) administer professional topical F treatments, the timing of which shouldalso be gauged to caries risk (This may not be needed in low riskindividuals) and5) administer systemic topical F if indicated. (The latter is currently underreview. Present Academy of Pediatric Dentistry recommendations arepresented below.
FLUORIDE SUPPLEMENTS F F in drinking water AGE <0.3ppm 0.3- >0.6ppm 0.6ppm 6m-3y 0.25 0 0 3-6y 0.5 0.25 0 6-16y 1.0 0.5 0 Academy of Pediatric Dentistry current recommendations
SUMMARY OF PREVENTIVE F1. Determine F intake2. Determine caries risk3. Devise personalized plan based on risk level.4. Stress bioavailability of F.5. Monitor F intake of young patients in an effort to prevent fluorosis.
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