dental structure and fluoridation

الرحمن الله بسمالصالة وأفضل الرحيم

على التسليم وأتمالمرسلين خير محمد

Dental Structure and Fluoridation

Dr. Iyad M.ABOU RABII

DDS. OMS. MSc. PhD

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.

Mineralisation

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) .

Mineralization

Mineralization

Localization of mineral within the collagen fibril.

Hydroxy Apatite (HA) and fibrillo-carbonato-apatiteTheory of synthesis fibrillo-carbonato-apatite

Hydroxyapatite CrystalsSamson

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


تتوزع شوارد •الكالسيوم في زمرتين

Ca II, Ca I

على Ca I تتوضع •رؤوس المضلع

السداسي .

على Ca II تتوضع •رؤوس مثلثات ثالثية

ضمن المضلع السداسي وينحرف كل مثلث عن

.درجة60اآلخر بزوية

في مركز رباعيات Pتوضع Oوجوه

OO

O

OHتوضع شوارد داخل

Ca II مثلثات


شوارد الفوسفات تنتظم في اثنين من رباعيات

الوجوه (بحيث تقع ذرة الفوسفور ففي المركز , وذرات األوكسجين األربع

في الذرى )

تتوزع شوارد الهيدروكسيل •داخل مثلث كالسيوم الفئة

ويكون توضعها ) CaIIالثانية (غير متناظر ألنها يمكن أن

تبرز إلى كال االتجاهين بشكل -OH أو HO-

في مركز رباعيات Pتوضع Oوجوه

OO

O


Ca II مثلثات


يمكن لشوارد الفلور � أن تدخل إلى هذه أيضا � الفراغات فتشغل مكانا� يقع في مستوى مركزياشوارد كالسيوم الزمرة

الثانية في مركز رباعيات Pتوضع Oوجوه

OO

O


Ca II مثلثات

Enamel rod Structure

Dental structure (Enamel)Enamel.

A, Its rod structure as seen in ground sections with the light microscope. B, Electron micrography shows that enamel consists of a mass of crystallites organized into rod and interrod enamel.

Fluoridation

A. Goals of fluoride administration

B. Non-professional fluoride administration

1. Systemic

2. Topical gels

3. Rinses

4. Dentifrice

C. Professional administration

1. Topical

2. Varnish

Contents

GOALS OF FLUORIDE (F) ADMINISTRATION

Do no harm

Prevent decay on in tact dental surfaces

FF

FF

Arrest active decay

Remineralize decalcified teeth

1.

2.

3.

4.

FF

Fluorosis or toxicity

Do not harm the patient

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.

1.

TEXT

POTENTIAL HARM

5 mg F / kg body 5 mg F / kg body weightweight

20 kg 6 year old, PTD= 100 mg F100 mg F

10 kg 2 year old PTD = 50 mg F50 mg F

230 mg230 mg F/ tube toothpaste

ACT91-97 mg91-97 mg F/ container of F mouthrinse

Symptoms:Symptoms:

1.1. VomitingVomiting

2.2. Excess salivary Excess salivary and mucous and mucous dischargedischarge

3.3. Cold wet skinCold wet skin

4.4. Convulsion at Convulsion at higher dosehigher dose

Probable toxic dose:

Topical F, 12,300 ppm F pH= 3.5

61.5 61.5 mgmg F/ 5 ml

Do not harm the patient

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

1.

TEXT

FF

CaCa

FF

CaCa

Counter Measures:

1. Emetics

2. 1% calcium chloride

3. Calcium gluconate

4. milk

Divalent cations like Ca cause precipitation, of F and prevent absorbtion in the intestine.

FF CaCa

FF

CaCa

FF CaCa

FFCaCa

FFCaCa

FFCaCa

A serious systemic consequence is binding of F to Ca which needed for heart function.

POTENTIAL HARM

FF CaCa

FFCaCa

FFCaCa

FFCaCa

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.

Do Not Harm the Patient

2.

TEXT

10

9

8

7

6

5

4

3

2

FLUOROSIS

0.0 0.5 1.0 2.0 3.0 4.0

DMFT

PPM F IN DRINKING WATER

slight

severe

moderate

mild

F in excess of 0.1mg/ kg body weight = fluorosis

POTENTIAL HARM

FLUOROSIS

FF

FF

Excess F affects mineralization of developing teeth

Up to age 6 is the critical age for fluorosis. After age 8, risk is past.

Enamel prism

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.

Do Not Harm the Patient

2.

TEXT

FLUOROSIS

F in excess of 0.1mg/ kg body weight = fluorosis

Maxium safe dose for a 5 year old = 2 mg F / day

Maxium safe dose for a 2 year old = 1 mg F / day 1 2 3 4

mg F

supplements toothpaste

fluids food

DW Banting JADA 123:86,1991

Daily F intake of a 20 kg 4 year olds with different water F

0.5 ppm water F1.2 ppm water F

FLUOROSIS

Children under 2 years swallow 50% of toothpaste

5 year olds swallow 25% of toothpaste

Toothpaste = 1 mg F / gram (1000 ppmF)

1 to 3 grams

“pea” size amount (0.5g) is recommenred for fluorosis susceptible children.

moderate

severe

mild

pitting

Prevention of Caries

Deposition of fluorapatite (FHA) in sound tooth structure: 1st theory

•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.

1.

TEXT


Deposition of fluorapatite (FHA) in sound tooth structure:

Deposition of FHA is accomplished both by

1.systemic intake of F during tooth development

2.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).

1.

TEXT

MECHANISMS OF F PROTECTION

F F F F F F

F F F F F

FF

Saliva (S)

Plaque (P)

Tooth (T)

DEPOSITION

Increase FHA levels maximally in intact dental surfaces.

Theory:

Topical F is the best method for deposition.

FF

FF

FF

FF

FF

FFFF

FFCaCa

PO4

PO4

CaCa

Neutral pH

remineralization

DEPOSITION OF F

FF

FF

FHA

FHA

FHAFHAHA

pH 5.0

Ca

P

FHA is more acid resistant than HA

H+H+

H+H+

CO3CO3

Mg

H+H+

H+H+Mg and CO3 do not repreci-pitate

F

F

F

F

This has better F uptake due to more porosity

DEPOSITION OF F

Best F uptake is late pre-eruption and early post-eruption

FF

F F

FF

FFFF

FFFF

F

F

F

F

Mature enamel

Surface build-up of F

FF

FF

FF

Enamel fluid

Young enamel

Drinking water

Permanent teeth

Primary teeth

F3000900

No F2000600

Maximal F levels of in outer 5 microns

3000

2000

1000

PPM Fluoride

outer 2 microns = 6000 ppm fluoride (max. uptake)

Fluoride uptake is higher in a decalcified area

FF

5 um

DEPOSITION OF F

CaCaCaCa CaCaCaCaCaCaFF FF

FF

As fluoride reacts strongly with calcium it does not penetrate far into the tooth.

3000 ppm F3000 ppm F

1500 ppm F1500 ppm F

FF

DEPOSITION OF F:

Maxium uptake can not be exceeded. (3000 to 4000 ppm F in outer 5 um)

The F-rich surface can be abraded away.

Bioavailability of F: A second theory of caries prevention asserts that F in the vicinity of carious activity (in enamel fluid) prevents dissolution of HA crystals. Although this mechanism requires only low levels of F (less than 100ppm to as low as 1ppm), F must be present when the acid challenge takes place and therefore must be supplied continually.

Examples of topical applications which ensure bioavailability are fluoridated drinking water and fluoridated dentifrices. A major source of bioavailable F is residual F in plaque and pellicle. F in plaque minerals such as CaF2 or calculus or in protein complexes is released

during bacterial acid production.


2.

TEXT

BIOAVAILABILITY

F

FF

S

P

T F

ACIDACID

SUGAR

Provide continual low level of F to enamel fluid. The benefit occurs at the time of decalcification.

Theory:

MECHANISMS OF F PROTECTION

Water fluoridation is an example of a source.

BIOAVAILABILITY OF F

SUGAR

Low level of F FF

SS

HH++

H+H+H+H+

H+H+

FF

FF

FF

FF

SSSS

saliva

Plaque and enamel fluid

plaque

Intact HA crystals

HH++

FFDecalcifying HA crystals

J Arends. JDR 69(SI):601,1990

Decalcification of enamel crystals:

FF Stable FHA

F Loosely bound or adsorbed F

FF

F

F

F

FF F

F

F

F

FFACIDACID

Protection from dissolution

FF from plaque fluid

H+H+

H+H+


FF

FF

Loosely-bound F

will eventually

become stable

FHA.


FF

FF

F F

F

FF

F

Protection only where is

F

H+H+

H+H+

H+H+

H+H+

H+H+


FF

CaCa

PO4

PO4

CaCa

FHA with no

Incomplete protection

FF

H+H+

H+H+

H+H+

H+H+

H+H+

F



FF

F

H+H+

H+H+MS

Effect on bacteria:

H+H+

H+H+

FF

FF

FF

FF

SSSSHH

++

FF

H+H+

H+H+

The presence of

fluoride at the time of

glycolytic activity will also

inhibit of plaque

acidogenesis.

SOURCES OF BIOAVAILABLE F

1. saliva

0.08

0.02

ppm F in saliva after drinking

1 3 5 h

F F F F

S

P

T

4. RESIDUAL F

ACACTT

2. Fluoridated water

3. Home care products

Calcium Fluoride

F F F F F

Topical F

CaF2 precipitates in plaque during topical F treatment

FHAFHA

No FHANo FHA

No FHANo FHA

FF FF

10 ppm F added to drinking water

LESIONS (mean)

MS

8

30

5

DEPOSITION

BIOAVAILABILITY

Larson RH. Caries Res 10:321, 1976

sugar

BIOAVAILABILITY VERSUS DEPOSITION OF F

Rodent studies:

plus

0

1

2

3

4

5

0.05 0.1 1 5

calcium loss

F ppm in solution

pH

5

4.5

4


pH 5.0

HA

calciumphosphate

JM Ten Cate. JDR 69(SI):614,1990

Research evidence:

F

F

Add F:

Summary of preventive F procedures and recommendations:

The older view of caries prevention was that FHA deposition in non-carious dental surfaces should be maximized by systemic F administration during tooth development, and post-eruptively by topical F treatments.

It was believed that increased FHA provided increased protection against caries.

Although implementation of high FHA deposition has proved beneficial, it does not afford as much protection as bioavailable F. Moreover, the high doses of F required, systemically or topically (which often becomes systemic intake) are partly responsible for the increasing incidence of fluorosis.


3.

TEXT

Summary of preventive F procedures and recommendations:

Current clinical recommendations for preventive F measures are

1) to determine total F intake per day from all sources in order to assess over or under F exposure

2) determine caries risk

3) institute a regimen commensurate with individual caries risk status which emphasizes bioavailability of post-eruptive topical F (e.g. regular use of F dentifrice and other home products if indicated)

4) administer professional topical F treatments, the timing of which should also be gauged to caries risk (This may not be needed in low risk individuals) and

5) administer systemic topical F if indicated. (The latter is currently under review. Present Academy of Pediatric Dentistry recommendations are presented below.


3.

TEXT

FLUORIDE SUPPLEMENTS

AGE<0.3ppm0.3-0.6ppm

>0.6ppm

6m-3y0.2500

3-6y0.50.250

6-16y1.00.50

F in drinking water

FF

Academy of Pediatric Dentistry current recommendations

TEXT

1.1. Determine F intakeDetermine F intake

2.2. Determine caries riskDetermine caries risk

3.3. Devise personalized plan based on Devise personalized plan based on risk level.risk level.

4.4. Stress bioavailability of F.Stress bioavailability of F.

5.5. Monitor F intake of young patients Monitor F intake of young patients in an effort to prevent fluorosis.in an effort to prevent fluorosis.

SUMMARY OF PREVENTIVE F

ThankThank youyou

dental structure and fluoridation

Documents