Fluoride

Question 1

Formula of hydroxyapatite

Answer 1

C10(PO4)6(OH)2

Question 2

Formula of carbonate- hydroxyapatite

Answer 2

Ca5(PO4CO3)3(OH)

Question 3

Problem with carbonate hydroxyapatite

Answer 3

Dissociates into ions much more readily than hydroxyapatite
Presence of carbonate group makes it more vulnerable to acid attack
Crystals are less well packed, therefore acid can pass between crystals and contact with crystals deeper within the structure

Question 4

Structure of hydroxyapatite

Answer 4

Crystalline form

Crystals are closely packed - hexagonal arrangement

Question 5

Formula of Fluorapatite

Answer 5

Ca10(PO4)6F2

Question 6

Benefit of fluoroapatite

Answer 6

Makes it more resistant to acid attack
Fluoride can be incorporated into the surface of the enamel during development
May also be absorbed into the surface of the enamel if added to the oral environment after eruption

Question 7

How is fluoride exploited clinically

Answer 7

In toothpaste, varnish, water

Question 8

Fluoride adsorbed onto the surface of the intact enamel may give a surface zone rich in fluroapatite up to

Answer 8

2000ppm

Question 9

Fluoride incorporated into the bulk of the enamel during tooth development gives a fluoride concentration in the enamel in the region of

Answer 9

20-100 ppm

Question 10

Fluoride incorporated onto the surface of enamel during remineralisation may give a surface veneer of apatite rich in fluorapatite with concentrations up to

Answer 10

30,000 ppm

Question 11

How does fluoride act to protect the tooth

Answer 11

Inhibition of bacterial metabolism
Inhibition of demineralisation of enamel
Promotion of remineralisation of the enamel surface

Question 12

What is fluorosis

Answer 12

Excess fluoride leads to enamel hypomineralisation