hard tissue pathology - caries III Early Enamel Lesion

Question 1

what is the basic enamel structure?

Answer 1

Tightly packed hydroxyapatite crystals.
Each crystal separated by pores.
Pores filled with water and organic matrix.
Acids remove mineral from crystal surface-crystal shrinks in size.
Pores enlarge and tissue becomes porous.

Question 2

what is the name of earliest sign of the enamel lesion?

Answer 2

white spot lesion

Question 3

is the white spot lesion reversible?

Answer 3

Reversible at this stage-Saliva, oral hygiene, fluoride.

Question 4

when may demineralisation occur?

Answer 4

May occur after one week of plaque accumulation.
Reversible at this stage.

Question 5

what is remineralisation?

Answer 5

restoring minerals to demineralised structures
Remineralised lesions more resistant to further acid attack-resembles scar tissue.
White spot becomes less obvious-may even disappear.
Also saliva is remineralising fluid.

Question 6

What are microscopic features of early ennamel lesion?

Answer 6

white spot lesion
Commonly seen on extracted teeth as small,opaque,white area cervical to contact point.

Question 7

what is the histological picture of early enamel lesion?

Answer 7

Early enamel lesion is cone shaped-apex towards dentine.
Shape follows direction of prisms.
Spreads laterally on the surface of tooth.
Divided into 4 zones-translucent,dark, body and surface.

Question 8

what are the 4 zones of enamel caries?

Answer 8

translucent, dark, body and surface

Question 9

what is the translucent zone ?

Answer 9

First recognisable alteration from normal enamel
Appears structureless
Demarcated from normal enamel and dark zone by darker line
Pore volume of below 1%

Question 10

what is the dark zone?

Answer 10

Lies between translucent zone and body of lesion.
More porous than translucent zone.
Pore volume 2-4%.

Question 11

what is the body of lesion zone?

Answer 11

Largest area.
Striae of retzius well marked
Pore volume 5% at periphery and up to 25% at centre.

Question 12

what is the surface zone?

Answer 12

unaffected area.

Pore volume of <1%.

High degree of mineralization.

High fluoride content.

Question 13

what are 4 ways of management of early lesions?

Answer 13

OHI
Diet
fluoride
Saliva - Capable of regulating pH of oral cavity- bicarbonate and phosphate production.

Question 14

Early enamel lesion shape -

Answer 14

cone shape apex towards dentine shape follows the direction of prisms spreads latterly

Question 15

Dentinal lesions -

Answer 15

roughly cone shaped apex towards the pulp and base towards the adj

Question 16

Fissure lesions

Answer 16

cone shaped but the base of the cone is at the ADJ and broadens as it approaches dentine