hard tissue pathology - caries III Early Enamel Lesion Flashcards
what is the basic enamel structure?
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.
what is the name of earliest sign of the enamel lesion?
white spot lesion
is the white spot lesion reversible?
Reversible at this stage-Saliva, oral hygiene, fluoride.
when may demineralisation occur?
May occur after one week of plaque accumulation.
Reversible at this stage.
what is remineralisation?
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.
What are microscopic features of early ennamel lesion?
white spot lesion
Commonly seen on extracted teeth as small,opaque,white area cervical to contact point.
Colour change based on increased porosity-alters way light is scattered.
what is the histological picture of early enamel lesion?
On smooth surface, lesion is usually cone shaped-apex towards dentine.
Shape follows direction of prisms.
Centre of cone corresponds to deepest portion of lesion-also oldest and most active.
Spreads laterally on the surface of tooth.
Divided into 4 zones-translucent,dark, body and surface.
what are the 4 zones of enamel caries?
translucent, dark, body and surface
what is the translucent zone ?
First recognisable alteration from normal enamel.
Demarcated from normal enamel and dark zone by darker line.
Pore volume of <1%
Pores located at junctional sites
what is the dark zone?
Lies between translucent zone and body of lesion.
More porous than translucent zone.
Pore volume 2-4%.
Pores both large and small.
Small pores probably represent areas of mineral re-deposition.
Arrested lesions show well developed dark zones at front, within body and at surface of lesion.
what is the body of lesion zone?
Largest area.
Striae of Retzius well marked. (Incremental growth lines during enamel development)
Pore volume 5% at periphery and up to 25% at centre.
what is the surface zone?
unaffected area.
Pore volume of <1%.
High degree of mineralization.
High fluoride content.
Active de- and re-mineralisation.
Surface zone may be manifestation of remineralisation.
what are 4 ways of management of early lesions?
OHI
Diet
fluoride
Saliva - Capable of regulating pH of oral cavity- bicarbonate and phosphate production.
