Histopathology of dental caries Dr Maji Jose Smooth

Histopathology of dental caries Dr. Maji Jose

Smooth surface caries Pit and fissure caries Dr. Maji Jose

Histopathology of dental caries • Histopathology of Enamel caries • Histopathology of dentinal caries Dr. Maji Jose

Histopathology of Enamel caries Macroscopic picture • Pit and fissure caries spread in triangular pattern following direction of enamel rods with – base towards dentin and apex towards the enamel surface. Dr. Maji Jose

• Carious lesion of pits and fissures develop from attack on their walls. • In cross section, the gross appearance of pit and fissure lesion is inverted V with a narrow entrance and a progressively wider area of involvement closer to the DEJ. Dr. Maji Jose

Early and late pit and fissure caries Dr. Maji Jose

• Smooth surface caries also spread in triangular pattern with – base towards the enamel surface and apex towards dentin. • In the region of DEJ caries spread laterally and extend to dentin in triangular pattern with – base towards the DEJ and apex towards the pulp Dr. Maji Jose

Dr. Maji Jose

Darling’s Zones of enamel caries (Zones from deepest to most superficial) • • Translucent Zone Dark zone Body of the lesion Surface layer Dr. Maji Jose

Smooth Surface Enamel Caries – Early lesion • The lesion is roughly triangular with the base at the tooth surface and the apex (arrow) pointing towards the dentin. Dr. Maji Jose

Translucent Zone Dark Zone Body of lesion Prominent striae of retzius Intact Surface zone Dr. Maji Jose

Zones of enamel caries Dr. Maji Jose

Zone 1 - Translucent Zone Lies at the most advancing front( deeper part) First recognizable change Not always present Polarized light reveals increased porosity in this zone than normal enamel, with a pore volume of 1% compared to 0. 1% in sound enamel. • Appear as a translucent zone/ structureless in longitudinal ground section of enamel when quinoline is used as the mounting media • • Dr. Maji Jose

This zone appear translucent because…… • the mounting media with same refractive index as enamel, flow into the pours in the zone, which are located at the prism boundaries and other junctional sites, making the structural lines invisible Dr. Maji Jose

Translucent Zone also shows… • Increased fluoride content • Decreased magnesium carbonate rich minerals • Around 1. 2% mineral lost • No protein / organic content loss Dr. Maji Jose

Dark Zone • • Lies adjacent and superficial to translucent zone. Called as positive zone 1. Always present 2. Positive birefringence in contrast to negative birefringence of normal enamel. Dr. Maji Jose

• Polarized light shows pore volume of 2 -4%, but the pore size is smaller than that of translucent zone. Smaller pore size is due to represipitation of minerals lost from translucent zone • Appear brown in ground section and vary in thickness Dr. Maji Jose

• Due to small size of pores, when quinoline having a large molecular size is used for mounting, the medium do not flow into the pore and the pore remain filled with air making this zone dark. • when aqueous medium is used as a mountant this zone appear light • Mineral lost is 6% Dr. Maji Jose

Body of the lesion • Largest zone located between dark zone and surface zone • Under polarizes light this zone shows 5% pore volume at the periphery and 25% at the center Dr. Maji Jose

• Appear as a relatively translucent zone compared to normal enamel in longitudinal ground section. • Striae of Retzius appear marked in contrast to the translucency Dr. Maji Jose

• It is the zone of greatest demineralization with mineral loss of around 24%. • Corresponding increase in unbound water and organic content is seen due to ingress of saliva and bacteria Dr. Maji Jose

Surface Zone • Most superficial zone of around 40 micons thickness • Mineral loss is about 1 -10% • Pour volume is less than 5% • Shows negative birefringence above the positive birefringence of body of lesion, when section is examined in water with polarized light Dr. Maji Jose

• Surface layer remain intact, and breaks down only after caries reaches dentin. • Greater resistance of this layer is due to 1. greater degree of mineralization 2. high concentration of fluoride 3. grater amount of insoluble proteins Dr. Maji Jose

Pit and fissure caries • Similar to smooth surface caries except for variation in anatomic structure • Caries begin in relation to fissures which may show different pattern such as broad or narrow funnels, constricted hour glasses, multiple invaginations with inverted ‘y’ shape divisions and irregularly shaped. Dr. Maji Jose

Ultra-structural changes • Scattered destruction of individual apatite crystals both in prism and their borders • Progressive dissolution of crystals- broadening of inter-crystalline spaces • Increased porosity of enamel • Crystals at prism border appear largerdemineralization • Diffuse destruction of apatite crystalsbacterail invasion Dr. Maji Jose

Caries of Dentin…. . • Differs from enamel caries because…. 1. Dentin is a vital structure which is able to show a reparative response. 2. Dentin has more organic component Dr. Maji Jose

Macroscopic structure/ pattern of spread • In both pit and fissure and smooth surface caries, in the region of DEJ caries spread laterally and then extend to dentin in triangular pattern with base towards the DEJ and apex towards the pulp. • Apex is more apical to the base, because the caries follow the direction of dentinal tubules Dr. Maji Jose

Shape: Dentine Caries Dr. Maji Jose

Dr. Maji Jose

H/P of Dentinal caries…. • Zone of fatty degeneration of Tomes’ dentinal fibers • Zone of dentinal sclerosis • Zone of demineralization/ decalcification • Zone of bacterial invasion • Zone of destruction/decomposed dentin Dr. Maji Jose

Zones in advanced dental caries • The 5 “D’s” for Dentinal caries. • Deepest inner zone to outermost zone: 1)Fatty Degeneration 2)Dentinal sclerosis 3)Demineralization 4)Discoloration and bacterial penetration 5)Disintegration and necrosis. 1&2 – vital response. 3, 4, 5 – bacterial damage. Dr. Maji Jose

5 4 3 2 1 1. Zone of fatty degeneration of Tomes fibres. 2. Sclerotic dentine zone. 3. Zone of deeper demineralization. 4. Zone of discolouration and bacterial penetration. 5. Necrotic zone (zone of destruction). Dr. Maji Jose

Zone of fatty degeneration of Tomes’ dentinal fibers • Earliest change that can be appreciated at the most advancing front of dentinal caries. • Dentinal tubules are normal in structure • Characterized by deposition of fat globules in dentinal tubules that can be demonstrated by Sudan red stain. • Significance of this change may be … 1. predisposing factor that favor dentinal sclerosis. 2. fat may contribute to impermeability of dentinal tubules Dr. Maji Jose

Zone of dentinal sclerosis • Seen at the advancing front and sides of lesion. • Sclerosis is the reaction of vital dentinal tubules and pulp. • Mineral deposition occurs in dentinal tubules leading to obliteration, that tend to seal them off against further penetration by microorganism. Dr. Maji Jose

• Dentinal sclerosis is minimal in rapidly progressing caries and most prominent in slow chronic caries. • Appear as translucent in ground section of teeth under transmitted light and dark under reflected light. Dr. Maji Jose

Zone of demineralization • This is a narrow zone superficial to sclerosed dentin. • This change precedes bacterial invasion • Demineralization occur due to diffusion of acid released by the micro-organisms ahead of bacterial invasion. • Micro-organisms are not found in this zone • This zone is not infected but affected. Dr. Maji Jose

Zone of bacterial invasion • In this zone bacteria invade and multiply in the dentinal tubules • First wave of organism are acidogenic mainly lactobacilli that produce acid which decalcify dentin. • Second wave is mixture of acidogenic and proteolytic organisms which attack the demineralized matrix. Dr. Maji Jose

• Walls of the tubules are softened and individual tubules may confluence but general structure of organic component is retained. • Softened dentinal tubules are extended due to packing of tubules by micro-organisms and debris and take an elliptical shape which is parallel to the dentinal tubules. This is termed as liquifaction focci of Miller • Liquifaction focci may be multiple , giving the tubule a beaded appearance Dr. Maji Jose

Caries in dentin Colonies of bacteria (purple streaks) fill dentinal tubules and begin to digest the organic matrix producing small caverns called “beads”. Dr. Maji Jose

Bacterial colonies in tubules. Dr. Maji Jose

Bacterial colonies in tubules. Dr. Maji Jose

Zone of decomposed dentin Transverse clefts filled with bacterial colonies in the zone of disintegration at the surface of the carious lesion of dentin. Dr. Maji Jose

Transverse clefts Dr. Maji Jose

Bacterial colonies distorting the tubules Dr. Maji Jose

Zone of destruction/ decomposed dentin • In this zone the foci of liquefaction enlarges and increase in number. • Decalcification of walls of individual tubules leads to their coalescence • Expansion of the tubules by further multiplication and packing of organisms leads to compression and distortion of adjacent tubules so that their course is bent around the liquefaction foci. Dr. Maji Jose

• Destruction of dentin spread through the lateral branches of dentinal tubules and along the incremental lines lead to formation of cracks or clefts which is perpendicular to the tubules. These are called transverse clefts. • At this stage the bacteria extend to peritubular and inter tubular dentin and architecture of dentin is destroyed Dr. Maji Jose

• Tertiary dentin/ reparative dentin formation can also be appreciated at the pulpal end of affected tubules Dr. Maji Jose

Caries in secondary dentin • Runs a similar course to that in primary dentine. • Slower: fewer tubuli. • Sometimes: lateral spread between secondary dentine and primary dentine. Dr. Maji Jose

Thank you Dr. Maji Jose