Caries of Enamel & Dentin

White spot

The first clinical sign of initial (incipient) caries, caused by a change in the optical properties of enamel due to demineralization or hypomineralization

Fluorosis

A type of hypomineralization that appears smooth, shiny, well-mineralized, and non-porous, unlike the chalky/rough appearance of caries when air-dried

Subsurface lesion

The histologic hallmark of early enamel caries; the enamel surface is microporous but macroscopically appears sound/intact

Surface zone

Outermost zone of an early enamel lesion; ~10-100 µm thick, always present, 1-5% pore volume, 10% mineral loss by volume, higher in fluoride and protein, lower in magnesium and carbonate

Body of the lesion

Zone of an early enamel lesion that has lost the largest proportion of mineral; always present, 5-25% pore volume, 24% mineral loss by volume, increased bound water and organic content from saliva diffusion

Dark zone

Zone superficial to the translucent zone; present in 90-95% of cases, 2-4% pore volume, 6.3% mineral loss by volume, contains some pores smaller than the translucent zone (suggests remineralization)

Translucent zone

The advancing front of an early enamel lesion; present in ~50% of cases, 1% pore volume (vs 0.1% in normal enamel), 1.2% mineral loss by volume, rise in fluoride, fall in carbonate/Mg/Ca/PO4, no loss of organic material

Evidence of remineralization in the dark zone

During remineralization the dark zone increases in size (extending into the former body of the lesion); lesions without dark zones develop them after exposure to remineralizing fluids

Polarized Light Microscopy (PLM)

Histologic method that uses pore size/number and imbibition media of different molecular sizes/refractive indices (quinoline, Thoulet's medium, water) to distinguish the zones of an enamel lesion

Transverse Microradiography (TMR)

Laboratory method that produces a densitometric tracing of mineral volume percent across a lesion to quantify mineral loss

Demineralization

Passive transport of Ca2+ and H2PO4- out of the lesion and H+ ion diffusion into the lesion, driven by concentration gradients; H+ diffusion is the primary driving force and ambient fluoride inhibits dissolution

Remineralization

Ca2+ and H2PO4- diffusion into the lesion driven by concentration gradients, with lesion pH remaining near 7; mineral ion diffusion is the primary driving force and ambient fluoride induces surface mineral precipitation

Crystal dissolution pattern

In caries, hydroxyapatite crystal dissolution begins at the center/core of the crystal (least mineralized area)

Surface etching

Increase in intercrystalline spaces during the caries process due to slight etching of crystal surfaces, seen as irregular crystal margins

Dentinal tubules

Structures extending from the predentin border to the dentino-enamel junction (DEJ), filled with dentinal fluid and housing odontoblastic processes

Zone of necrotic dentin (Zone A)

Highly destroyed, softened, discolored dentin with demineralization, partial decomposition, collagen breakdown, and large masses of bacteria (part of infected dentin)

Zone of infected tubules (Zone B)

Bacterial invasion confined within dentinal tubules, with collagen breakdown and hydrolytic enzyme activity; part of infected dentin, and bacteria do not pass beyond this zone

Infected dentin

Irreversibly demineralized and denatured dentin (Zones A and B) with bacterial invasion; soft, moist, and easily removed with a spoon excavator; not reparable, must be removed

Zone of demineralization (Zone C)

Evidence of decalcification with no bacterial penetration, fairly normal tubules, loss of peritubular dentin, and decreased crystal size; part of affected dentin

Affected dentin

Demineralized but non-infected dentin (Zone C) that can be remineralized and should be preserved during restoration

Zone of sclerosis (Zone D)

Hypermineralized dentin; dead tracts (empty tubules after odontoblast death) become filled with mineral to form blind tracts, made of sclerotic dentin

Reparative/tertiary dentin (Zone E)

Dentin layer formed by the pulp in response to injury to compensate for lost dentin thickness

Caries detector dyes

Dyes that stain affected/remineralizable dentin on cavity walls to help clinicians selectively remove infected dentin while preserving affected dentin for good adhesion

Soprolife

Light-induced fluorescence evaluator device that connects to a computer for image display, patient follow-up, and treatment-aide mode

PROFACE / SIROInspect (FACE)

Fluorescence-Aided Caries Excavation device; bacteria in infected dentin leave behind porphyrins that fluoresce red under 405 nm violet light, indicating areas needing excavation

E1 lesion

Radiographic caries classification: less than half way through proximal enamel

E2 lesion

Radiographic caries classification: more than half way through proximal enamel, not penetrating past the DEJ

D1 lesion

Radiographic caries classification: slightly past the DEJ

D2 lesion

Radiographic caries classification: less than half way through dentin toward the pulp

D3 lesion

Radiographic caries classification: half or more through dentin

Bitewing radiographic appearance of caries

Appears as a dark, fuzzy, triangle-shaped radiolucency on the side of the tooth, at or just below the contact point

Dark shadow sign

Clinical sign of caries undermining dentin beneath intact enamel, seen as a grayish shadow through the enamel