Demineralization Remineralization < 초기 우식의 진단 및 치료 > Demineralization Remineralization 단국대학교 대학원 치의학과 소아치과학 전공 석사 2학기 강지은

Contents Introduction Enamel changes during early caries lesion development Demineralization Arrest of the caries lesion Remineralization Reference

1. Introduction

1. Introduction Enamel - Composed mostly of mineral in the form of Hydroxyapatite (HAp) Ca10(PO4)2(OH)2 - Organic components - HAp ions generally substituted affecting the stability and acid solubility of the crystals

The importance of the mineral phase in enamel 5/10

1. Introduction Arrangement of microcrystal - Pararrel to major axis - Soluble than tale part Arrangement of microcrystal - Inclined to major axis - Resistant than body part

1. Introduction The space between the crystals - Occupied by water, organic material The color, hardness and other properties of enamel - Very high mineral content and minimal acellular matrix - Similar to those of hydroxyapatite

1. Introduction More than 40 trace elements have been identified in enamel various ways to be incorporated into enamel - Ion exchange in the hydration shell layer of water adjacent to the crystal - Direct absorption on the surface of the crystal - Substitution with components of the crystal of similar size and charge

1. Introduction Substitution of PO43– ions by carbonate - Carbonate is present in relatively high levels when teeth erupt - Less stable enamel - More susceptible to demineralization

1. Introduction Acid solubility of a tooth and its caries resistance - Final mineral composition - Crystal size and shape - Proximity of the crystals

2. Enamel changes during early caries lesion development

2. Enamel changes during early caries lesion development What occurs in the mouth at any site if a ‘protected area’ is created at a part of the tooth surface, so that dental plaque is allowed to accumulate undisturbed by mechanical forces for days and weeks?

2. Enamel changes during early caries lesion development 그림 3.8-12 before After 1 week

2. Enamel changes during early caries lesion development After 4 weeks

2. Enamel changes during early caries lesion development 1 week -------------------------------------> 4weeks

2. Enamel changes during early caries lesion development Why does mineral loss occur predominantly underneath the enamel surface? Not fully understood Explanatory models Salivary proline-rich proteins Other salivary inhibitors such as statherin - Dual function

2. Enamel changes during early caries lesion development Why does mineral loss occur predominantly underneath the enamel surface? Prevent spontaneous and selective precipitation of calcium phosphate or crystal growth of these salts directly onto the enamel surface Tend to inhibit demineralization

2. Enamel changes during early caries lesion development Why does mineral loss occur predominantly underneath the enamel surface? The inhibitors are macromolecules  Cannot penetrate into the deeper parts of the enamel, their stabilizing role appears to be limited to the surface

2. Enamel changes during early caries lesion development Initial stages of the caries lesion - Partial dissolution of the tissue - Leaving a 20-50-µm-thick, rather well-mineralized surface layer - Subsurface body of the lesion with a mineral loss of up to 30-50% extending deep into the enamel and dentin

How does such early lesions change when dental plaque is removed? 2. Enamel changes during early caries lesion development How does such early lesions change when dental plaque is removed?

2. Enamel changes during early caries lesion development Immediately after removal of 4 weeks of local protection 1 week after

2. Enamel changes during early caries lesion development Immediately after removal of 4 weeks of local protection 2 weeks after

2. Enamel changes during early caries lesion development Immediately after removal of 4 weeks of local protection 1 week after

2. Enamel changes during early caries lesion development 2 weeks later 3 weeks after

3. Demineralization

3. Demineralization Why is apatite solubility increased by acid? The solubility of hydroxylapatite and other calcium phosphates is greatly affected by pH Ca5(PO4)3OH ↔ 5Ca2+ + 3PO43- + OH- ↓ H + ↓ H + HPO42- H2O ↓ H + H2PO42-

3. Demineralization

3. Demineralization Dissolution of a hydroxyapatite crystal - not isotropic - proceed more rapidly along the C-axis  Central cavity in partialy dissolved crystals

3. Demineralization Solubility of FAp Solubility of HAp

3. Demineralization Supersaturation with respect to fluorapatite - Responsible for the maintenance and integrity of the surface layer More supersaturated the solution with respect to fluorapatite - Thicker and less demineralized the surface layer

3. Demineralization Pore volume distribution

3. Demineralization White-spot Characteristic chalky surface - Increase in the internal enamel porosity  loss of translucency  opaque enamel

4. Arrest of the caries lesion

4. Arrest of the caries lesion Remineralization = Arrest of caries lesion progression ?

4. Arrest of the caries lesion 1. Removal of the acid-producing origin of the disease (The cariogenic plaque) 2. Wear and polishing of partly dissolved external microsurface of the active lesion 3. (Subtle rearrangement of crystals that is likely to occur after exposure to saliva or the redeposition of dissolved minerals in the subsurface lesion parts)

4. Arrest of the caries lesion Remineralization is not the cause of the arrest of further progress of the lesion, although reprecipitation of mineral from oral fluids may be consequence of lesion arrest

Caries development 4. Arrest of the caries lesion Cavitation - Discoloration of tooth surface due to exogenic tinted material  proof of previous caries - Hardening of residual exposure surface - Discoloration

5. Remineralization

5. Remineralization Remineralization of dental lesions requires… - The presence of partially demineralized apatite crystals that can grow to their original size as a result of exposure to solutions supersaturated with respect to apatite

5. Remineralization Salivary components in the remineralization process Saliva - Series of substances which are involved in the remineralization process - Inorganic compounds, mainly calcium, phosphate, and fluoride and organic elements - Maintain calcium and phosphate supersaturation

5. Remineralization Salivary components in the Remineralization process Other salivary factors involved in remineralization - Salivary flow - Buffer capacity - Saturation level of mineral elements in the tooth especially calcium, phosphate, and fluoride

5. Remineralization Slow diffusion - Difficult to maintain the necessary supersaturation in the lesion fluid  remineralization of the lesion body is not obtained Surface layer of the lesion Protect the underlying lesion body not only from demineralization but also from remineralization

6. Reference Dental caries – The Disease and its Clinical Management 2nd edi. Fejerskov and Edwina Kidd 소아청소년 치과학 치과보존학 Defining, classifying, and placing incipient caries lesions in perspective Dent Clin N Am 49 (2005) 701–723 Mount GJ Austrailia

6. Reference Principles of demineralization: modern strategies for the isolation of organic frameworks. Part I. Common definitions and history Micron. 2008 Dec;39(8):1062-91 Ehrlich H, Koutsoukos PG, Demadis KD Germany The caries environment: saliva, pellicle, diet, and hard tissue ultrastructure Dent Clin North Am. 2010 Jul;54(3):455-67 Hara AT, Zero DT USA

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