dr. thendral -remineralization

ContentsIntroduction

Definition of De / Remineralization

Rationale

De / Remineralization Cycle

Factors influencing

Structure of hydroxyapatite

Role of oral environmentRole of Plaque

Role of Saliva

Role of Fluorides

Methods of Detecting De / Remineralization

Recent Advances

Conclusion

References

INTRODUCTION EARLY 1960 - MASSLER, FUSAYAMA & BRANSTORM

Science of De / Remineralization

Dental caries- Dynamic process:

Demineralization of the hard dental tissue by the acidic products of bacterial metabolism – alternates with periods of Remineralization.

Loss of tooth mineral - compensated by mineral deposition (consequences in operative and preventive dentistry).

Non-Restorative clinical strategies become a realistic option (iatrogenic nature of restorative treatment.

Demineralization Process of Removing minerals (ions) from dental enamel.

"Dissolving the Enamel."

Mineral ions removed from hydroxyapatite latticework without destroying its structural integrity

Loss of the hydroxyapatite's crystalline latticework structure - Cavity

Latticework can be strengthened and restored through the process of remineralization.

(Damle)

Remineralization

Restoring mineral ions - to the hydroxyapatite's latticework structure.

Remineralization is three-dimensional,

must be replaced with "same shape, size and the same electrical charge as those lost from the

lattice.

(Damle)

Demineralization-Remineralization

Healthy rods Demineralized rods Remineralized rods

De-Remineralization Rods

Rationale for De / Remineralization pH

Driving force for dissolution and precipitation of HAP.

At low pH - saturation concentration of the calcium and phosphate ions with respect to apatite is than at high pH.

At neutral pH - saliva and plaque fluid are super-saturated with respect to HAP - mineral will precipitate if a suitable precipitation nucleus is available.

Consumption of fermentable sugars acid production in the plaque - results in pH & calcium and phosphate concentration needed for saturation.

(Anders Thylstrup & Ole Fejerskov)

Acid ions react Phosphates in saliva and plaque, until the critical pH for the dissociation of HAP is reached at approximately pH 5.2 - 5.5. Further in pH causes partial or full dissolution of the surface crystallites.

Stored fluoride - reacts with Ca2+ and HPO42- ion breakdown

products, forming FLUORAPATITE or fluoride enriched apatite.

If the pH further below 4.5 - critical pH for Fluorapatite dissolution fluorapatite dissolve.


Rationale for De / Remineralization

If acid ions are neutralized,

Ca2+ and HPO4 2- ions are retained - Reverse process of

remineralization occurs.

Composition of the apatite formed - depends on the composition of the solution from which it is precipitated, (plaque fluid/saliva).

Periodic cycling of pH - in a step by step modification of chemical composition of the outer layers of enamel which becomes somewhat less soluble with time.

Process is known as the post-eruptive maturation of the enamel.


Rationale for De / Remineralization

Ca10(PO4)6(OH)2

+H+ -H+

Ca2+ + HPO4 2- + OH

+ F-

Ca10(PO4)6(OH).F/(F2)

Conversion of HAP to FAP

Fluorohydroxyapatite

De – Remineralization Cycle

pH cycle - depends on

Strength of the acid that is present

Frequency and duration of its production

Remineralization potential in each particular situation

Factors influencing De /Remineralization

Demineralized

Remineralized

Destabilizing factorsDiet plaque = plaque acids

in salivary flow

buffering

Acidic saliva

Erosive acids

Protective factorsSalivary buffering capacity

Ca2+ and PO43-

Buffering & Rm

Oral clearance

Fluoride contact - topical

Contributing Factors to DM / RM Balance

Structure of unit cell of HAP

ROLE OF ORAL ENVIRONMENT

Role of Plaque

Participates in repair & protection of enamel surface.

Negative charge of enamel surface when immersed in saliva - immediately neutralized by a layer of ions of opposite charge

Layer-called the Hydration layer or “Stern Layer”,

consists mostly of calcium (90%) and phosphate (10%).

Composition varies with the pH, ionic strength and the type of ions present in the solution.

Pellicle

Role of PlaqueMechanism of protein adsorption :

Proteins displace the ions in the hydration layer and forms interactions with the hydroxyapatite surface proper.

Acidic proteins interact mostly with calcium in the hydration layer.

Basic proteins bound to negatively charged areas on the surface proper and to a lesser extent to the phosphates in the hydration layer.

Pellicle

Firmly adherent bio-film formed by microbial colonization of pellicle.

Composition:

Two main compartments

Extracellular phase- contains an aqueous phase called the plaque fluid which is in direct contact with enamel & responsible for chemical reactions at this interface.

Cellular phase – major component is protein IgA, IgG, salivary proteins & plasma type proteins are present

Dental plaque

Role of Saliva

DCNA

Role Of Saliva

Prevention of dental caries

Provides calcium, phosphate, proteins, lipids, antibacterial substances, and buffers.

Flow lowers the risk of cavity formation is normal salivary flow (>0.7 ml/minute)

Saliva prevents tooth dissolution

Concepts of ionic product and solubility product , the pK in relation to the effect of pH on HAP dissolution and the dissociation equilibrium of HAP.

Saliva & Tooth dissolution


Common ion effect in mouth is an important phenomenon

Exogenously supplied fluid, supersaturated with respect to tooth mineral, in which the calcium and phosphate ion concentrations can be greatly altered by(elements of the diet).

In plaque fluid, calcium ion activity is affected by pH-sensitive calcium-binding components which cause the calcium activity to increase if the pH drops. Both these will significantly affect the ionic product of the fluid and thus, the dissociation equilibrium of the tooth mineral.

Fluoride ion can replace hydroxyl ions in the hydroxyapatite crystal and - considered to be a common ion of hydroxyl.

Fluoride-containing toothpastes the fluoride concentration is about 1500 ppm which is equivalent to 0.08M.

800,000 times more concentrated than hydroxyl ions at neutral pH so there is significant pressure for fluoride ions to precipitate with calcium and phosphate as Fluorohydroxyapatite.

Re-mineralization with Fluorohydroxyapatite is one of the major ways

that fluoride works to protect teeth.

As the fluid surrounding the tooth becomes acidic a point is reached when it ceases to be supersaturated and any further in pH results in mineral dissolution. - "Critical pH" & normally in the region of pH 5.2-5.5 depending on the particular saliva composition of the individual.

THE CRITICAL pH

Saliva

Bicarbonate > Phosphate > Protein

BufferingpH buffers resist change in the acidity or alkalinity of a solution by mopping up or releasing hydrogen ions

to counter the effect of added acid or base

but - narrow pH range.

Hydrogen ions are not permanently removed from the system.

Concentration of carbonic acid - remarkably constant at about 1.3mMol/L

As rate of saliva production increases the more bicarbonate ion is produced as a by-product of cell metabolism.

Saliva and Buffering

The Stephan Curve describesthe effect of saliva flow on the pH-changes happening in plaque after a

challenge by a cariogenic food.dental plaque was challenged with a fermentable carbohydrate by asking a volunteer to rinse with 10mls of 10% sucrose solution for 10 seconds. Average plaque samples were removed at intervals and the pH recorded.reveals a rapid drop in plaque pH, followed by a slower rise until the resting pH is attained. The time course varies between

individuals and the nature of the challenge.The initial drop is usually rapid with the

lowest pH being attained within a very few minutes. However, pH recovery can take anything

between 15 and 40 minutes depending to a large extent on the acid-neutralizing properties of the individual's saliva.

The basic Stephan Curve

Effect of Saliva on Diffusion

Stephan Curve

Role of Fluorides Reduce dental caries.

Inhibition of demineralization

Enhancement of remineralization.

By inhibiting mineral loss at the crystal surfaces and by enhancing the rebuilding or remineralization of calcium and phosphate in a form more resistant to subsequent acid attack.

Mechanism of action of fluoride

Stabilizing the enamel crystal Preventing enamel demineralization Favoring recrystallization of dissolved enamel surfaces Fluoride should be bound permanently to the enamel crystal in the form of Fluorapatite. Fluoride ion substitutes for the hydroxyl ion in the apatite structure giving rise

to a reduction of crystal volume concomitant increase in the structural stability.

Large crystals with fewer imperfections are formed - stabilizes the lattice and presenting a smaller surface area / unit volume for dissolution.

Also enamel which mineralizes under the fluoride influence has a lower carbonate content, thus giving a reduced solubility.


Fluoridefirmly bound when - incorporated in the crystalline lattice of hydroxyapatite

or loosely bound when it is adsorbed to apatite forming calcium fluoride deposits.

In the research on the cariostatic effect of fluoride, considerable emphasis is placed on the role of free fluoride ions in the oral fluid.

CaF - formed during treatments with high concentration fluoride solutions.

Act as fluid reservoir on tooth surface and release fluoride ions at low pH.

Fluoride ion along with calcium and phosphate diffuses into the lesion and precipitates as Fluorohydroxyapatite. The acid cycle thus contributes to the conversion of loosely to firmly bound fluoride.


A controlled demineralization of enamel and dentin, the acid etch technique has revolutionized the restorative procedures in dentistry.

Reliable and durable adhesion has been achieved between the resin and tooth structure with the acid etch technique.

Acid etching transforms the smooth enamel into a very irregular surface by removal of prismatic and inter-prismatic mineral crystals.

It also increases the free surface energy of enamel for better wetting and for the infiltration of the monomers and

also contributes to the retention of the resin composites.

Etching


Intra-oral Cariogenicity test :Koulourides et al.(1974) and

testing de- & remineralization in vivo.

model consists of an appliance, an existing partial denture or a full denture placed in the mouth of a subject. Each side of the appliance contains an enamel slab which is covered with Dacron mesh to act as a plaque entrapment medium. The appliance is placed in the mouth of the test subject and removed after a short period. One of the enamel slab is immersed extra-orally in the test solution (sucrose) and the other in a standard solution (xylitol). This immersion is carried out for 10 minutes, four times daily. The test continues usually for one week. The surface micro hardness of the enamel is assessed before and after the in vivo experiment. The differences are quantified by the change in diamond indentation length or depth.

Brudevold model :Clarkson (1986)

utilizes a palatal appliance containing 8 enamel blocks upon which is grown plaque inoculated with Streptococcus mutans. This is then placed in the mouth and exposed to the test solution or test food for 45 – 60 minutes. Assessment is made by the Iodide Permeability method. A positive change in iodide permeability implies demineralization and a negative change implies inhibition or lack of demineralization. It is also possible for pH to be monitored by touch electrode by this method.

mainly assess the cariogenic potential of the foods and the response of saliva to food is neither measured nor taken into consideration.


Newer tests - developed to determine the pH and buffering capacity of the saliva which can measure the de- remineralization potential of the saliva.

Saliva check Buffer Kit is a simple diagnostic tool for

Measuring how well a patient's saliva is protecting their teeth

Helping diagnose the potential cause of Salivary dysfunction

Completing caries risk evaluations.

Saliva Check - Buffer is recommended

For patients presenting with new dental problems( caries, erosion, sensitivity, attrition)

Prior to extensive reconstructive and cosmetic procedures

As part of caries risk evaluation for all patients


Saliva check -Buffer Kit is a 5 steps test for measuring both resting and stimulated saliva.Saliva testing

A simple in-office test is now available for evaluating how well saliva is protecting teeth.Saliva testing involves both the stimulated and unstimulated saliva.

The functions and characteristics of these two forms of saliva are different. By evaluating both, the test results become very useful become very useful diagnostic and powerful communication tools.

Testing resting ( unstimulated ) saliva

Step-1. Visual examination hydration

Step 2. Visual examination viscosity

Step 3. Resting pH of unstimulated saliva

Step 4. Stimulated flow quantity

Step 5. Stimulated flow buffering capacity ( quality)



LASER INDUCED FLUORESCENCE:

DIAGNOdent (Kavo)

Recent AdvancesRemineralization of enamel subsurface lesions by CPP-ACP

- Buffers free calcium and phosphate ion activities with respect to tooth enamel depressing demineralization and enhancing remineralization.

Recaldent™ acts in a unique way to deliver calcium and phosphate to the tooth enamel and thus promote remineralization, or rebuilding, of the tooth. Peptide part of Recaldent, the CPP-maintains calcium and phosphate in an amorphous, soluble form. CPP bind to surface of the tooth and

to bacteria in plaque surrounding the tooth, thus presenting this soluble calcium phosphate at a high concentration at the tooth surface.

In its amorphous, soluble form, the calcium and phosphate can penetrate into the tooth enamel and remineralize the tooth enamel

CPP-ACP products

White spot prevention /removal Post bleaching. Post scaling and root planing. Dentinal hypersensitivity. Treatment of erosion and incipient carious lesions. Caries prevention. Promote fluoride activity

Dental polymers that contain bioactive ACP contain filler capable of responding to environmental pH changes by releasing Ca and PO4

Remineralizing agent in sealants, adhesives, base and lining materials

where protection against mineral loss and restoration of mineral in dental

tissues would be desirable.

Bio active composites

was developed in Australia by Pacific Biolink Pty Ltd)

Milk protein based formulation – significantly augment the natural salivary “remineralization” process. -helps buffer plaque acids and forms a barrier at the tooth surface which helps minimize the adhesion of bacteria. At low pH the calcium phosphate is released boosts the ability of saliva to prevent demineralization and promote

remineralization by natural means.

Topacal C-5® corrects this imbalance by assisting saliva to prevent demineralization and promotes remineralization process to improve tooth enamel.

Topacal C-5®

Conclusion The ultimate outcome of the caries diagnostic process in clinical practice is the decision concerning the need for treatment

The development of newer methodologies of caries detection are critical to reduce the possibility of an incorrect diagnosis

There is no single diagnostic method on the horizon that can reliably detect precavitated lesions on all tooth surfaces

Research yet to provide the high degree of sensitivity & specificity needed to detect early lesions

Non-restorable precavitated lesions

References Dissertation submitted by THENDRAL,SRDC, SRMC, Chennai- “A comparative evaluation of remineralization potential of glass ionomer cements and a fluoride releasing composite resin on juxatapositioned interproximal caries – an in-vitro study”

Ann.M.Bynum and Kevin.J.Donly: Enamel de/ remineralization on teeth adjacent to fluoride releasing materials without dentifrice exposure: Journal of Dentistry for Children

1999; March-April: 89-91. Anusavice KJ: Caries risk assessment: Operative Dentistry suppl 2001; 6: 19-26 Chow LC, Vogel G.L: Enhancing remineralization: Operative Dentistry suppl 2001; 6:27-38. Chow.L, Takagi, C M Carey : Remineralization effects of a Two-solution Fluoride Mouth rinse: An in situ study: J Dent Res 2000; 79(4): 991-995. Donly K J et al: Evaluating the effects of fluoride-releasing dental materials on adjacent interproximal caries: J Am Dent Assoc. 1999 Jun; 130(6): 817-825. Donly K J. Enamel and dentin demineralization inhibition of fluoride-releasing materials: Am J Dent. 1994 Oct; 7(5): 275-8. Duggal. M. S, K J Toumba, B T Amaechi, M B Kowash, and S M Higham: Enamel demineralization in situ with various frequencies of carbohydrate consumption with and without fluoride toothpaste: J Dent Res 2001; 80(8): 1721-1724.FazziR, Vieria D Fad Zucas SM: Fluoride release and physical properties of a fluoride-containing amalgam: J Prosthet Dent. 1977 Nov; 38(5): 526-31

Fejerskov.O.Thylstrup l: Rationale use of fluorides in caries prevention: a concept based on the possible cariostatic mechanisms: Acta Odontalogica Scadinavica 1981; 39: 241-249 Featherstone and Zero: An in-situ model for simultaneous assessment of inhibition of demineralization and enhancement of remineralization : J Dent Res. 1992; 71: 804-810. Francci C, Halls towers: Fluoride release from restorative materials and its effects on dentin demineralization: Journal of Dental Research; Vol 78, 1647-1654. Graham J Mount: Glass Ionomer cements: Past, Present, Future: Operative Dentistry 1994; 19: 82-90. HienNgo, Y S Hsu:69 http://www.gcasia.info/content_researchpapers.html (1 to 5) [12/6/2005 12:25:23 AM] Jang K T, et al: Remineralizing effects of glass ionomer restorations on adjacent interproximal caries: J Dent Child 2001; Mar-Apr; 68(2): 125-128. John Hicks, Franklin Garcia-Godoy and Catherine Flaitz: Biological factors in dental caries: role of remineralization and fluoride in the dynamic process of demineralization and remineralization (part 3): The Journal of Clinical Paediatric Dentistry 2004; 28(3): 203- 214 Ki-Taeg Jang, Franklin Garcia-Godoy, Kevin J Donly and Adriana Segura: Remineralising effects of glass ionomer restorations on adjacent interproximal caries: Journal of Dentistry for Children 2001; March-April: 125-128.

References

Kitasako, Nakajima, Foxton, Aoki, Pereira and Tagami: Physiological remineralization of artificially demineralised dentin beneath glass ionomer cements with and without bacterial contamination In Vivo: Operative Dentistry 2003; 28(3): 274-280.

Reynolds E C, Cai, Shen and Walker: Retention in plaque and remineralization of enamel lesions by various forms of calcium in a mouth rinse or sugar-free chewing gum: J Dent Res 2003; 82(3): 206-211

Rolla et al: Critical evaluation of the composition and use of fluorides with emphasis on the role of calcium fluoride in caries inhibition: J Dent Res 1990; 69: 780-785.

Ten Cate: Remineralization of caries lesions extending into dentin: J Dent Res 2001; 80(5): 1407-1411.

Ten Cate J M and Van Duinen: Hypermineralization of dentinal lesions adjacent to glass ionomer cement restorations: J Dent Res 1995; 74(6): 1266-1271.

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References

Graham J Mount: Atlas of Glass Ionomer Cements: A Clinician’s Guide Third Edition

Per Axelsson: Introduction to Risk Prediction and Preventive Dentistry Quintessence Publishing co,

S.G Damle :Textbook Of Pediatric Dentistry :Second Edition ;Arya (medi) Publishing House

Anders Thylstrup & Ole Fejerskov Textbook of Clinical Cariology Second Edition Munksgaard

The Dental Clinics of North America: Cariology; oct 1999; 43 (3)

References

dr. thendral -remineralization

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