Micro-leakageMicro-leakageOfOf

RestorationsRestorations

DefinitionDefinition: : penetration of fluids, bacteria, ions along restoration / penetration of fluids, bacteria, ions along restoration /

tooth structure interface.tooth structure interface.

It is affected by : It is affected by : tooth & restoration & the condition tooth & restoration & the condition of the oral cavity.of the oral cavity.

Effects Of Micro leakageEffects Of Micro leakage

1-1- Penetration of bacteria , bacterial products & saliva into Penetration of bacteria , bacterial products & saliva into gap between restoration & cavity walls.gap between restoration & cavity walls.

2-2- pulpal irritation , inflammation, & even necrosis can pulpal irritation , inflammation, & even necrosis can result from this penetration.result from this penetration.

3-3-marginal discoloration & staining ( bad esthetics ).marginal discoloration & staining ( bad esthetics ).

4-4- bacteria can demineralize the cavity walls adjacent to the bacteria can demineralize the cavity walls adjacent to the restoration leading to caries recurrence.restoration leading to caries recurrence.

5-5- deterioration of the physical & biological properties of deterioration of the physical & biological properties of the restoration.the restoration.

Recurrent of cariesRecurrent of caries

discolorationdiscoloration

Methods Of Assessment & Recording Methods Of Assessment & Recording The Severity Of Micro-leakage At The Severity Of Micro-leakage At

Tooth \ Restoration Interface:Tooth \ Restoration Interface:

1-1- air-pressure technique. air-pressure technique.

2-2- bacterial penetration. bacterial penetration.

3-3- dyes ex: basic fusin or methylene blue. dyes ex: basic fusin or methylene blue.

4-4- radio-active isotopes. radio-active isotopes.

5-5- scanning electron microscope (S.E.M.) scanning electron microscope (S.E.M.)

Dye penetrationDye penetration

Factors Affecting The Occurrence & Factors Affecting The Occurrence & Severity Of Micro Leakage:Severity Of Micro Leakage:

1- dimensional changes in restorative materials 1- dimensional changes in restorative materials duringduring & before& before completion of the setting completion of the setting reaction.reaction.

2- dimensional changes of restorative materials 2- dimensional changes of restorative materials afterafter completion of the setting reaction. completion of the setting reaction.

3- solubility in the oral cavity .3- solubility in the oral cavity . 4- inadequate condensation of the restorations.4- inadequate condensation of the restorations. 5- occlusal loads.5- occlusal loads. 6- presence or absence of smear layer. 6- presence or absence of smear layer.

1-1- Dimensional Changes Of Dimensional Changes Of Restorative Materials During & Restorative Materials During &

Before Completion Of The Setting Before Completion Of The Setting Reaction.Reaction.

A-A- polymerization shrinkage of resinous restorations. polymerization shrinkage of resinous restorations.

B-B- contraction & expansion of amalgam. contraction & expansion of amalgam.

C-C- setting contraction of G.I.C. setting contraction of G.I.C.

D- D- setting contraction of silicate cement.setting contraction of silicate cement.

2-2- Dimensional Changes Of Restorative Dimensional Changes Of Restorative Materials After Completion Of The Materials After Completion Of The

Setting Reaction.Setting Reaction.

A-A- difference in coefficient of thermal expansion between difference in coefficient of thermal expansion between restoration & tooth structure . restoration & tooth structure .

ex:ex: ** Amalgam about 2-3 times more than that of tooth. Amalgam about 2-3 times more than that of tooth.

**** Acrylic resin about 7 times than that of tooth. Acrylic resin about 7 times than that of tooth.

B-B- modulus of elasticity. modulus of elasticity.

C-C- wear . wear . D-D- creep. creep.

E- E- hygroscopic expansion.hygroscopic expansion.

C0fficient of thermal expansion of C0fficient of thermal expansion of restorative materials relative to tooth restorative materials relative to tooth

enamelenamelMaterialMaterialC.T.E (x 10C.T.E (x 106 /6 /CC

Tooth (crown enamel) Tooth (crown enamel) 11.411.4

Dentin Dentin 8.38.3

Aluminous porcelain Aluminous porcelain 6.66.6

Pure titanium Pure titanium 8.58.5

Type II glass ionomer Type II glass ionomer 11.011.0

Pure gold Pure gold 14.014.0

Dental amalgam Dental amalgam 25.025.0

Composites Composites 20.0-25.020.0-25.0

Denture resin Denture resin 81.081.0

Pit and fissure resin Pit and fissure resin 58.058.0

Inlay waxInlay wax400.0400.0

3- 3- Solubility In The Oral Fluids:Solubility In The Oral Fluids:

** Solubility of glass ionomer cement. Solubility of glass ionomer cement.

** Solubility of silicate cement. Solubility of silicate cement.

** Solubility of luting cement. Solubility of luting cement.

- Zinc phosphate cement.- Zinc phosphate cement.

- Zinc polycarboxylate cement.- Zinc polycarboxylate cement.

4-4- Inadequate Condensation Of Inadequate Condensation Of Restorations:Restorations:

Poor condensationPoor condensation of restoration against cavity of restoration against cavity walls leads to voids along the cavity margins & walls leads to voids along the cavity margins & in the restorative material itself.in the restorative material itself.

This contribute to a higher degree of micro-This contribute to a higher degree of micro-leakage & inferior mechanical properties. leakage & inferior mechanical properties.

5- 5- Occlusal Loads:Occlusal Loads:

A-A- in class II : application of occlusal forces on class in class II : application of occlusal forces on class II restored teeth may cause elastic deformation of II restored teeth may cause elastic deformation of the tooth substance. the tooth substance.

The facial & lingual walls can flex away from the The facial & lingual walls can flex away from the restoration toward the outside , & so, increase width restoration toward the outside , & so, increase width of the gap.of the gap.

B-B- occlusal forces transferred from the restoration occlusal forces transferred from the restoration may create hygroscopic pressure on the fluid in the may create hygroscopic pressure on the fluid in the gap ( between tooth surface & restorative material ) gap ( between tooth surface & restorative material ) which can be pushed together with bacteria into the which can be pushed together with bacteria into the dentinal tubules towards the pulp.dentinal tubules towards the pulp.

6-6- Presence Or Absence Of Presence Or Absence Of Smear Layer. Smear Layer.

Microleakage Of Different Microleakage Of Different Restorative MaterialsRestorative Materials

I – amalgam .I – amalgam .

II – composite .II – composite .

III – glass ionomer restorations .III – glass ionomer restorations .

IV – indirect constructed restorations IV – indirect constructed restorations ..

I- Amalgam RestorationsI- Amalgam Restorations

All All freshly seatedfreshly seated amalgam restorations are amalgam restorations are leaky & that is why the use of 2 layers of leaky & that is why the use of 2 layers of copalite cavity copalite cavity varnishvarnish on the walls & margins on the walls & margins of the prepared cavity in order to reduce the of the prepared cavity in order to reduce the leakage around the restoration.leakage around the restoration.

By aging in the oral cavity , the amalgam By aging in the oral cavity , the amalgam restorations will undergo restorations will undergo tarnish & corrosiontarnish & corrosion..

The corrosive products of The corrosive products of sulfides & oxidessulfides & oxides will precipitate along the interface leading to will precipitate along the interface leading to gradual closure of the micro spaces between gradual closure of the micro spaces between the material & the walls of the cavity.the material & the walls of the cavity.

II– II– CompositeComposite Restorations: Restorations:

The freshly seated acid etched composite resin The freshly seated acid etched composite resin restorations exhibit tightly sealed margins restorations exhibit tightly sealed margins against micro leakage opposite to amalgam.against micro leakage opposite to amalgam.

These leakage proof margins are due to These leakage proof margins are due to micro pores micro pores created by acid etching technique & the subsequent created by acid etching technique & the subsequent low viscosity resinous sealant low viscosity resinous sealant which forms tiny which forms tiny micro tags providing retention & sealing at the micro tags providing retention & sealing at the restoration margins.restoration margins.

So At First :So At First : This hybrid combination This hybrid combination blocks the leaky interface. blocks the leaky interface.

But Due To :But Due To :

1-1- Direction & degree of polymerization shrinkage. Direction & degree of polymerization shrinkage.

2-2- temperature cycle in the oral cavity. temperature cycle in the oral cavity.

3-3- modulus of elasticity of the material. modulus of elasticity of the material.

4-4- type & magnitude & direction of masticatory type & magnitude & direction of masticatory forces applied to restoration . forces applied to restoration .

this relation soon ruptures creating a this relation soon ruptures creating a marginal gap.marginal gap.

Microleakage between Bacteria inside Microleakage between Bacteria inside dentinaldentinal

tooth and restoration tubule tooth and restoration tubule

This Marginal Gap Creates An Increasingly This Marginal Gap Creates An Increasingly Deteriorating Conditions For Both Tooth & Deteriorating Conditions For Both Tooth & Restoration :Restoration :

For Tooth In Form Of :For Tooth In Form Of :

** Hypersensitivity Hypersensitivity

** recurrent caries. recurrent caries.

** Pulpal affection. Pulpal affection.

Restoration In Form Of :Restoration In Form Of :

** Physical. Physical.

** Chemical. Chemical.

** Esthetical degradation. Esthetical degradation.

Due to leak out of ingredients & hydrophilic Due to leak out of ingredients & hydrophilic nature of the resinous matrix. nature of the resinous matrix.

III – Glass Ionomer III – Glass Ionomer Restorations:Restorations:

Freshly applied G.I.C. Exhibit tightly sealed margins Freshly applied G.I.C. Exhibit tightly sealed margins due to:due to:

1- 1- their adhesive potential.their adhesive potential.

2-2- low setting contraction . low setting contraction .

3-3-coffecient of thermal expansion & contraction near coffecient of thermal expansion & contraction near that of tooth structure .that of tooth structure .

by time : by time : these tightly sealed margins will deteriorate these tightly sealed margins will deteriorate due to solubility in oral fluids specially with due to solubility in oral fluids specially with increasedincreased acidityacidity of oral fluids & ingested materials. of oral fluids & ingested materials.

Resin modified glass ionomerResin modified glass ionomer

IV –IV – Indirect Constructed Indirect Constructed Restorations Restorations .. They are cemented by luting cements.They are cemented by luting cements. Intra-coronally or extra-coronally Intra-coronally or extra-coronally Their Leakage Are Affected By :Their Leakage Are Affected By :1-solubility of materials .1-solubility of materials .2-its adhesive properties.2-its adhesive properties.3-the length of the margins.3-the length of the margins.4-the nature of the marginal joint.4-the nature of the marginal joint.5-the type of bevel.5-the type of bevel.6-the acidity of oral fluids.6-the acidity of oral fluids.

Composite InlayComposite Inlay

It has many advantages over direct composite:It has many advantages over direct composite:

1-1- control of polymerization shrinkage. control of polymerization shrinkage.

Which occurs outside patient mouth & only Which occurs outside patient mouth & only small luting cement leakage.small luting cement leakage.

2-2- better mechanical propertiesbetter mechanical properties (compressive strength, tensile strength & (compressive strength, tensile strength & hardness.) Due to combined photo & thermal hardness.) Due to combined photo & thermal initiation & polymerization curing modalities. initiation & polymerization curing modalities.

3-3- better reproduction of the better reproduction of the contour, contact & contour, contact & occlusal relations occlusal relations of the future restorationof the future restoration

4- 4- better marginal adaptationbetter marginal adaptation. As the . As the dualdual curingcuring adhesive cement seals the marginal gap specially adhesive cement seals the marginal gap specially at the critical inconspicuous gingival marginal at the critical inconspicuous gingival marginal area. Specially after introduction of area. Specially after introduction of ultra-sonically ultra-sonically aided cementing seating devices ( seimens sono-aided cementing seating devices ( seimens sono-cem) . cem) . that provide a remarkable decrease in the that provide a remarkable decrease in the film thickness & superior adaptation for the highly film thickness & superior adaptation for the highly viscous adhesive resinous cement.viscous adhesive resinous cement.

Prevention Of MicroleakagePrevention Of Microleakage

1- 1- cavity preparation.cavity preparation.

2- 2- smear layer removal.smear layer removal.

3-3- conventional varnish.conventional varnish.

Complete infiltration partial removal complete Complete infiltration partial removal complete removalremoval

1-1- Cavity PreparationCavity Preparation

A- A- all cavity walls are smooth, clean & dry for all cavity walls are smooth, clean & dry for maximum adaptation of the restorationmaximum adaptation of the restoration. .

B-B- all unsupported enamel must be removed to all unsupported enamel must be removed to prevent further fracture & marginal defects.prevent further fracture & marginal defects.

2- Smear Layer Removal:2- Smear Layer Removal:To obtain maximum adaptation of the restoration to To obtain maximum adaptation of the restoration to

the prepared cavity walls the prepared cavity walls superficial smear layersuperficial smear layer removal should be removed , because it may removal should be removed , because it may interfere with adaptation & as a potential area for interfere with adaptation & as a potential area for bacterial growth.bacterial growth.

N.B: It is essential to leave the deep portion of the N.B: It is essential to leave the deep portion of the smear layer “smear plug”smear layer “smear plug” which acts as natural which acts as natural cavity liner inhibiting bacterial penetration into cavity liner inhibiting bacterial penetration into dentinal tubules dentinal tubules I.EI.E : Decrease dentine permeability. : Decrease dentine permeability.

3- Conventional Varnish:3- Conventional Varnish: Amalgam restorations are susceptible to early Amalgam restorations are susceptible to early

penetration at the amalgam / tooth interface.penetration at the amalgam / tooth interface.

* The use of cavity varnish has been accepted as * The use of cavity varnish has been accepted as the most reliable method of reducing micro-the most reliable method of reducing micro-leakage around amalgam restorations.leakage around amalgam restorations.

* The conventional varnishes composed of * The conventional varnishes composed of resin resin dissolved in organic solvent such as acetone , dissolved in organic solvent such as acetone , chloroform or ether.chloroform or ether.

* * Two applicationsTwo applications of copal varnish were more of copal varnish were more effective than effective than oneone only. only.

Limitations Of Conventional VarnishesLimitations Of Conventional Varnishes

1-1-donot bonddonot bond at tooth structure or amalgam , but at tooth structure or amalgam , but reduce only micro-leakage but not prevent it.reduce only micro-leakage but not prevent it.

2-2- it acts as a it acts as a mechanical barriermechanical barrier in the gap in the gap allowing micro-leakage between the amalgam allowing micro-leakage between the amalgam & varnish , & between varnish & tooth & varnish , & between varnish & tooth structure. structure.

3-3- it is not sufficient in reducing it is not sufficient in reducing dentin dentin permeabilitypermeability. .

4-4- partial dissolutionpartial dissolution of the varnish . of the varnish .

NAno leakageNAno leakageIs nano metrisized spaces around the Is nano metrisized spaces around the

collagen fibrils within the hybrid layer collagen fibrils within the hybrid layer that have not been completely that have not been completely infiltrated by resininfiltrated by resin

-It occur at the button of the hybrid -It occur at the button of the hybrid layer or scattered along its thicknesslayer or scattered along its thickness

-The deeper the etching into dentin the -The deeper the etching into dentin the higher the degree of nano leakage higher the degree of nano leakage because the degree of resin because the degree of resin infiltration not equal to depth of infiltration not equal to depth of demineralization demineralization

Bonding to dentin in total etch adhesive system Bonding to dentin in total etch adhesive system

Dentinal substrate after etching the Dentinal substrate after etching the Dentinal substrates after Dentinal substrates after primingpriming

smear layer has been removed the blue the water replaced by smear layer has been removed the blue the water replaced by hydrophilichydrophilic

coloration represent the water content primer coloration represent the water content primer

After adhesive resin aplicationAfter adhesive resin aplication

After polymerization resin infilterate After polymerization resin infilterate polymerized dentinpolymerized dentin

Bonding to dentine in self etch adhesive system Bonding to dentine in self etch adhesive system

(after preparation smear layer and smear plug)(after preparation smear layer and smear plug)

After application of acidic resin after application of After application of acidic resin after application of adhesiveadhesive

-For this reason the degree of nano -For this reason the degree of nano leakage with self etching system is leakage with self etching system is less than systems using acidic less than systems using acidic conditioners as single stepconditioners as single step

-Nano leakage accelerates degradation -Nano leakage accelerates degradation of the bond and failure of the of the bond and failure of the restorationrestoration