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Micro-leakage Of Restorations

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... * Hypersensitivity ... After adhesive resin aplication After polymerization resin infilterate polymerized dentin Bonding to dentine in self ... – PowerPoint PPT presentation

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Title: Micro-leakage Of Restorations


1
Micro-leakage Of Restorations

2
Definition
  • penetration of fluids, bacteria, ions along
    restoration / tooth structure interface.
  • It is affected by tooth restoration the
    condition of the oral cavity.

3
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4
Effects Of Micro leakage
  • 1- Penetration of bacteria , bacterial products
    saliva into gap between restoration cavity
    walls.
  • 2- pulpal irritation , inflammation, even
    necrosis can result from this penetration.
  • 3-marginal discoloration staining ( bad
    esthetics ).
  • 4- bacteria can demineralize the cavity walls
    adjacent to the restoration leading to caries
    recurrence.
  • 5- deterioration of the physical biological
    properties of the restoration.

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Recurrent of caries
7
discoloration
8
Methods Of Assessment Recording The Severity Of
Micro-leakage At Tooth \ Restoration Interface
  • 1- air-pressure technique.
  • 2- bacterial penetration.
  • 3- dyes ex basic fusin or methylene blue.
  • 4- radio-active isotopes.
  • 5- scanning electron microscope (S.E.M.)

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Dye penetration
11
Factors Affecting The Occurrence Severity Of
Micro Leakage
  • 1- dimensional changes in restorative materials
    during before completion of the setting
    reaction.
  • 2- dimensional changes of restorative materials
    after completion of the setting reaction.
  • 3- solubility in the oral cavity .
  • 4- inadequate condensation of the restorations.
  • 5- occlusal loads.
  • 6- presence or absence of smear layer.

12
1- Dimensional Changes Of Restorative Materials
During Before Completion Of The Setting
Reaction.
  • A- polymerization shrinkage of resinous
    restorations.
  • B- contraction expansion of amalgam.
  • C- setting contraction of G.I.C.
  • D- setting contraction of silicate cement.

13
2- Dimensional Changes Of Restorative Materials
After Completion Of The Setting Reaction.
  • A- difference in coefficient of thermal
    expansion between restoration tooth structure .
  • ex Amalgam about 2-3 times more than that of
    tooth.
  • Acrylic resin about 7 times than that
    of tooth.
  • B- modulus of elasticity.
  • C- wear . D- creep.
  • E- hygroscopic expansion.

14
C0fficient of thermal expansion of restorative
materials relative to tooth enamel
Material C.T.E (x 10?6 /?C
Tooth (crown enamel) 11.4
Dentin 8.3
Aluminous porcelain 6.6
Pure titanium 8.5
Type II glass ionomer 11.0
Pure gold 14.0
Dental amalgam 25.0
Composites 20.0-25.0
Denture resin 81.0
Pit and fissure resin 58.0
Inlay wax 400.0
15
3- Solubility In The Oral Fluids
  • Solubility of glass ionomer cement.
  • Solubility of silicate cement.
  • Solubility of luting cement.
  • - Zinc phosphate cement.
  • - Zinc polycarboxylate cement.

16
4- Inadequate Condensation Of Restorations
  • Poor condensation of restoration against cavity
    walls leads to voids along the cavity margins
    in the restorative material itself.
  • This contribute to a higher degree of
    micro-leakage inferior mechanical properties.

17
5- Occlusal Loads
  • A- in class II application of occlusal forces
    on class II restored teeth may cause elastic
    deformation of the tooth substance.
  • The facial lingual walls can flex away
    from the restoration toward the outside , so,
    increase width of the gap.

18
  • B- occlusal forces transferred from the
    restoration may create hygroscopic pressure on
    the fluid in the gap ( between tooth surface
    restorative material ) which can be pushed
    together with bacteria into the dentinal tubules
    towards the pulp.

19
6- Presence Or Absence Of Smear Layer.

20
Microleakage Of Different Restorative Materials
  • I amalgam .
  • II composite .
  • III glass ionomer restorations .
  • IV indirect constructed restorations .

21
I- Amalgam Restorations
  • All freshly seated amalgam restorations are leaky
    that is why the use of 2 layers of copalite
    cavity varnish on the walls margins of the
    prepared cavity in order to reduce the leakage
    around the restoration.

22
  • By aging in the oral cavity , the amalgam
    restorations will undergo tarnish corrosion.
  • The corrosive products of sulfides oxides
    will precipitate along the interface leading to
    gradual closure of the micro spaces between the
    material the walls of the cavity.

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

25
  • These leakage proof margins are due to micro
    pores created by acid etching technique the
    subsequent low viscosity resinous sealant which
    forms tiny micro tags providing retention
    sealing at the restoration margins.

26
  • So At First This hybrid combination
    blocks the leaky interface.
  • But Due To
  • 1- Direction degree of polymerization
    shrinkage.
  • 2- temperature cycle in the oral cavity.
  • 3- modulus of elasticity of the material.
  • 4- type magnitude direction of masticatory
    forces applied to restoration .
  • this relation soon ruptures creating a marginal
    gap.

27
Microleakage between Bacteria inside
dentinal tooth and restoration
tubule
28
  • This Marginal Gap Creates An Increasingly
    Deteriorating Conditions For Both Tooth
    Restoration
  • For Tooth In Form Of
  • Hypersensitivity
  • recurrent caries.
  • Pulpal affection.

29
  • Restoration In Form Of
  • Physical.
  • Chemical.
  • Esthetical degradation.
  • Due to leak out of ingredients hydrophilic
    nature of the resinous matrix.

30
III Glass Ionomer Restorations
  • Freshly applied G.I.C. Exhibit tightly sealed
    margins due to
  • 1- their adhesive potential.
  • 2- low setting contraction .
  • 3-coffecient of thermal expansion contraction
    near that of tooth structure .
  • by time these tightly sealed margins will
    deteriorate due to solubility in oral fluids
    specially with increased acidity of oral fluids
    ingested materials.

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33
Resin modified glass ionomer
34
IV Indirect Constructed
Restorations .
  • They are cemented by luting cements.
  • Intra-coronally or extra-coronally
  • Their Leakage Are Affected By
  • 1-solubility of materials .
  • 2-its adhesive properties.
  • 3-the length of the margins.
  • 4-the nature of the marginal joint.
  • 5-the type of bevel.
  • 6-the acidity of oral fluids.

35
Composite Inlay
  • It has many advantages over direct composite
  • 1- control of polymerization shrinkage.
  • Which occurs outside patient mouth only small
    luting cement leakage.
  • 2- better mechanical properties
    (compressive strength, tensile strength
    hardness.) Due to combined photo thermal
    initiation polymerization curing modalities.

36
  • 3- better reproduction of the contour, contact
    occlusal relations of the future restoration
  • 4- better marginal adaptation. As the dual
    curing adhesive cement seals the marginal gap
    specially at the critical inconspicuous gingival
    marginal area. Specially after introduction of
    ultra-sonically aided cementing seating devices (
    seimens sono-cem) . that provide a remarkable
    decrease in the film thickness superior
    adaptation for the highly viscous adhesive
    resinous cement.

37
Prevention Of Microleakage
  • 1- cavity preparation.
  • 2- smear layer removal.
  • 3- conventional varnish.

38
Complete infiltration partial removal
complete removal
39
1- Cavity Preparation
  • A- all cavity walls are smooth, clean dry for
    maximum adaptation of the restoration.
  • B- all unsupported enamel must be removed to
    prevent further fracture marginal defects.

40
  • 2- Smear Layer Removal
  • To obtain maximum adaptation of the restoration
    to the prepared cavity walls superficial smear
    layer removal should be removed , because it may
    interfere with adaptation as a potential area
    for bacterial growth.
  • N.B It is essential to leave the deep portion
    of the smear layer smear plug which acts as
    natural cavity liner inhibiting bacterial
    penetration into dentinal tubules I.E Decrease
    dentine permeability.

41
  • 3- Conventional Varnish
  • Amalgam restorations are susceptible to early
    penetration at the amalgam / tooth interface.
  • The use of cavity varnish has been accepted as
    the most reliable method of reducing
    micro-leakage around amalgam restorations.
  • The conventional varnishes composed of resin
    dissolved in organic solvent such as acetone ,
    chloroform or ether.
  • Two applications of copal varnish were more
    effective than one only.

42
Limitations Of Conventional Varnishes
  • 1-donot bond at tooth structure or amalgam , but
    reduce only micro-leakage but not prevent it.
  • 2- it acts as a mechanical barrier in the gap
    allowing micro-leakage between the amalgam
    varnish , between varnish tooth structure.
  • 3- it is not sufficient in reducing dentin
    permeability.
  • 4- partial dissolution of the varnish .

43
  • NAno leakage
  • Is nano metrisized spaces around the collagen
    fibrils within the hybrid layer that have not
    been completely infiltrated by resin

44
  • -It occur at the button of the hybrid layer or
    scattered along its thickness
  • -The deeper the etching into dentin the higher
    the degree of nano leakage because the degree of
    resin infiltration not equal to depth of
    demineralization

45
Bonding to dentin in total etch
adhesive system Dentinal substrate
after etching the Dentinal
substrates after priming smear layer has been
removed the blue the water replaced by
hydrophilic coloration represent the water
content
primer
46
After adhesive resin aplication
47
After polymerization resin infilterate
polymerized dentin
48
Bonding to dentine in self etch adhesive system
(after preparation smear layer
and smear plug)
49
After application of acidic resin
after application of adhesive
50
  • -For this reason the degree of nano leakage with
    self etching system is less than systems using
    acidic conditioners as single step
  • -Nano leakage accelerates degradation of the bond
    and failure of the restoration

51
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