CHEN Zhi

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Operative Dentistry 3

• CHEN Zhi
• Wuhan University School of Stomatology

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Indication of Operative Dentistry

• Caries
• Malformed, discolored,
• or fractured teeth
• Restoration replacement.

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Tooth-colored restoration

• For Class ?,? and ?,
• Esthetic Dentistry
• For Class ?and ?,

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What are Tooth-colored materials?
What is their working mechanism?
What are the cavity preparation futures for
tooth-colored restoration?
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What are steps for tooth-colored restoration?
What are the advantage disadvantage of
tooth-colored restoration?
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Tooth-Colored Materials

• Composite resin
• Glass ionomer cement
• Compomer

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Composite Resin
Traditional composites
Hybird composites
Flowable composites
Condensable composites
Packable
Universal composites
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Glass Ionomer

• Chemical adhesion to dentin

• Release Fluoride

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Compomer
Compomer
Composite

Ionomer
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Dental Adhesionor Dental Bonding
Adhesion is a process of solid and/or liquid
interaction of one material with another at a
single interface.
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Enamel bonding system
Enamel bongding depends on resin tags becoming
interlocked with the surface irregularities
created by etching.
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Macrotags form between enamel rod
peripheries.
Microtags smaller tags form across
the end of each rod.
Macrotags and microtags are the basis for
micro-mechanical bonding.
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Dentin bonding system
The difficulties of dentin bonding
More water---wet bonding
Lower calcification
Richer organic---collagen network
Smear layer
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The bond strength is primarily related to
micro-mechanical bonding to the intertubular
dentin which occures between tubules along the
cut dentin surface.
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Dentin Bonding Agent, DBA
Early DBA were hydrophobic, bonded directly to
the dentin smear layer. Bond strengthslt6MPa.
Later DBA removed the smear layer but tended to
over-etch dentin. Bond strengths1012MPa.
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DBA were chemically modified to be more
hydrophilic. Bond Strengths1820MPa.
Careful dentin conditioning, Coupled with
hydrophilic primer, Bond Strength2235MPa.
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The Development of DBA
Enamel etch (1955)
Dentine etch (1960)
Treatment of smear layer (1980)
Wet Bonding technique(1990)
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First generation
Second generation
Third generation
Fourth generation Total etch technique
Fifth generation One bottle system
Sixth generation All in one,2000
Seventh generation
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Cavity Preparation
Three designs of cavity preparation
1.Conventional
2.Beveled conventional
3.Modified
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Beveled conventional cavity preparations are
similar to conventional preparation, in that the
outline form has external, box-like walls, but
with beveled enamel margin.
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Beveled enamel margin
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Beveled conventional cavity designs for Class ?,
? and ? preparations
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The advantages
The ends of enamel rods are more etched
The increase in etched surface results in a
stronger bond
Increase the retention and reduce
marginal leakage and discoloration.
More esthtically
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Modified cavity preparation
Have neither specified cavity wall structure nor
specified pulpal depth, and have enamel margins.
Conserve more tooth structure.
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Modified cavity preparation
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Initial Clinical Procedure
Local anesthesia
Preparation of the operating site
Shade selection
Isolation of the operating site with rubber
dam or cotton rolls
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Rubber dam
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Clinical Procedure
Cavity preparation
Acid etching enamel conditioning dentin
Matrix application
Application of bonding agent
Insertion of composite
Finishing procedures
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Matrix application
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Final procedures
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Cases
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Conservative Operative Dentistry
Minimal intervention dentistry
is regards as a main stream in caries
treatment in the 21st century.
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Principles of Minimal Intervention dentistry

• Remineralization of early lesions
• Reduction in cariogenic bacteria, to elminate the
  risk of further demi-neralization and cavitation
• Minimum surgical intervention of ca-vitated
  lesions
• Repair rather than replacement of defective
  restorations

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The day is surely coming, and perhaps within the
lifetime of you young men before me, when we will
be engaged in practicing preventive, rather than
reparative, dentistry.

• GV Black in 1896

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University Minnisota School of Dentistry
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http//202.114.104.243/jpkc/ysysbx/index.html
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Thanks