CHEN ZhiCHEN Zhi

Wuhan University School of StomatologyWuhan University School of Stomatology

Operative Dentistry 3Operative Dentistry 3

Indication of Operative DentistryIndication of Operative Dentistry

Caries; Malformed, discolored,

or fractured teeth; Restoration replacement.

Tooth-colored restoration

For Class Ⅲ ，Ⅳ and Ⅴ ，— Esthetic Dentistry

For Class and Ⅰ Ⅱ ，

What are Tooth-colored materials?

What is their working mechanism?

What are the cavity preparation futures for tooth-colored restoration?

What are steps for tooth-colored restoration?

What are the advantage & disadvantageof tooth-colored restoration?

Tooth-Colored Materials

Composite resin

Glass ionomer cement

Compomer

Composite Resin

Traditional composites

Hybird composites

Flowable composites

Condensable composites Packable

Universal composites

Glass Ionomer

Chemical adhesion to dentin

Release Fluoride

Compomer

Compomer =

Composite + Ionomer

Dental Adhesionor

Dental Bonding

Adhesion is a process of solid and/orliquid interaction of one material withanother at a single interface.

Enamel bonding system

Enamel bongding depends on resin tagsbecoming interlocked with the surfaceirregularities created by etching.

Macrotags: form between enamel rod peripheries.

Microtags: smaller tags form across the end of each rod.

Macrotags and microtags are the basisfor micro-mechanical bonding.

Dentin bonding system

The difficulties of dentin bonding:

More water---wet bonding

Lower calcification

Richer organic---collagen network

Smear layer

The bond strength is primarily relatedto micro-mechanical bonding to theintertubular dentin which occures between tubules along the cut dentinsurface.

Dentin Bonding Agent, DBA

Early DBA were hydrophobic, bonded directly to the dentin smear layer. Bond strengths ＜ 6MPa.

Later DBA removed the smear layer buttended to over-etch dentin.Bond strengths≈10~12MPa.

DBA were chemically modified to be more hydrophilic.Bond Strengths≈18~20MPa.

Careful dentin conditioning,Coupled with hydrophilic primer,Bond Strength≈22~35MPa.

The Development of DBAEnamel etch

(1955)

Dentine etch (1960)

Treatment of smear layer (1980)

Wet Bonding technique(1990)

First generation

Second generation

Third generation

Fourth generation: Total etch technique

Fifth generation: One bottle system

Sixth generation: All in one,2000

Seventh generation

Cavity Preparation

Three designs of cavity preparation:

1.Conventional

2.Beveled conventional

3.Modified

Beveled conventional cavity preparationsare similar to conventional preparation,in that the outline form has external,“box-like” walls, but with beveled enamel margin.

Beveled enamel margin

Beveled conventional cavity designs for Class , and preparationsⅢ Ⅳ Ⅴ

The advantages :

The ends of enamel rods are more etched

The increase in etched surface results ina stronger bond

Increase the retention and reduce marginalleakage and discoloration.

More esthtically

Modified cavity preparation

Have neither specified cavity wall structurenor specified pulpal depth, and have enamelmargins.

Conserve more tooth structure.

Modified cavity preparation

Initial Clinical Procedure

Local anesthesia

Preparation of the operating site

Shade selection

Isolation of the operating site with rubber dam or cotton rolls

Rubber dam

Clinical Procedure

Cavity preparation

Acid etching enamel & conditioning dentin

Matrix application

Application of bonding agent

Insertion of compositeFinishing procedures

Matrix application

Final proceduresFinal procedures

Cases

Conservative Operative Dentistry

Minimal intervention dentistry

is regards as a main stream in caries treatment in the 21st century.

Principles of Minimal Intervention dentistry

Remineralization of early lesions Reduction in cariogenic bacteria, to el

minate the risk of further demi-neralization and cavitation

Minimum surgical intervention of ca-vitated lesions

Repair rather than replacement of defective restorations

“The day is surely coming, and perhapswithin the lifetime of you young menbefore me, when we will be engaged inpracticing preventive, rather than reparative, dentistry. ”

— GV Black in 1896

University Minnisota School of Dentistry

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