COMPOSITES FOR CLASS II CAVITIES

SEMINAR-DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS

VESTA ENID LYDIA .RIII BDS CSICDSR-MADURAI

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Dental composite resins

are types of synthetic resins which are used in dentistry as restorative material or adhesives.

Synthetic resins evolved as restorative materials since they were insoluble, aesthetic, and insensitive to dehydration and were inexpensive.

It is easy to manipulate them as well.

Composite resins are most commonly composed of Bis-GMA monomers or some Bis-GMA analog, a filler material such as silica and in most current applications, a photoinitiator. Dimethacrylates are also commonly added to achieve certain physical properties such as flowability.

Further tailoring of physical properties is achieved by formulating unique concentrations of each constituent.

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History of useInitially, composite restorations in dentistry were very prone to leakage and breakage due to weak compressive strength

In the 1990s and 2000s, composites were greatly improved and are said to have a compression strength sufficient for use in posterior teeth.

Today's composite resins have low polymerization shrinkage and low coefficients of thermal shrinkage, which allows them to be placed in bulk while maintaining good adaptation to cavity walls.

The placement of composite requires meticulous attention to procedure or it may fail prematurely

 

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ADA STATEMENT ON   POSTERIOR RESIN-BASED

COMPOSITES  

1.composites used successfully till date in

o CLASS V RESTORATIONS.

o RESTORING ESTHETICALLY IMPORTANT AREAS.

o IN PATIENTS ALLERGIC OR SENSITIVE TO METALS.

2.other places where composites can be used are

o PIT AND FISSURE SEALING.

o PREVENTIVE RESIN RESTORATIONS.

o INITIAL CLASS I AND II LESIONS.

MODERATE-SIZED CLASS I AND II RESTORATIONS 3.LITERATURE DOES NOT SUPPORT THE SUCCESFULL USE IN

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o TEETH WITH HEAVY OCCLUSAL STRESS.

o IN SITES THAT CAN’T BE ISOLATED.

IN PATIENTS ALLERGIC TO RESIN-BASED COMPOSITES.

 4.FUTURE RESEARCH IN COMPOSITES SHOULD ADDRESS

o REDUCTION IN POLYMERIZATION SHRINKAGE.

o IMPROVED DENTIN/ENAMEL BONDING TECHNIQUES.

o IMPROVED PLACEMENT AND INSTRUMENTATION TECHNIQUES.

o IMPROVED CURING METHODS.

o CONTACT WEAR BEHAVIOR.

o POLYMERIZATION INITIATORS.

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o ALTERNATIVE MATRIX SYSTEMS.

o MORE EXTENSIVE RESTORATIONS??

CASE SELECTION  

Cavity preparation design

Location of margin

Location of restoration

Size of restoration

 OCCLUSION CONCERNS/ANTAGONISTIC CUSP:

o GREATLY AFFECTS DEGRADATION OF COMPOSITE.

o INCREASED LOCALIZED WEAR ON THE COMPOSITE SURFACE WITH INCREASED CONTACT AREA.

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o INCREASED GENERALIZED WEAR ON THE CONTACT FREE AREA.

o BULK FRACTURE AND MARGINAL DETERIORATION.

 ANTAGONISTIC CUSP:

o PRE-OP: USE OF ARTICULATING PAPER.

o DESIGN OUTLINE FORM TO AVOID CONTACT AREA.

o MODIFY THE OPPOSING CUSP TO REDIRECT THE CONTACT AREA AWAY FROM RESTORATION.

o ENAMELOPLASTY OF OPPOSING CUSP TO FLATTEN THE OCCLUSAL LOAD OVER A WIDER AREA.

 MATERIAL OPTIONS  

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HYBRID RESIN  

MICROFILL ED RESIN

HYBRID RESIN INTERNAL & MICROFILL RESIN ON OUTER 1 MM.

PACKABLE RESIN

PACKABLE RESIN WITH MICROFILL ON OUTER 1 MM.

  CLINICAL TECHNIQUE

ISOLATION RECOMMENDATIONS 

Rubber Dam Isolation is Mandatory:

o Failure to maintain a dry field will result in clinical failure.

o Prevention of moisture contamination and protection of gingival tissues is of paramount importance.

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o Select shade before rubber dam application.

Dentin shade up to the DEJ level.

Incisal or enamel shade for final increment.

PRE-WEDGING  

Gains interproximal separation to  facilitate tight contact area. 

INITIAL: 90 um movement.

AFTER 30 SECONDS: o 30 um is lost.

90% RECOVERY: within 30 seconds

    removal of wedge.   

CAVITY PREPARATION 

ADHESIVE PREPARATION FOR POSTERIOR COMPOSITES

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DIFFERS FROM TRADITIONAL AMALGAM PREPARATIONS IN MANY WAYS.  

PREPARATION IS SHALLOWER.

RETENTION IS PROVIDED THROUGH BONDING 

PREPARATION IS NARROWER:

o 1.  LESS OCCLUSAL CONTACT AREA.

o 2.  REDUCES WEAR.

o 3.  DECREASES AFFECT OF POLYMERIZATION SHRINKAGE. 

o 4.  IMPROVED MARGINAL INTEGRITY.

o 5.  LESS CUSPAL DEFLECTION.  

PREPARATION HAS ROUNDED INTERNAL LINE ANGLES:

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o 1.  CONSERVES TOOTH STRUCTURE.

o 2.  DECREASES STRESS CONCENTRATION.

o 3.  ENHANCES RESIN ADAPTATION DURING   PLACEMENT.

NO EXTENSION FOR PREVENTION:

o 1.  OCCLUSAL SURFACE IS  INVADED ONLY IF CARIES DICTATES IT. 

o 2.  TREAT ADJACENT PITS AND FISSURES WITH SEALANTS.   PROXIMAL BOX PREPARATION CONCERNS  

SLOT PREPARATIONS:

o MECHANICAL RETENTION ISN’T IMPORTANT.

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o DON’T EXTEND THE PREPARATION BEYOND THE MARGINAL RIDGE BY MORE THAN 2 MM.   

GINGIVAL MARGIN   CONCERNS  

SLOT PREPARATION OR CONVENTIONAL CLASS II PREP:

o GINGIVAL FLOOR EXTENDED ONLY TO DEPTH OF CARIOUS LESION. 

o CONSERVE ENAMEL FOR BONDING AND MICROLEAKAGE PREVENTION.

OCCLUSAL MARGIN OF PREPARATION  

o BEVELED OCCLUSAL CAVOSURFACE MARGIN:

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o SIGNIFICANTLY INCREASES THE WEAR RATE COMPARED TO CONVENTIONAL BUTT JOINT CAVOSURFACE MARGINS.

o WHY?  THE BU-LI DIMENSION IS INCREASED AND INFLUENCES THE AFFECT OF THE ANTAGONISTIC CUSP

PULPAL PROTECTION  

Postoperative sensitivity concerns:

o effects of polymerization contraction and/or marginal leakage with bacterial invasion.

o Hermetically seal the dentin with your choice of dentin bonding agent material.

o Place a light curable resin modified glass ionomer cement that has the fluoride releasing

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properties you may desire.

DENTIN/ENAMEL BONDING  

Another Clinical Decision to Make:

o your choice of one of the currently available dentin bonding agents following the manufacturer’s instructions.

CRITERIA FOR MATRICES  

RE-ESTABLISH CONTOUR

FORM POSITIVE CONTACT

SEAL GINGIVAL MARGIN

ALLOW ADEQUATE BULK OF MATERIAL

LIMITED THICKNESS

PRODUCE SMOOTH SURFACE

CRITERIA FOR MATRICES  

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PERMIT NON-DISRUPTIVE WITHDRAWAL

MUST AVOID TOOTH DISTORTING PRESSURES

MUST BE EASY TO PLACE  

ALLOW FOR A VARIETY  OF RESTORATIVE MATERIALS 

 COMPOSITE PLACEMENT TECHNIQUES  

1.SEGMENTAL PLACEMENT: < 5.0 MM.

o 1.  FLOWABLE RESIN (0.5-1.0 MM LAYER)

 

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o 2.  DENTIN SHADE OF PACKABLE RESIN. NO MORE THAN 3.0-3.5 MM INCREMENTS. 

o 3.  TINT PLACEMENT (OPTIONAL).

o 4.  ENAMEL SHADE (UNIVERSAL HYBRID)

2.BULK FILL TECHNIQUE:

o A MAJOR CLAIM OF PACKABLE COMPOSITE MANUFACTURERS.

o Increments should be no greater than 2mm to obtain a uniform and maximum cure.

o Increase cavity depth resulted in decreased effectiveness of polymerization for all exposure times.

o Increased exposure time resulted in an increased hardness ratio and effective

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polymerization at depths of 3-4 mm.

THREE-SITED   LIGHT CURING

TECHNIQUE  

FIRST INCREMENT:  o CURED THROUGH THE LIGHT-

REFLECTING WEDGE IN A GINGIVAL-PROXIMAL DIRECTION.

LARGER 2ND and 3RD INCREMENT: o CURED FROM BUCCAL AND

LINGUAL.

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o ENSURES SHRINKAGE VECTORS TOWARD THE CAVITY MARGINS.

FINAL INCREMENT: o ADDED TO THE OCCLUSAL

ASPECT.

FINISHING PROCEDURES  

12-B BLADE TO REMOVE INTERPROXIMAL GINGIVAL EXCESS.

FINE-DIAMOND FINISHING STRIPS.

ALUMINUM OXIDE FINISHING DISCS.

CARBIDE FINISHING BURS.  

   

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