Composite

2

o In materials and science, a solid formed from 2 or more distinct phases that have been combined to produce properties superior to or immediate to those of the individual constituents; also a term used in dentistry to describe a dental composite

• Consists of at least two distinct phases normally formed

by blending together components having different structures and properties.

Applications

• Restoration for anterior and posterior teeth

• Pits and fissure sealants

• Bonding of ceramic veneers

• Cementation of fixed prosthesis

components

Matrix

Filler

Coupling Agent

Initiators and accelerators

pigments

Resin Matrix

• Bis-GMA (bisphenol-A glyceril methacrylate)

• UDMA (urethane dimethacylate)

• TEGDMA (triethylene glycol dimethacrylate)

If the composite is made up of just the resin matrix, it is called

Unfilled Resin

Matrix

• Phase that polymerizes to form a solid mass and that bonds to the tooth structure.

• Weakest and the least wear resistant phase

• Absorbs water, stain and discolor

• Minimize the filler content

• = stronger composite material

Filler Particles

• Silica particles

• Quartz

• Glass ( Ba, Sr, Zr)

If the composite is made up of the resin matrix AND fillers, it is called

Filled Resin

Factors for durability of Co Resin

Filler Size • Determines the

surface smoothness.

• Larger particles = rougher surface

• Composites are most often classified by the filler size.

Filler Content • As the filler content

increases, the resin content decreases

• Hardness and abrasion resistance increases

Filler Particles

• Increase fillers, increase mechanical properties

– strength

– abrasion resistance

– esthetics

– handling 0

0.5

1

1.5

2

Fra

ctu

re T

ough

ness

0 28 37 48 53 62

% Filler Volume

Ferracane J Dent Res 1995

Coupling Agent

• Chemical bond

– filler particle - resin matrix

• transfers stresses

• Organosilane (bifunctional molecule) – siloxane end bonds to hydroxyl groups on filler

– methacrylate end polymerizes with resin

CH3-C-C-O-CH2-CH2-CH2-Si-OH

CH2

O OH

OH

Bonds with filler

Silane

Bis-GMA

Bonds with resin

Phillip’s Science of Dental Materials 2003

Coupling Agents

• Chemical bond

– filler particle - resin matrix

• Improves physical and mechanical properties

• Inhibits leaching by preventing water from penetrating along the resin-filler interface

Optical Modifiers / Pigments

• Provides the opacity or translucency needed to make the composites similar to the natural tooth tissue

• Metal oxide particles

– Titanium dioxide

– Aluminum oxide

Color Determination

• Should be as close to that of the natural tooth as possible.

POLYMERIZATION SYSTEMS

• Chemical Cure

• Light cure

• Dual cure

Polymerization Systems

a. Chemically Activated Materials

- 2 paste systems

1. tertiary amine

2. BPO initiator

- mix at chairside until 2 colors blend

• B. Light activated Materials - Single paste - Materials set when exposed to a very bright

light.

- Light sources: - Halogen light - Plasma arc light - Argon laser - Blue emitting diodes

• B. Light activated Materials

• SYRINGE single paste

• Free radical initiating system consist of

• Photointiator molecule and amine activator

• Light exposure ( correct wavelength)

• Photoinitiator : camphorquinone

• Amine Accelarator : DEAEMA ( diethyl-amino-ethyl-methacrylate)

• C. Dual Cure

• Consists of 2 light curable pastes

• BPO and aromatic tertiary amine

• Light curing – promoted by amine/CQ combination

• Chemical- amine/BPO interaction

• APPLICATION:

• Cementation of bulky ceramic inlays

CLASSIFICATION OF RESIN-BASED COMPOSITES

CATEGORY AVE PARTICLE SIZE (µm)

CONVENTIONAL / MACROFILLED

8-12

SMALL PARTICLE 1-5

MICROFILLED 0.04-0.4

HYBRID 1

Macrofilled Composites

• conventional composites,

• traditional composites

• Properties:

– Filler is quartz

– Filler used: finely ground amorphous silica and quartz

– Filler loading: 70-80 wt% or 60-70 vol%

• May be used as a restoration in stress bearing areas such as Class IV and II sites

Macrofilled Composites

• Clinical Considerations:

– Produces a rough surface during abrasive wear

– Finishing of the restoration also produces a roughened surface

– Tend to discolor over time

– Poor resistance to occlusal wear

Small Particle • To improve surface smoothness and

retain or improve the properties of traditional composites.

• High filler loading than traditional • Filler: amorphous silica ,

incorporate glasses • Compressive strength > macro and

micro • Tencile strength : x2 micro and 1.5x

macro • INDICATIONS: • high stress and abrasion prone (cl

IV)

Microfilled Composites

• Properties: – Filler used: colloidal silica

– Filler size: 0.04 um colloidal silica(200-300 times smaller than the ave particle size of traditional composites)

– Filler loading: 80 wt%, 60 vol%

• Polish very smooth

• Appearance like enamel

Microfilled Composites

• Clinical considerations:

– Bond between the composite particles and the matrix is relatively weak, making it not suitable for use as stress bearing restoration

– Produces the smoothest finish

– Indicated for: Class III and Class V cavities

Hybrid Composites

• Properties: – Filler used: colloidal silica AND glass

containing heavy metals

– Filler size: 0.4- 1um

– Filler loading: 75-80 wt%

• Physical and mechanical properties rane between those of the

traditional and SPF

composites

Hybrid Composites

• Clinical considerations:

– Indicated for Class III and IV cases

– Indicated for Class I and II cases

– Indicated for Class V cases

Special Use Composite Materials

• Flowable

• Condensable / Packable

Flowable Composites

• Has a reduced filler content to make the material “flowable”

• Indicated for Class I restorations in the gingival areas

• Used as a cavity base or liner especially for Class II preparations wherein access is difficult to achieve

• Used as a pit and fissure sealant

Condensable composite

• Has a filler particle that inhibits the filler particles by sliding to one another

• Stiffer, thicker feel

Classification of Resin-Based Composites and Indications for Use