Dental CompositeClassification and Composition

DefinitionAcomposite is a material made from two or more constituent materials with significantly differentphysicalorchemical propertiesthat, when combined, produce a material with characteristics different from the individual components.The individual components remain separate and distinct within the finished structure.https://en.wikipedia.org/wiki/Composite_material

ComponentsMatrixFillerCoupling AgentInitiators and acceleratorsPigments

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 Note: Although Bis-GMA is more properly called an oligomer, we shall use the term monomer when referring to it.

Bowens Oligomer/ResinABCStructure of (A) Methyl methacrylate,(B) Triethylene Glycol Dimethacrylate,and (C) Bis-GMA.

Bowens Oligomer/ResinThe notable features of Dr. Bowens oligomer are polar side groups that increase chain to chain hydrogen bonding and two reactive C=C groups. Since each C=C group can participate in the formation of a growing polymer chain, the oligomer is called bifunctional.Bifunctional monomers and oligomers result in cross-linking and greatly improve the strength of the resulting polymer

FillerSilica particles Quartz Glass ( Ba, Sr, Zr)

FillerSizeDetermines the surface smoothness. Larger particles = rougher surface

Content (percentage)As the filler content increases, the resin content decreases. Therefore, polymerization shrinkage decreases, and the coefficient of thermal expansion becomes more like that of tooth structure. Hardness and abrasion resistance increase as well

Volume Vs WeightThere is a difference between filler content as measured by weight and by volume. Because the filler phase is much denser than the resin phase, the volume percentage is typically 10% to 15% lower than the weight percentage.

Manufacturers like to report the weight percentage because it is higher. Physical properties are determined by the volume percentage, so it is the favorite of scientists.

Filler Particle Size

Scanning electron micrographs of two dental composites (B and D) and their filler particles (A and C).The smaller filler particles result in composite restorations with a smoother surface. (Courtesy of BISCO, Inc.)ABCD

Filler percentage

Coupling AgentThe coupling agent couples, or transfers, stress from the relatively weak matrix to the relatively strong filler. Dental composites use ceramic filler particles coated with silane coupling agents. Silane coupling agents work a bit like soap; they have a different chemical group at each end of the molecule. Silane coupling agents are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end, as illustrated

Coupling AgentThe coupling agent couples, or transfers, stress from the relatively weak matrix to the relatively strong filler. Dental composites use ceramic filler particles coated with silane coupling agents. Silane coupling agents work a bit like soap; they have a different chemical group at each end of the molecule. Silane coupling agents are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end, as illustrated

Coupling AgentThe coupling agent couples, or transfers, stress from the relatively weak matrix to the relatively strong filler. Dental composites use ceramic filler particles coated with silane coupling agents. Silane coupling agents work a bit like soap; they have a different chemical group at each end of the molecule. Silane coupling agents are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end, as illustrated

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The coupling agent couples, or transfers, stress from the relatively weak matrix to the relatively strong filler. Dental composites use ceramic filler particles coated with silane coupling agents. Silane coupling agents work a bit like soap; they have a different chemical group at each end of the molecule. Silane coupling agents are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end, as illustrated

Coupling Agent

Coupling AgentThe coupling agent couples, or transfers, stress from the relatively weak matrix to the relatively strong filler. Dental composites use ceramic filler particles coated with silane coupling agents. Silane coupling agents work a bit like soap; they have a different chemical group at each end of the molecule. Silane coupling agents are molecules that react with the polymer matrix at one end and with the ceramic filler at the other end, as illustrated

Optical Modifiers/PigmentsProvides the opacity or translucency needed to make the composites similar to the natural tooth tissue

Metal oxide particles as radio-opacifiers: Titanium dioxide Aluminum oxide

Clinical AspectConfiguration factor (C-factor): refers to the number of bonded surfaces to the number of un-bonded surfaces in a dental restoration.

Configuration factor (C-factor): refers to the number of bonded surfaces to the number of un-bonded surfaces in a dental restoration.

C-factorWith an increasing C factor the developing polymerization shrinkage of bonded composites increases too (Feilzer et al. 1987).The developing polymerization shrinkage in a composite generate stress on the bonded interface that are in competition with the developing bond strength of the setting restorative (Adhesive) to the cavity surfaces, which may result in (partial) debonding, marginal leakage and post-operative pain

Polymerization shrinkage can be minimized by using:

"soft-start" polymerization instead of high-intensity light curingincremental layering to reduce the effects of polymerization shrinkage; anda stress-breaking liner, such as filled adhesive, flowable composite, or resin-modified glass ionomersthe application of non or low shrinking restorative materials

C-factor

Polymerization shrinkage can be minimized by using:

"soft-start" polymerization instead of high-intensity light curingincremental layering to reduce the effects of polymerization shrinkage; and a stress-breaking liner, such as filled adhesive, flowable composite, or resin-modified glass ionomersthe application of non or low shrinking restorative materialsC-factor

Polymerization shrinkage can be minimized by using:

"soft-start" polymerization instead of high-intensity light curingincremental layering to reduce the effects of polymerization shrinkage; and a stress-breaking liner, such as filled adhesive, flowable composite, or resin-modified glass ionomersthe application of non or low shrinking restorative materialsC-factor

Polymerization shrinkage can be minimized by using:

"soft-start" polymerization instead of high-intensity light curingincremental layering to reduce the effects of polymerization shrinkage; and a stress-breaking liner, such as filled adhesive, flowable composite, or resin-modified glass ionomersthe application of non or low shrinking restorative materialsC-factor

Polymerization shrinkage can be minimized by using:

"soft-start" polymerization instead of high-intensity light curingincremental layering to reduce the effects of polymerization shrinkage; and a stress-breaking liner, such as filled adhesive, flowable composite, or resin-modified glass ionomersThe application of non or low shrinking restorative materialsC-factor

Types and Properties of Dental CompositesMacro filledMicro filled Hybrid (including nano)Special indications

Types and Properties of Dental Composites

Macro/Micro/Hybrid

Macro filled Composites

The first type (1960s) Macrofilled composite.

The filler type Quartz

Particle sizes of 10 to 25 m.

Filler content is 70% to 80% by weight.

Major disadvantages of macrofilled compositesThe large size of the filler particles results in a restoration that feels rough to the dental explorer (Roughness)Plaque accumulation and staining is greater with this type

Macrofills have little clinical importance at this time except that some Orthodontists still use them

Micro filled composites

late 1970s Microfilled Particle size (0.030.5 m). Microfill composites polish very smooth and lustrous and the surface appearance is very similar to enamel.The filler type is fused silica.

Low percentage filler (4050%).

The surface area of the very small filler particles requires much more resin to wet the surface of the filler particles. This high resin content results in an increased coefficient of thermal expansion and lower strength.

Micro filled composites

The polymerization shrinkage of microfilled composites is less than expected based on the total resin content. Some (or all) of the filler particles are actually composite filler particles. The resin of these composite filler particles has already been polymerized. Therefore, this resin cannot polymerize and does not increase polymerization shrinkage. It does increase the coefficient of thermal expansion. Additional uncured matrix components are combined with the composite filler particle to make the microfilled composite paste.

Shiny but Fragile

Hybrid CompositesLate 1980s These composites are strong and polish well. Their filler content is 75% to 80% by weight. The filler particles (0.5 to 1 m) size, wider range of particle sizes (0.13 m) thats why called hybrid (or blended).

Hybrid composites are very popular; their strength and abrasion resistance are acceptable for small to medium Class I and II restorations. Their surface finish is nearly as good as that of microfills; thus, they are also used for Class III and IV restorations.

Hybrid Composites

Hybrid composites are very popular; their strength and abrasion resistance are acceptable for small to medium Class I and II restorations. Their surface finish is nearly as good as that of microfills; thus, they are also used for Class III and IV restorations.

Hybrid Composites

Popular / Fair

Improved Hybrid Composites (Nanohybrid)Manufacturers improved the clinical performance of composite materials. They continue to maximize the amount of filler present by controlling the particle size and distribution. The average particle size has decreased and nanosized particles have been added. Nano-sized particles are approximately 100 times smaller than the thickness of a human hair. The results are slight improvements in strength and polymerization shrinkage.

Improved Hybrid Composites (Nanohybrid)Hybrid composites currently on the market are a result of manufacturers efforts to improve the clinical performance of composite materials. They continue to maximize the amount of filler present by controlling the particle size and distribution. The average particle size has decreased and nanosized particles have been added. Nano-sized particles are approximately 100 times smaller than the thickness of a human hair. The results are slight improvements in strength and polymerization shrinkage. The most notable improvement is the smooth surface of modern well-polished composite materials. These materials have largely replaced microfilled compositions

Developments on Matrix Vs on Filler

Filtek P90 / SiloraneThe low-shrinking Filtek P90 Low Shrink Posterior Restorative is based on the new ring-opening silorane chemistry, which is a totally new class of compounds for use in dentistry.

Sphere tech/ Ceram X One

Sphere tech/ Ceram X One

Special Use Composite Materials

Flowable composites flow into the cavity preparation because of their Lower viscosity.

Special Use Composite Materials

Manufacturers have decreased the filler content of the material to reduce the viscosity and increase the flow of these materials.

Low Viscosity

Special Use Composite Materials

A weakerLess Abrasion-resistant Typically used as the Initial increment of a composite restoration and then covered with a hybrid material.

Special Use Composite MaterialsCondensable composites (Packable) To make placement easier.

In general, condensable composites have a filler particle feature that inhibits the filler particles from sliding by one another.

A thicker, stiffer feel results, and the manufacturers call these products condensable. Clinical research has shown these materials with a different feel are not an improvement over hybrid composite materials; most performed poorly and few are still on the market.

P60

Special Use Composite MaterialsCondensable composites (Packable) To make placement easier.

In general, condensable composites have a filler particle feature that inhibits the filler particles from sliding by one another.

A thicker, stiffer feel results, and the manufacturers call these products condensable. Clinical research has shown these materials with a different feel are not an improvement over hybrid composite materials; most performed poorly and few are still on the market.

Special Use Composite MaterialsCondensable composites (Packable) To make placement easier.

In general, condensable composites have a filler particle feature that inhibits the filler particles from sliding by one another.

A thicker, stiffer feel results, and the manufacturers call these products condensable. Clinical research has shown these materials with a different feel are not an improvement over hybrid composite materials; most performed poorly and few are still on the market.

Special Use Composite MaterialsBulkfill CompositesA 4 mm depth of cure reducing the need for incremental layering and risk of contamination.A flowable viscosity for easy adaptation less instrument manipulation.

Special Use Composite MaterialsBulkfill CompositesA 4 mm depth of cure reducing the need for incremental layering and risk of contamination.A flowable viscosity for easy adaptation less instrument manipulation.

Bulk Fill Flowable Restorative is especially suited for the following Indications:

Base under Class I and Class II direct restorationsLiner under direct restorative materialsPit and fissure sealant

Fiber Reinforced compositeINDICATIONS: Fiber reinforced composite is suitable for use as the reinforcing material for direct composite restorations, especially in large posterior cavities, for example:1. Cavities including 3 surfaces or more2. Cavities with missing cusps (Deep)3. Endodontically treated teeth (Surrounding a fiber post)4. Cavities after Amalgam replacement5. Cavities where Onlays & Inlays would also be indicated

Fiber Reinforced compositeEver X Posterior By GC

Clinical HintOptionally, apply first a thin layer of flowable composite to the cavity floor before the application of everX Posterior. Place the everX Posterior on top of the flowable composite and pack it in the cavity.

Fiber Reinforced compositeEver X Posterior By GC

Note: everX Posterior should always be covered with a layer of light-cured universal restorative composite, for sufficient wear resistance

Fiber Reinforced compositeCONTRAINDICATIONS1. Do not use for pulp capping.2. At least one horizontal dimension of the cavity should exceed 3 mm.3. In rare cases the product may cause sensitivity in some people. If any such reactions are experienced, discontinue the use of the product and refer to a physician.4. The product is not suitable for patients with a history of hypersensitivity to methacrylate monomers.5. Do not use as final approximal and surface composite layer.

The professional man has no right to be other than a continuous student (G.V. Black)

Resources/ReferrencesClinical Aspects of dental materials 4th edition by Marcia Gladwin and Michael Bagby.Composite resin presentation on www.slideshare.net by Wilda Bianca.Polymerization shrinkage of composite materials on www.slideshare.net by Mohammed H. Nabulsi BDS, MFDS, RCS. (Ireland).Stresses in adhesive restorations dental courses by indian dental academy channel on www.slideshare.net www.gc-dental.comwww.dentsplymea.com A review of polymerization shrinkage stress: current techniques for posterior resin restorations (Article) By Luca Giachetti Md,DMD. Daniele Scaminaci Russo DDS. Claudia Bambi DDS. Romano Grandini Md, DMD.P90 study booklet by Alfred Viehbeck global technical director at 3M ESPE.