Resin Keyterms

Activator

Source of energy used to activate an initiator and produce free radicals. Three energy sources are currently used to dissociate an initiator into free radicals:

(1) heat, which supplies thermal energy;

(2) an electron-donating chemical such as a tertiary amine, which forms a complex and reduces the necessary thermal energy to that available at ambient temperature; and

(3) visible light, which supplies energy for photoinitiation in the presence of a photosensitizer such as camphorquinone (CQ).

Activation

Process by which sufficient energy is provided to induce an initiator to generate free radicals and cause polymerization to begin.

Chemically activated resin

Resin system consisting of two pastes—(one containing an initiator (e.g., benzoyl peroxide) and the other an activator (e.g., an aromatic tertiary amine)—which, when mixed together, release free radicals that initiate polymerization.

Composite

In materials science, a solid formed from two or more distinct phases (e.g., filler particles dispersed in a polymer matrix) that have been combined to produce properties superior to or intermediate to those of the individual constituents; also a term used in dentistry to describe a dental composite or resin-based composite.

Coupling agent

A bonding agent applied to the surfaces of reinforcing particles (filler) to ensure that they are chemically bonded to the resin matrix. Organo-silane compounds are the more common class of dental composite coupling agents.

Microfilled & Nanofilled composite

type of resin according to filler particle size.

Dental composite

Highly cross-linked polymeric materials reinforced by a dispersion of amorphous silica, glass, crystalline, mineral, or organic resin filler particles and/or short fibers bonded to the matrix by a coupling agent.

Dual-cure resin

Dental composite that contains both chemically activated and light-activated components to initiate polymerization and potentially overcome the limitations of either the chemicalor light-cure systems when used alone.

Filler

—Inorganic, glass, and/or organic-resin particles that are dispersed in a resin matrix to increase rigidity, strength, and wear resistance, to decrease thermal expansion, due to water sorption, and reduce polymerization shrinkage.

Hybrid composite

—A particle-filled resin that contains a graded blend of two or more size ranges of filler particles to achieve an optimal balance among the following properties: ease of manipulation, strength, modulus (relative rigidity), polymerization shrinkage, wear resistance, appearance, and polishability. Nanohybrids contain at least one dispersed filler with particle sizes of 100 nm or less (see nanofilled, below)

Inhibitor

—A chemical added to resin systems to provide increased working time and extended storage life by minimizing spontaneous polymerization, usually through free-radical scavenging mechanisms

Initiator

—A free radical−forming chemical used to start the polymerization reaction. It enters into the chemical reaction and becomes part of the final polymer compound; thus it is not a catalyst although often incorrectly labeled as such.

Light-cured/photocured/photoinitiated composite

—Particle-filled resin consisting of a single paste that becomes polymerized through the use of a photosensitive initiator system (typically camphorquinone and an amine) and a light-source activator (typically visible blue light). See also activator and initiator

Matrix

A plastic resin material that forms a continuous phase upon curing and binds the reinforcing filler particles.

Ormocer

- an acronym for organically modified ceramics, which are inorganic-organic copolymers.

(ceramic with resin)

Packable composite

A hybrid resin composite designed for use in posterior areas where a stiffer consistency facilitates condensation into a cavity form in a manner similar to that used for lathe-cut amalgams, also known as condensable composite

Silorane

A tetrafunctional epoxy siloxane monomer that cures via ring-opening polymerization. When the rings open, they lengthen and occupy more space; the resulting expansion offsets a portion of the polymerization shrinkage

Silorane

new type of matrix system used for composite nowadays. New composition to lessen polymerization shrinkage.