A polymerization lamp is a lamp that is part of the basic equipment of dental offices. It is needed for curing fillings.
What is a polymerization lamp?
Polymerization lamps are special lamps that have a blue light. Composite fillings, also known colloquially as plastic fillings, can be cured in this light. Polymerization lamps are special lamps that emit a blue light. Composite fillings, commonly referred to as plastic fillings, can be cured in this light. The light produced by the polymerization lamps is a cold light. Cold light is the term used to describe a light with a particularly reduced infrared component.
Shapes, types and kinds
In the case of polymerization lamps, a distinction is made between halogen and LED lamps. Units with built-in halogen lamps generate a lot of heat. However, since cold light is required for polymerization, otherwise damage to the pulp may occur, these units must be cooled with a built-in blower. One disadvantage of halogen lamps is their diminishing power. With normal use, the luminosity already decreases significantly within two to six years. Because of these disadvantages, LED lamps are increasingly being used in dental practices. LEDs were first used as light sources in polymerization lamps in 1995. The advantage of LED lamps is their low heat generation. The lamps generate significantly less heat and therefore consume less electricity. Therefore, even the use in battery-powered devices is possible. Halogen lamps must always be connected to the mains. It is important that the light output is evenly and effectively distributed over the entire light beam. This is referred to as a balanced beam profile. A polymerization lamp can be evaluated on the basis of its light output. This provides information on the average beam intensity, measured via the so-called emitted wavelength spectrum of the light emission window. In addition to mains-operated and battery-operated lamps, a distinction can also be made between conventional and soft-start polymerization lamps. While conventional lamps provide full light output immediately after being switched on, soft-start lamps emit only reduced light output in the first ten to twenty seconds after being switched on. This is actually intended to reduce possible stresses in the fill. However, studies showed that soft polymerization has neither advantages nor disadvantages.
Structure and mode of operation
Nowadays, light-curing resins are used for fillings and veneers made of resin. These are usually so-called composites. Composites are filling materials that consist of an organic resin matrix on the one hand and an inorganic filler on the other. Polymerization, i.e. in the broadest sense the curing of the material, takes place in three steps. Put simply, during polymerization, free radicals of certain molecules in the composite seek out another free radical. This creates stable compounds and the material hardens. To get this chemical reaction going, so-called initiators are added to the plastic material. These are used to form the radicals. A prerequisite for the formation of the radicals from the initiators is, in turn, the light from the polymerization lamp. This triggers a starting reaction (initiation). Within a short time, more and more radicals are formed and thus more and more compounds (growth reaction / propagation). The more molecules are formed, the more stable the compound and thus the plastic filling becomes. Once all the molecules present have bonded, polymerization ends. An energy dose of 12 to 16 J/cm² is required for polymerization with the polymerization lamp. The deeper the filling, the less light still hits the filling material. Very deep fillings must therefore be cured in several layers.
Medical and health benefits
In the past, dentistry generally used three materials to fill tooth cavities: Amalgam, gold or silver. These materials harden on their own. But gradually the disadvantages of these filling materials became noticeable. Dental amalgam consists of a significant amount of mercury. Mechanical stress can cause the amalgam to come out of the teeth in pieces over time.The result can be a mercury load on the body. This manifests itself in various complaints. Gold and silver have the disadvantage that they cannot be molded directly on the tooth. Therefore, a plaster model of the tooth must first be created. A gold inlay can be formed from this plaster mold. Other disadvantages of gold fillings are the conspicuous color and the electrochemical reactions that occur when they come into contact with other metal fillings such as silver fillings. In order to meet health and aesthetic requirements, more and more plastic fillings have been used. Plastic fillings can be designed in respective tooth colors and are therefore inconspicuous. They are mercury-free and stabilize the tooth substance by adhering to the dentin. Also, undercuts requiring tooth substance, as in the case of amalgam fillings, are not necessary with plastic fillings. In the 1970s, UV lamps were mainly used to cure these fillings. However, these lamps posed various health risks. On the one hand, there was a risk of blindness during treatment due to the proximity to the eyes, and on the other hand, the lamps increased the risk of skin cancer in the face. Therefore, in the early 1980s, the dangerous UV lamps were replaced by blue light lamps, the precursors of today’s polymerization lamps. Thanks to the polymerization lamps available today, the insertion and curing of resin fillings can now be done quickly and safely.
