Which are the photoactivation times that have to be used for different types of composites?
For each composite, a certain curing time must be used. For example, composites and hybrid microhybrids, nanoparticulate be photoactivated for 20 seconds (to enamel resins, more translucent) and 40 seconds (resins to dentin, more opaque). Microparticulate composites must be photoactivated for 60 seconds.
What is the wavelength and what is its importance in photoactivation?
Wavelength is related to the color of light emitted by the device. For example, in the case of LED equipment used for curing, the color of the light emitted by them is blue light (± 470 nm). The importance of having a suitable wavelength for photoactivation is related to the absorbency of light by the photoinitiator (camphorquinone) present in the composition of most photocured resin materials by promoting a more adequate polymerization. Furthermore, a system for photoactivation with blue LED wavelength of around 470 nm also promote less heating of the restorative material and the tooth structure by only emit light blue, unlike what happens with a halogen light source that does not emit light only blue.
What are the key parameters to perform a proper photoactivation?
Wavelength, light intensity and exposure time. For this wavelength, light sources which have a wavelength close to the absorption spectrum of camphorquinone (± 470nm) are shown more efficient. Thus, systems LEDs have this characteristic, because emit blue light around 470nm range of ± 20nm. About to light intensity, values within a range of 400-600 mW/cm2 presents sufficient to polymerize 2mm composite. The exposure time depends on the composite resin that is using. In general for resins translucent (enamel) is recommended 20 seconds and opaque resins (dentin) is recommended 40 seconds of exposure.
The acrylic fiber tips are efficient?
They are efficient and this factor is mainly related to the method by which they are produced. Acrylic fibers produced by the machining method exhibit fewer defects on its surface or inner portion as compared to other manufacturing methods. Such defects can hinder the transmission of light appropriately.
Profª Drª Alessandra Rastelli
Composite resins to enamel and dentin require more or less power photoactivation and why?
The activation time of the resins must be the time recommended by the manufacturer. Resins to dentin, usually because they are more opaque, need a longer photoactivation of the resin enamel, and resins dark colors (A3, 4, A4) also need more time photoactivation resins clear that (A1 ; B1).
What is light intensity of a photoactivation device?
The intensity of a photoactivation device is determined by the ratio of the power (W) emitted by the area (cm2) of the same and is given in W/cm2.
Profº Drº Marcus Vinicius