High-Power LED Units Currently Available for Dental Resin-Based Materials-A Review.

The pursuit of less time-consuming procedures led to the development of high-power light-curing-units (LCU) to light-cure dental-resin-based-materials. This review aims to describe high-power light-emitting-diode (LED)-LCUs, by a bibliometric systematization of in vitro and in vivo studies. The research-question, by PICO model, aimed to assess the current knowledge on dentistry-based high-power LED-LCUs by analyzing to what extent their use can promote adverse events on materials and patients' oral condition when compared to low-power LED-LCUs, on daily dental practice. PubMed and B-on database search focused on high-power (≥2000 mW/cm2) LED-LCUs outputs. Studies assessing performance of high-power LED-LCUs for light-curing dental-resin-based-materials were included. From 1822 screened articles, 21 fulfilled the inclusion criteria. Thirty-two marketed units with high levels of radiant emittance (≥2000 mW/cm2 up to 6000 mW/cm2) were identified. Most output values vary on 2000-3000 mW/cm2. The highest output found was 6000 mW/cm2, in FlashMax™P3. Reports suggest that light-curing protocols with lower emittance irradiance and longer exposure outperforms all other combination, however in some clinical procedures high-power LED-LCUs are advocated when compared to low-power LED-LCUs. Moreover, long time exposures and over-curing can be dangerous to the biological vital pulp, and other oral tissues. Evidence showing that high-power LCUs are the best clinical option is still very scarce.

Transmission of violet and blue light through conventional (layered) and bulk cured resin-based composites.

OBJECTIVES: This study measured the transmission of light in the 'violet' (350≤λ≤425nm) and 'blue' (425<λ≤550nm) spectral ranges from a polywave(®) LED curing light through different thicknesses of four commercial, resin-based composites (RBCs). MATERIAL AND METHODS: Samples of conventional layered RBCs (Tetric EvoCeram A2, Filtek Supreme Ultra A2B), and bulk-curing resins (Tetric EvoCeram Bulk Fill IVA, and SureFil SDR Flow U) were prepared. Three samples of each RBC were made at thicknesses of 0.1, 0.7, 1, 2, and 4-mm. The uncured RBC specimens were affixed at the entrance aperture of a 6-inch integrating sphere and light-cured once for 20s using a polywave(®) LED curing light (Bluephase G2) on its high power setting. The spectral radiant power transmitted through each RBC in the 'violet' and 'blue' regions was measured using a fiberoptic spectrometer. RESULTS: As RBC thickness increased, an exponential attenuation of transmitted light was measured (R(2)>0.98). Attenuation was greater for the 'violet' than for the 'blue' spectral regions. At the light tip, the violet light component represented 15.4% of the light output. After passing through 4-mm of RBC, the violet light represented only between 1.2-3.1% of the transmitted light depending on the RBC. Depending on RBC, approximately 100mW from the Bluephase G2 was transmitted through 0.1-mm of RBC in the 'violet' range, falling at most to 11mW after passing through 2-mm of RBC, and to only 2mW at 4-mm depth. CONCLUSIONS: Increasing RBC thickness results in an exponential decrease in light transmission. This attenuation is RBC-dependent with shorter wavelengths (violet) attenuated to a greater extent than longer wavelengths (blue). CLINICAL RELEVANCE: Despite the increased translucency of bulk curing RBCs, spectral radiant power shorter than 425nm from a curing light is unlikely to be effective at a depth of 4-mm or more.