A recent alternative to QTH, LED curing http://www.selleckchem.com/products/baricitinib-ly3009104.html units are increasingly used in dental practice. The LED has the advantages of extended of lifetimes of over 10000 h, little degradation of light output over time, and resistance to shock, overheating, and vibration.2 The spectral output of LEDs consists of the absorption peak of CQ (400�C500 nm, peak at 470 nm), the most used photoinitiator in resin composites. Comparative studies demonstrated that the type of LCU is an important factor for both curing efficiency and generated heat.8,9 However, few studies have investigated the cytotoxicity of composites with different curing methods. The determination of the possibly toxic effect of composites is a matter of interest. In view of the great variety of LCUs and filling materials currently in use, the question is which combinations cause the least toxic effects.
The present study aimed to explore, in an in vitro model, the possible cytotoxicity of various composite�CLCU combinations. MATERIALS AND METHODS Sample preparation The A3 shades of composites Filtek P60, Filtek A110, Filtek Supreme, Filtek Z250 (3M ESPE, St. Paul, MN, USA) and SDI Rok (SDI Ltd., Victoria, Australia) were evaluated in this study. The composition of each material is detailed in Table 1. For each material, disc-shaped samples (2 mm diameter and 2 mm in thickness) were prepared using Teflon molds. These molds were placed on flat glass plates on top of Mylar strips (Moyco Union Broach, York, USA) and then filled in bulk with composites. The composites were then covered with an acetate strip and gently pressed with another flat glass plate.
Next, excess material was removed with a scalpel (Otto R��ttgers GmBH, Solingen, Germany). The top glass plate was removed to polymerize the samples. The samples were polymerized and randomly divided into two groups (n=6/group) according to the LCU: 1) QTH/40secs (Optilux 501, Kerr, Orange, CA) and 2) LED/20secs (Elipar Freelight II, 3M/ESPE, Seefeld, Germany). The LCUs were all used in standard mode (continuous, constant light intensity). Before photoactivation, the irradiance of both curing units was confirmed with QTH and LED radiometers (Kerr/Demetron, Orange, CA, USA). The output spectrum for the LED was concentrated within the 425�C500 nm wavelength range, while that of the Optilux 501 is considerably wider (375�C520 nm).
However, the spectral flux of the LED was much higher at 425�C475 nm, the effective range of CQ the photo-initiator for both resins (Figure 1). Figure Batimastat 1. Cell viability of the samples polymerized by LED and QTH light curing units. Table 1. Materials, manufacturers, and approximate resin composition (According to manufacturers�� information). Cell proliferation The cells used for the experiment were L929 mouse fibroblasts. The cells were grown as monolayer cultures in 25T-flasks (Corning, NY, USA) in Dulbecco��s Modified Eagle��s Medium/F12 (DMEM/F12) (Sigma Chemical Co. St.