Abstract
The aim of this study was to investigate the influence of different composite resins - Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) - on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25%) was significantly higher than that of Heliomolar (12%). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.
Highlights
The restorative composite resins have undergone continuous development during the most recent decades (1)
Composite formulations have continued to evolve since bisphenol A glycidyl methacrylate (Bis-GMA) was first introduced to dentistry by Bowen in 1962 (2), and have been modified in various ways based on different properties, like viscosity or polarity
The aim of this study was to investigate the influence of different composite resins on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens
Summary
The restorative composite resins have undergone continuous development during the most recent decades (1). Composite formulations have continued to evolve since bisphenol A glycidyl methacrylate (Bis-GMA) was first introduced to dentistry by Bowen in 1962 (2), and have been modified in various ways based on different properties, like viscosity or polarity. These changes were produced by variations of functional groups. All commercially available composite resins have their common basis in the radical polymerization of methacrylates (1). These materials are composed of an organic matrix, load particles (glass, quartz and/or melted silica) and a bonding agent, usually an organic silane, that has a dual characteristic, enabling chemical bonding with the load particle and co-polymerization with the monomers of the organic matrix (3). Two major properties of composites that still have to be improved are polymerization shrinkage and the related
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
