| Author/Editor | Šušterčič, D | |
| Title | Določanje stopnje polimerizacije dentalnih kompozitnih materialov z elektronsko paramagnetno resonanco | |
| Type | monografija | |
| Place | Ljubljana | |
| Publisher | Medicinska fakulteta | |
| Publication year | 1994 | |
| Volume | str. 84 | |
| Language | slo | |
| Abstract | Composite resins are widely used as restorative materials in conservative dentistry and as dental materials in fixed prosthodontic. Their application value is defined by their mechanical properties which depend on the degree of polymerization. In linear polymers the average degree of polymerization is determined by the average length of molecules, whereas in composites where we have solid matrix due to crosslinking of molecules the degree of polymerization can not be defined in the same way. Therefore we used Electron paramagnetic resonance (EPR) and Knoop microhardness test for the evaluation of polymerization. From EPR spectra it can be concluded that the free radical in composite resins is methyl-methacrylate. The radical concentration depends on duration of irradiat on time and light intensity. At longer exposure time free radical concentration increases linear to the 1.5 mm sample thickness. In thicker samples even much longer light exposure do not influence free radical concentration, due to limited penetration of polymerization light. The effect of limited light penetration in radical concentration is similar to the effect observed in surface hardness. We have found out that hardness increases and reaches the maximum value on the second day after irradiation. We also studied qualitative influence of argon laser on composite resins polymerization. The surface microhardness achieved by laser light polymerization is higher than hardness achieved by halogen polymerization light which is used in our everyday clinical practice. The effect of argon laser on polymerization of dental composite resin and its mechanical properties requires further and detailed investigation. | |
| Descriptors | COMPOSITE RESINS ELECTRON SPIN RESONANCE SPECTROSCOPY HARDNESS TESTS POLYMERS BISPHENOL A-GLYCIDYL METHACRYLATE FREE RADICALS LASERS |