We describe a real-time holographic technique used to observe dental contraction due to photo-polymerization of dental filling during LED lamp illumination. An off-axis setup was used, with wet in-situ processing of the holographic plate, and consequent recording of interference fringes using CCD camera. Finite elements method was used to calculate internal stress of dental tissue, corresponding to experimentally measured deformation. A technique enables selection of preferred illumination method with reduced polymerization contraction. As a consequence, durability of dental filling might be significantly improved.
tri cal En gi neer ing, Uni ver sity of Bel grade, Bel grade, Ser bia 2 Pub lic Com pany Nu clear Fa cil i ties of Ser bia, Bel grade, Ser bia 3 Di rec tor ate of Mea sures and Pre cious Met als, Bel grade, Serbia 4 Fac ulty of Me chan i cal En gi neer ing, Uni ver sity of Bel grade, Bel grade, Ser bia Sci en tific pa per
The purpose of this research was to investigate the influence of modulated photoactivation on cuspal movement. Eight class II MOD composite restorations were analyzed under various photoactivation protocols in a real-time manner using holographic interferometry. During the first photoactivation protocol, the composite restoration was illuminated for 200 s continuously. In the second protocol, the polymerization lamp was first turned on for 5 s, then turned off for 120 s, and again turned on for a final 195 s. In both protocols, radiant exposure was the same. A significant decrease (p < 0.05) in cuspal deflection was found for two-step irradiation (average value of total cuspal deflection was 5.03 ± 0.62 µm) compared to continuous irradiation (average value of total cuspal deflection was 5.95 ± 0.65 µm). The two-step photoactivation protocol was found preferable, since it resulted in a significantly lower cuspal deflection (11% lower, compared to the continuous illumination).
Polymerization contraction of dental photo-polymer composites induces internal stress, in a tooth cavity. This stress is measured indirectly by, first, holographic determination of tooth deformation, with consequent calculation of stress using finite element method. Real time holographic technique enabled observation of dental deformation in all stages of polymerization. Specially constructed blue-LED light source was used to polymerize photopolymer composite. We have found that polymerization continues even after illumination is over. Consequently, stress is increased, too.
Monitoring of the atmosphere and determination of the types and amounts of pollutants is becoming more important issue in complex and global monitoring of the environment. On the geocomponent and geocomplex level problem of monitoring the environment is attracting the attention of the scientific experts of different profiles (chemists, physicists, geographers, biologists, meteorologists), both in the national and international projects. Because of the general characteristics of the Earth's atmosphere (Dynamically Ballanced Instability DBI) and the potential contribution to climate change solutions air-pollution monitoring has become particularly important field of environmental research. Control of aerosol distribution over Europe is enabled by EARLINET systems (European Aerosol Lidar NETwork). Serbia’s inclusion into these European courses needs development of the device, the standardization of methods and direct activity in determining the type, quantity and location of aerosol. This paper is analyzing the first step in the study of air-pollution, which is consisted of the realization of a functional model of LIDAR remote sensing devices for the large particle pollutants
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