engleski

Efficiency of light curing units in Zagreb, Croatia

Objectives: Intensity of light curing unit (LCU) plays an essential role in achieving good monomer conversion and thus reduces the risk of secondary caries and increases longevity of dental fillings. The intensity of light in LCU is gradually decreasing during time and leads to poor polymerization, which can not be detected clinically. The purpose of this study was to establish whether the intensity of LCU in dental offices in Zagreb satisfies minimum operational requirements, light intensity higher than 300mW/cm2. Methods: The light intensity of 101 LCU in dental offices in Zagreb was measured using Bluephase&reg ; ; ; meter (Ivoclar Vivadent, Shaan, Liechtenstein). Six measurements were taken for each unit, three at the beginning of illumination and the other three at the period 35-40s from the beginning. Data about the type of LCU, manufacturer, age, frequency of use and existence of integrated radiometer were also taken. Results: The average light intensity was 436mW/cm2 and it varied widely, from 0 to 1120mW/cm2. 37% of LCU had light intensity less than 300mW/cm2. 54% of LCU were halogen (mean value 473mW/cm2) and 46% were LED (mean value 366mW/cm2). LCU were in average nine years old. Conclusion: Though the average light intensity of LCU in Zagreb fulfill the general requirements for efficient polymerization of composite-resin materials, the fact that 37% of curing units are insufficient should caution dentists to regularly monitor the condition of their appliances. The light intensity of LED LCU is less than halogen LCU. Due to peak wavelength of LED LCU similar to the excitation wavelength of commonly used photoinitiator camphorquinone and lower heating of composite, higher degree of polymerization and reduced polymerization shrinkage can be expected. This study was supported by grant 065-0352851-0410 of MZOS, Croatia.

light curing unit; light intensity

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