engleski

Influence of LED Intensity on the Temperature Rise in Composite

Objectives: Heat generated during resin polymerization may be influenced by hardening process of the material and by heat of the curing lamp, thus could be damaging to pulpal tissue. The aim of this study was to test if the increase in light intensity of LED LCU influences the temperature rise in composite. Methods: K-type thermocouple with Metex M 3850 D digital multimeter was used for the measurements of temperature rise in Tetric Ceram A2 (Ivoclar Vivadent) composite resin sample cured by different light sources. It was connected to laboratory personal computer using Metex software which enables observation of the temperature increase on the screen. Composite materal was placed in plastic moulds 4x4x4 mm and cured by three LED curing units of different intensities: low intensity - Lux-o-Max (Akeda Dental) of 150 mW/cm2, medium intensity - Flash lite (Discus Dental) of 500 mW/cm2 and high intensity - L.E. Demetron (Kerr) of 800 mW/cm2 and three modes of halogen curing unit Astralis 7 (Ivoclar Vivadent). The thermocouple tip was placed at a depth of 1 mm into the resin composite before illumination and stayed placed for 80 seconds. Results: Under the illumination with low intensity LED LCU the temperature rises from 2.2(1.2) to 6.4(2.2) ; with medium intensity from 4.1(1.1) to 12.0(2.1) and with high intensity from 7.0(1.9) to 17.1(2.3). Illumination with halogen LCU resulted in temperature rise from 4.6(0.8) to 7.0(1.8) for puls mode, 7.2(1.7) to 8.4(2.4) for low intensity mode and from 9.4(1.9) to 14.0(1.5) for high intensity mode. Conclusion: New LED light curing units of high intensity, obligate for optimal and faster polymerization of composites, produce high temperature rise in the sample, thus conflicting the theory of LED as "cold light source". It could be of vital importance in curing of adhesive first composite layer when dentin thickness is reduced.

blue diodes; temperature rise; composite resins

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