Effect Of Led Exposure Time On The Temperature Rise, Depth Of Cure And Microhardness Of Nanohybrid Composite Resin

Abstract

It has been reported that depth of cure of composite resin can be
achieved by prolonged light curing but causing temperature rise that could harm
the pulp and resulted uncomfortable condition to patient. Objectives: To evaluate
the effect of light-emitting-diode (LED) light curing unit on the temperature rise,
depth of cure and microhardness of nanohybrid composite resin. Materials and
Methods: Sixty specimens of nanohybrid composite resin (Tetric N Ceram,
Ivoclar-Vivadent, Lichtenstein) with diameter of 5 mm, thickness of 5 mm were
divided into 3 groups: Group I (n=20) were light-cured for 15 seconds, Group II
(n=20) for 20 seconds, Group III (n=20) for 40 seconds using LED light curing
unit (Hilux/Ledmax, Japan). The temperature rise was measured using digital
thermometer at initial time to the highest temperature peak. The depth of cure was
measured by scraping method. Microhardness was determined using Vickers
Microhardness Tester at each 1 mm depth of the composite resin. Data were
analyzed using Kruskal-Wallis and Mann-Whitney tests. Results: There were
significant differences on temperature rise, depth of cure and hardness of
nanohybrid composite resin at each 1 mm depth after light exposure time of 15,
20, and 40 seconds. The highest depth of cure was achieved after curing for 40
seconds but the highest microhardness was achieved after curing for 20 seconds at
1 mm from the top of specimens. Conclusion: Exposure time of 20 seconds
produced low temperature rise, depth of cure and the highest VHN than the other
exposure time.