The purpose of this study was to evaluate the compensation effect of exposure duration increase to decreased light intensity of visible-light curing unit.
The specimen with 2mm thickness was made of Restorative Z-100T" i (A2 shade, 3M Dental Products, USA) and cured with Optilux"i (Demetron Research Co. U.S.A.).
The light intensity was controlled to 420 mW/cm , 540 MW/cm?, 630 MW/Cm and caring time, also, controlled to 40, 60, 80 seconds.
Cured specimen was stored in a light-proof container for 24 hours to post-irradation v vas completed.
Microhardness of top and bottom surface of specimen were measured to evaluate the depth of cure.
The obtained results were as follows :
1. The microhardness of top and bottom surface of the composite resin specimen was increased significantly as light intensity and exposure time was increased (P<0.01).
2. Light intensity was more correlated with bottom microhardness(r >0.438) than top micro-hardness( 7 _>0.213), and exposure time was more correlated with top microhardness(r >0.424) than bottom microhardness(r >0.335).
3. The regressive equation was obtained in this study as follows H=0.07 x T+0.012 X I+76 ( H : Microhardness(KHN), T : Exposure time, I : Light intensity)
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