4 종의 발광반도체 광중합기로 중합한 콤포짓트 레진의 누프경도 비교

Abstract

This study was to evaluate Knoop Hardness of a microhybrid composite polymerized by four kinds of light emitting diode(LED) curing lights and 3M ESPE Quartz Tungsten Halogen(QTH) curing unit as control group. EliparTM FreeLight 2(3M ESPE Co., USA), L.E.Demetron I(Kerr), Allegro(Denmat), Ultra-Lume LED 5(Ultradent) were used to polymerize Filtek Supreme 2(3M ESPE) composite resin. A stainless steel split mold with a cylindrical cavity 4 ㎜ in diameter and 4 ㎜ in depth was used. Composite resin was filled into this mold, covered with Mylar strip, and evened with a glass plate. The composite resin was irradiated for 10 seconds with each light guide tip. Five specimens were made for each light curing unit and Knoop hardness of specimens were measured at the top surface and then section specimens from top to bottom along the central axis. Knoop hardness was measured at 0.5mm intervals from the irradiated surface to the bottom of each specimen with a micro hardness tester(HMV-1, Shimadzu Co., Japan) using 100g load and a dwell time of 10 seconds. Three measurements were taken at 0, 2, 4 ㎜, and the average was calculated. Knoop hardness number(KHN) results were compared and analysed using ANOVA Student t-test(p<0.05). The results obtained were as follow: 1. Knoop hardness did not decrease significantly for all LED LCUs when curing depth is less than 2 ㎜(p>0.05). 2. Knoop hardness decreased noticeably when curing depth is 4 ㎜(p<0.05). 3. The top surface hardness of Filtek Supreme 2 is higher than those of Filtek Supreme 2 cured by L.E.Demetron and Elipar FreeLight. 4. The curing efficiency of the curing lights showed following descending order of UltraLume 5, L.E.Demetron I, Rembrandt Allegro, EliparTM FreeLight 2, 3M Curing Light 2500. In conclusion, LED curing lights with higher intensity output power significantly improve the Knoop hardness of microhybrid composite resin at the same curing time compare to QTH as control and Knoop hardness decreased significantly with the increase of curing depth.