치아 경조직을 통해 중합된 콤포짓트 레진의 누프경도와 중합심도

Abstract

Light curing units(LCUs) are used for the polymerization of dental composites. Recent trends in light curing technology include replacing the halogen LCUs with LCUs using light emitting diodes(LEDs) to reduce curing times and to vary the LCUs light output within a curing cycle. This study was to investigate the time dependence of the Knoop hardness and depth of cure dental composites with LED (Elipar Freelight 2, 3M ESPE Co., USA) and QTH LCUs(Visilux 2, 3M ESPE Co., USA). Two dental composites(Filtek Z250, Filtek Supreme) and a compomer(Compoglass F) were selected. The curing depth was measured using a digital micrometer(Mitutoyo, Japan) for irradiance periods of 20 and 40s. Knoop hardness values were performed on composite discs by direct irradiation and indirect irradiation through dental hard tissue(2 mm enamel-dentin in thickness) using microhardness (Shimadzu Type-M microhardness tester, Shimadzu Ltd, Kyoto, Japan). The results obtained were as follows: 1. It was concluded that the Curing depth of composites decreased when the light was directed through a dental hard tissue. Significant differences among the groups were observed as follows : Control ＞ Group 3(2 mm)＞ Group 1(Primary)＞ Group 2(Permanent) p＜0.05). 2. The curing depth was the lowest in the group 2 using Visilux 2(p＜0.05). 3. The values of Knoop hardness were higher in order of control group, group 3, group 1, and group 2(p＜0.05). 4. The values of Knoop hardness on the surface were higher significantly than those of at below 2 mm regardless of types of light curing unit(p＜0.05). In conclusion , there was a proportional relationship between curing depth and values of Knoop hardness and permanent teeth decreased the curing depth(transmission of light) more than primary teeth.