증기압 멸균 소독에 의한 치과용 석고의 물성변화

Abstract

Gypsum products have potential contamination by infectious human pathogens, which could be transmitted from patient to the gypsum model via impression materials. Therefore disinfection and sterilization of gypsum products are recommended. Steam sterilization: namely autoclaving is widely available in dentistry. The aim of this study was to investigate degradation of mechanical properties for dental gypsum after steam sterilization. The effect of autoclaving on compressive strength, weight loss and dimensional accuracy of specimens of commercial die stone such as Crystal Rock(CR : Maruishi), Die Keen(DK : Columbus Dental), Resin Rock(RR : Whip Mix), Tuff Rock(TR : Talladium) were estimated, and experimental gypsums{(EP) : 0.5wt% accelerator, 0.02wt% retarder, 0.1wt% surface agent, 0.1wt% Poly Vinyl Acetate} were also measured the above properties after autoclaving. For each group, five cylindrical(6mm in diameter and 12mm long) specimens made with manufactures water:powder ratio. All specimens were dried in oven until reaching the constant mass. After dried, they were autoclaved at 12 degrees C for 20 minute, dried again. Compressive strength was measured before and after autoclaving using mechanical testing machine at a cross-head speed of 0.5mm/min. The dimensional accuracy was estimated by length change of specimens with digital caliper before and after autoclaving. For statistical analysis, ANOVA Tukeys Studentized Range (HSD) test and T test were used. Compressive strength and weight were decreased in all samples after autoclaving. There is significant difference between CR, DK and RR, TR in after autoclaving(p<0.05). EP exhibited the highest compressive strength after autoclaving. The weight was significantly decreased in all group except RR after autoclaving(p<0.05). The dimensional accuracy was not significantly increased in all group except CR. As this result, we found that resin-containing dental stone is more appropriate for autoclaving in dentistry.