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Ⅱ급 와동에서 각종 구치용 수복물의 파절강도에 관한 실험적 연구
조영곤,허승면,이계혁 大韓齒科保存學會 1993 Restorative Dentistry & Endodontics Vol.18 No.2
The purpose of this study was to evaluate the fracture strength of class Ⅱ restored premolars with amalgam, posterior composite, amalgam-Ketac silver, resin-Ketac silver restorations at marginal ridge. Fifty extacted maxillary and mandibular premolar teeth that were caries free, fracture free, and restoration free were selected and randomly divided into five groups : Group 1:10 intact teeth, Group 2:10 teeth with class Ⅱ cavities and restored with, amalgam, Group 3:10 teeth with class Ⅱ cavities and restored with posterior resin, Group 4:10 teeth with class Ⅱ cavities and restored with amalgam-ketac silver, Group 5:10 teeth with class Ⅱ cavities and restored with resin-Katac silver. All teeth were mounted in base of dental stone within metal rings of 2cm diameter, exposing only the crown portion. Class Ⅱ mesio-occlusal or disto-occlusal cavities were prepared into specimens of Group 2 throung 5 by using a No. 710 fissure bur. The occlusal portion was prepared to a faciolingual width of 1.5mm and a pulpal depth of 1.5mm. The proximal protion was prepared to a faciolingual width of 4mm, a occlusogingival height of 4mm, and a gingival floor of 1.5mm. The teeth in Group 2 and 3 were resotored with silver amalgam and posterior resin respectively. In Group 4 and 5, proximal portions were first filled with Ketac silver 1.5mm gingivally and remaining cavities were restored with amalgam and posterior resin respectively. All specimens were stored in 100% relative humidity at 37℃ for 48 hours before testing. All teeth were subjected to a compressive load in a Universal Instron Testing Machine at marginal ridges. The loads required to fracture the restorations were recorded in killograms and the data obtained were subjected to statisticall analysis. The results were all follow: 1. The fracture strength of Group 1 which were unprepared were 100±10.0 kg and the higher values than Group 2, 3, 4, 5 which were prepared and resotred. 2. In restored groups, Group 2 had the higher fracture strength(81.8±12.4 kg) than other groups and Group 4 had the lowest fracture strength(66.8±9.2kg). 3. There were significant differences between fracture strength of between Group 1 and Group 3, 4, 5(P<0.05), but not significant difference between fracture strength of Group 2, 3, 4, 5(P>0.05).