지르코니아의 표면거칠기와 굽힘강도와의 상관관계

Abstract

ABSTRACT

Corelation between with Surface Roughness and Flexural Strength of Zirconia Ceramic

Han, Seok-dong, D.D.S. Advisor : Prof. Kang, Dong-Wan , D.D.S., M.S.D., Ph. D. Department of Dentistry, Graduate School of Chosun University

Statement of problem & Purpose: Ceramic is a very important material in the field of esthetic dentistry. Especially, due to the recent increase in the requirement of esthetics, all ceramic crowns of various materials are used Especiallly, zirconia is most frequently used since it shows very high flexural strength through transformation toughening compared to other ceramics. However, ceramic shows generally high brittleness and these materials shows a decrease of strength as the size of surface indentation increases. The purpose of this study is to research the effect of surface roughness changes of zirconia to flexural strength of zirconia. Materials and methods: After complete sintering of yttrium Tetragonal Zirconia Polycrystal(Y-TZP) in 1500℃, it were cut with the size of 25mm in width, 3mm in length and 2mm in height. The specimen in the control group were polished using #1000 diamond mesh. The specimen in the experimental group were classified into 12 groups according to types of surface roughness formed by the #400, #325, #230 and #120 diamond mesh in the vertical, oblique and horizontal direction to each longitudinal axis of the specimen and each group had five specimen. Using surfcorder SE-1700, a surface roughness measuring instrument, surface roughness were measured. Flexural strength was measured using universal testing machine. Result: In the surface roughness formed with the vertical and oblique direction, larger values were shown as the number of diamond mesh decreased(P<0.05). However, no significant difference were shown between the control and group1-a, the group1-a and group2-a, and the group1-b and group2-b. Flexural strength showed no significant difference according to surface roughness(P<0.05). Significant difference was only shown in the control and group2-c. Concluson: No significant relationship between surface roughness and flexural strength was present.