ImpaCT Of SURfaCe ROUghNeSS ON flexURal STReNgTh aND fRaCTURe TOUghNeSS Of IN-CeRam ZIRCONIa

. AbstrAct Objective. In clinical practice, core material can be exposed after adjustments, which may result in loss of ceramic glaze. The objective of this study is to evaluate the effect of surface roughness on the flexural strength and fracture toughness of In-Ceram zirconia core material. Materials and methods. Forty In-Ceram zirconia specimens were prepared and divided into two main groups (n=20) according to the type of mechanical test. Group 1, for flexural strength test and Group 2, for fracture toughness test. Each group was further subdivided into two subgroups (n=10) according to type of surface treatment. Subgroup A, glazed while subgroup B, finished and polished. Qualitative evaluation of two representative specimens of each subgroup has been done with the assessment of SEM. The flexural strength and the fracture toughness tests were determined. Statistical significant among groups was analyzed using Mann-Whitney test and Kendall’s tau test. Results. Glazed subgroups had the smoothest surface, while the finished and polishing subgroups had the coarsest. Glazed subgroups demonstrated significantly the higher mean flexural strength values (385.38±45.42) and the higher fracture toughness values (6.07±1.00). Conclusion. Surface roughness has adversely affected the flexural strength and the fracture toughness of In-Ceram zirconia.