Purpose : The purpose of this study was to compare the surface characteristics of TiAlN, ZrN, and DLC coated milling tools and to compare the marginal fit of zirconia cores manufactured by coated milling tools.

Material and Methods : TiAlN, ZrN, and DLC coated tools were analyzed by field-emission scanning electron microscopy, X-ray diffractometer, surface roughness tester, vickers hardness tester, adhesion strength tester, and wear resistance tester to evaluate the surface characteristics and cutting performance. Measured values was analyzed through the use of Kruskal-Wallis H test and Bonfferoni post-hoc analysis. To evaluate the marginal gap according to the change in cutting efficiency after a certain use of the milling tool, each of 10 zirconia cores were manufactured using coated milling tools. The marginal gap were determined and measured using silicone replica technique. For accurate measurement, digital microscope and Image J program were used. ANOVA, Kruskal-Wallis H test and Scheffe, Bonfferoni post-hoc analysis were performed for the statistics analysis.


Results : The size of the coating particles was large in the order of TiAlN > ZrN > DLC, and the density of the coating particles was high in the order TiAlN > ZrN > DLC. The surface roughness and hardness values of coated tools were also high in the order of TiAlN > ZrN > DLC. ZrN coating showed the best for the adhesion strength, and DLC coating showed the best for the wear resistance. The mean marginal fit of zirconia cores were 25.32 ㎛ in ZrN, 27.90 ㎛ in DLC, and 37.70 ㎛ in TiAlN. The marginal gap of three types coated tools were lower than that of non-coated tool(56.90 ㎛). There was significant statistically difference between coated and non-coated tools(p<.01).

Conclusions : Zirconia cores of all groups showed the clinical acceptable marginal gap of within 120 ㎛. It is expected that the coating of the milling tool make increase the tool life and there will be an effect of increasing the marginal fit when used for a long time.