The purpose of this study is to evaluate functionalized multiwalled carbon nanotubes (fMWCNTs) as a potential coating material for dental zirconia from a biological perspective: its effect on cell proliferation, viability, morphology, and the attachment of an osteoblast-like cell. Osteoblast-like (Saos-2) cells were seeded on uncoated and fMWCNT-coated zirconia discs and in culture dishes that served as controls. The seeding density was 104？cells/cm2, and the cells were cultured for 6 days. Cell viability, proliferation and attachment of the Saos-2 cells were studied. The results showed that Saos-2 cells were well attached to both the uncoated and the fMWCNT-coated zirconia discs. Cell viability and proliferation on the fMWCNT-coated zirconia discs were almost the same as for the control discs. Better cell attachment was seen on the fMWCNT-coated than on the uncoated zirconia discs. In conclusion, fMWCNTs seem to be a promising coating material for zirconia-based ceramic surfaces to increase the roughness and thereby enhance the osseointegration of zirconia implants. 1. Introduction During the last few years, the popularity of dental zirconia implants has increased because they are tooth colored, biocompatible and have an osseointegration ability comparable to dental titanium implants [1, 2]. A fractography study by Gahlert et al. (2012) [1], however, indicates that the fracture initiation site of dental zirconia implants is often located to the stress concentration area in the thread; the grooves on the implant surface created by sandblasting often lead to stress concentration due to their notch effect. The purpose of sandblasting is to increase the surface area and roughness of the dental zirconia implant and thus improve osseointegration [3]. Sandblasting can, however, introduce defects on the surfaces of zirconia implant, which will act as potential fracture initiation sites [1]. The survival of dental zirconia implants should, therefore, improve if methods other than sandblasting could be used. In 1991 carbon nanotubes (CNTs) were discovered by Iijima [4]. This material has been shown to have a large surface area, good mechanical strength, ultra-light weight, and excellent chemical and thermal stability [5]. The nanotubes are structures of single or multiple sheets of graphene rolled up to form single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). Since their discovery CNTs have been used in many fields, such as in electrical and mechanical applications and for biological and medical purposes [6]. The lack of solubility
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