Ceramic dental materials, especially alumina (20 %vol)-yttrium stabilized tetragonal zirconia poly crystal (A-Y-TZP20), have been considered as alternatives to metals for endosseous dental implant application. For increasing the bone-to-implant contact as well as the speed of bone formation, a new surface modification can be effective. The aim of this study was to design microgroove patterns by femtosecond laser on A-Y-TZP20 nano-composite disks for endosseous dental implant application. The phase composition and the morphology of the A-Y-TZP20 nano-composite samples were characterized using X-ray diffraction and Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy techniques. Statistical analysis was submitted to Kolmogorov-Smirnov test and Student's t test for independent variables, with a 5 % significance level. EDAX analysis revealed a significant decrease in the relative content of contaminants like carbon (p < 0.05) in laser surface-treated group as compared to non surface-treated group. X-ray diffraction did not show any change in the crystalline structure induced by laser processing. It was concluded that the femtosecond laser is a clean and safe method for surface modification of A-Y-TZP20.

IntroductionTitanium and its alloys as a dental implant have shown a high successful rate.1 Most metals or alloys are prone to corrosion process. Therefore, management and control of corrosion is a crucial point from biological aspects and may not limit to a local problem because the produced particles may migrate to far sites from the implant. Also it is important in terms of biocompatibility.2 So, the inert ceramic materials were suggested as alternatives to metals.3 Zirconia ceramic has been included in dentistry for different applications. In the design of implant, type of material and surface conditions have an impact on reliable osseointegration.5 Also, the degree of roughness is important. The different methods have been used to design the surface roughness.6 Beside effects of micro and nanoscale topography on different cells functions have examined in numerous studies. [7][8][9][10][11][12][13] This result has been explained by good cellular behavior. 7,10,13,14 In vitro and animal studies on zirconia have confirmed good biocompatibility and mechanical strength. 15,16 The osteoblastic response to different surface topographies of zirconia showed the higher cell proliferation in rough surfaces as compared to the smooth surface.17 Therefore the type of modification on morphology and viability L929 on A-Y-TZP20 substrate was evaluated by an invitro method. Methods Deposition of Hydroxyapatite Methods:In study evaluated viability of fibroblast cell following surface treatment. Therefore, viability L929 cells were characterized using MTT assay and scanning electron microscopy. Results:The viability assessment determined significant differences A-Y-TZP20 without surface treatment as compared to laser surface treatment (B), laser surface treatment + hydroxyapatiteyttrium stabilized tetragonal zirconia nanocomposite coat (C) and control. This study demonstrated that L929 cells approximately proliferated and spread on A-Y-TZP20 nanocomposite disk in laser surface treatment(B), Laser surface treatment + hydroxiapatite-yttrium stabilized tetragonal zirconia nanocomposite coat (C) groups similar to control group. Conclusion: Laser surface treatment showed positive effect on the viability of L929 cells.