W J Li1, Q Ding1, F S Yuan2, F B Sun3, J Q Zheng2, R Bao4, L Zhang1. 1. Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing 100081, China. 2. Center for Digital Dentistry, Peking University School and Hospital of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health, Beijing 100081, China. 3. School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. 4. School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China.
Abstract
OBJECTIVE: To evaluate the effects of femtosecond laser treated microgrooved surface on microscopic topography, phase transformation, and three-points flexural strength of zirconia, and to provide reference for surface microstructure optimization of zirconia implant. METHODS: According to different surface treatment methods, 57 computer aided design/computer aided manufacture (CAD/CAM) zirconia bars (20.0 mm×4.0 mm×1.4 mm) were evenly divided into three groups: sintered group, no treatment after sintering, taken as control; sandblasted group, sandblasted with 110 μm aluminium oxide (Al2O3) after sintering; microgrooved group, femtosecond laser fabricated microgrooves with 50 μm width, 30 μm depth, and 100 μm pitch. Surface microscopic topography was observed with scanning electron microscope (SEM) and 3D laser microscope. Further, surface roughness in each group and microgroove size were measured. Crystal phase was analyzed with X-ray diffraction. Specimens were subjected to three- points flexural strength test, and Weibull distribution was used to analyze their strength characteristics. RESULTS: SEM showed that sintered surface was flat with clear grain structure; sandblasted surface exihibited bumps and holes with sharp margins and irregular shape; microgrooves were regularly aligned without evident defect, and nano-scale particles were observed on the surface inside of the microgrooves. Ra value of microgrooved group [(9.42±0.28)] μm was significantly higher than that of sandblasted group [(1.04±0.03) μm] and sintered group [(0.60±0.04) μm], and there was statistical difference between sandblasted group and sintered group (P < 0.001). The microgroove size was precise with (49.75±1.24) μm width, (30.85±1.02) μm depth, and (100.58±1.94) μm pitch. Crystal phase analysis showed that monoclinic volume fraction of sandblasted group (18.17%) was much higher than that of sintered group (1.55%), while microgrooved group (2.21%) was similar with sintered group. The flexural strength of sandblasted group (986.22±163.25) MPa had no statistical difference with that of sintered group (946.46±134.15) MPa (P=0.847), but the strength in microgrooved group (547.92±30.89) MPa dropped significantly compared with the other two groups (P < 0.001). Weibull modulus of sintered, sandblasted, microgrooved groups were 7.89, 6.98, and 23.46, respectively. CONCLUSION: Femtosecond laser was able to form micro/nanostructured microgrooves on zirconia surface, which deleteriously affected the flexural strength of zirconia.
OBJECTIVE: To evaluate the effects of femtosecond laser treated microgrooved surface on microscopic topography, phase transformation, and three-points flexural strength of zirconia, and to provide reference for surface microstructure optimization of zirconia implant. METHODS: According to different surface treatment methods, 57 computer aided design/computer aided manufacture (CAD/CAM) zirconia bars (20.0 mm×4.0 mm×1.4 mm) were evenly divided into three groups: sintered group, no treatment after sintering, taken as control; sandblasted group, sandblasted with 110 μm aluminium oxide (Al2O3) after sintering; microgrooved group, femtosecond laser fabricated microgrooves with 50 μm width, 30 μm depth, and 100 μm pitch. Surface microscopic topography was observed with scanning electron microscope (SEM) and 3D laser microscope. Further, surface roughness in each group and microgroove size were measured. Crystal phase was analyzed with X-ray diffraction. Specimens were subjected to three- points flexural strength test, and Weibull distribution was used to analyze their strength characteristics. RESULTS: SEM showed that sintered surface was flat with clear grain structure; sandblasted surface exihibited bumps and holes with sharp margins and irregular shape; microgrooves were regularly aligned without evident defect, and nano-scale particles were observed on the surface inside of the microgrooves. Ra value of microgrooved group [(9.42±0.28)] μm was significantly higher than that of sandblasted group [(1.04±0.03) μm] and sintered group [(0.60±0.04) μm], and there was statistical difference between sandblasted group and sintered group (P < 0.001). The microgroove size was precise with (49.75±1.24) μm width, (30.85±1.02) μm depth, and (100.58±1.94) μm pitch. Crystal phase analysis showed that monoclinic volume fraction of sandblasted group (18.17%) was much higher than that of sintered group (1.55%), while microgrooved group (2.21%) was similar with sintered group. The flexural strength of sandblasted group (986.22±163.25) MPa had no statistical difference with that of sintered group (946.46±134.15) MPa (P=0.847), but the strength in microgrooved group (547.92±30.89) MPa dropped significantly compared with the other two groups (P < 0.001). Weibull modulus of sintered, sandblasted, microgrooved groups were 7.89, 6.98, and 23.46, respectively. CONCLUSION: Femtosecond laser was able to form micro/nanostructured microgrooves on zirconia surface, which deleteriously affected the flexural strength of zirconia.
Authors: Rafael Arcesio Delgado-Ruíz; Gerardo Gomez Moreno; Antonio Aguilar-Salvatierra; Aleksa Markovic; Jose Eduardo Mate-Sánchez; José Luis Calvo-Guirado Journal: Clin Oral Implants Res Date: 2015-03-25 Impact factor: 5.977