Traini T, Mangano C, Sammons R L, Mangano F, Macchi A, Piattelli A
Dental School, University of Chieti-Pescara, Chieti, Italy.
Dent Mater. 2008 Nov;24(11):1525-33. doi: 10.1016/j.dental.2008.03.029. Epub 2008 May 27.
This work focuses on a titanium alloy implants incorporating a gradient of porosity, from the inner core to the outer surface, obtained by laser sintering of metal powder. Surface appearance, microstructure, composition, mechanical properties and fractography were evaluated.
All the specimens were prepared by a selective laser sintering procedure using a Ti-6Al-4V alloy powder with a particle size of 1-10 microm. The morphological and chemical analyses were performed by SEM and energy dispersive X-ray spectroscopy. The flexure strength was determined by a three-point bend test using a universal testing machine. The surface roughness was investigated using a confocal scanning laser microscope. The surface roughness variation was statistically evaluated by use of a Chi square test. A p value of <0.05 was considered statistically significant.
The original surface microstructure consisted of roughly spherical particles, diameter range 5-50 microm. After exposure to hydrofluoric acid some of these were removed and the microsphere diameter then ranged from 5.1 microm to 26.8 microm. Following an organic acid treatment, particles were replaced by grooves 14.6-152.5 microm in width and 21.4-102.4 microm depth. The metal core consisted of columnar beta grains with alpha and beta laths within the grains. The alloy was composed of 90.08% Ti, 5.67% Al and 4.25% V. The Young's modulus of the inner core material was 104+/-7.7 GPa; while that of the outer porous material was 77+/-3.5 GPa. The fracture face showed a dimpled appearance typical of ductile fracture.
In conclusion, laser metal sintering proved to be an efficient means of construction of dental implants with a functionally graded material which is better adapted to the elastic properties of the bone. Such implants should minimize stress shielding effects and improve long-term performance.
本研究聚焦于一种通过金属粉末激光烧结获得的、从内芯到外表面具有孔隙率梯度的钛合金植入物。对其表面外观、微观结构、成分、力学性能和断口形貌进行了评估。
所有试样均采用选择性激光烧结工艺制备，使用粒径为1 - 10微米的Ti - 6Al - 4V合金粉末。通过扫描电子显微镜（SEM）和能量色散X射线光谱仪进行形态和化学分析。使用万能试验机通过三点弯曲试验测定弯曲强度。使用共聚焦扫描激光显微镜研究表面粗糙度。通过卡方检验对表面粗糙度变化进行统计学评估。p值<0.05被认为具有统计学意义。
原始表面微观结构由直径范围为5 - 50微米的大致球形颗粒组成。暴露于氢氟酸后，其中一些颗粒被去除，微球直径随后在5.1微米至26.8微米之间。经过有机酸处理后，颗粒被宽度为14.6 - 152.5微米、深度为21.4 - 102.4微米的凹槽所取代。金属芯由柱状β晶粒组成，晶粒内有α和β板条。该合金由90.08%的钛、5.67%的铝和4.25%的钒组成。内芯材料的杨氏模量为104±7.7吉帕；而外多孔材料的杨氏模量为77±3.5吉帕。断口表面呈现出韧性断裂典型的韧窝形貌。
总之，激光金属烧结被证明是构建具有功能梯度材料的牙科植入物的有效方法，这种材料更适合骨骼的弹性特性。此类植入物应能最大限度地减少应力屏蔽效应并改善长期性能。
