ADVANCED ENGINEERING MATERIALS Valiev et al./Nanostructured Titanium for Biomedical Applications One objective of this effort was to design fabricate and implant a nanostructured CP Grade 4 titanium dental post to clinically demonstrate the benefits associated with na- nostructuring outlined previously.Toward this end,a reduced diameter implant post Nanoimplant was designed and fabricated. a b) c This implant sustains the same load as a con- Fig.1.Microstructure of Grade 4 CP Ti:a)the initinl coarse grained rod;b,c)after ECAP TMT (Optical and electron photomicrographs). ventional 3.5 mm-diameter titanium im plant,the former having the added capabili- ty of being used as a pillar in cases of Table 1.Mechanical properties of conventionally processed and nanostructured CP Grade 4 titanium. insufficient thickness of the alveolar bone. The certified system of Timplant manu- State Processing/treatment UTS,MPa YS,MPa Elongation,Reduction Fatigue factured to standard EN ISO 13485:2003 was conditions % Area,% strength at 10cycles used during development of the Nanoim- plant implant.The implants are shown in Conventional Ti 700 530 25 分 340 As received Figure 4,the nanoimplant intraosseal diame- ter 2.4 mm,having a strength equivalent to nTi 1240 1200 12 42 620 ECAP+TMT the conventional of 3.5 mm diameter im- plant. annealed 940 840 16 530 Ti-6AL-4V ELI To date over 250 Nanoimplants have been implanted,most of them as immediate load implants,with all results indicating the excellent primary stability of Nanoimplants 10%elongation to failure)normally seen after rolling or when compared to other implant types [http://www.tim- drawing. plant.cz/e_stomatolog.asp].For example,a 55-year-old male Further room temperature,laboratory air fatigue studies of with edentulous mandible and maxilla was treated by inser- nanostructured and conventional CP titanium were per- tion of conical implants laterally and NanoimplantsR in the formed per ASTME 466-96 at a load ratio R (min/omax)=0.1 narrow anterior part.Primary retention of all implants was and loading frequency of 20 Hz.Table 1 also shows that the very good;on the day of surgery the patient received a com- fatigue strength of nanostructured CP titanium at 105 cycles plete provisional bridge.Post-operation healing at the sur- is almost two times higher than conventional CP titanium gery site occurred without complications,with subsequent at- and exceeds that of the Ti-6Al-4V alloy.12 tachment of a definitive metalloceramic bridge completing Cytocompatibility tests utilizing fibroblast mice cells L929 the treatment. were undertaken to verify the previously reported benefits of Thus,nanostructuring of titanium by SPD processing has nanostructured CP titanium vis a vis conventional coarse made material with significantly superior mechanical perfor- grained CP Ti.This study was performed as described else- mance when compared to conventional CP Grade 4 titanium. where2 with hydrofluoric acid surface etching being per- formed prior to cell exposure.Figure 2 shows the etched con- ventional and nanostructured titanium surfaces,respectively. The differences in surface roughness of these materials are T五 CPTi easily seen,a homogeneous and nanometer-sized roughness being apparent for nanostructured titanium compared with the much coarser structure for etched CP Grade 4 titanium. The cell attachment investigation shows that fibroblast co- lonization of the CP Grade 4 titanium surface dramatically in- creases after nanostructuring,Figure 3.For example,the sur- face cell occupation for conventional CP Ti was 53.0%after 72 hrs in contrast to 87.2%for nanostructured CP Grade 4 (Tab.2).The latter observations also confirm the previous studies,4 showing that cell-adhesion on nanostructured titanium is greater than on conventional CP Grade 4 tita- nium.This result suggests that a high osteointegration rate 300x should be expected with nanostructured CP Grade 4 titanium Fig.2.Surface relief after hydrofluoric acid treatment of nanostructured (left)and Cp when compared to conventional titanium. Grade 4 titanium(right)surfaces. http://www.aem-journal.com 2008 WILEY-VCH Verlag GmbH Co.KGaA,Weinheim ADVANCED ENGINEERING MATERIALS 2008,10,No.810 % elongation to failure) normally seen after rolling or drawing. Further room temperature, laboratory air fatigue studies of nanostructured and conventional CP titanium were per￾formed per ASTM E 466-96 at a load ratio R (rmin/rmax) = 0.1 and loading frequency of 20 Hz. Table 1 also shows that the fatigue strength of nanostructured CP titanium at 106 cycles is almost two times higher than conventional CP titanium and exceeds that of the Ti-6Al-4V alloy.[1,2] Cytocompatibility tests utilizing fibroblast mice cells L929 were undertaken to verify the previously reported benefits of nanostructured CP titanium vis à vis conventional coarse grained CP Ti. This study was performed as described else￾where,[12] with hydrofluoric acid surface etching being per￾formed prior to cell exposure. Figure 2 shows the etched con￾ventional and nanostructured titanium surfaces, respectively. The differences in surface roughness of these materials are easily seen, a homogeneous and nanometer-sized roughness being apparent for nanostructured titanium compared with the much coarser structure for etched CP Grade 4 titanium. The cell attachment investigation shows that fibroblast co￾lonization of the CP Grade 4 titanium surface dramatically in￾creases after nanostructuring, Figure 3. For example, the sur￾face cell occupation for conventional CP Ti was 53.0 % after 72 hrs in contrast to 87.2 % for nanostructured CP Grade 4 (Tab. 2). The latter observations also confirm the previous studies,[9,13,14] showing that cell-adhesion on nanostructured titanium is greater than on conventional CP Grade 4 tita￾nium. This result suggests that a high osteointegration rate should be expected with nanostructured CP Grade 4 titanium when compared to conventional titanium. One objective of this effort was to design, fabricate and implant a nanostructured CP Grade 4 titanium dental post to clinically demonstrate the benefits associated with na￾nostructuring outlined previously. Toward this end, a reduced diameter implant post Nanoimplant® was designed and fabricated. This implant sustains the same load as a con￾ventional 3.5 mm-diameter titanium im￾plant, the former having the added capabili￾ty of being used as a pillar in cases of insufficient thickness of the alveolar bone. The certified system of Timplant® manu￾factured to standard EN ISO 13485:2003 was used during development of the Nanoim￾plant® implant. The implants are shown in Figure 4, the nanoimplant intraosseal diame￾ter 2.4 mm, having a strength equivalent to the conventional of 3.5 mm diameter im￾plant. To date over 250 Nanoimplants® have been implanted, most of them as immediate load implants, with all results indicating the excellent primary stability of Nanoimplants® when compared to other implant types [http://www.tim￾plant.cz/e_stomatolog.asp]. For example, a 55-year-old male with edentulous mandible and maxilla was treated by inser￾tion of conical implants laterally and Nanoimplants® in the narrow anterior part. Primary retention of all implants was very good; on the day of surgery the patient received a com￾plete provisional bridge. Post-operation healing at the sur￾gery site occurred without complications, with subsequent at￾tachment of a definitive metalloceramic bridge completing the treatment. Thus, nanostructuring of titanium by SPD processing has made material with significantly superior mechanical perfor￾mance when compared to conventional CP Grade 4 titanium. Valiev et al./Nanostructured Titanium for Biomedical Applications COMMUNICATIONS 2 http://www.aem-journal.com © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ADVANCED ENGINEERING MATERIALS 2008, 10, No. 8 Fig. 1. Microstructure of Grade 4 CP Ti: a) the initial coarse grained rod; b, c) after ECAP + TMT (Optical and electron photomicrographs). Table 1. Mechanical properties of conventionally processed and nanostructured CP Grade 4 titanium. State Processing/treatment conditions UTS, MPa YS, MPa Elongation, % Reduction Area, % Fatigue strength at 106 cycles 1 Conventional Ti As received 700 530 25 52 340 2 nTi ECAP + TMT 1240 1200 12 42 620 3 annealed Ti-6Al-4V ELI 940 840 16 45 530 Fig. 2. Surface relief after hydrofluoric acid treatment of nanostructured (left) and CP Grade 4 titanium (right) surfaces