Advanced Materials in Dental and Orthopedic Applications: Session I
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Biomaterials Committee
Program Organizers: Tolou Shokuhfar, University of Illinois at Chicago; Grant Crawford, South Dakota School of Mines and Technology; Terry Lowe, Colorado School of Mines; Luis Rocha, UNESP, Univ. Estadual Paulista, Faculdade de Ciências; Rajendra Kasinath, DePuy Synthes Products, LLC

Monday 8:30 AM
February 27, 2017
Room: Pacific 14
Location: Marriott Marquis Hotel

Session Chair: Holly Martin, Youngstown State University; Terry Lowe, Colorado School of Mines; Tolou Shokuhfar, University of Illinois at Chicago

8:30 AM  Invited
Examining the Long-Term Exposure Effects of Simulated Body Fluid on the Behavior of Chitosan Bonded to Titanium Using Three Biocompatible Solvents: Holly Martin1; Eruj Arif1; Cameron Carroll1; Vincent Pilolli1; Snjezana Balaz2; 1Department of Chemical Engineering, Youngstown State University; 2Department of Physics and Astronomy, Youngstown State University
    Both the prevention of post-operation infections and the osseointegration of implants into the surrounding bone is highly desirable as a way to increase implant life spans. Chitosan, which comes from shrimp shells, is a biopolymer that has both antibacterial and bioactivity behavior. To increase the bond strength of chitosan to titanium, aminopropyltriethoxysilane (APTES) has been deposited using various solvents, including toluene, acetone, ethanol, and heptane. The highest adhesion strength was shown to be due to toluene, with heptane producing slightly lower results. However, toluene is also carcinogenic, so any replacement solvent must produce similar adhesion strengths with lower health risks. The research presented continues the examination of adhesion strengths of these chitosan coatings based on solvent used for deposition, by comparing the exposure to simulated body fluid over an extended period of time. To determine potential health risks, the concentration of any residual solvent will also be assessed.

9:00 AM  
A New Ni-free Beta-Ti Alloy with Large and Stable Room Temperature Super-elasticity: Song Cai1; J Schaffer1; 1Fort Wayne Metals Research Products Corp.
    NiTi alloys have been largely used in medical applications benefited from their large super-elastic properties. However, allergic reactions caused by Ni have been continuously reported in some patients. To solve this, a Ni-free Ti-Hf based beta alloy was recently developed. Its’ mechanical properties and deformation behavior were investigated by cyclic tensile testing and in-situ synchrotron X-ray diffraction. Due to the reversible stress-induced martensite phase transformation, this material was able to fully recover 4% deformation strain after proper heat treatment. A maximum recoverable strain of above 5% can be achieved after 6% deformation strain. In addition, this alloy does not show room temperature aging effect that often observed in other beta Ti alloys with similar super-elastic behavior. Therefore, its mechanical properties are more stable at room temperature, which makes it a very good candidate for medical applications that require large strain recovery and a Ni-free environment.

9:20 AM  
A Novel Strengthening Strategy Using Stacking Faults for Biomedical Co–Cr–Mo Alloys: Kenta Yamanaka1; Manami Mori2; Shigeo Sato3; Akihiko Chiba1; 1Tohoku University; 2National Institute of Technology, Sendai College; 3Ibaraki University
    We recently proposed a novel processing strategy for achieving high-strength biomedical Co–Cr–Mo alloys: multipass “low-strain-per-pass” thermomechanical processing. The objective of this study is to fully understand the relevant strengthening mechanisms. Co–28Cr–6Mo–0.13N (mass%) alloy specimens prepared by multipass hot rolling showed an increase in the dislocation density with an increase in hot-rolling reduction. Furthermore, an advanced X-ray diffraction line-profile analysis based on extended convolutional multiple whole profile fitting (eCMWP) quantitatively revealed for the first time that a dramatic increase in stacking faults occurs during the multipass hot-rolling process and that the contribution of accumulated stacking faults successfully explains the significant increase in the yield stress with greater height reduction of the hot-rolled alloy. These results indicate the possibility of “stacking fault strengthening” and will help in guiding the design/manufacturing strategy for high-strength Co–Cr–Mo alloys for highly durable medical devices.

9:40 AM  
Biomimetic Tooth Repair: Amelogenin-derived Peptides Enable In Vitro and In Vivo Enamel Remineralization: Deniz Yucesoy1; Carolyn Gresswell1; Sanaz Saadat1; Hanson Fong1; Sami Dogan1; Mehmet Sarikaya1; 1University of Washington
    Demineralization of enamel is the earliest clinical sign of dental caries and if left untreated it can progress to clinical caries and other dental ailments. Incorporating a functional mineral layer that can be fully integrated into underlying molecular tooth structure in repairing damaged enamel has been a long-standing challenge. We described a protocol to remineralize enamel both in vitro in extracted human teeth and in vivo in a rat model using designed peptides in a variety of media, including water based solutions, gels and pastes. The amelogenin-derived peptides, ADPs, were designed using biocombinatorial selection via phage display, similarity analysis using bioinformatics, and an iterative binding and mineralization assays to control Ca-P minerals, their morphology and formation kinetics. The principles and procedures laid out here constitute the basis for translation into practical clinical application to address demineralization-related problems both as preventive dental health care as well as therapeutics.

10:00 AM Break

10:20 AM  
Cellular Response of Escherichia Coli to Mg-2Zn-2Gd Alloy with Different Grain Structure: Mechanism of Disruption of Colonization: Pramanshu Trivedi1; K.C. Nune1; R.D.K. Misra1; A.K. Patel2; K. Balani2; R. Jayganthan2; 1University of Texas at El Paso, Texas; 2Indian Institute of Technology
    We describe here, the grain size dependent bactericidal effect of magnesium alloy. In this context, Mg-2Zn-2Gd alloy that was subjected to multiaxial forging (MAF) to obtain different grain size in the range of ~44 µm to ~710 nm. Contact angle measurements using goniometer and wettability were assessed with water, SBF, n-Hexane and DMEM. The antimicrobial activity and the mechanism of inhibition of Escherichia coli (E. coli) bacterial cell attachment were determined as a function of grain size. The higher surface energy of ultrafine-grained Mg-2Zn-2Gd alloy led to the release of more Mg+2 ions at an early stage, which consequently increased the pH of fluid in the vicinity of the implant, therefore producing unfavorable environment for the survival of bacteria. This led to damage of bacterial cell walls and reducing their adhesion. Furthermore, a significant degree of apatite formation was indication of high bioactivity in the ultrafine-grained alloy.

10:40 AM  
Characterization of Chitin Synthesized from Snail Shell: Samson Adeosun1; Oluwashina Gbenebor1; Emmanuel Akpan1; Adebayo Olaleye1; 1University of Lagos
    Thermogravimetric analysis was used to analyze chitin thermal stability present in unprocessed and processed snail shell samples using different concentrations of HCl and NaOH. The result shows that 42% of CaCO3 in the snail shell decomposes between 699-779 0C while decomposition of chitin (2.11%) starts at 275 0C and ends at 335 0C. De-mineralization and de-proteinization of the snail shell using 1.5M HCl and 0.4M NaOH eliminates CaCO3 formation and sample shows existence of 60 % chitin decomposing between 346 and 412 oC. The XRD of virgin snail shell showing the main diffraction face intensity for CaCO3 occurring at 2 = 29.5o with other CaCO3 peaks occur at = 30.2o, 39.3o, 41.0o, 44.2o, 45.9o, 48.9o, 51.5o, 53.1o and 55.6o. Chitin present occurs at reflection 2 = 36.3o with weak intensity and the XRD shows no evidence of CaCO3 but two chitin crystalline peaks at 20.6o and 26.3o with 78 % lowest crystallinity index.

11:00 AM  
Failure Analysis and Fatigue Properties of a New Generation ß-based Ti-Nb Alloy and Cp-4 Titanium Osteosynthesis Plates: André Reck1; Andreas Kaiser2; Stefan Pilz1; Ulrich Thormann2; Volker Alt2; Annett Gebert3; Christian Heiß2; Martina Zimmermann1; 1Dresden University of Technology; 2University Hospital Giessen-Marburg GmbH; 3Leibniz Institute for Solid State and Materials Research Dresden
     A reliable database regarding the fatigue properties of an implant alloy is one key factor for a successful application in the human body. Identification of potential failure causes is consequently very important for a more reliable fatigue life prediction of already existing and new metallic implant materials.Thus, this work focuses on fatigue testing of new metastable binary Ti-Nb-alloys including detailed analysis of the fracture surfaces with SEM, EDX and FIB. Furthermore, broad numbers of in-vivo tested CP-Titanium (ASTM Grade 4) osteosynthesis plates (rat model) were subject to in-depth failure analysis after explantation. Results revealed a complex damage condition where the high notch sensitivity of Ti-based alloys is the major reason for early failure or severe damage in most of the cases. Fatigue data for the new alloy generation is promising provided that the notch influence can be controlled. Funded by the German Research Foundation (DFG) under SFB/Transregio 79.

11:20 AM  
Functionalization of Dental Titanium Implants for Improved Osteointegration: Genevieve Pourroy1; Fabienne Perrin-Schmitt2; Van Quang Le1; Mathilde Giraudel1; Caroline Fischer2; Géraldine Koenig2; Leandro Jacomine3; Luc Behr4; Alain Chalom4; Laurence Fiette4; Alexis Morlet4; Adele Carradò1; 1Université de Strasbourg IPCMS; 2Université de Strasbourg INSERM, UMRS1121; 3Institute Charles Sadron; 4Institut Mutualiste Montsouris
    This study aims to improve the strength and quality of the titanium (Ti)-hydroxyapatite (HA) interface to prevent long-term failure of the implanted devices originating from coating delamination and to test it in an in-vivo model. Thermochemical treatments of the acid-etched dental commercial Ti implants were combined with sol-gel HA coating processes to obtain a nanoporous hydroxyapatite/sodium titanate bilayer. The in vitro results on murine MC3T3-E1 and human SaOs-2 cells confirm the advantage of this coating regarding the capacity of cell growth and differentiation. Functional and histopathological evaluations of the coated Ti implants were performed at 22, 34 and 60 days of implantation in a dog lower mandible model. Osteoconduction and osteointegration mean scores were higher for test implants compared to the controls at 22 and 34 days.

11:40 AM  
Biodegradable Boron Coating for Wound Healing and Bone Regeneration Implants Via; DIMOX, Rheocasting and Thixocasting: Bakr Rabeeh1; Nora Abu Bakr1; 1German University in Cairo, GUC
    Boron-based organic and inorganic materials have gained tremendous interest in recent years. The objective is to provide borate glass composite comprising a porous core material (e.g., aluminum/alumina matrix) which has been coated or impregnated via semi-solid capillary action with an inorganic filler material capable of increase bioactive limitation especially for diabetic patients. The application of thixocasting technique along with direct metal oxidation, DIMOX, and semisolid rheocasting have confirmed. Microstructural and mechanical characterization is established by applying scanning electron microscopy, SEM, energy dispersive X-ray spectroscopy, EDX and 3-point bending testing. The results provide an overview of recent needs in boron-bioactive coating structures that are very effective in implemented applications. Bioactive amorphous and crystalline form of boron-based bioactive coating is intrinsically synthesis for multifunctional hybrid bioactive composite materials.