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SIMONA CAVALU_Titania vs. ceria addition to alumina / zirconia composites

Titania vs. ceria addition to alumina / zirconia composites: structural aspects and biological tolerance.

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SIMONA CAVALU_Titania vs. ceria addition to alumina / zirconia composites

  1. 1. Titania versus ceria addition to alumina/zirconia composites: structural aspects and biological tolerance Simona Cavalu ProfessorPreclinical Sciences DepartmentFaculty of Medicine and Pharmaceutics University of Oradea ROMANIA
  2. 2. MOTIVATION There is a continuous input from bioengineering for reaching a high level of comfort, improving reliability, finding new applications. This development is also a response to the growing number of patients afflicted with traumatic or non-traumatic conditions: the number of implants is continuously growing, due to the increase in persons suffering of arthritis and joint problems. As the average age of population grows, the need for medical devices to replace damaged or worn tissues increases. As patients have become more and more demanding regarding esthetic and biocompatibility aspects of their dental restorations
  3. 3. MOTIVATION Al2O3 ZrO2 Excellent hardness and wear  Was introduced to overcome the properties. limitations of alumina. Fracture toughness values are  When properly manufactured, lower than those of the metals zirconia has a higher strength, but used in orthopedic surgery. only 50% of alumina’s hardness. Chemical and hydrothermal  Unstable material. The tetragonal stability. phase tends to transform into the monoclinic phase. The addition of It is a brittle material, with low stabilizing materials (Y2O3)during resistance to the propagation manufacture, can control the phase of cracks. transformation of zirconia. Al2O3, ZrO2, TiO2 have been considered as bioinert ceramics since they cannot induce apatite formation in SBF. They do however support bone cell attachment, proliferation and differentiation.
  4. 4. THE IDEAL CERAMIC IS A HIGH PERFORMANCE BIOCOMPOSITE THAT COMBINES THEEXCELLENT MATERIAL PROPERTIES OF ALUMINA IN TERMS OF CHEMICAL STABILITY ANDLOW WEAR AND OF ZIRCONIA WITH ITS SUPERIOR MECHANICAL STRENGTH ANDFRACTURE TOUGHNESS. Alumina/zirconia ceramics were successfully used in total hip/knee arthroplasty in the last decades. For dental application: root canal posts, orthodontic brackets, implant abutments and all- ceramic restaurations.
  5. 5. GOAL An evaluation of the structural and biocompatibility properties of a new zirconia toughened alumina ceramics. The composition of proposed materials for this study: 80Al2O3-20YSZ (vol%) 80Al2O3-20YSZ (vol%) with 5 wt% TiO2 80Al2O3-20YSZ (vol%) with 5 wt% CeO2 prepared by using modern processing technologies – spark plasma sintering.
  6. 6. METHODS Investigation of the structural changes induced by TiO2 (CeO2) addition to Al2O3/ ZrO2 are made by FTIR spectroscopy and X-ray diffraction (XRD) analysis . Scanning Electron Microscopy (SEM) used for microstructure and morphology investigation of the samples. In order to perform in vivo tests, the rabbit model has been applied for biocompatibility evaluation. The model has been accepted as a model for the effects of systemic disease on osseointegration. Histological examination of the tissue is performed to detect any immunological or inflammatory responses. XPS - surface modifications of the proposed alumina/zirconia ceramics upon different fluoride treatments (NaBF4 and SnF2) .
  7. 7. RESULTS- SEM80Al2O3-20YSZ (vol%) 80Al2O3-20YSZ (vol%) with 5 wt% TiO2 80Al2O3-20YSZ (vol%) with 5 wt% CeO2 . Formation of elongated grains of CeAl11O18 due to the reduction of CeO2 Ce2O3 in reaction with Al2O3 at high temperature.
  8. 8. RESULTS: XRD I. Akin& all, Ceramic Int. 37 (2011) 3273- 3280
  9. 9. 1088 x 465RESULTS- FTIR 797 1168 780 515 617 693 648 30 Intensity (a.u.)SPECTROSCOPY 20 Fig. 1 FTIR spectra of (100-x)Al2O3·xZrO2 10 ceramic composites. • Al-O stretching vibration of AlO4 group (tetrahedral) at 1088 , 1168 cm-1, 780/797 cm-1. 0 •Al O6 group (octahedral) at 617/648 cm-1 and 560 485 465 cm-1. 1400 1200 1000 800 600 400 -1 Wavenumber (cm ) 465 648 (100-x)[90Al2O3·10ZrO2]·xTiO2 465 617 x 617 (100-x)[90Al2O3·10ZrO2]·xCeO2 648 x Intensity/ a.u. 5 5 Intensity/ a.u. 3 3 0 0 Al2O3 Al2O3 1200 1000 800 600 400 -1 Wavenumbers (cm ) 1200 1000 800 600 400 -1 Wavenumber (cm )Fig.2 FTIR spectra of Fig. 3 FTIR spectra of (100-(100-x)[90Al2O3·10ZrO2].xTiO2 composites. x)[90Al2O3·10ZrO2].xCeO2 ceramic composites
  10. 10. MACHINED ALUMINA/ZIRCONIA CERAMICS -CYLINDRICAL SHAPE, SUITABLE FOR ANIMALMODEL (RABBIT) Alumina/zirconia ceramics are bioinert materials: once placed in the natural tissue, it has a minimal interaction with the surrounding tissue, generally a fibrous capsule might form around the implants. Surface properties control the amount and quality of cells adhered on the implant and consequently, the tissue growth. Surface treatment techniques: sandblasting, acid-etched, organic (protein) or inorganic (Ca/P) coating.
  11. 11. BIOTOLERANCE - ANIMAL MODEL
  12. 12. HISTOLOGICAL SECTIONS H& E tests osteoblastsA network of woven bony trabecular architecture with cellular infiltration wasobserved.The periosteal regions were completely closed with new blood capillaries aroundthe implant site. No signs of inflammatory reaction such as necrosis or reddeningsuggesting implant rejection were found upon histological examination.
  13. 13. HISTOLOGY: IMPLANT-BONE MARROW CELLSINTERACTIONGoldner’s Trichrome stain: aluminazirconia specimens with ceria addition maycause some problems due to smallvascular congestion occurring concomitantwith the proliferation of the new bone in thecontact area.
  14. 14. HISTOLOGY:IMPLANT- HOSTBONE INTERACTIONGoldner’s Trichrome stain:Thedetails reveals the new boneproliferation and and youngtrabecular bone at the interface andthe periost (d).
  15. 15. IMPROVING THE BIOLOGICAL TOLERANCE The surfaces modifications and post-synthesis treatment also influences the performances of the bioceramics designed to dental and orthopedic applications. In order to improve the biological tolerance of the proposed ceramics, the surface modifications of alumina and alumina/zirconia bioceramics are investigated upon different treatments with sodium tetrafluoroborate and stannous fluoride respectively.
  16. 16. XPS AFTER FLUORIDE TREATMENTBy comparing the results we can notice that both specimens presents a highsensitivity to the SnF2 treatment. The effectiveness of surface treatment is moreevident on the sample with TiO2 addition. Further in vitro tests are required to beperformed in order to establish a correlation between the effectiveness ofsurface treatment in improving the bioactivity of alumina/zirconia composites.
  17. 17. CONCLUSIONS Ceramics with the composition 80Al2O3-20YSZ (vol%) + with 5 wt% TiO2 (CeO2) were prepared by Spark Plasma Sintering. XRD pattern show characteristic peaks of tetragonal zirconia with different intensities. No monoclinic phase was detected. FTIR spectra presents a special behavior with respect to the evolution of the structural units related to Al-O and Zr-O stretching vibrations . SEM images show the details including the size and shape of the alumina and zirconia grains demonstrating that Spark Plasma Sintering makes possible the densification of the composites.
  18. 18. CONCLUSIONS Based on the histological analysis, one can conclude that both specimens (with TiO2 and CeO2) present a satisfactory tolerance toward the host bone. With respect to the bone marrow, we observed that alumina zirconia specimens with ceria addition may cause some problems due to small vascular congestion occurring concomitant with the proliferation of the new bone in the contact area. Fluoride-based treatment is proposed to condition the surfaces improving the bioactivity of alumina/zirconia composites.
  19. 19. THE TEAM: •Prof. dr. Viorica Simon Babes-Bolyai University, Faculty of Physics & Institute of Interdisciplinary Research in Bio-Nano-Sciences, Cluj-Napoca, Romania. •*Assist. prof. Cristian Ratiu , University of Oradea, Faculty of Medicine and Pharmaceutics, Oradea, Romania. *Prof. dr. Gultekin Goller and assist. prof. Ipek Akin, Istanbul Technical University, Materials Science Department. Romania-Turkey Bilateral Cooperation 2011-2012 and CNCS-UEFISCDI project PNII-ID-PCE 2011-3- 0441 contract nr. 237/2011 .

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