Boston University Libraries OpenBU
    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    •   OpenBU
    • Goldman School of Dental Medicine
    • GSDM: Historical Theses and Dissertations (BU access only)
    • View Item
    •   OpenBU
    • Goldman School of Dental Medicine
    • GSDM: Historical Theses and Dissertations (BU access only)
    • View Item

    Effect of nano-ceramic fibers on fracture toughness of In-Ceram Alumnina ceramics

    Thumbnail
    Date Issued
    2007
    Author(s)
    Bahanshal, Mohammed
    Share to FacebookShare to TwitterShare by Email
    Export Citation
    Download to BibTex
    Download to EndNote/RefMan (RIS)
    Metadata
    Show full item record
    Permanent Link
    https://hdl.handle.net/2144/38822
    Abstract
    Dental ceramics are attractive materials because of their natural appearance, durable chemical properties, optical properties and biocompatibility. However, brittleness and low tensile strength represent a major weakness of some dental ceramic materials. Interpenetrating phase ceramics were developed to provide sufficient strength and toughness for use as all-ceramic fixed partial dental prostheses (FPDPs) and posterior crowns. In-Ceram Alumina ceramics (Vita Zahnfabrik, Bad Sackingen, Germany) was the first member of this class of dental ceramics. The material has favorable esthetics and strength, combined with a successful clinical history. However, this material possesses insufficient mechanical properties for use as a substructure for posterior 3-unit FPDPs. Objectives 1 -To reinforce In-Ceram Alumina ceramic material by adding alumina nano-fibers in an attempt to inhibit crack propagation. 2-To measure the fracture toughness of the reinforced material by using the single-edge-notched-beam technique. Materials and Methods: In-Ceram Alumina blocks (VITA In-Ceram Alumina BA-28) were cut to form bars with the following dimensions: 2 mm x 4mm x 28 mm. A mixture of alumin nano-ceramic fibers (Angonide, Sanford, USA) and In-Ceram Alumiina powder (Vita Zahnfabrik) was applied between 2 alumina In-Ceram bars joining the 2 bars to form a thick bar having, between the 2 bars, a layer of alumina powder with nano-fibers. A total of 120 bar specimens were subdivided into 2 groups according to sintering temperatures, 1120 degrees C and 1350 degrees C. Then, each group was subdivided into 6 sub-groups, a control group (n=10) and 5 test groups (according to the group’s fiber content of 5 %, 10 %, 20%, 30 % and 40 % weight %).A notch, 0.4 mm wide and 0.3 to 0.4 mm in depth, was created on 1 side ; then glass infiltration was performed according to the manufacturer's recommendation. The specimens were loaded in a 3-point bending fixture by using a universal testing machine (Model # 4202; Instron Corp, Canton, Mass.) with a 10-kN load cell at 0.5-mm/min cross-head speed. Bars were placed so that the notch was in maximal tension. Fracture toughness was then calculated according to the following equation: KIc = [3 LPa^5 /2 bw^2] x/(a/w) Where (P) is the fracture load in a 3-point bending test, (L) is the span tested, (a) is the depth of the notch, (b) is the width of the specimen, (w) is the height of the specimen, and / (a/w) is an extended series which provides the geometric correction of the single-edge-notched-beam technique, 3 –point bend specimens. Results: The fracture toughness of the In-Ceram Alumina ceramics sintered at 1120 degree C increased significantly when 5 %, 10 %, and 20 % nano-fiber content was added. The fracture toughness values were 4.69 MPa[nu]m, 5.21 MPa[nu]m, 4.635 MPa[nu]m respectively compared with the control group, which was 3.73 MPa[nu]m. Increasing the fiber content to 30 % or 40 % did not significantly increase the fracture toughness compared to the control group. When a sintering temperature of 1350 degrees C was used, the addition of nanofibers, in any concentration, did not significantly improve the fracture toughness of In-Ceram Alumina ceramics. Conclusion: Adding 5, 10 or 20 weight % of nano-fibers to In-Ceram Alumina powder, sintered at 1120 degree C , significantly increased fracture toughness values (P = 0.004), (P[less than] 0.001), (P = 0.008) respectively.
    Description
    PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.
     
    Thesis (MSD)--Boston University, Goldman School of Dental Medicine, 2007 (Dept. of Restorative Sciences and Biomaterials; Division of Postdoctoral Prosthodontics).
     
    Includes bibliographical references: leaves 56-57.
     
    Rights
    This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.
    Collections
    • GSDM: Historical Theses and Dissertations (BU access only) [657]


    Boston University
    Contact Us | Send Feedback | Help
     

     

    Browse

    All of OpenBUCommunities & CollectionsIssue DateAuthorsTitlesSubjectsThis CollectionIssue DateAuthorsTitlesSubjects

    Deposit Materials

    LoginNon-BU Registration

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Boston University
    Contact Us | Send Feedback | Help