Abstract

Zirconia dental implants have become more popular in the field of implant dentistry. However, concerns have been raised regarding low temperature degradation and its influence on phase stability and micro-structural integrity in terms of increased micro-crack formation. In the case of dental implants, this could possibly result in delamination and interference with bone to implant contact and eventually lead to loss of integration and failure. Nevertheless, no study has reported the effects on commercially available Zirconia dental implants. The primary aims of this study was to determine if there is a correlation between ageing duration and 1) depth of tetragonal-monoclinic phase transformation (t-m transformation), 2) micro-crack formation of commercially available Zirconia dental implants. A secondary aim was to compare the depth of t-m transformation, micro-crack formation as the result of ageing between different commercially available Zirconia dental implants. Accelerated aging at increased temperature, moisture and pressure were performed using an autoclave technique to artificially age Zirconia dental implants. There were a total of 36 implants from four companies, three of which were commercially

available. Each group had nine implants, with three samples evaluated prior to aging and three at 15 and 30 hours of aging. Focused ion beam-scanning electron microscopy analysis was performed to determine the microstructural features of the surface and bulk of as-received implants and to investigate the aging effect on microstructural integrity defined by the t-m transformation and formation of micro-cracks on the aged implants. Pre-existing grain transformation around surface porosities and micro-cracks were most evident in types A, B, C and were significantly higher in A compared to C (p ≤ 0.05). No significant differences were found among groups at 15 hours. At 30 hours, the depth of the t-m transformation and quantity of micro-cracks increased for A, C and D and a significantly higher transformation was found for type A compared to type B (p ≤ 0.05). Type B microstructure seemed to be least affected by LTD at 30 hours. A strong correlation between ageing duration and depth of t-m transformation at 15 and 30 hours was found (p ≤ 0.01) for all implants combined. Within the limitations of this study we concluded that aging led to loss in micro-structural integrity described by transformation of grains and increased number of porosities and microcracks for types A, C and D, a finding most apparent at 30 hours. The effect of aging on microstructural integrity is likely more related to composition and structural details of implants, than their surface treatment.

LLU Discipline

Periodontics

Department

Periodontics

School

School of Dentistry

First Advisor

Sahl, Erik

Second Advisor

Lundgren, Tord

Third Advisor

Viecilli, Rodrigo

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2016

Date (Title Page)

6-2016

Language

English

Library of Congress/MESH Subject Headings

Dental Implants;

Subject - Local

Zirconia dental implants; Low-temperature Degradation; Tetragonal-monoclinic phase transformation; micro-crack formation; Accelerated aging

Type

Thesis

Page Count

56

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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