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Radiation Backscatter of Zirconia

Leghuel, Hatim A
http://rave.ohiolink.edu/etdc/view?acc_num=osu1377012297

Abstract Details

2013, Master of Science, Ohio State University, Dentistry.
ABSTRACT Introduction: Cancer is still the second cause of death worldwide with head and neck cancer being about 3% of the total number of diagnosed cases. Surgery is still one of the most effective treatment modalities. It often causes debilitating morbidity to the oral-pharyngeal structures. Currently, certain cases are being treated primarily with radiation and/or chemoradiation since the outcomes when compared to surgery are similar. When high-energy radiation (photons) interact with electron-dense materials. Secondary electrons are produced from radiation interaction with materials such as metals, which is termed “Radiation backscatter”. This results in adjacent tissues receiving an additional, unintended dose. And the visual artifacts that caused by them during CT scanning adversely affect the quality of the scan and its diagnostic value. Research has been done in the past to determine the amount of radiation backscatter caused by various dental materials and it was determined that gold and gold alloys causes the most scatter followed by amalgam and titanium respectively. The use of Zirconium has increased significantly in medicine and dentistry during the past forty years. It was first introduced in medical prosthetics in 1969 as an orthopedic hip replacement implants. Currently, Zirconia restorations are a large percentage of the dental marketplace. There has been a great increase in the demand for zirconia-based restorations, both by patients, and dentists. Aggressive marketing programs for more esthetically pleasing restorations have driven this demand. The aim of our study is to compare dose enhancement factor/ backscatter of Zirconia to other commonly used dental materials. Due to the density of Zirconia compared to other previously testes dental materials we hypothesize that there is a decrease in dose enhancement around Zirconia compared to Gold and Amalgam and an increase in dose enhancement when compared to Titanium and Lithium Disilicate. Materials and methods: Two studies were conducted the first one was using Dosimetry (thin window parallel plate electron chamber) to measure the amount of ionizing radiation backscatter or dose enhancement factor at the tissue-material interface from radiation energies of 6MV and 10 MV on 50mmx50mmx2mm samples made of (amalgam, YTZP zirconia, CPT & Lithium Disilicate) with and without stent materials (1,2,3 mm thick) The second experiment aimed at obtaining computerized tomography (CT) images to determine the relative amount of scatter artifacts produced by each of the tested materials and to measure the Hounsfield units of each material tested. Results: The first study showed that the highest Radiation dose enhancement from backscatter of 60% for amalgam, 30% for zirconia, 20% titanium and only 10% for lithium Disilicate was measured at the surface of the material. No difference noticed in the amount measured between the two different radiation energies. When using 2mm stent material all materials produced an insignificant amount of scatter except for amalgam that produced only 10% of increased radiation. While 3mm thickness reduced the backscatter by all tested materials to almost none. Our second study showed a clear advantage of Lithium Disilicate crowns since they produced an insignificant distortion to the CT images in comparison to the extensive CT image distortion caused by metal artifacts produced by Gold, Zirconia and PFM crowns) Discussion Our study result values agreed with previous research done on amalgam and titanium, and knowing the harmful effect of high-energy ionizing radiation on healthy cells and the reduction of the quality of life that accompanies these effects; its more beneficial to use alternative materials like lithium Disilicate to be able to produce clear and usable diagnostic CT images, and to reduce the amount of radiation overdose surrounding metallic restorations. Conclusions 1. Gold, Zirconia and PFM restorations have a deteriorating effect on the quality of CT images due to artifacts produced by scatter from high-density and metallic restorations. Lithium disilicate restorations on the other hand cause minimal artifacts. 2. The greatest increase in backscatter radiation measured in direct contact with the tested materials and found to be: • 60%for amalgam. • 30% for zirconia. • 20% for Titanium. • 10% for Lithium Disilicate. 3. 4. Within the limits of our study No difference noticed in the amount of backscatter radiation measured between the two radiation energies 6MV and 10MV. 4. At a thickness of 2 mm all tested materials produced an insignificant amount of backscatter except for amalgam, which is confined by tooth structure that reduces its backscatter effect.
Robert Seghi (Advisor)
67 p.
Dentistry; Health Care; Health Sciences; Materials Science; Medical Imaging; Physics; Radiation
Cancer, Radiation therapy, Backscatter radiation, Zirconia, Lithium Disilicate, Titanium, Metal artifact, CT scan

Recommended Citations

Citations

  • Leghuel, H. A. (2013). Radiation Backscatter of Zirconia [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1377012297

    APA Style (7th edition)

  • Leghuel, Hatim. Radiation Backscatter of Zirconia. 2013. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1377012297.

    MLA Style (8th edition)

  • Leghuel, Hatim. "Radiation Backscatter of Zirconia." Master's thesis, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1377012297

    Chicago Manual of Style (17th edition)

osu1377012297
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This open access ETD is published by The Ohio State University and OhioLINK.