Thesis (M.S.)--University of Michigan, 1995. / Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 1999. / Disk of copy 1 shelved at the back of the text. Includes bibliographical references (leaves 154-159).

Thesis (M. D. S.)--University of Hong Kong, 2002. / Also available in print.

Thesis (Ph.D.)--University of Hong Kong, 2004. / Also available in print.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1989. / Typescript (photocopy). Includes bibliographical references (leaves 52-53).

Thesis (doctoral)--Freie Universität Berlin, 1980.

Thesis (M.D.S.)--University of Hong Kong, 2002.

Made available in DSpace on 2014-06-11T19:35:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-29Bitstream added on 2014-06-13T19:05:07Z : No. of bitstreams: 1 pierri_j_dr_arafo.pdf: 3628153 bytes, checksum: fa1a39047c990b824665426ff4169b19 (MD5) / As próteses cerâmicas sem metal têm sido cada vez mais utilizadas em função das vantagens apresentadas, como biocompatibilidade, resistência à compressão, estabilidade de cor, radiopacidade e baixa condutibilidade térmica e elétrica. O potencial desses materiais em mimetizar os tecidos dentais também tem contribuído para aumentar sua indicação, atendendo a crescente exigência estética dos pacientes. Apesar dessas características favoráveis, percentuais consideráveis de insucesso clínico têm sido observados, demonstrando que as propriedades mecânicas dos materiais utilizados ainda precisam ser melhoradas. Uma alternativa ainda pouco explorada na odontologia é a utilização de inclusões nanométricas como reforço em matriz também cerâmica, obtendo-se os nanocompósitos cerâmicos. Assim, o objetivo do presente estudo foi avaliar as propriedades de dureza, tenacidade e limite de resistência à fadiga flexural de nanocompósito denso de matriz de alumina com inclusões nanométricas de zircônia, visando sua aplicação em infraestruturas de próteses odontológicas livres de metal. As amostras foram produzidas seguindo metodologia estabelecida em estudos anteriores, que consiste nas seguintes etapas: 1) mistura das matérias primas por meio de desaglomeração da alumina pura e da ZrO2 nanométrica em moinho de bolas convencional; 2) adição da suspensão contendo as partículas nanométricas com a alumina por gotejamento contínuo da suspensão alcóolica de ZrO2 e mistura em moinho de bolas convencional; 3) secagem dos pós no interior do moinho de bolas, sob agitação, em temperatura próxima da ambiente, com auxílio de fluxo de ar perpendicular à abertura do frasco de moagem; 4) preparo das amostras com a mistura obtida, aplicando-se prensagem uniaxial (50 MPa), seguida de prensagem isostática... / Metal free prosthesis became popular because of the advantages presented by the ceramic materials, such as biocompatibility, compressive strength, color stability, radiopacity and low thermal and electrical conductivity. The potential of these materials to mimic the dental tissues and the patient’s demand for aesthetic treatments have also contributed to their increased popularity. Despite these favorable characteristics, considerable percentage of clinical failure has been observed, demonstrating that their mechanical properties still need improvements. An alternative yet little explored in dentistry is the use of nanometric inclusions as reinforcement, resulting in ceramic nanocomposites. Thus, the objective of this study was to evaluate the hardness, toughness and flexural fatigue properties of a nanocomposite comprised of alumina matrix reinforced with nano-inclusions of zirconia, expected to be used as infrastructure for metal-free prosthesis. The samples were produced following the method established in a previous study, which consists of the following steps: 1) mixture of pure alumina and nano-ZrO2 powders in conventional ball mill, 2) addition of the suspension containing the particles with nanometric alumina suspension by continuous drip of ZrO2 and mixing in conventional ball mill, 3) drying the powder inside the ball mill, stirred at ambient temperature, with the aid of air flow perpendicular to the opening of the bottle crushing; 4) sample preparation applying a uniaxial (50 MPa), followed by isostatic pressing (200 MPa). The samples were made in prismatic form (25 X 5 X 2 mm) for flexural fatigue test (n = 30) and disc-shaped (chips) with 10 mm diameter and 5 mm thickness for testing toughness and hardness (n = 10); 5) removal of organic components added during the preparation of powders and... (Complete abstract click electronic access below)

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Dental Technology in the Faculty of Health and Wellness Sciences at the Cape Peninsula University of Technology 2014 / A pure nylon denture base does not bond chemically to the acrylic teeth processed into the denture. A mechanical bond is created by boring retention holes (diatorics) into the tooth structure. Concerns are that this form of retention might be insufficient. The purpose of this study is, firstly, to compare the retention of acrylic denture teeth in pure nylon dentures with that of teeth in conventional acrylic denture bases (the acrylic test pieces serving as the control standard), and secondly, to explore whether the technique prescribed for creating diatorics in acrylic teeth for use with pure nylon denture bases potentially has a weakening effect on the acrylic tooth structure. Two sets of 26 identical anterior one-tooth test pieces were created. The first set, labelled N, comprises two different pure nylon denture base materials labelled N1 and N2 – all have diatorics in the acrylic teeth. The second set, labelled A, comprised the same acrylic denture base. The set labelled A1 is the control standard without diatorics in the acrylic teeth and the set labelled A2 has diatorics within the acrylic teeth. A compressive load was applied to these test pieces at an angle of 45 degrees on the palatal surface of the tooth until fracture occurred or maximum load was reached. Resulting data from the first part of the research was analysed by One-Way ANOVA analysis. Resulting data for the second part of the research was analysed via the Chi-square cross- tabulation method. The One-Way ANOVA test revealed that there is no statistical difference in the mean fracture or maximum load in Newton values between the two A (acrylic denture base) groups. There is also no statistical difference in the mean fracture or maximum load in Newton values between the two N (pure nylon denture base) groups. There is, however, a statistically significant difference in the mean fracture or maximum load in Newton values of Group A in comparison to Group N. The Chi-square cross-tabulation indicated that the A groups have very similar breakage patterns, and the N groups have similar breakage patterns respectively. It is concluded that the mechanical retention of acrylic denture teeth in pure nylon denture bases is weaker than the mechanical and chemical retention of acrylic denture teeth in acrylic denture bases. It is also concluded that when diatorics are created as prescribed within the tooth, these do not weaken the tooth structure.

Magister Scientiae Dentium - MSc(Dent) / Both light-cured (LC) and chemically-cured (CC) acrylic resin custom tray materials are used at the Oral Health Centre, Faculty of Dentistry, University of the Western Cape. At present, the CC acrylic is the standard for formal undergraduate teaching and training. The LC material is not part of routine didactic teaching as little evidence-based scientific information is available with regards to its properties and its usage in the clinical environment. Negative effects have caused researchers to focus on alternatives and to research for other materials with more advantageous properties. The objectives of this study was to determine the linear dimensional shrinkage and fracture toughness of light-cured acrylic custom tray materials and compare it to the chemically-cured type. Also to evaluate the acceptance of light-cured acrylic resin custom trays by undergraduate students. / South Africa