Bone defects resulting from non-unions, fractures, significant revision joint replacements, tumour resection and osteolysis present a clinical problem. While autografts are considered the gold standard, ubiquitous use of this reparative technique is limited by graft supply and site morbidity. Recent progresses in tissue engineering using stem cells, bone enhancing molecules and gene therapy have provided more hypotheses for bone defect treatment. In vivo assessment to test these hypotheses requires animal models to mimic human conditions. Immunodeficient or nude animals have the advantage of hosting materials from human and other xenographic origins without immuno-intolerance or rejection. A thorough understanding of the biology in nude animals is vital for the further advancement of connective tissue healing and regeneration strategies. Nude mice are excellent xenographic hosts for in- vivo characterisation and provide a reproducible animal source. The immune deficiencies of nude compared to normal animals may however, influence bone healing and need to be addressed. This dissertation (a) investigated potential bone defect models in nude mice and nude rats (b) incorporated the selected bone defect model to evaluate the effect of T cell deficiency and age on bone defect healing in nude animals (c) determined the feasibility of a critical size defect (CSD) in nude mice. A distal-femur-condylar-defect (DFCD) model was successfully performed in nude mice and rats. The model was found to have some advantages as a bone defect model: (1) located at a weight-bearing skeletal site (2) no requirements for an internal or external fixator (3) does not obstruct or limit mobility (4) location is not in close proximity to any major organs such as the brain (5) easy identification of surface anatomy (6) defect size is standardised and reproducible (7) does not require lengthy and complicated surgery and (8) cost effective. This dissertation confirmed that bone healing in nude mice is similar to that of normal immunocompetent mice. Absence of T lymphocytes did not delay or inhibit bone repair. Use of older nude mice did not seem to affect the healing rate, in contrast to older normal mice, which showed delay in bone healing in the initial phase. Establishment of critical sized defects in mice at a weight-bearing location was not feasible due to the robust healing of murine. This dissertation recommends that the DFCD model could be utilized for the assessment of xenogenic materials at early time point.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M. Orth.)--University of Hong Kong. / Includes bibliographical references (leaves 108-133, 174-177).

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 131-154).

Thesis (M.Orth.)--University of Hong Kong. / Includes bibliographical references (leaves 108-133, 174-177). Also available in print.

Thesis (M.Orth.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 229-253). Also available in print.

Thesis (doctoral)--Lund University, 1994. / Added t.p. with thesis statement inserted.

Orientador: Frederico Andrade e Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T01:24:11Z (GMT). No. of bitstreams: 1 Cvijic_Gojko_M.pdf: 808997 bytes, checksum: 9dea6418612a9a36ca0683f628728557 (MD5) Previous issue date: 2009 / Resumo: Varias pesquisas tem mostrado que aumento de energia na superfície e a fabricação do implante na ausência de ar, aumenta a hidrofilia da superfície reduzindo o tempo da osseointegração. O objetivo desse estudo foi a avaliar o tempo de vida útil e o Nível de Reabsorção Óssea (NRO) entre os implantes com superfícies química (SLActive) e fisicamente (SLA) tratadas, instalados em maxilas previamente enxertadas com osso autógeno em bloco, e carregados com coroas unitárias parafusadas. Foram utilizados 17 voluntários e 20 implantes (10 com superfície SLA e 10 com superfície SLActive). Dez semanas após a instalação dos implantes no grupo controle (SLA) e 4 semanas no grupo teste (SLActive), foram iniciados os procedimentos para a confecção das próteses parafusadas. Os pilares foram apertados com força de 35Ncm, 12 semanas após a colocação dos implantes com superfície SLA e após 6 semanas com a superfície SLActive. As radiografias periapicais foram tomadas e avaliadas no ato da colocação dos implantes, no dia de aperto do pilar, e, 1 e 3 meses com a coroa definitiva em função. Foi realizada a comparação do NRO entre dois tipos de superfícies. Dois implantes SLActive foram perdidos durante o aperto dos pilares. Os resultados mostraram que NRO ao redor dos implantes com 3 meses em função foi menor no grupo teste quando comparado com grupo controle. Os implantes com superfície SLActive instalados na maxila, na área tratada com enxerto ósseo em bloco, e carregados com coroas unitárias 6 semanas após a instalação, tiveram menor vida útil quando comparados com implantes com superfície SLA. / Abstract: Many researches have shown that higher energy of dental implants and production in chamber without air, enlarge surface hidrofilicity and reduce osseointegration time. The aim of this study was to evaluate the survival rate and the Level of Bone Resorption (LBR) between the implants with chemically and physically treated surfaces, placed in maxillae previously treated with bone block grafts, and loaded with single screwed crowns. Seventeen patients were treated with 20 implants (10 with SLA and 10 with SLActive surface). Ten weeks after implant placement in control group (SLA) and four weeks in test group (SLActive) we began with prosthodontical treatment. The abutments were tightened with 35Ncm, 12 weeks after placement of implants with SLA surface, and after 6 weeks with SLActive surface. Periapical radiographies were made and evaluated after implant placement, after abutment tightening, 1 and 3 months with crown in function. We have done a comparison of LBR between two surfaces. The results have shown that LBR around the implants in function was smaller in the test group comparing to the control group, while implants with SLActive surfaces placed in maxillae, previously treated with bone block graft, and loaded with single screwed crowns 6 weeks after, have smaller survival rate comparing to SLA implants. / Mestrado / Protese Dental / Mestre em Clínica Odontológica

7 p. / Grafting cucurbits onto rootstocks resistant to diseases and abiotic stresses can be a methodto overcome limited availability of effective pre-plant fumigants or land to rotate and to allowearlier planting. Commonly used rootstocks for cucurbits have resistance to Fusarium (race1&2) as well as cold tolerance, among other favorable traits like increased vigor of the scion. Grafting of cucurbits was developed in Asia primarily to allow production without rotation, because arable land is so limited. In the US, crop rotation schedules for seedless watermelon can be 3 years or longer reducing the amount of watermelon a grower can produce in a season. We have been growing grafted and non-grafted seedless watermelon on the same field/plot for 4 years, with no fumigation or off-season rotation of other crops. During the last 2 years, we planted early (March 1) to determine if grafting could overcome low night temperatures in addition to disease pressures. Treatments included grafted and non-grafted plants, covering with frost protection and non-covered. The results of the last 2 years indicate that grafted plants yielded nearly twice as much as non-grafted plants, suggesting that grafting can be a promising technology for Arizona watermelon producers.