Thesis (M.D.S.)--University of Adelaide, Dental School, 2001. / Includes bibliographical references (leaves 68-76).

Made available in DSpace on 2014-06-11T19:31:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2004Bitstream added on 2014-06-13T20:41:20Z : No. of bitstreams: 1 sousa_ha_dr_araca.pdf: 1664411 bytes, checksum: 8fb8470dab0600cadc30a00a2b17662b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Not available.

Made available in DSpace on 2014-06-11T19:24:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-12Bitstream added on 2014-06-13T20:31:51Z : No. of bitstreams: 1 silva_gf_me_arafo.pdf: 11965708 bytes, checksum: 569274cdbc2fa1d75e754bdc37d497c5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O sucesso do tratamento de dentes com perfurações de furca está diretamente relacionado ao tipo de material utilizado no preenchimento destas perfurações. Um material selador ideal deve possuir boas propriedades físicas, químicas e biológicas, sendo, o Mineral Trióxido Agregado (MTA) um dos materiais indicados. Assim, o objetivo desse estudo foi avaliar a resposta biológica de três materiais seladores: MTA-Angelus branco® (MTA), Endo-C.P.M.-Sealer® (CPM) e cimento de óxido de zinco e eugenol (OZE). Para isso, foram utilizados os primeiros molares superiores de 60 ratos; o primeiro molar superior do lado esquerdo hígido foi utilizado como controle e o do lado direito foi realizada a perfuração no assoalho da câmara pulpar com uma fresa nº ¼. Os materiais foram manipulados e inseridos na perfuração e a cavidade de acesso foi selada com ionômero de vidro. Decorrido os períodos de 07, 15, 30 e 60 dias, os animais foram sacrificados e os fragmentos das maxilas removidos e fixados em formaldeído. Após a descalcificação em EDTA, os fragmentos de maxila foram desidratados, diafanizados e incluídos em parafina. Os cortes foram corados com hematoxilina & eosina (H&E), tricrômico de Masson ou submetidos ao método do TRAP (“Tartrate Resistant Acid Phosphatase”) para realização das análises morfológica e morfométrica. A análise morfométrica foi realizada sob três parâmetros: espessura do ligamento periodontal (LP), número de células inflamatórias/mm2 (CI) e número de osteoclastos TRAP-positivos. Os resultados morfométricos revelaram aumento significante (p_0,05) no espaço do LP,em todos os períodos, em relação ao controle. Entretanto, aos 60 dias, este espaço foi menor em todos os grupos experimentais; o OZE foi o que provocou maior espessamento do LP, não havendo diferenças significantes... / The therapy success in the treatment of root perforations depends on the material used to fill them. The best sealing material should present good physical, chemical and biological properties. More recently, the mineral trioxide aggregate (MTA) has been indicated for sealing of root perforations. Thus, the aim of the present study was to evaluate the biological response of three sealing materials: White MTA-Angelus (MTA), Endo- C.P.M.-Sealer (CPM) and zinc-oxide and eugenol cement (OZE). Sixty adult rats weighing 250g were divided into three groups: MTA, CPM and OZE. Furcal perforations were performed in maxillary first molars with a round bur no. ¼; the contra-lateral maxillary first molars – without perforations - were used as control. The perforations were carried out and the materials were placed into these defects; access cavities were sealed with glass ionomer. After 07, 15, 30 and 60 days, the animals were killed, and fragments of maxilla containing first molars were removed and immediately immersed in 4% formaldehyde. After decalcification in EDTA, the specimens were processed and embedded in paraffin. Sections were stained with hematoxylin-eosin, Masson’s trichrome and submitted to TRAP (Tartrate Resistant Acid Phosphatase) reaction. The morphometric analysis, in the furcation region of the periodontal ligament, was performed considering three parameters: thickness of periodontal ligament (PL), number of inflammatory cells (IC) and number of TRAP-positive osteoclasts in the alveolar bone surface. The experimental groups showed, in all periods, significant increase (p_0.05) in the PL thickness in comparison to control group; this thickness was more accentuated in the OZE group. The periodontal space in the CPM group was less thick in all experimental periods in comparison to MTA and OZE groups, except in the period of 60 days; in this period, statistical differences in the periodontal space were not detected between CPM and MTA groups.

Orientador: Antonio Cesar Perri de Carvalho / Resumo: Não disponível. / Abstract: Not available. / Doutor

Indiana University-Purdue University Indianapolis (IUPUI) / It has been proposed that jaw deformation during function may be a contributor to supraosseous tooth eruption. This could be through a transient pressure gradient in the flexed bone and/or tension in the PDL fibers produced by socket deformation. Thus, the purpose of this study was to determine if forces applied to a fresh frozen canine mandible can lead to occlusal displacement of a tooth. Seven hemisected canine mandibles (14 specimens) were used to test this hypothesis. A force cycle (10 N to 100 N to 300 N) was applied by a Bionix testing machine (MTS TM Systems Corp., Minneapolis, Minn.) to the mandible in three point bending. Digital radiographs were taken at each change in force level using computer digitized radiography (CDR, TM Schick Technologies, Inc., Long Island City, N.Y.). By measuring the relative movement of metal markers (1 mm steel balls) placed into the mandible and the crown of the 2nd premolar, the amount of tooth eruption was calculated. With cyanoacrylate cement (Archer® Instant Bonding Adhesive, Tandy Corp, Ft. Worth, Texas) injected into the PDL space of the same tooth, the test was repeated one week later. These "ankylosed" teeth served as controls. The eruption distances were compared between the experimental and the ankylosed teeth by means of repeated measures analysis of variance. The only significant occlusal displacement was noted as the force was initially raised to 100 N (21.7 ± 40.6 μm). Due to the possible breakdown of the cyanoacrylate cement, the ankylosed teeth also showed evidence of eruption with the continued application of force. Although significant eruption was noted, the displacements were very small. PDL degradation, viscoelastic behavior, measurement of small displacements, limited resolution radiography, and two dimensional analysis are contributing factors to the uncertainty of the results. Further investigation is required to determine if jaw deformation during function is a viable mechanism leading to the occlusal displacement of teeth.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Orthodontics research investigates the methods in which tooth displacement may be directed in the tooth-periodontal ligament-bone-complex. In the biological environment, the periodontal ligament is the soft tissue responsible for the absorption of forces on teeth and has a direct connection to tooth mobility. Current research is limited in that it must be conducted in an in-vivo capacity. A major advancement in orthodontics research would be a testing method that allows for the development and analysis of orthodontic devices without a patient present. This study outlines the development and testing methods for the validation of an artificial periodontal ligament to be used in conjunction with an artificial-tooth-periodontal ligament-bone-complex. The study focused on finding the criteria in which consistent results were produced, the mixture that best simulated the human periodontal ligament’s mechanical behavior, and the robustness of the artificial-periodontal ligament-bone-complex. This study utilized a geometrically accurate denture mold filled with varying compositions of an artificial periodontal ligament for testing. Experiments focused on findings of viscoelasticity, curing times, and instantaneous responses of the teeth under direct orthodontic loading, as well as the changes in response from different teeth within the denture mold. Tests confirmed that a mixture composed of 50\% Gasket Sealant No. 2 and 50\% RTV 587 Silicone produced a substance that could adequately serve as an artificial periodontal ligament.

A obturação do canal radicular é uma etapa fundamental para o sucesso do tratamento endodôntico. É desejável que os materiais empregados nesta fase não interferiram negativamente com o reparo tecidual, mas preferencialmente estimulem a regeneração dos tecidos periapicais. Recentemente, cones de guta-percha combinados com material biocerâmico foram desenvolvidos com esta finalidade. Sendo assim, o objetivo deste estudo foi investigar o potencial citotóxico e biomodulador de cones de guta-percha convencionais, de cones de guta-percha contendo biocerâmica e de cones de polímero sobre células de ligamento periodontal in vitro. Cultura de fibroblastos de ligamento periodontal foi estabelecida a partir de terceiro molar humano. As células foram estimuladas com extratos de cones de guta-percha convencional, de cones de guta-percha contendo biocerâmica e de cones de polímero em diluição seriada para teste de viabilidade celular por meio do método MTT (Brometo de Difeniltetrazólio 3-(4,5-Dimetiltiazol-2-yl) após 72 h. Em seguida, a diluição de 1/5 foi empregada para estimulação das células por 72 h para detecção da expressão gênica de colágeno tipo I e proteína cementária 1 (CEMP-1) por RT-qPCR. Os dados foram estatisticamente analizados por meio de ANOVA sendo considerados significativos valores de p < 0,05. Os resultados observados de forma que, em extrato puro em extrato puro 1:1, houve comprometimento da viabilidade celular tanto para o extrato de cone de guta-percha quanto para o extrato do cone Cpoint podendo ser considerados citotóxicos. Nas outras diluições não houve diferença significativa neste parâmetro. Em relação à expressão gênica de colágeno, não foram observadas diferenças significativas quando da presença dos extratos. Para CEMP-1, significativa indução da expressão gênica foi observada para o cone de guta-percha. Conclui-se, através da análise dos resultados, que o cone de guta-percha e o cone de polímero são os mais citotóxicos em extrato puro, porém a guta-percha foi o único material que induziu uma expressão significativa de CEMP-1 que auxilia no reparo tecidual. O Col1 não foi induzido em nenhuma das amostras, porém também não foi inibido que indica que nenhum dos 3 tipos de cone interfere no reparo tecidual. / Root canal obturation is a fundamental step for successful endodontic treatment. It is desirable that the materials employed at this stage did not adversely interfere with tissue repair but rather stimulate the regeneration of the periapical tissues. Recently, gutta-percha points combined with bioceramic materials were developed for this purpose. Thus, the objective of this study was to investigate the cytotoxic and biomodulatory potential of conventional gutta-percha points, gutta-percha points containing bioceramics and polymer points on periodontal ligament cells in vitro. Culture of periodontal ligament fibroblasts was established from one human third molar. The cells were stimulated with extracts of cones of conventional gutta-percha points, gutta-percha containing bioceramics and polymer points in serial dilution for cell viability test using the MTT assay [Diphenyltetrazolium Bromide 3- (4,5)]. Next, the 1/5 dilution was used to stimulate the cells for 72 h to detect the gene expression of type I collagen and cement protein 1 (CEMP-1) by RT-qPCR. Data were statistically analyzed by means of ANOVA being considered significant values of p <0.05. The results observed was that in a pure 1: 1 extract, there was impairment of cell viability for both the guta-percha cone extract and the Cpoint cone extract and could be considered cytotoxic. At the other dilutions, no significant difference on this parameter was observed. Regarding the gene expression of collagen, no significant differences were observed at the presence of extracts. For CEMP-1, significant induction of gene expression was observed for gutta-percha points. In conclusion, the analysis of the results showed that the gutta-percha and polymer points are the most cytotoxic at pure extract, however gutta-percha was the only material that induced a significant expression of CEMP-1 which assists the tissue repair. Col1 was not induced in any of the samples but was also not inhibited indicating that none of the 3 cone types interfere in tissue repair.

Includes bibliographical references (leaves 355-403)

The pressure-tension hypothesis is the governing dogma of orthodontic tooth movement. This theory proposes that the application of loads to the crown of a tooth during orthodontic mechano-therapy results in differential site-specific reactionary strains in the para-dental tissues. Briefly, following the application of orthodontic load the bone and periodontal ligament (PDL) on one side of the tooth is placed in compression favoring bone resorption, while on the other side of the tooth they are placed in tension favoring osteogenesis The present in vitro model provides a surrogate for the PDL on the tension side of the tooth during orthodontic tooth movement and aims to identify mechanically induced changes in the expression of osteo-regulatory cytokines in human PDL cell cultures in response to tensile mechanical strain. Materials and Methods: PDL explants were obtained from pathology free bicuspids of two human subjects following extraction of the teeth for orthodontic purposes. Following serial passage, cells were plated on Uniflex� plates and consigned to either the experimental or control groups. Experimental cells were exposed to a cyclic uniaxial tensile mechanical strain for 6,12 or 24 hours using the Flexercell FX 4000 strain unit. Total RNA was extracted using a two-step procedure and samples were analysed using real-time RT-PCR assays for a range of osteo-regulatory cytokines. Results: Human PDL cells expressed mRNA for a range of cytokines of known significance to osteogenesis and osteoclastogenesis in response to mechanical stimulation. Conclusions: The production of osteo-regulatory cytokines by PDL cells in response to mechanical strain suggests that these cells have the potential to contribute to the osseous modeling of orthodontic tooth movement. The presence of osteogenic signalling drive in response to tensile strain tends to support the basic assertions of the pressure-tension hypothesis.