Magister Scientiae Dentium - MSc(Dent) / Objectives:Substances leaching from denture- base polymers have been associated with cytotoxicity and allergic reactions. This study examined the effect of polishing,mixing ratios, water immersion temperatures and different thicknesses on the sorption and solubility of a heat-polymerized, denture-base polymer. The effect of different water immersion temperatures on the flexural strength of the denture base, was tested as well. The next component of this study, is the testing of the most significant sorption and solubility findings on in vitro cell viability. Materials and Methods:Disc shaped specimens from a heat-polymerized, denture-base polymer (Vertex®) were prepared, based on ISO 1567 specifications for sorption and solubility testing, following the manufacturers’ instructions. The following tests were performed: 1) Sorption and solubility of two groups (n = 12 each) of polished and unpolished discs were established and compared by means of the Mixed procedure; 2) Sorption and solubility of three groups (n = 12 each) with different mixing ratios were compared by means of the Mixed procedure; 3) Four groups (n = 14 each) were immersed in water at different temperatures, sorption and solubility were compared by means of pairwise comparison and the Median test; 4) Specimens with different thicknesses (n = 36) were compared, again, by means of pairwise comparison and the Median test; 5) To test the influence of different water-soaking temperatures on the flexural strength of the disc, strips were prepared from the disc used in test no. 3. The flexural strength was compared, by means of the Median test; 6) To test the influence of no postpolymerization treatment, polishing and water immersion on the cytotoxicity of mouse fibroblast cells, (n = 9) for each test group, were prepared. A preliminary test was performed beforehand, over a period of 24 hours, up to a maximum period of four weeks. The Balb/c 3T3 mouse fibroblast cells were cultured and incubated for 24 hours in Eagles medium. Eluates prepared from the disc and medium without any disc (control) replaced the medium. Cytotoxicity was assessed by MTT-assay. Optical density values were obtained at 24 and 48 hour intervals. The data was analyzed by means of the Means procedure.Results:In the entire thesis, the data was analyzed using SAS on a 0.01 probability level.Between polished and unpolished groups, no significant difference in water sorption (p> 0.01) was found, but there was a difference in solubility (p<0.01).Different mixing ratios did not alter sorption (p = 0.34) or solubility (p = 0.68).However, a difference (p<0.01) in sorption and solubility was found among the different temperature and thickness groups. Soaking the denture base in water at different temperatures did not alter its flexural strength (p = 0.48). Cell viability levels were noted in all the experimental groups in the MTT assay test. The analysis was a two-factor study, with one factor being the group, and the other, being time. The interaction between these factors was found to be significant, indicating that the effect of the groups varied by time (and vice versa).Conclusion:The processes of the soaking in warm water and the polishing of a denture-base polymer, reduce its solubility. Therefore, it is recommended that dentures are soaked in warm water before polishing. Within the limits of this study, the mixing ratios may be changed without affecting sorption or solubility. As solubility increases within the increasing denture-base thickness, it is recommended that unnecessarily thick dentures be avoided.Short- and long-term exposure to eluates of a PMMA, has a negative effect on cell viability. For water-stored and polished discs, this effect is time-dependent, with a higher viability for 48 hours’, than for 24 hours eluates. Polishing is associated with lower solubility. At 24 hours, the polished discs, indeed, had a lower cytotoxic effect than the untreated discs: it may be recommended that dentures be polished on the fitting surface as well.The cytotoxic potential of PMMA-eluates appears to fluctuate over time.

Resumo: Embora a etiologia da estomatite por prótese total seja frequentemente associada à Candida albicans, a literatura também indica que a infecção pode ser associada à outros fatores. Neste ínterim, o objetivo deste estudo foi avaliar a correlação entre a prevalência da estomatite por prótese total, o grupo sanguíneo ABO, presença de Candida ssp. e a higienização da prótese total. Foram avaliados 30 pacienttes (média de idade de 61,13 +-11,96 anos) portadores de prótese total superior, sendo que 23 eram do sexo feminino. O exame clínico incluiu a avaliação da mucosa do palato e a avaliação da higienização da prótese total. A qualificação da higiene da prótese total foi feita por meio da visualização do biofilme com o uso de evidenciadores de placa, nas superfícies internas das próteses. As amostras micológicas foram obtidas da mucosa do palato (região central), da superfície interna da prótese total (região central) e do dorso da língua, por meio da técnica de impressão ("imprint"), utilizando discos de filtro de papel, colocados diretamente em placas de cultura contendo meio seletivo CHROMagar Candida. As espécies isoladas foram identificadas por meio da prova de produção de clamidoconídeo e pelo sistem API 20C AUX, além da pré-identificação fornecida pelo uso do meio seletivo. Amostra sanguínea foi coletada para determinação do tipo sanguíneo do paciente (sistema ABO e Rh). As análises estatísticas dos resultados foram feitas utilizando testes não paramétricos (Spearman, Mann-Whitney e Kruskal-Wallis). Em nosso estudo, 53,33% dos pacientes apresentaram estomatite por prótese total e a identificação de Candida ssp. foi positiva para 80% dos pacientes. O grau de higiene das próteses... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Although the etiology of denture stomatitis has been commonly related to Candida albicans, some previous studies indicate that the infection could be associated to other factors. The aim of this study was to evaluate the correlation between the prevalence of denture stomatitis, ABO blood groups, mycological status and denture cleanliness. Thirty patients with mean age of 61.13+-11.96 yeas being 23 female using complete maxillary dentures were investigated. Oral examinations included clinical diagnosis of denture stomatitis as well as the evaluation of denture cleanliness. The denture cleanliness was assessed using a stain as plaque detector in the fitting denture surface. The yeast cultures from the palatal mucosa, fitting denture surface and dorsum of the tongue were obtained using an imprint at CHROMagar Candida. The determinations of the species of the isolates was performed by chlamydospore formation and sugar assimilation using API 20C AUX. Venous blood was collected for ABO blood group determination. Spearman correlation, non-parametric t test and analysis of variance were performed to analyse the data. In this study, 53.33% of the patients presented denture stomatitis and the identification of Candida spp. was positive in 80% of the samples. The denture clean liness was classified as poor in 93.33% of the dentures. A statistical correlation was found between yeast detection and denture stomatitis (r=0.8250; p<0,0001) and between Candida ssp. and denture cleanliness (r=0,4666; p=0,0248). Although, majority of the patients were from blood group O no statistical correlation was found between clinical variables and mycological results. Candida albicans was the most frequent yeast isolated (60.94%) followed by C. tropicalis, C. glabrata... (Complete abstract, click electronic address below) / Orientador: Maria Regina Sposto / Coorientador: Maria José Soares Mendes Giannini / Banca: Carlos Eduardo Vergani / Banca: Jacks Jorge Junior / Mestre

Magister Scientiae Dentium - MSc(Dent) (Restorative Dentistry) / Loss of teeth has a negative impact on appearance, nutrition, function and diet. Rehabilitation of tooth loss is an important function of oral health care. Rehabilitation with removable prosthesis of mandibular terminal edentulous areas has been associated with more negative outcomes than of tooth-bounded regions.

No description available.

Purpose: The aim of this study was to establish clinically relevant guidelines for the selection of clasps for removable partial dentures (RPDs) by adapting RPD clasp arms of differing materials and diameter to a three-dimensional model based on the average curvature of premolars and molars. Method: Randomly selected discarded casts were collected that had intact first premolars and first molars. The normal clasp position for the buccal surfaces of these teeth was drawn on the cast and the teeth were then sectioned to this line, and scanned using a flatbed scanner. The average curvature and length for each group was determined using a graphics-drawing programme and a 3D model was printed using these data. Clasp materials were then be adapted to these models using the wrought wires: Leowire (Leone, Fiorentino, Italy) (stainless steel); Remanium Hard (Dentaurum, Pforzheim, Germany) (stellite alloy of chromium and cobalt); Noninium (Dentaurum, Pforzheim, Germany) (stainless steel, nickel free); and cast clasps cast in the stellite alloy Vitallium (Dentsply, Ontario, Canada). Two diameters of the wrought wire clasp groups were used (0.9mm and 1.0mm). Ten samples for each diameter and material were adapted to the 3D models as they would in a clinical case. Each clasp was then randomly deformed beyond its proportional limit in a tensile testing machine (Instron Corporation, High Wycombe, United Kingdom) and the forces exerted at that limit and at deflections of 0.25 mm, 0.5 mm, and 0.75 mm were measured, as these are the clinically encountered undercuts. Statistical analysis was carried out to determine if the forces exerted at these deflections were within the proportional limit of the clasp, but also significantly within the realistic limit (defined as two standard deviations from the proportional limit) to allow for variations in manufacture and application of the clasp arms. Results: The results confirmed the effect of material, length, and diameter on flexibility for the wrought wires. A table was produced with guidelines for those clasps which could be used safely within their realistic limits and therefore should provide longevity of service. The greatest force exerted on premolar clasp length arms was provided by Leowire at 0.25mm undercut (606g); although it was 2% greater than its realistic limit, this was considered sufficiently within the safety factor to iii recommend its clinical use. The greatest force exerted on molar clasp length arms was provided by Remanium Hard at a deflection of 0.5 mm (417g). Cast clasps for premolars should not be prescribed as they were all well above their realistic limits. Cast clasps should only be selected for molars if the clasp arm is longer than 14.5mm. At a deflection of 0.25 mm the cast arm exerted a force of 773g but whilst this was below its proportional limit, it was higher than its realistic limit. Conclusions: The results of this study provide valid guidelines for the clinical application of clasp arms in removable partial dentures. It is recommended that clinical studies be carried out to confirm the longevity of clasp arms based on these data. / MT2016

Resumo: Este estudo avaliou a efetividade de diferentes tempos de irradiação por microondas na desinfecção de uma resina rígida para reembasamento imediato. Duzentos e quarenta corpos-de-prova (10 x 10 x 1 mm) da resina reembasadora rígida Tokuso Rebase Fast foram confeccionados e esterilizados por meio de óxido de etileno. Os corpos-de-prova foram então individualmente inoculados (107 ufc/mL) com meio de cultura de Tryptic Soy Broth (TSB) contendo um dos microrganismos avaliados (P. aeruginosa, S. aureus, C.albicans e B. subtilis). Após 48 h de incubação a 37oC, os corpos-de-porva foram agitados por 1 min e deixados em repouso por 9 min, seguido de nova agitação para suspender qualquer microrganismo aderente. Após a inoculação, os corpos-de-prova foram divididos em 6 grupos, cada um com 10 amostras para cada microrganismo. Os corpos-de-prova foram individualmente imersos em 200 mL de água e submetidos à irradiação em microondas, a uma potência de 650 W em um dos seguintes tempos experimentais: G I - 1 min; G II - 2 min; G III - 3 min; G IV - 4 min e G V - 5 min. Quarenta amostras não irradiadas (G 0) serviram como controle positivo. A seguir, 25 æL da suspensão resultante das diluições seriadas de 10-3 a 10-6 foram semeados em placas de Petri contendo os meios de cultura seletivos para cada microrganismo. Todas as placas foram incubadas a 37oC por 48 h. Após a incubação, as colônias foram quantificadas em ufc/mL e os dados analisados estatisticamente pelos testes de Kruskal-Wallis e de Dunn. Os corpos-de-prova irradiados foram imersos em meio de cultura e incubados a 37oC por 7 dias. Quarenta e quatro corpos-de-prova foram preparados para microscopia eletrônica de varrredura (MEV). De acordo com os resultados, todos os... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the effectiveness of microwave disinfection of a hard chairside reline resin after different exposure times. Two hundred-forty specimens (10 x 10 x 1 mm) of the reline resin Tokuso Rebase Fast were fabricated and subjected to ethylene oxide sterilization. The specimens were then individually inoculated (107 cfu/mL) with Tryptic Soy Broth media (TSB) containing one of the tested microorganisms (P. aeruginosa, S. aureus, C.albicans and B. subtilis). After 48 hours at 37°C, the samples were vortexed for 1 minute and allowed to stand for 9 minutes followed by a short vortex to resuspend any organisms present. After inoculation, the specimens were divided into six groups to provide a sample size of ten for each microorganism. Each specimen was individually immersed in 200 mL of water and subjected to microwave irradiation at 650 W during one of the following exposure times: G I - 1 min, G II - 2 min, G III - 3 min, G IV - 4 min and G V - 5 min. Forty non-irradiated specimens (G 0) were used as positive controls. Replicate specimens (25 æL) of suspension were plated at dilutions of 10-3 to 10-6 on plates of selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. After incubation, colonies were counted (cfu/mL) and the data were statistically analyzed by the Kruskal-Wallisþs and the Dunnþs tests. Forty-four specimens of each material were prepared for SEM. All specimens of G III, G IV and G V groups showed consistent sterilization of all microorganisms after microwave irradiation. Specimens of G II group inoculated with C. albicans were also sterilized after microwave irradiation. Specimens of G II inoculated with S. aureus, B. subtilis, and P. aeruginosa showed microbial growth (turbidity) after 7-day incubation. The specimens of G I demonstrated positive cultures for all microorganisms after... (Complete abstract, access undermentioned electronic address) / Orientador: Ana Cláudia Pavarina / Coorientador: Denise Madalena Palomari Spolidorio / Banca: Ana Lucia Machado / Banca: Alma Blásida Concepción Elizaur Benitez Catirse / Mestre

Thesis (M.S.)--University of Michigan, Ann Arbor, 1975. / Typescript (photocopy). Includes bibliographical references (leaves 73-80). Also issued in print.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1977. / Typescript (photocopy). Includes bibliographical references (leaves 45-50). Also issued in print.

Thesis (M.S.)--University of Michigan, 1974.

Thesis (M.S.)--University of Michigan, Ann Arbor, 1974. / Typescript (photocopy). Includes bibliographical references (leaves 34-36). Also issued in print.