Effects of oxygen in lungs of rats

PURPOSE: To analyze microscopically the effects of different concentrations of oxygen in the lungs of rats. METHODS: There were 20 rats distributed in three experimental groups (concentration of oxygen to 40%, 70% and 100%) and a control group. The animals were exposed to the oxygen in a chamber of acrylic during three days and after exposition, the animals were submitted to median thoracotomia to remove the lungs. The lung tissue of all of the animals was analyzed as regards presence of acute and chronic inflammation, capillary congestion, alveolar walls thick, interstitial and alveolar edema, alveolar hemorrhage, denudation capillary and alveolar endothelium areas and atelectasis. RESULTS: The analysis histopathologic revealed significant statistics difference for acute and chronic inflammation, capillary congestion, alveolar walls thick, interstitial and alveolar edema, alveolar hemorrhage, denudation capillary and alveolar epithelium areas. CONCLUSIONS: Exposition to the oxygen during 72 hours in the concentration of 40% does not produce significant histopathologic alterations in the lung tissue; in the concentration of 70%, can promotes the alveolar walls thick and capillary congestion and in the concentration of 100% can cause death and originate diffuse pulmonary lesion. .

Avaliação da resistência à remoção de mini-implantes para ancoragem ortodôntica / Evaluation of resistance to the removal of mini-implants for orthodontic anchorage

Introdução: A movimentação ortodôntica é limitada por forças recíprocas de ação e reação. Tendo em vista esses aspectos, a utilização dos mini-implantes surge como um novo conceito de ancoragem em Ortodontia. Objetivo: Avaliar a resistência à remoção de mini-implantes para ancoragem ortodôntica. Metodologia: Usou-se costela de porco onde foram fixados 20 mini-implantes de titânio da marca SIN de 1,6mm de diâmetro e 8mm de comprimento e seccionados em 20 blocos (osso/mini-implante) de 6X10 mm e inseridos em tubos de PVC de 10X16 mm e divididos em dois grupos (n=10), grupo I: autoperfurantes; grupo II: autorrosqueantes. Foi avaliada a força de remoção (Tira Test 2420). Resultado: Os resultados em Newton (N) foram analisados estatisticamente pelo teste de Fisher, com significância de 5%. A força média para remoção de todos os mini-implantes foi de 87,0 N ± 26,6, sendo para os autoperfurantes de 92,4 N ± 33,0 e 82,2 N ± 19,6 para os autorrosqueantes. O teste de Fischer mostrou não haver diferença estatisticamente significante entre os grupos (p=0.575). Conclusão: Os mini-implantes analisados apresentam resistência à tração suficientemente superior àquela necessária para as aplicações clínicas; Não houve diferença significante entre os dois tipos de mini-implantes analisados.

Introduction: Orthodontic movement is limited by reciprocal forces of action and reaction. In view of this, the use of mini-implants has emerged as a new concept in orthodontic anchorge. Objective: To evaluate resistance to the removal of mini-implants for orthodontic anchorage. Methods: We used pork ribs onto which 20 titanium mini-implants titanium of the SIN brand, 1.6 mm in diameter and 8 mm in length, were fixed, sectioned into 20 blocks (bone/mini-implant), 6x10 mm, and inserted into PVC tubes, 10x16 mm, and divided into two groups (n= 10) as follows: group I: self-perforating screws; group II: self-threaded screws. An evaluation was made of the removal force (Strip Test 2420) Result: The results obtained in Newton (N) were statistically analyzed by Fisher's test with a significance of 5%. The mean force found for removal of all the mini-implants evaluated was 87.0 N ± 26.6, being 92.4 N ± 33.0 for the self-perforating screws and 82.2 N ± 19.6 for the self-threaded ones. Fischer's test showed no statistically significant differences between the groups (p=0.575). Conclusion: The mini-implants analyzed exhibit a resistance to traction higher than that required for clinical applications; there were no significant differences between the two types of mini-implants analyzed.

Efeito da clorexidina a 2% no mecanismo de adesão do cimento de ionômero de vidro: resistência ao cisalhamento / Chlorhexidine's effect at 2% in the mechanism of adhesion of glass ionomer: shear bond strength

Objetivo: O objetivo deste estudo foi verificar a influência da clorexidina gel a 2% na resistência de união ao cisalhamento do cimento de ionômero de vidro (CIV). Material e Métodos: Foram confeccionados 45 blocos de 10x10mm de dentes bovinos, incluídos em resina acrílica, lixados até obter uma superfície plana em dentina e divididos em 3 grupos (n=15): I - Controle: superfície limpa com spray, seca e restaurada com CIV-Vitro Molar; II - superfície limpa com spray, seca, seguida de aplicação de clorexidina gel a 2%, deixada em repouso por 2 minutos, limpa com "bola" de algodão e restaurada; III - lavagem, aplicação de clorexidina gel a 2%, deixada em repouso por 2 minutos, limpeza com spray, seca e restaurada. Os corpos de prova foram submetidos ao teste de cisalhamento em uma máquina TIRATest 2420. Resultados: Os resultados foram avaliados pelo teste Kruskal-Wallis (p<0,05). Verificou-se diferença significante em função do tratamento aplicado p=0,049. Conclusão: A aplicação da clorexidina por 2 minutos e lavagem posterior comportou-se semelhante ao grupo-controle.

Objective: The goal of this study was to investigate the interference of chlorhexidine gel at 2% by shear tests the adhesion of Glass Ionomer Cement. Material and Methods: The 45 bovine teeth were used and made of blocks of 10x10 mm, including acrylic resin and polished until a flat dentin surface. Then randomly divided into 3 groups (n = 15): I - Control: the surface was cleaned with spray (water/air), dried and restored with glass ionomer Vitro Molar (DFL) II - the surface washed with spray (water/air), dried, followed by the application of chlorhexidine gel at 2%, left to stand for 2 minutes, cleaned with a "ball" of cotton and restored; III - the washing was done with an application of chlorhexidine gel at 2%, left rest to for 2 minutes, then cleaned with spray (water/air), dried and restored. The specimens were subjected to shear stress by the machine TIRATest 2420. Results: The results were analyzed by Kruskal-Wallis (p < 0,05). From the graphical analysis, we found the shear stresses with p = 0,049. It showed a significant difference between the tensions according the treatment applied. Conclusion: The application of chlorhexidine for 2 minutes and posterior rinsing behaved similar to the control group.

Evaluation of shear bond strength of orthodontic resin and resin modified glass ionomer cement on bonding of metal and ceramic brackets

Objective:The aim of this study was to evaluate the shear bond strength of orthodontic resin and resin-modified glass ionomer cement on bonding of metal and ceramic brackets. Material and methods: Forty bovine teeth were sectioned and embedded into PVC with chemically-cured acrylic resin. The labial surfaces were flattened and received prophylaxis with pumice and water. Then they were divided into four groups, according to the bonding material and the type of bracket. Group 1: metallic bracket + Transbond XT; Group 2: metallic bracket + Vitremer; Group 3: ceramic bracket + Transbond XT; Group 4: ceramic bracket + Vitremer. The bonding was performed according to the manufacturers’ recommendations. The shear bond strength test was conducted in a universal testing machine (TIRAtest 2420) at a crosshead speed of 0.5 mm/min. Then, the fractured surfaces were evaluated using a stereomicroscope (x15 magnification) to check the adhesive remnant index. Data was subjected to two-way ANOVA and Tukey’s test for pairwise comparisons (a = 0.05).Results: The results suggested a non-significant effect of the interaction (p > 0.97), and only main factors were significant (p = 0.0001). The bond strength of Transbond XT was statistically higher than Vitremer. Ceramic brackets obtained the highest values of resistance when compared with metal brackets. Conclusion: The ceramic brackets bonded with Transbond XT orthodontic resin have excellent bond strength results.

Avaliação do desajuste marginal de copings para coroa total metalocerâmica em términos cervicais tipo chanfro e ombro com bisel 45° / Evaluation of the marginal fit in copings for full metaloceramic crown with chamfer and beveled shoulder finish line

Objetivo: O propósito deste estudo foi avaliar os desajustes marginais que ocorrem em copings para coroas totais metalocerâmicas confeccionados em liga de níquel-cromo adaptadas a modelos-padrão com términos cervicais em chanfro e ombro biselado em 45º. Métodos: Para isso foram usinados dez troquéis metálicos para cada tipo de terminação cervical a partir de cilindros de aço simulando preparos dentais para coroas totais metalocerâmicas. Os copings foram adaptados aos respectivos modelos-padrão formando um corpo-de-prova, sendo sua margem cervical analisada antes e após a cimentação dos mesmos, com cimento de fosfa-to de zinco, por meio de um microscópio óptico auxiliado por um sistema de análise de imagem. Resultados: Os resultados de desajustes foram submetidos ao teste de Wilcoxon e T de Student, com os quais se verificou não haver diferença estatisticamente significativa entre as duas modalidades de terminação cervical. Conclusão: Com base nos dados obtidos, pode-se concluir que os desenhos cervicais avaliados são semelhantes em seu comportamento em relação à adaptação marginal.