ABSTRACT
BACKGROUND: Porous silicon carbide has excellent physical and chemical properties and can be used to repair complex shapes and long weight-bearing bone defects, but it has no biological activity and cannot promote bone remodeling and integration. OBJECTIVE: A tantalum (Ta) coating was deposited on the surface of the porous silicon carbide scaffold to evaluate its biological activity. METHODS: The chemical vapor deposition method was used to deposit a Ta coating on the surface of the porous silicon carbide scaffold. The optimal experimental parameters were explored by setting different gas reaction flow rates and temperatures. The Ta coating was prepared with the best experimental parameters to test the mechanical properties of porous Ta. Human osteoblasts were co-cultured with the Ta coating specimens, and were observed by scanning electron microscopy after 3 and 7 days of cultivation. RESULTS AND CONCLUSION: (1) After the optimization of experimental parameters, the best experimental conditions were controlled as follows: deposition temperature of 1 050 °C, hydrogen flow rate of 180 mL/min and chlorine flow rate of 100 mL/min. (2) The compressive strength of the Ta coated specimen was (61.4±3.2) MPa; the yield strength was (45.8±2.9) MPa; and the elastic modulus was 4.8 GPa. (3) Scanning electron microscopy demonstrated that after 3 days of co-cultivation, a large number of cells adhered to the surface of the porous silicon carbide scaffold that is coated with Ta and the porous structure. Some of the cells protruded from the pseudopod and were connected to each other. After 7 days of co-cultivation, the cell protrusions fused to form a sheet covering the surface of the porous Ta. In the porous structure, the cells protruded from the pseudopods, cross-linked to each other across the pores, secreted in the matrix, and coated the microparticle structure, gradually spreading in the pores. (4) The results show that the Ta coating on the surface of porous silicon carbide scaffold has good mechanical properties and biological activity.
ABSTRACT
A técnica de microabrasão do esmalte é considerada uma alternativa conservadora e efetiva para remoção de manchas e irregularidades superficiais do esmalte e diferentes pastas podem ser usadas para essa finalidade. Objetivo: O objetivo desse estudo foi comparar a eficácia da técnica de microabrasão do esmalte com fluorose utilizando duas diferentes pastas. Material e Métodos: Paciente, gênero feminino, 18 anos de idade, foi submetida ao tratamento de microabrasão do esmalte, sendo que na arcada superior direita foi manipulada e aplicada a pasta à base de pedra-pomes (SSWhite) e ácido fosfórico a 37% (Alpha Etch, DFL) na proporção de 1:1 e na arcada superior esquerda uma pasta à base de ácido hidroclorídrico a 6,6% e óxido de silício (Micropol, DMC Equipamentos Ltda). Nas duas hemi-arcadas foi realizado o mesmo protocolo clínico por três vezes, sendo que a aplicação da pasta foi de 1 mm de espessura e a realização da microabrasão se deu por fricção mecânica com taça de borracha acoplada em baixa rotação por 10 s. Em seguida os dentes foram polidos com disco de feltro e pasta diamantada e aplicado flúor tópico APF 1,23% por 3 min. Resultados: Os resultados clínicos foram similares em ambas arcadas, independente da pasta utilizada. O sucesso na remoção de manchas no esmalte está dieretamente relacionada com o correto diagnóstico e a precisa indicação da técnica de microabrasão. Conclusões: Foi possível concluir que a as duas diferentes pastas utilizadas para a microabrasão do esmalte foram efetivas na remoção de machas intrínsecas por fluorose com resultados similares e com o restabelecimento estético dos dentes envolvidos.
The technique of enamel microabrasion is considered an aesthetic alternative conservative and effective for stain removal or surface irregularities of the enamel and different materials or pastes can be used for this purpose Objetives: The objective of this study was to compare the efficiency of the technique of enamel microabrasion using two different pastes at removing hypoplastic stains by fluorosis. Methods: The female patient, 18 years, was submitted to enamel microabrasion, and in the right half of the maxilla was manipulated in the proportion of 1:1 by volume a paste of pumice (SSWhite) and 37% phosphoric acid (Etch Alpha, DFL), and in the left half of the maxilla used paste based on hydrochloric acid and 6.6% silicon carbide (Micropol, DMC Equipment Ltd.). In both hemi-arches was performed the same clinical protocol and repeated three times, by the application of 1.0 mm thickness of paste and realized the enamel microabrasion through mechanical friction with rubber cup at low speed for 10 s. Then, the teeth were polished with felt disc and diamond paste, and topical fluoride APF 1.23% for 3 min was applied. Results: The clinical outcome was similar for both hemi-arches, regardless of the used technique. The success in removing stains on tooth enamel is directly related to a correct diagnosis and accurate indication of microabrasion technique. Conclusions: It can be concluded that the two pastes used in the enamel microabrasion were effective for removing intrinsic stains from fluorosis, with similar results and with the re-establishment of aesthetics of the teeth involved.