RESUMO
AIM: To evaluate the influence of several niobium pentoxide (Nb(2) O(5) ) concentrations on the radio-opacity, flow, film thickness, microhardness and degree of conversion of an experimental root canal sealer. METHODOLOGY: An experimental dual-cured root canal sealer was produced with a methacrylate-based comonomer blend. Nb(2) O(5) was added at four different concentrations: 0, 80, 100 and 120 wt%. Radio-opacity was evaluated according to ISO 6876 using a digital system (n = 5). Flow and film thickness were determined in accordance with ISO 6876 (n = 3). Microhardness was evaluated with 50 g for 15 s (n = 5). Degree of conversion was evaluated with FTIR immediately after photocuring and after 1, 7 and 14 days. The data were analysed using anova and Tukey's test. The degree of conversion over time was evaluated using RM-anova (α = 0.05). RESULTS: The groups with 80 wt% and 100 wt% of filler showed no significant difference in radio-opacity from that of equivalent 2 mmAl (P > 0.05). The addition of 120 wt% resulted in radio-opacity values higher than 2 mmAl (P < 0.05). The flow was not significantly different amongst the different groups (P > 0.05). All groups had a film thickness of <50 µm (ISO 6876). All groups with Nb(2) O(5) were associated with higher values of microhardness than the control group. The group with 0 wt% was associated with a higher degree of conversion at all times. All groups except those with 80 wt% had higher values for degree of conversion after 14 days than immediately after photocuring. CONCLUSION: The addition of Nb(2) O(5) increases radio-opacity and microhardness; this material may be a promising filler for the production of a new endodontic sealer.
Assuntos
Metacrilatos/química , Nióbio/química , Óxidos/química , Materiais Restauradores do Canal Radicular/química , Cânfora/análogos & derivados , Cânfora/química , Meios de Contraste/química , Dureza , Humanos , Teste de Materiais , Tamanho da Partícula , Fotoiniciadores Dentários/química , Polimerização , Poliuretanos/química , Cimentos de Resina/química , Reologia , Autocura de Resinas Dentárias , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , ViscosidadeRESUMO
AIM: To evaluate the effect of different concentrations of nanostructured hydroxyapatite on the radiopacity, flow and film thickness of an experimental root canal sealer. METHODOLOGY: An experimental dual-cured root canal sealer was produced with a methacrylate-based co-monomer blend. Nanostructured hydroxyapatite/calcium tungstate solutions (ratios 10:90, 20:80, 30:70 and 40:60) were added to produce the sealer. Radiopacity was evaluated using a digital system and an aluminium step wedge (n=5). Flow and thickness tests were conducted in accordance with ISO 6876 (n=3). The data were analysed using one-way anova and Tukey's test (α=0.05). RESULTS: All groups had levels of radiopacity in accordance with ISO 6876. The flow of the experimental sealers was not significantly different (P=0.204). All groups had a film thickness in accordance with ISO 6876 and with no statistical difference (P = 0.654). CONCLUSION: The addition of up to 40% HA(nano) to root canal sealers did not alter their radiopacity and film thickness.
Assuntos
Materiais Biocompatíveis/química , Durapatita/química , Metacrilatos/química , Nanoestruturas/química , Materiais Restauradores do Canal Radicular/química , Peróxido de Benzoíla/química , Compostos de Cálcio/química , Cânfora/análogos & derivados , Cânfora/química , Meios de Contraste/química , Humanos , Teste de Materiais , Tamanho da Partícula , Poliuretanos/química , Cimentos de Resina/química , Silanos/química , Sonicação , Propriedades de Superfície , Temperatura , Fatores de Tempo , Toluidinas/química , Compostos de Tungstênio/química , ViscosidadeRESUMO
This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 µm, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission.
RESUMO
PURPOSE: The purpose of this study was to investigate dentin rehardening in the remaining carious dentin after indirect pulp treatment (IPT) using microhardness analysis after 37 to 71 months. METHODS: Eighteen teeth submitted to IPT and capped with calcium hydroxide (CH) or gutta-percha (GP) were evaluated (treated group). Ten sound molars and 10 molars with deep acute carious lesions were selected to serve as positive and negative control groups, respectively. In the treated group, restorations and pulp-capping materials were removed. In the positive control group, 3- to 4-mm deep cavities were prepared. In the negative control group, the carious tissue was removed. Microhardness analysis was performed at 10-, 35-, 60-, 85-, and 110-microm depths. Data were analyzed using 1-way analysis of variance (P<.05). RESULTS: Microhardness values for sound, carious, and treated groups at 10-, 35-, 60-, 85-, and 110-microm depths showed a statistically significant difference (PAssuntos
Capeamento da Polpa Dentária/métodos
, Dentina/fisiopatologia
, Hidróxido de Cálcio/uso terapêutico
, Criança
, Cárie Dentária/terapia
, Guta-Percha/uso terapêutico
, Dureza
, Humanos
, Dente Molar
, Esfoliação de Dente
, Remineralização Dentária/métodos
, Dente Decíduo
RESUMO
The main purpose of this work was the investigation of the immobilization of chromium ion present in the ash from the incineration of chromium-tanned leather shavings (ACS) by means of vitrified ceramic bodies. To achieve the immobilization samples were initially produced adding soda-lime glass to ACS. After that, new formulations were produced with the addition of pure oxides, TiO(2) and MgO, to the soda-lime glass and ACS sample. These samples were conformed by pressing and fired in an eletrical furnace, at temperatures of 750, 800, 950 and 1000 degrees C. The ceramic bodies were evaluated with respect to their physical properties and mineralogical composition by X-ray diffraction and energy dispersive spectroscopy (EDS) mapping. The chromium immobilization was characterized by leaching tests according to Brazilian Regulations (NBR 10005). The results confirmed the immobilization of the chromium ion within the allowed limits of Brazilian Regulations, NBR 10004 (5mg/L), with the use of glass and vitrification/densification agents such as titanium and magnesium oxides.
Assuntos
Cromo , Resíduos Industriais/prevenção & controle , Eliminação de Resíduos/métodos , Brasil , Cerâmica/química , Vidro/química , Incineração , Óxidos/químicaRESUMO
The aim of this work was to evaluate the use of mineral coal fly ash as a raw material in the production of ceramic tiles. The samples of fly ash came from Capivari de Baixo, a city situated in the Brazilian Federal State of Santa Catarina. The fly ash and the raw materials were characterized regarding their physical chemical properties, and, based on these results; batches containing fly ash and typical raw materials for ceramic tiles were prepared. The fly ash content in the batches varied between 20 and 80 wt%. Specimens were molded using a uniaxial hydraulic press and were fired. All batches containing ash up to 60 wt% present adequate properties to be classified as several kinds of products in the ISO 13006 standard () regarding its different absorption groups (pressed). The results obtained indicate that fly ash, when mixed with traditional raw materials, has the necessary requirements to be used as a raw material for production of ceramic tiles.
Assuntos
Carbono , Cerâmica/química , Carvão Mineral , Conservação dos Recursos Naturais , Material Particulado , Silicatos de Alumínio , Carbonato de Cálcio , Argila , Cinza de Carvão , Compostos de Potássio , Gerenciamento de ResíduosRESUMO
The leather tannery industry produces a significant amount of solid and hazardous wastes. Chromium-containing wastes like tanned shavings used to be incinerated in order to recover energy. The incineration process generates ashes that must be disposed of. This paper is a report on the results of the evaluation of technological properties and environmental compatibility of products made of alumina and ashes from incinerated chrome tanned shavings. The raw materials, tannery ashes and alumina were mixed together in different proportions. The ceramic bodies were molded using a hydraulic press and fired with a heating rate of 100 K/h until 1400 degrees C for 4 h in a muffle furnace. The ceramic specimens were characterized regarding physical, mechanical and thermal properties. Leaching tests, according to Brazilian, German and Dutch regulations, were performed on ceramic bodies containing different additions of ash. Results show that the ceramic materials produced are acceptable for refractory applications.