ABSTRACT
STATEMENT OF PROBLEM: Fully stabilized monolithic zirconia (FSZ) has been developed as an alternative to zirconia veneered with porcelain. However, how sintering conditions might affect its microstructure and optical and mechanical properties is unclear. PURPOSE: The purpose of this in vitro study was to determine the effect of different sintering temperatures on the microstructure and optical and mechanical properties of FSZ. MATERIAL AND METHODS: Bar-shaped FSZ specimens were prepared and divided into 2 groups (n=15) according to final sintering temperatures (1450 °C and 1600 °C). The average reflectance, opacity, translucency parameter, and sum of light absorption-scattering values were obtained by using a spectrophotometer, and ΔE00 was calculated. The 3-point bend test was performed in a universal testing machine. Scanning electron microscopy (SEM) was conducted for microstructure analysis. Crystalline phase quantification was obtained by X-ray diffraction (XRD). Data were analyzed by using D'Agostino-Pearson and Student t tests (α=.05). RESULTS: A significant difference was detected in the reflectance and sum of light absorption-scattering values between the 2 groups. The translucency parameter, opacity, and flexural strength showed no statistical differences. ΔE00 was 0.98. XRD indicated cubic (47.41% for 1450 °C; 46.04% for 1600 °C) and tetragonal content (52.59% for 1450 °C; 53.96% for 1600 °C). No monoclinic content was found. SEM images showed more definite grain boundaries in the 1600-°C group. Mean grain size was 0.49 µm for the 1450-°C group and 1.99 µm for the 1600-°C group. CONCLUSIONS: Higher sintering temperatures increased the grain size but did not change the crystal phase concentration. A significant difference was found in the reflectance and sum of light absorption-scattering, but no differences were found among the translucency parameter, opacity, or flexural strength.
Subject(s)
Dental Materials , Flexural Strength , Ceramics , Humans , Materials Testing , Surface Properties , Temperature , ZirconiumABSTRACT
Aim: This study investigated the influence of yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) thickness on fracture load of porcelain-veneered crowns (FL), fracture toughness of porcelain (FT), and the shear bond strength zirconia/porcelain (SBS). Methods: Artificial first molar was prepared for full crown (N=45) with different occlusal reduction. Y-TZP cores were made with different thickness at the occlusal face (1mm, 2mm and 3mm) (n=15). The cores were veneered with VM9 Vita porcelain with 1.0 mm layer. For FL testing, axial load was applied to the mesiolingual cusp of the crowns. For FT testing, flat Y-TZP plates (5X5 mm) with 1, 2 or 3 mm thickness were veneered with 1.0 mm porcelain layer (n=10). FT by indentation fracture technique was measured close to the interface and at the top surface. For SBS by knife-edge shearing rod, cylindrical porcelain with 5 mm in diameter and 3 mm was applied on flat Y-TZP plates (1, 2 and 3 mm thickness) (n = 10). Results: Data analyzed by 1-Way ANOVA for FL of crowns and SBS between Y-TZP and porcelain were not significant. Two-way ANOVA for FT was significant for zirconia thickness and measurement area. The post-hoc test showed higher values for the groups with 2 and 3mm, and higher values at the interface, irrespectively of Y-TZP thickness. Conclusion: The zirconia thickness did not affect the FL of veneered crowns and the SBS between the ceramics, but FT of porcelain was lower in thinner zirconia substructure and close to the interface Y-TZP/Porcelain
Subject(s)
Zirconium , Dental Porcelain , Flexural StrengthABSTRACT
OBJECTIVES: The aim of this study was to analyze the capacity of a new modified laser surface to stimulate calvarial osteoblasts isolated from neonatal mouse bones to differentiate and form mineralized nodules. METHODS: Titanium discs were subjectezd or not to laser irradiation according to specific parameters and characterized. Osteoblasts isolated from neonatal mouse calvaria were cultured over the discs, and the capacity of these cells to proliferate (MTT assay), form mineralized nodules (Alizarin red assay), and enhance alkaline phosphatase activity (ALPase activity) was analyzed. Real-time PCR was used for quantification of gene expression. RESULTS: Laser-irradiated titanium discs (L) presented a rough nano-to-micrometric oxidized surface contrasting with the smooth pattern on polished discs (P). The Ra on the micrometric level increased from 0.32 ± 0.01 µm on P surfaces to 10.57 ± 0.39 µm on L surfaces. When compared with P, L promoted changes in osteoblast morphology, increased mineralized nodule formation in osteoblasts cultured on the surfaces for 14 days, and enhanced ALPase activity at days 7 and 14. Transcription factors triggering osteoblast differentiation (Runx2 and Sp7) and genes encoding the bone extracellular matrix proteins collagen type-1 (Col1a1), osteopontin (Spp1), and osteocalcin (Bglap) were upregulated in cells on L surfaces compared with those on P surfaces at days 1-14. CONCLUSION: Laser treatment of titanium surfaces created a rough surface that stimulated osteoblast differentiation. CLINICAL RELEVANCE: Laser treatment of titanium generates a reproducible and efficient surface triggering osteoblast differentiation that can be of importance for osteointegration.
Subject(s)
Cell Differentiation/physiology , Lasers, Solid-State , Osteoblasts/physiology , Skull/cytology , Titanium/chemistry , Animals , Mice , Mice, Inbred C57BL , Microscopy, Electron, Scanning , Osseointegration/radiation effects , Real-Time Polymerase Chain Reaction , Spectrometry, X-Ray Emission , Surface PropertiesABSTRACT
A osseointegração, requisito indispensável para o sucesso dos implantes dentários, é um processo lento, caracterizado, sequencialmente, pelas etapas de adesão, diferenciação e proliferação celular, bem como pela aposição e mineralização da matriz óssea depositada por osteoblastos. Acelerar o processo de osseointegração significa reduzir o tempo de espera para a aplicação segura de uma carga funcional sobre os implantes de titânio (Ti). Sabe-se que vários fatores, tal como a topografia da superfície do Ti, influenciam diretamente o processo de osseointegração. Assim, desde que foi demonstrado que alguns padrões específicos de superfície do Ti são capazes de bio-estimular osteoblastos, favorecendo e acelerando a osseointegração, diversas técnicas de baixo custo, rápida execução e altamente reproduzíveis, tem sido propostas para tratar a superfície dos implantes. Desta maneira, o objetivo da presente pesquisa foi avaliar a capacidade de superfícies de Ti, modificadas com laser pulsado de alta potência (L) ou usinadas (U), de estimular a diferenciação e maturação de células obtidas de calvária de camundongos cultivadas sobre elas. Para isto, foram realizados ensaios laboratoriais para determinar a atividade mineralizadora das células (coloração com vermelho de alizarina e fosfatase alcalina), o metabolismo (MTT assay) e morfologia celular (MEV). A fim de melhor caracterizar a diferenciação de osteoblastos, foi realizada a reação de polimerização em cadeia (PCR) quantitativa em tempo real para analisar a expressão, pelas células cultivadas sobre as superfícies de Ti, de genes que codificam os fatores de transcrição Runx2 e Sp7 e proteínas específicas da matriz extracelular mineralizada...
The osseointegration, which plays a fundamental role in the dental implantation success, is characterized by cell adhesion, differentiation, proliferation as well as deposition and mineralization of of bone matriz by osteoblasts. To make the osseointegration process faster means reducing the period to apply a safe functional stress on the titanium (Ti) implants. A number of factors, such as the topographical surface of Ti enhances the osseointegration process. Different Ti surface treatments capable of bio-estimulating osteoblasts to accelerate the osseointegration have been evaluated. Current studies have shown that osseointegration of Ti devices is enhanced by surface roughness. In this way, the aim of the present investigation was to assess the capacity of Ti surfaces irradiated with high potency laser (L) or polished (U) to stimulate the differentiation and maturation of cells obtained from calvarian bone of mouse. Then, laboratorial protocols to evaluate the mineralizing cell activity (alizarin red assay), cell metabolism (MTT assay) as well as the morphology (SEM) of cells cultured on the Ti surfaces were carried out. To better characterize the osteoblast differentiation, the real time qPCR for expression of genes that code to the transcription factors Runx2 and Sp7 were performed. Additionaly, this protocol was also used to assess specific proteins of extracellular matrix (Spp1, Alpl, e Col1a1). The numeric data were subjected to statistical analysis. Our data demonstrated that the Ti surface L improved the osteoblast maturation capacity of calvarial osteoblasts grown over this surface. Scanning electron microscopy (SEM) revealed spheres and protrusions created by laser treatment. Laser profilometry showed a disordered surface with micrometric and/to nanometric scales features (Ra = 10.57μm). When compared to polished...
Subject(s)
Animals , Mice , Cells, Cultured , Lasers , Nanotechnology , Osteoblasts , TitaniumABSTRACT
A osseointegração, requisito indispensável para o sucesso dos implantes dentários, é um processo lento, caracterizado, sequencialmente, pelas etapas de adesão, diferenciação e proliferação celular, bem como pela aposição e mineralização da matriz óssea depositada por osteoblastos. Acelerar o processo de osseointegração significa reduzir o tempo de espera para a aplicação segura de uma carga funcional sobre os implantes de titânio (Ti). Sabe-se que vários fatores, tal como a topografia da superfície do Ti, influenciam diretamente o processo de osseointegração. Assim, desde que foi demonstrado que alguns padrões específicos de superfície do Ti são capazes de bio-estimular osteoblastos, favorecendo e acelerando a osseointegração, diversas técnicas de baixo custo, rápida execução e altamente reproduzíveis, tem sido propostas para tratar a superfície dos implantes. Desta maneira, o objetivo da presente pesquisa foi avaliar a capacidade de superfícies de Ti, modificadas com laser pulsado de alta potência (L) ou usinadas (U), de estimular a diferenciação e maturação de células obtidas de calvária de camundongos cultivadas sobre elas. Para isto, foram realizados ensaios laboratoriais para determinar a atividade mineralizadora das células (coloração com vermelho de alizarina e fosfatase alcalina), o metabolismo (MTT assay) e morfologia celular (MEV). A fim de melhor caracterizar a diferenciação de osteoblastos, foi realizada a reação de polimerização em cadeia (PCR) quantitativa em tempo real para analisar a expressão, pelas células cultivadas sobre as superfícies de Ti, de genes que codificam os fatores de transcrição Runx2 e Sp7 e proteínas específicas da matriz extracelular mineralizada (Spp1, Alpl, e Col1a1). Os dados numéricos obtidos foram submetidos a análise estatística. A superfície L foi capaz de aumentar a formação de nódulos de mineralização aos 14 dias em comparação com a superfície U (ensaio de vermelho de alizarina, p<0,05). Esta atividade mineralizadora, estimada também pela presença da enzima fosfatase alcalina, foi observada desde o período de 7 dias e se manteve até o dia 14. O ensaio de MTT revelou que esta maior capacidade mineralizadora não foi decorrente do aumento da proliferação celular, pois o metabolismo foi maior aos 14 dias em células cultivadas sobre a superfície U em comparação à superfície L (MTT assay, p<0,05). Os genes que codificam para fatores de transcrição estimuladores de diferenciação de osteoblastos (Runx2 e Sp7), assim como os genes que codificam para as proteínas osteopontina (Spp1), fosfatase alcalina (Alpl) e cadeia 1 do colágeno tipo 1 (Col1a1) foram aumentados no período entre 24 horas até os 14 dias em células cultivadas em contato com a superfície L. De acordo com a metodologia empregada neste estudo, foi possível concluir que a criação de topografias híbridas (micro, submicro e nano) com laser de alta potência bioestimula a diferenciação terminal de osteoblatos a partir de células obtidas de calvária de camundongos e acelera o processo biológico de síntese e mineralização de matriz óssea
The osseointegration, which plays a fundamental role in the dental implantation success, is characterized by cell adhesion, differentiation, proliferation as well as deposition and mineralization of of bone matriz by osteoblasts. To make the osseointegration process faster means reducing the period to apply a safe functional stress on the titanium (Ti) implants. A number of factors, such as the topographical surface of Ti enhances the osseointegration process. Different Ti surface treatments capable of bio-estimulating osteoblasts to accelerate the osseointegration have been evaluated. Current studies have shown that osseointegration of Ti devices is enhanced by surface roughness. In this way, the aim of the present investigation was to assess the capacity of Ti surfaces irradiated with high potency laser (L) or polished (U) to stimulate the differentiation and maturation of cells obtained from calvarian bone of mouse. Then, laboratorial protocols to evaluate the mineralizing cell activity (alizarin red assay), cell metabolism (MTT assay) as well as the morphology (SEM) of cells cultured on the Ti surfaces were carried out. To better characterize the osteoblast differentiation, the real time qPCR for expression of genes that code to the transcription factors Runx2 and Sp7 were performed. Additionaly, this protocol was also used to assess specific proteins of extracellular matrix (Spp1, Alpl, e Col1a1). The numeric data were subjected to statistical analysis. Our data demonstrated that the Ti surface L improved the osteoblast maturation capacity of calvarial osteoblasts grown over this surface. Scanning electron microscopy (SEM) revealed spheres and protrusions created by laser treatment. Laser profilometry showed a disordered surface with micrometric and/to nanometric scales features (Ra = 10.57µm). When compared to polished Ti (U), laser modified titanium (L) increased the nodule formation as well as the alkaline phosphatase (ALPase) activity at 7 and 14 days. These effects were not due to increased cell proliferation since no difference in metabolic activity on cells cultured over U and L surfaces after 1 and 3 days, and decreased activity after 7 days on L compared to U, as demonstrated by MTT assay. Relative quantification of gene expression (qPCR) revealed that transcription factors triggering osteoblast differentiation (Runx2 and Sp7) were up-regulated at 1, 3, 7 and 14 days on L surface. Genes encoding to the extracellular bone matrix proteins collagen type-1 (Col1a1) and osteopontin (Spp1) were also increased at 1, 3, 7 and 14 days. Alkaline phosphatase (Alpl) transcript was increased in osteoblasts after 3 an 14 days of culture on L surface as compared to M surface. Treatment of titanium with high power laser created a rough surface that stimulates osteoblast differentiation and maturation, which turn faster the biological process of synthesis and mineralization of bone matrix
