On the role of laser-induced microstructures in influencing the surface energy of magnesia partially stabilized zirconia bioceramic

Surface energy must in some way be connected to surface chemistry and is therefore an important determinant of a biomaterial’s functions. This work elucidates the basic phenomena and wetting mechanisms associated for a widely used bioinert ceramic, magnesia partially stabilized zirconia (MgO-PSZ) following CO2 laser treatment. Contact angles for a set of test liquids were used to measure the wettability characteristics and to reduce the surface energy of the MgO-PSZ before and after CO2 laser treatment. CO2 laser treatment of the MgO-PSZ surface was seen to effect an improvement in the material’s wettability characteristics. Furthermore, it was found that the extent of wettability modi®cation was closely related to the microstructure induced by CO2 laser radiation on the surface of the MgO-PSZ

HRTEM study of orthorhombic zirconia in MgO-PSZ

High-resolution transmission electron microscopy (HRTEM) was used to study the phase of orthorhombic ZrO2 formed in magnesia partially stabilized zirconia (MgO-PSZ) during HRTEM specimen preparation. Based on the three reported crystal structures of orthorhombic ZrO2, with the space groups Pbcm, Pbc2(1) and Pbca, here it is shown that orthorhombic ZrO2 formed in MgO-PSZ has the Pbcm structure

Grinding Temperature Measurements in Magnesia-Partially-Stabilized Zirconia Using Infrared Spectrometry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65185/1/j.1151-2916.2003.tb00019.x.pd

On the correlation between Nd:YAG laser-induced wettability characteristics modification and osteoblast cell bioactivity on a titanium alloy

The factors responsible for modifications to the wettability characteristics of a titanium (Ti6Al4V) alloy bio-metal following Nd:YAG laser treatment and the effects thereof on the response of osteoblast cells were considered in this work. It was found that interaction of the Nd:YAG laser beam with the Ti6Al4V alloy resulted in the wettability characteristics of the bio-metal improving. Such improvements in the wettability characteristics of the Ti6Al4V alloy were found to be due to: an increase in the surface roughness; and increase in the surface oxygen content and an increase in the polar component of the surface energy. From the cell response tests it was determined that the osteoblast cell adhesion and proliferation on the Nd:YAG laser treated Ti6Al4V alloy samples was considerably greater than on the untreated samples. By isolating the effects of surface roughness it was possible to confirm or refute the existence of a correlation between wettability characteristics and osteoblast cell bioactivity for the Nd:YAG laser treated Ti6Al4V alloy. The findings indicated that the aspects of wettability characteristics: surface oxygen content and polar component of the surface energy play an important role in promoting cell proliferation, particularly when surface roughness was simultaneously increased. Thus it was possible to conclude that the wettability characteristics of the Nd:YAG laser treated Ti6Al4V alloy were correlated to osteoblast cell bioactivity

A scoping review on the surface modification of zirconia dental implants by laser texturing

O objetivo deste trabalho foi realizar uma revisão integrativa da literatura sobre a influência da irradiação a laser para aprimorar os aspetos topográficos da superfície de implantes de zircônia e o processo de cicatrização óssea. Foi realizada uma pesquisa eletrônica na base de dados PUBMED, usando os seguintes termos de pesquisa: “zirconia” AND “laser” AND “surface modification” OR “surface treatment” AND “dental implants” OR “bone” OR “osteoblast” OR “osseointegration”. Dos artigos identificados, 15 estudos foram selecionados nesta revisão. Os resultados relataram que a irradiação com laser foi capaz de promover alterações morfológicas nas superfícies de zircônia com aumento da rugosidade. O aumento na rugosidade foi registrado em escalas micro- e nano-métrica e resultou em um aumento na molhabilidade e adsorção de proteínas. Além disso, a adesão, a disseminação, a proliferação e a diferenciação de células osteogênicas aumentaram após a irradiação a laser, principalmente com um laser em fentosegundo, 10nJ de energia, e frequência de 80 MHz. Após 3 meses de osseointegração, os estudos in vivo em cães revelaram uma percentagem média de contato osso-implante para superfícies de zirconia (em torno de 47,9 ± 16%) quando comparados às superfícies padrão de titânio (61,73 ± 16,27%), demonstrando não haver diferença significativa entre os diferentes materiais. A técnica de irradiação a laser revelou ser sensível à vários parâmetros como tempo, intensidade e frequência. Os parâmetros do laser podem ser ainda otimizados e controlados para alcançar uma modificação da superfície e resposta biológica desejáveis tendo em consideração ao processo de osseointegraçã

Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces

Background Osseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility make zirconia a suitable material for dental implants, although surface processings are still problematic. The aim of the present study was to compare osteoblast behavior on structured zirconia and titanium surfaces under standardized conditions. Methods The surface characteristics were determined by scanning electron microscopy (SEM). In primary bovine osteoblasts attachment kinetics, proliferation rate and synthesis of bone-associated proteins were tested on different surfaces. Results The results demonstrated that the proliferation rate of cells was significantly higher on zirconia surfaces than on titanium surfaces (p < 0.05; Student's t-test). In contrast, attachment and adhesion strength of the primary cells was significant higher on titanium surfaces (p < 0.05; U test). No significant differences were found in the synthesis of bone-specific proteins. Ultrastructural analysis revealed phenotypic features of osteoblast-like cells on both zirconia and titanium surfaces. Conclusion The study demonstrates distinct effects of the surface composition on osteoblasts in culture. Zirconia improves cell proliferation significantly during the first days of culture, but it does not improve attachment and adhesion strength. Both materials do not differ with respect to protein synthesis or ultrastructural appearance of osteoblasts. Zirconium oxide may therefore be a suitable material for dental implants

Preparation and Characteristics of tetragonal phase zirconia using dolomite

Tetragonal zirconia polycrystal ceramics were stabilized by three different type of dolomite (white, black, cream). The TZP powders were synthesized by co-precipiatation method using ZrOCl2 and 3,4,5,6mol% dolomite solution with HCl .The precipitated gel were washed to give soft agglomerate with higher green density. The powder exhibited the tetragonal phase at 850°C temperature due to their small crystallite size. The phase evolution was the function of calcinations temperature. The densification behaviour shows a higher shrinkage rate for the compacts with white dolomite stabilized. These powders were compacted by uniaxial pressing and fired at 1400 to 1600°C for 4hrs.The relative density was higher for white dolomite stabilized TZP as compared to the other two for all sintering temperature and also it will increasing with temperature. This also retained the metastable tetragonal phase. The observed sintered compacts show an isotropic shrinkage which explains the better density and high hardness and compressive strength (in case of black dolomite) even at higher temperature

Microstructure and mechanical properties of bulk and plasma-sprayed y2O3-partially stabilized zirconia

Bulk 8.0 weight percent yttria partially stabilied zirconia (PSZ) was studied by light microscopy, transmission electron microscopy, X-ray analysis, microhardness testing, and fracture toughness testing. The as received PSZ contained spheroidal and grain boundary precipitates up to 4 micrometers in size. Spheroids up to 1.26 micrometers were metastable tetragonal; large spheroids were monoclinic. Grinding the PSZ into powder did not cause a significant amount of tetragonal to transform to monoclinic. This indicates that transformation toughness is not a significant mechanism in PSZ. Aging the PSZ at 1500 C caused the fine tetragonal precipitates to grow from 0.06 to 0.12 micrometers, in 250 minutes. A peak hardness of 1400 kg/sq mm was attained after 50 minutes. Solution annealing and quenching the as received PSZ eliminated the large precipitates, but fine tetragonal precipitates reformed on quenching. Aging at 1500 C caused the fine 0.02 micrometers tetragonal precipitates to grow into plates about 0.10 by 0.50 micrometers. A peak hardness of 1517 kg/sq mm was obtained after 250 minutes. On further aging, monoclinic percipitates formed along grain boundaries. The fracture toughness of the aged and unaged solution annealed and quenched PSZ was found to be between 2 and 3 MN /square root of m cubed. This range of fracture toughness is consistent with PSZ's that do not undergo transformation toughening

Effect of heat treatment on compressive fracture strength and microstructure of CNC milled zirconia dental restoration

Zirconia is commonly used in dental crown restoration due to its high strength, non-reactive and aesthetic properties compared to other materials. Zirconia crown fabricated using CNC milling machine can produce a final product with high accuracy and less time-consuming. However, the milling process affects the quality of the zirconia's surface, as a result of the tool and workpiece contact during the milling operation. This can lead to disruption of the microstructure and affect the fracture toughness of the zirconia crown. This deterioration becomes more apparent when the zirconia is not heat treated, but the suitable heat treatment temperature which can simultaneously improve the surface quality of the dental restoration is not known. Hence, the aims of this study are to analyse the compressive fracture strength of CNC milled zirconia dental restorations after being exposed to various heat-treatment temperatures, and to study the effectiveness of heat treatment in improving the surface quality of dental restoration. Therefore, eighteen samples from Y-TZP zirconia are grouped into two groups, which are the heat-treated and the untreated group. Three samples are set for the untreated and the remaining 15 samples are divided into 3 groups of different temperature which are 1400°C, 1500°C and 1600°C, with three samples per temperature setting. After heating, surface roughness of each sample is taken. Then, specimens are subjected to a single-load-testing to determine their compressive fracture strength. Next, the specimens are sputter coated to enhance the image before analysing the fractography under the SEM machine. This study shows that heat treatment does influence the compressive fracture toughness and surface roughness compared to untreated samples. However, there is no significant differences can be seen when the temperature increases. Nevertheless, it shows that the grain size increases when the temperature increases. Hence, optimum temperature to achieve better compressive fracture toughness and surface quality could not be determined. For future study, CNC machine must be more user-friendly and data- informative when fabricating the dental crown. Meanwhile, in order to determine the specimen's surface roughness, an optical profilometer should be employed in the future. The heating treatment furnace should have a heating and cooling rate for each temperature. Last but not least, since this experiment yielded no results about the transformation phase of the sample after being heat treated, X-Ray Diffraction (XRD) should be used in future researc

Influência da texturização de superfícies de zircónia por laser Nd:YAG à nano e micro escala no comportamento celular de osteoblastos

Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2020Objetivos: Avaliar o comportamento in vitro dos hFOB1.19 em contacto com diferentes superfícies de zircónia tetragonal policristalina estabilizada com ítrio (Y-TZP) texturizadas a laser Nd:YAG com padrões semelhantes aos obtidos por jateamento e ataque ácido. Materiais e Métodos: Osteoblastos fetais humanos (hFOB 1.19) foram cultivados durante 14 dias, em Y-TZP sinterizada (grupo A), Y-TZP modificada por jateamento e ataque ácido (grupo B) e por laser Nd:YAG cujo padrão consistiu em sulcos paralelos e perpendiculares espaçados entre si por 10 µm (grupo C) e por 20 µm (grupo D). Viabilidade e proliferação celular foram avaliadas ao 1º, 3º, 7º e 14º dia; a quantificação da interleucina 1β e de osteocalcina ao 1º e 3º dia pela técnica de ELISA; obtenção de imagens de microscopia eletrónica de varrimento (FEG- SEM) e de fluorescência ao 1º e 3º dia. A comparação entre os diferentes grupos foi realizada com recurso ao teste one-way ANOVA ou ao de Kruskal-Wallis, de acordo com o mais apropriado, e o teste de Tukey a fim de identificar diferenças estatisticamente significativas entre grupos. O nível de significância estabelecido foi p < 0.05. Resultados: Relativamente à viabilidade e proliferação celular, apenas se observaram diferenças estatisticamente significativas aos 7 dias de cultura, com valores superiores para o grupo A comparativamente ao grupo B (p=0,016). Na produção de interleucina 1β e de osteocalcina não se verificaram diferenças significativas, exceto aos 3 dias onde se verificou um aumento na produção de interleucina 1β no grupo D comparativamente ao grupo A (p=0,010). Pelas imagens de FEG-SEM e de fluorescência, verificou-se em todos os grupos adesão celular inicial no 1º dia e sem diferenças na morfologia celular. Conclusão: O comportamento in vitro dos hFOB 1.19 parece ser equivalente entre as superfícies de zircónia texturizadas a laser Nd:YAG e as superfícies jateadas e submetidas a ataque ácido.Aim: Evaluate the behavior of hFOB1.19 in contact with different surfaces of yttrium-stabilized polycrystalline zirconia (Y-TZP) Nd:YAG laser textured with patterns similar to the obtained by sandblasthing and acid-etching. Materials and Methods: Human fetal osteoblasts (hFOB 1.19) were cultured during fourteen days on sintered Y-TZP (group A), sandblasthing and acid-etching Y-TZP (group B) and Nd:YAG laser Y-TZP which pattern consisted parallel and perpendicular lines crossing 10 µm (group C) or 20 µm (group D) apart from each other. Cell viability and proliferation were assessed after one, three, seven, and fourteen days; quantification of interleukin 1β and osteocalcin after one and three days using the ELISA technique. Morphology and cell adhesion were observed using scanning electron microscopy (FEG-SEM) and fluorescence microscopy after one and three days of culture. The comparison between groups was performed using the one-way ANOVA test or the Kruskal-Wallis test, according to the most appropriate, and the Tukey post-hoc test to identify statistically significant differences between groups. The level of significance was p <0.05. Results: Cell viability and proliferation were only statistically significant after seven days of culture, with higher values for group A compared to group B (p = 0.016). In the production of interleukin 1β and osteocalcin there were no significant differences, except after three days where was an increase in the production of interleukin 1β in group D compared to group A (p = 0.010). From the FEG-SEM and fluorescence images, initial cell adhesion was verified in all groups after one day and no differences was observed in cell morphology. Conclusion: The in vitro behaviour of hFOB 1.19 appears to be equivalent between the Nd: YAG laser-textured zirconia surfaces and sandblasthing and acid-etching surfaces