RESUMEN

Crystal surfaces play a pivotal role in governing various significant processes, such as adsorption, nucleation, wetting, friction, and wear. A fundamental property that influences these processes is the surface free energy, γ. We have directly calculated γ(T) for low-index faces of Lennard-Jones (LJ), germanium, and silicon crystals along their sublimation lines using the computational cleavage technique. Our calculations agree well with experimental values for Si(111) and Ge(111), highlighting the accuracy of the method and models used. For LJ crystals, we identified a premelting onset at Tpm = 0.75Tm, marked by a sharp increase in atom mobility within the second outermost surface layer. Notably, Tpm closely aligned with the endpoint of the LJ melting line at negative pressures, Tend = 0.76Tm. We hypothesize that the emergence and coexistence of a liquid film atop the LJ crystal at Tpm < T < Tm correspond to the metastable melting line under negative pressures experienced by stretched crystal surfaces. Furthermore, our study of thin LJ crystal slabs reveals that premelting-induced failure leads to recrystallization below the homogeneous freezing limit, offering a promising avenue to explore crystal nucleation and growth at extremely deep supercoolings. Finally, no evidence of premelting was detected in the model crystals of Ge and Si, which is consistent with the experimental observations. Overall, our findings offer valuable insights into crystal surface phenomena at the atomic scale.

RESUMEN

In this article, we investigate the structural relaxation of lithium silicate glass during isothermal physical aging by monitoring the temporal evolution of its refractive index and enthalpy following relatively large (10-40 °C) up- and down-jumps in temperature. The Kohlrausch-Williams-Watts function aptly describes the up- and down-jump data when analyzed separately. For temperature down-jumps, the glass exhibits a typical stretched exponential kinetic behavior with the non-exponentiality parameter ß < 1, whereas up-jumps show a compressed exponential behavior (ß > 1). We analyzed these datasets using the non-exponential and non-linear Tool-Narayanaswamy-Moynihan (TNM) model, aiming to provide a comprehensive description of the primary or α-relaxation of the glass. This model described both up- and down-jump datasets using a single value of ß ≤ 1. However, the standard TNM model exhibited a progressively reduced capacity to describe the data for larger temperature jumps, which is likely a manifestation of the temperature dependence of the non-exponentiality or non-linearity of the relaxation process. We hypothesize that the compressed exponential relaxation kinetics observed for temperature up-jumps stems from a nucleation-growth-percolation-based evolution on the dynamically mobile regions within the structure, leading to a self-acceleration of the dynamics. On the other hand, temperature down-jumps result in self-retardation, as the slow-relaxing denser regions percolate in the structure to give rise to a stretched exponential behavior.

RESUMEN

Magnetic hyperthermia (MHT) is a therapy that uses the heat generated by a magnetic material for cancer treatment. Magnetite nanoparticles are the most used materials in MHT. However, magnetite has a high Curie temperature (Tc~580 °C), and its use may generate local superheating. To overcome this problem, strontium-doped lanthanum manganite could replace magnetite because it shows a Tc near the ideal range (42-45 °C). In this study, we developed a smart composite formed by an F18 bioactive glass matrix with different amounts of Lanthanum-Strontium Manganite (LSM) powder (5, 10, 20, and 30 wt.% LSM). The effect of LSM addition was analyzed in terms of sinterability, magnetic properties, heating ability under a magnetic field, and in vitro bioactivity. The saturation magnetization (Ms) and remanent magnetization (Mr) increased by the LSM content, the confinement of LSM particles within the bioactive glass matrix also caused an increase in Tc. Calorimetry evaluation revealed a temperature increase from 5 °C (composition LSM5) to 15 °C (LSM30). The specific absorption rates were also calculated. Bioactivity measurements demonstrated HCA formation on the surface of all the composites in up to 15 days. The best material reached 40 °C, demonstrating the proof of concept sought in this research. Therefore, these composites have great potential for bone cancer therapy and should be further explored.

RESUMEN

The surface free energy of solids, γ, plays a crucial role in all physical and chemical processes involving material surfaces. For the first time, we obtained γ directly from molecular dynamics simulations using a crystal cleavage method. The approach was successfully realized in a Lennard-Jones system by inserting two movable external walls, each consisting of a single crystal layer, into a bulk crystal to create flat, defect-free surfaces. The cleavage technique designed allowed us to calculate the surface free energy according to its definition and avoid surface premelting. The temperature dependence of γ was determined for the (100) and (110) crystal planes along the whole sublimation line and its metastable extension, up to T = 1.02 · Tm, where Tm is the melting point. Good agreement with indirect values of γ(T) was found. The proposed computational cleavage method can be applied to other solids of interest, providing valuable insight into the understanding of chemical and physical surface processes, and demonstrates the successful import of the cleavage method, traditionally used in technical preparation and study of crystal surfaces, into a modern atomistic simulation.

RESUMEN

OBJECTIVES: This study aimed to optimize the crystallization process and the microstructure of a new bioactive glass-ceramic (GC) previously developed by our research group to obtain machinable glass-ceramics. METHODS: Differential scanning calorimetry (DSC) analyses were conducted to explore the characteristic temperatures and construct a semi-quantitative nucleation curve. The GC specimens were characterized by X-ray diffraction (XRD) and Rietveld refinement. Their brittleness index (B) and machinability were characterized and compared with IPS e.max-CAD®. Their Young's modulus, fracture toughness, and hardness were assessed. RESULTS: We found that the maximum crystal nucleation rate temperature of this GC is ~470 °C. Treatments were designed based on the 1st DSC peak onset (570 °C), 1st peak offset (650 °C), and 2nd peak offset (705 °C) crystallization temperatures of lithium metasilicate (LS, LiSi2O3) and lithium disilicate (LS2, Li2Si2O5). Rietveld refinement indicated an increase in LS2 and a reduction in LS and amorphous phase for increased temperatures and longer treatment times. Their B values indicate good machinability compared with that of the control group based on statistical analyses. As expected, lower levels of LS2 increase the machinability regardless of the rotation speed adopted, leading to a greater depth of cut and reduced Edge Chipping Damage Depth (ECDD). CONCLUSION: This bioactive GC with optimized microstructure presents high machinability. For treatment temperatures above 570 °C, the number of elongated LS2 crystals increases and decreases the amorphous phase content, which reduce the machinability of the GC, and should therefore be avoided. The best results were obtained using heat treatment at 570 °C, which produces LS crystals embedded in a glassy matrix (67%) with small contents of secondary phases.

Asunto(s)

Cerámica , Porcelana Dental , Módulo de Elasticidad , Dureza , Ensayo de Materiales , Propiedades de Superficie

RESUMEN

This study evaluated the gene expression profile of the human adipose-derived stem cells (hASCs) grown on the Biosilicate® /F18 glass (BioS-2P/F18) scaffolds. hASCs were cultured using the osteogenic medium (control), the scaffolds, and their ionic extract. We observed that ALP activity was higher in hASCs grown on the BioS-2P/F18 scaffolds than in hASCs cultured with the ionic extract or the osteogenic medium on day 14. Moreover, the dissolution product group and the control exhibited deposited calcium, which peaked on day 21. Gene expression profiles of cell cultured using the BioS-2P/F18 scaffolds and their extract were evaluated in vitro using the RT2 Profiler polymerase chain reaction (PCR) microarray on day 21. Mineralizing tissue-associated proteins, differentiation factors, and extracellular matrix enzyme expressions were measured using quantitative PCR. The gene expression of different proteins involved in osteoblast differentiation was significantly up-regulated in hASCs grown on the scaffolds, especially BMP1, BMP2, SPP1, BMPR1B, ITGA1, ITGA2, ITGB1, SMAD1, and SMAD2, showing that both the composition and topographic features of the biomaterial could stimulate osteogenesis. This study demonstrated that gene expression of hASCs grown on the scaffold surface showed significantly increased gene expression related to hASCs cultured with the ionic extract or the osteogenic medium, evidencing that the BioS-2P/F18 scaffolds have a substantial effect on cellular behavior of hASCs.

Asunto(s)

Diferenciación Celular , Vidrio/química , Células Madre Mesenquimatosas/citología , Osteogénesis , Andamios del Tejido/química , Línea Celular , Células Cultivadas , Humanos , Células Madre Mesenquimatosas/metabolismo

RESUMEN

Biosilicate is a bioactive glass-ceramic used in medical and dental applications. This study evaluated novel reparative materials composed of pure tricalcium silicate (TCS), 30% zirconium oxide (ZrO2 ) and 10 or 20% biosilicate, in comparison with Biodentine. Setting time was evaluated based on ISO 6876 standard, radiopacity by radiographic analysis, solubility by mass loss, and pH by using a pH meter. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and NR assays. Alkaline phosphatase (ALP) activity and alizarin red were used to evaluate cell bioactivity. Antimicrobial activity was assessed on Enterococcus faecalis by the direct contact test. The data were submitted to analysis of variance (ANOVA)/Tukey; Bonferroni and Kruskal-Wallis, and Dunn tests (α = 0.05). The association of Biosilicate with TCS + ZrO2 had appropriate setting time, radiopacity, and solubility, alkaline pH, and antimicrobial activity. TCS and Biodentine showed higher ALP activity in 14 days than the control (serum-free medium). All cements produced mineralized nodules. In conclusion, Biosilicate + TCS ZrO2 decreased the setting time and increased the radiopacity in comparison to TCS. Biosilicate + TCS ZrO2 presented lower solubility and higher radiopacity than Biodentine. In addition, these experimental cements promoted antimicrobial activity and mineralization nodules formation, suggesting their potential for clinical use.

Asunto(s)

Compuestos de Calcio/química , Vidrio/química , Silicatos/química , Circonio/química , Fosfatasa Alcalina , Antraquinonas , Materiales Biocompatibles , Cementos para Huesos , Neoplasias Óseas/patología , Compuestos de Calcio/farmacología , Compuestos de Calcio/toxicidad , Línea Celular Tumoral , Cementos Dentales , Enterococcus faecalis/efectos de los fármacos , Humanos , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Osteosarcoma/patología , Cemento de Silicato , Silicatos/farmacología , Silicatos/toxicidad , Solubilidad , Circonio/farmacología , Circonio/toxicidad

RESUMEN

The validity of the classical nucleation theory (CNT), the most important tool to describe and predict nucleation kinetics in supercooled liquids, has been at stake for almost a century. Here, we carried out comprehensive molecular dynamics simulations of the nucleation kinetics of a fast quenched supercooled germanium using the Stillinger-Weber potential at six temperatures, covering a supercooling range of T/Tm = 0.70-0.86, where Tm is the equilibrium melting temperature. We used the seeding method to determine the number of particles in the critical crystal nuclei at each supercooling, which yielded n* = 150-1300 atoms. The transport coefficient at the liquid/nucleus interface and the melting point were also obtained from the simulations. Using the parameters resulting directly from the simulations, the CNT embraces the experimental nucleation rates, J(T), with the following fitted (average) values of the nucleus/liquid interfacial free energy: γ = 0.244 and 0.201 J/m2, for the experimental and calculated values of thermodynamic driving force, Δµ(T), respectively, which are close to the value obtained from n*(T). Without using any fit parameter, the calculated nucleation rates for the experimental and calculated values of Δµ(T) embrace the experimental J(T) curve. Therefore, this finding favors the validity of the CNT.

RESUMEN

Can any liquid be cooled down below its melting point to an isentropic (Kauzmann) temperature without vitrifying or crystallizing? This long-standing question concerning the ultimate fate of supercooled liquids is one of the key problems in condensed matter physics and materials science. In this article, we used a plethora of thermodynamic and kinetic data and well established theoretical models to estimate the kinetic spinodal temperature, TKS (the temperature where the average time for the first critical crystalline nucleus to appear becomes equal to the average relaxation time of a supercooled liquid), and the Kauzmann temperature, TK, for two substances. We focused our attention on selected compositions of the two most important oxide glass-forming systems: a borate and a silicate-which show measurable homogeneous crystal nucleation in laboratory time scales-as proxies of these families of glass-formers. For both materials, we found that the TKS are significantly higher than the predicted TK. Therefore, at ambient pressure, at deep supercoolings before approaching TK, crystallization wins the race over structural relaxation. Hence, the temperature of entropy catastrophe predicted by Kauzmann cannot be reached for the studied substances; it is averted by incipient crystal nucleation. Our finding that TKS > TK for two real glasses corroborate the results of computer simulations for a pressurized silica glass.

RESUMEN

In a recent article, Schmelzer and Tropin [Entropy 2018, 20, 103] presented a critique of several aspects of modern glass science, including various features of glass transition and relaxation, crystallization, and the definition of glass itself. We argue that these criticisms are at odds with well-accepted knowledge in the field from both theory and experiments. The objective of this short comment is to clarify several of these issues.

RESUMEN

The diffusion mechanisms controlling viscous flow, structural relaxation, liquid-liquid phase separation, crystal nucleation, and crystal growth in multicomponent glass-forming liquids are of great interest and relevance in physics, chemistry, materials, and glass science. However, the diffusing entities that control each of these important dynamic processes are still unknown. The main objective of this work is to shed some light on this mystery, advancing the knowledge on this phenomenon. For that matter, we measured the crystal growth rates, the viscosity, and lead diffusivities in PbSiO3 liquid and glass in a wide temperature range. We compared our measured values with published data covering 16 orders of magnitude. We suggest that above a certain temperature range Td (1.2Tg-1.3Tg), crystal growth and viscous flow are controlled by the diffusion of silicon and lead. Below this temperature, crystal growth and viscous flow are more sluggish than the diffusion of silicon and lead. Therefore, Td marks the temperature where decoupling between the (measured) cationic diffusivity and the effective diffusivities calculated from viscosity and crystal growth rates occurs. We reasonably propose that the nature or size of the diffusional entities controlling viscous flow and crystal growth below Td is quite different; the slowest is the one controlling viscous flow, but both processes require cooperative movements of some larger structural units rather than jumps of only one or a few isolated atoms.

RESUMEN

Calcium phosphates and bioactive glass ceramics have been considered promising biomaterials for use in surgeries. However, their moldability should be further enhanced. We here thereby report the handling, physicochemical features, and morphological characteristics of formulations consisting of carboxymethylcellulose-glycerol and hydroxyapatite-tricalcium phosphate or Biosilicate® particles. We hypothesized that combining either material with carboxymethylcellulose-glycerol would improve handling properties, retaining their bioactivity. In addition to scanning electron microscopy, cohesion, mineralization, pH, and viscoelastic properties of the novel formulations, cell culture experiments were performed to evaluate the cytotoxicity and cell proliferation. Putty-like formulations were obtained with improved cohesion and moldability. Remarkably, mineralization in simulated body fluid of hydroxyapatite-tricalcium phosphate/carboxymethylcellulose-glycerol formulations was enhanced compared to pure hydroxyapatite-tricalcium phosphate. Cell experiments showed that all formulations were noncytotoxic and that HA-TCP60 and BGC50 extracts led to an increased cell proliferation. We conclude that combining carboxymethylcellulose-glycerol with either hydroxyapatite-tricalcium phosphate or Biosilicate® allows for the generation of moldable putties, improves handling properties, and retains the ceramic bioactivity.

Asunto(s)

Sustitutos de Huesos/química , Fosfatos de Calcio/química , Carboximetilcelulosa de Sodio/análogos & derivados , Durapatita/química , Vidrio/química , Glicerol/química , Animales , Línea Celular , Proliferación Celular , Supervivencia Celular , Elasticidad , Ratones , Viscosidad

RESUMEN

Understanding the conditions that favour crystallisation and vitrification has been a longstanding scientific endeavour. Here we demonstrate that the extremely high glass-forming ability of unseeded supercooled Na2O·Al2O3·6SiO2 (Albite) and B2O3-known for decades as "crystallisation anomaly"-is caused by insufficient crystal nucleation. The predicted temperatures of the maximum homogeneous nucleation rates are located well below their glass transition temperatures (Tg), in a region of very high viscosity, which leads to extremely long nucleation time-lags and low nucleation rates. This behaviour is due to the remarkably small supercoolings where the glass transition occurs for these liquids, which correspond to a very small driving force for crystallisation at and above the Tg, where crystallisation is normally observed. This meagre nucleation ability is caused by the significant difference in the structures of the supercooled liquids and their isochemical crystals. These findings elucidate the cause behind the crystallisation anomaly, and could be used for the design of other oxide glasses that are extremely stable against crystallisation.

RESUMEN

This study evaluated the biocompatibility of Biosilicate® scaffolds by means of histopathological, cytotoxicity, and genotoxicity analysis. The histopathologic analysis of the biomaterial was performed using 65 male rats, distributed into the groups: control and Biosilicate®, evaluated at 7, 15, 30, 45, and 60 days after implantation. The cytotoxicity analysis was performed by the methyl thiazolyl tetrazolium (MTT) assay, with various concentrations of extracts from the biomaterial in culture of osteoblasts and fibroblasts after 24, 72, and 120 h. The genotoxicity analysis (comet assay) was performed in osteoblasts and fibroblasts after contact with the biomaterial during 24, 72, and 96 h. In the histopathology analysis, we observed a foreign body reaction, characterized by the presence of granulation tissue after 7 days of implantation of the biomaterial, and fibrosis connective tissue and multinucleated giant cells for longer periods. In the cytotoxicity analysis, extracts from the biomaterial did not inhibit the proliferation of osteoblasts and fibroblasts, and relatively low concentrations (12.5% and 25%) stimulated the proliferation of both cell types after 72 and 120 h. The analysis of genotoxicity showed that Biosilicate® did not induce DNA damage in both lineages tested in all periods. The results showed that the Biosilicate® scaffolds present in vivo and in vitro biocompatibility.

Asunto(s)

Cerámica/química , Daño del ADN , Fibroblastos , Vidrio , Ensayo de Materiales , Osteoblastos , Andamios del Tejido/química , Animales , Fibroblastos/metabolismo , Fibroblastos/patología , Humanos , Masculino , Osteoblastos/metabolismo , Osteoblastos/patología , Ratas , Ratas Wistar , Factores de Tiempo

RESUMEN

PURPOSE: Bioactive glass and bioactive glass-ceramic cone implants were placed in the rabbit eviscerated socket to assess their biocompatibility. METHODS: Fifty-one Norfolk albino rabbits underwent evisceration of the right eye followed by implantation of cones made from Bioglass(®) 45S5 (control group) and two types of bioactive glass-ceramic (Biosilicate(®)), a single- and a two-phase bioactive glass-ceramic implants into the scleral cavity. Postoperative reactions, animal behavior and socket conditions were monitored daily. Clinical exam, biochemical evaluations, and orbit computed tomographic scan were done at 7, 90, and 180 days post-procedure. After that, the animals were euthanized, and the orbital content was removed and prepared to light microscopy with morphometric evaluation and scanning electron microscopy examination. Statistical analysis was done by parametric and non-parametric analysis of variance, complemented by Dunn's and Tukey's tests (p < 0.05). RESULTS: All animals did not develop systemic toxicity throughout the experimental period and also did not have orbit infection, implant migration or extrusion. Morphological analysis demonstrated pseudocapsule around all implants. Bioglass(®) and single-phase Biosilicate(®) implants induced less inflammation and pseudocapsule formation than two-phase Biosilicate(®) cones. Seven days post-procedure, the inflammatory reaction was intense and gradually decreased throughout the experiment. Tissue reaction was least intense in animals receiving Bioglass(®) implants. CONCLUSIONS: We observe discrete differences among the studied materials, with best responses obtained with use of Bioglass(®) 45S5 and single-phase Biosilicate(®). The authors agree these implants might be useful in the management of the anophthalmic socket.

Asunto(s)

Materiales Biocompatibles , Cerámica , Modelos Animales de Enfermedad , Evisceración del Ojo , Vidrio , Órbita/cirugía , Implantes Orbitales , Animales , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Órbita/diagnóstico por imagen , Implantación de Prótesis , Conejos , Radiografía

RESUMEN

Bioactive glasses having chemical compositions between 1Na(2)O-2CaO-3SiO(2) (1N2C3S) and 1.5Na(2)O-1.5CaO-3SiO(2) (1N1C2S) containing 0, 4 and 6 wt.% P(2)O(5) were crystallized through two stage thermal treatments. By carefully controlling these treatments we separately studied the effects on the mechanical properties of two important microstructural features not studied before, crystallized volume fraction and crystal size. Fracture strength, elastic modulus and indentation fracture toughness were measured as a function of crystallized volume fraction for a constant crystal size. Glass-ceramics with a crystalline volume fraction between 34% and 60% exhibited a three-fold improvement in fracture strength and an increase of 40% in indentation fracture toughness compared with the parent glass. For the optimal crystalline concentration (34% and 60%) these mechanical properties were then measured for different grain sizes, from 5 to 21 µm. The glass-ceramic with the highest fracture strength and indentation fracture toughness was that with 34% crystallized volume fracture and 13 µm crystals. Compared with the parent glass, the average fracture strength of this glass-ceramic was increased from 80 to 210 MPa, and the fracture toughness from 0.60 to 0.95 MPa.m(1/2). The increase in indentation fracture toughness was analyzed using different theoretical models, which demonstrated that it is due to crack deflection. Fortunately, the elastic modulus E increased only slightly; from 60 to 70 GPa (the elastic modulus of biomaterials should be as close as possible to that of cortical bone). In summary, the flexural strength of our best material (215 MPa) is significantly greater than that of cortical bone and comparable with that of apatite-wollastonite (A/W) bioglass ceramics, with the advantage that it shows a much lower elastic modulus. These results thus provide a relevant guide for the design of bioactive glass-ceramics with improved microstructure.

Asunto(s)

Cerámica/química , Vidrio/química , Animales , Materiales Biocompatibles/química , Cristalización , Elasticidad , Dureza , Humanos , Ensayo de Materiales , Estrés Mecánico

RESUMEN

This study aimed to investigate bone responses to a novel bioactive fully crystallized glass-ceramic of the quaternary system P(2)O(5)-Na(2)O-CaO-SiO(2) (Biosilicate®). Although a previous study demonstrated positive effects of Biosilicate® on in vitro bone-like matrix formation, its in vivo effect was not studied yet. Male Wistar rats (n = 40) with tibial defects were used. Four experimental groups were designed to compare this novel biomaterial with a gold standard bioactive material (Bioglass® 45S5), unfilled defects and intact controls. A three-point bending test was performed 20 days after the surgical procedure, as well as the histomorphometric analysis in two regions of interest: cortical bone and medullary canal where the particulate biomaterial was implanted. The biomechanical test revealed a significant increase in the maximum load at failure and stiffness in the Biosilicate® group (vs. control defects), whose values were similar to uninjured bones. There were no differences in the cortical bone parameters in groups with bone defects, but a great deal of woven bone was present surrounding Biosilicate® and Bioglass® 45S5 particulate. Although both bioactive materials supported significant higher bone formation; Biosilicate® was superior to Bioglass® 45S5 in some histomorphometric parameters (bone volume and number of osteoblasts). Regarding bone resorption, Biosilicate® group showed significant higher number of osteoclasts per unit of tissue area than defect and intact controls, despite of the non-significant difference in the osteoclastic surface as percentage of bone surface. This study reveals that the fully crystallized Biosilicate® has good bone-forming and bone-bonding properties.

Asunto(s)

Sustitutos de Huesos/farmacología , Cerámica/farmacología , Ensayo de Materiales , Tibia/lesiones , Tibia/patología , Animales , Resorción Ósea/metabolismo , Resorción Ósea/patología , Masculino , Tamaño de los Órganos , Osteoblastos/metabolismo , Osteoblastos/patología , Osteoclastos/metabolismo , Osteoclastos/patología , Ratas , Ratas Wistar , Tibia/metabolismo

RESUMEN

OBJECTIVES: The aims of this research were to evaluate the efficacy of a bioactive glass-ceramic (Biosilicate) and a bioactive glass (Biogran) placed in dental sockets in the maintenance of alveolar ridge and in the osseointegration of Ti implants. MATERIAL AND METHODS: Six dogs had their low premolars extracted and the sockets were implanted with Biosilicate, Biogran particles, or left untreated. After the extractions, measurements of width and height on the alveolar ridge were taken. After 12 weeks a new surgery was performed to take the final ridge measurements and to insert bilaterally three Ti implants in biomaterial-implanted and control sites. Eight weeks post-Ti implant placement block biopsies were processed for histological and histomorphometric analysis. The percentages of bone-implant contact (BIC), of mineralized bone area between threads (BABT), and of mineralized bone area within the mirror area (BAMA) were determined. RESULTS: The presence of Biosilicate or Biogran particles preserved alveolar ridge height without affecting its width. No significant differences in terms of BIC, BAMA, and BABT values were detected among Biosilicate, Biogran, and the non-implanted group. CONCLUSIONS: The results of the present study indicate that filling of sockets with either Biosilicate or Biogran particles preserves alveolar bone ridge height and allows osseointegration of Ti implants.

Asunto(s)

Proceso Alveolar/cirugía , Materiales Biocompatibles/farmacología , Cerámica , Implantación Dental Endoósea/métodos , Implantes Dentales , Vidrio , Oseointegración/efectos de los fármacos , Animales , Perros , Titanio , Alveolo Dental/cirugía

RESUMEN

The purpose of this study was to investigate the effects of Bioglass 45S5 and Biosilicate, on bone defects inflicted on the tibia of rats. Fifty male Wistar rats were used in this study, and divided into five groups, including a control group, to test Biosilicate and Bioglass materials of two different particle sizes (180-212 microm or 300-355 microm). All animals were sacrificed 15 days after surgery. No significant differences (P > 0.05) were found when values for Maximal load, Energy Absorption and Structural Stiffness were compared among the groups. Histopathological evaluation revealed osteogenic activity in the bone defect for the control group. Nevertheless, it seems that the amount of fully formed bone was higher in specimens treated with Biosilicate (granulometry 300-355 microm) when compared to the control group. The same picture occurred regarding Biosilicate with granulometry 180-212 microm. Morphometric findings for bone area results (%) showed no statistically significant differences (P > 0.05) among the groups. Taken together, such findings suggest that, Biosilicate exerts more osteogenic activity when compared to Bioglass under subjective histopathological analysis.

Asunto(s)

Cerámica , Silicatos/química , Tibia/crecimiento & desarrollo , Animales , Fenómenos Biomecánicos , Vidrio , Masculino , Ratas , Ratas Wistar , Tibia/patología