In vitro evaluation of the osteogenic and antimicrobial potential of porous wollastonite scaffolds impregnated with ethanolic extracts of propolis.

Context: The development of porous devices using materials modified with various natural agents has become a priority for bone healing processes in the oral and maxillofacial field. There must be a balance between the proliferation of eukaryotic and the inhibition of prokaryotic cells to achieve proper bone health. Infections might inhibit the formation of new alveolar bone during bone graft augmentation. Objective: This study aimed to evaluate the in vitro osteogenic behavior of human bone marrow stem cells and assess the antimicrobial response to 3D-printed porous scaffolds using propolis-modified wollastonite. Methodology: A fractional factorial design of experiments was used to obtain a 3D printing paste for developing scaffolds with a triply periodic minimal surface (TPMS) gyroid geometry based on wollastonite and modified with an ethanolic propolis extract. The antioxidant activity of the extracts was characterized using free radical scavenging methods (DPPH and ABTS). Cell proliferation and osteogenic potential using Human Bone Marrow Stem Cells (bmMSCs) were assessed at different culture time points up to 28 days. MIC and inhibition zones were studied from single strain cultures, and biofilm formation was evaluated on the scaffolds under co-culture conditions. The mechanical strength of the scaffolds was evaluated. Results: Through statistical design of experiments, a paste suitable for printing scaffolds with the desired geometry was obtained. Propolis extracts modifying the TPMS gyroid scaffolds showed favorable cell proliferation and metabolic activity with osteogenic potential after 21 days. Additionally, propolis exhibited antioxidant activity, which may be related to the antimicrobial effectiveness of the scaffolds against S. aureus and S. epidermidis cultures. The mechanical properties of the scaffolds were not affected by propolis impregnation. Conclusion: These results demonstrate that propolis-impregnated porous wollastonite scaffolds might have the potential to stimulate bone repair in maxillofacial tissue engineering applications.

Antibacterial and osteoinductive properties of wollastonite scaffolds impregnated with propolis produced by additive manufacturing.

Biocompatible ceramic scaffolds offer a promising approach to address the challenges in bone reconstruction. Wollastonite, well-known for its exceptional biocompatibility, has attracted significant attention in orthopedics and craniofacial fields. However, the antimicrobial properties of wollastonite have contradictory findings, necessitating further research to enhance its antibacterial characteristics. This study aimed to explore a new approach to improve in vitro biological response in terms of antimicrobial activity and cell proliferation by taking advantage of additive manufacturing for the development of scaffolds with complex geometries by 3D printing using propolis-modified wollastonite. The scaffolds were designed with a TPMS (Triply Periodic Minimal Surface) gyroid geometric shape and 3D printed prior to impregnation with propolis extract. The paste formulation was characterized by rheometric measurements, and the presence of propolis was confirmed by FTIR spectroscopy. The scaffolds were comprehensively assessed for their mechanical strength. The biological characterization involved evaluating the antimicrobial effects against Staphylococcus aureus and Staphylococcus epidermidis, employing Minimum Inhibitory Concentration (MIC), Zone of Inhibition (ZOI), and biofilm formation assays. Additionally, SaOs-2 cultures were used to study cell proliferation (Alamar blue assay), and potential osteogenic was tested (von Kossa, Alizarin Red, and ALP stainings) at different time points. Propolis impregnation did not compromise the mechanical properties of the scaffolds, which exhibited values comparable to human trabecular bone. Propolis incorporation conferred antibacterial activity against both Staphylococcus aureus and Staphylococcus epidermidis. The implementation of TPMS gyroid geometry in the scaffold design demonstrated favorable cell proliferation with increased metabolic activity and osteogenic potential after 21 days of cell cultures.

Effects of Propolis Impregnation on Polylactic Acid (PLA) Scaffolds Loaded with Wollastonite Particles against Staphylococcus aureus, Staphylococcus epidermidis, and Their Coculture for Potential Medical Devices.

Several diseases and injuries cause irreversible damage to bone tissues, which may require partial or total regeneration or replacement. Tissue engineering suggests developing substitutes that may contribute to the repair or regeneration process by using three-dimensional lattices (scaffolds) to create functional bone tissues. Herein, scaffolds comprising polylactic acid and wollastonite particles enriched with propolis extracts from the Arauca region of Colombia were developed as gyroid triply periodic minimal surfaces using fused deposition modeling. The propolis extracts exhibited antibacterial activity against Staphylococcus aureus (ATCC 25175) and Staphylococcus epidermidis (ATCC 12228), which cause osteomyelitis. The scaffolds were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, contact angle, swelling, and degradation. Their mechanical properties were assessed using static and dynamic tests. Cell viability/proliferation assay was conducted using hDP-MSC cultures, while their bactericidal properties against monospecies cultures (S. aureus and S. epidermidis) and cocultures were evaluated. The wollastonite particles did not affect the physical, mechanical, or thermal properties of the scaffolds. The contact angle results showed that there were no substantial differences in the hydrophobicity between scaffolds with and without particles. Scaffolds containing wollastonite particles suffered less degradation than those produced using PLA alone. A representative result of the cyclic tests at Fmax = 450 N showed that the maximum strain reached after 8000 cycles is well below the yield strain (i.e., <7.5%), thereby indicating that even under these stringent conditions, these scaffolds will be able to work properly. The scaffolds impregnated with propolis showed a lower % of cell viability using hDP-MSCs on the 3rd day, but these values increased on the 7th day. These scaffolds exhibited antibacterial activity against the monospecies cultures of S. aureus and S. epidermidis and their cocultures. The samples without propolis loads did not show inhibition halos, whereas those loaded with EEP exhibited halos of 17.42 ± 0.2 mm against S. aureus and 12.9 ± 0.5 mm against S. epidermidis. These results made the scaffolds possible bone substitutes that exert control over species with a proliferative capacity for the biofilm-formation processes required for typical severe infectious processes.

Fabrication of polycaprolactone/calcium phosphates hybrid scaffolds impregnated with plant extracts using 3D printing for potential bone regeneration.

The increase in critical bone diseases and defects in the world's population increases the need for bone substitutes to restore form and function. Organic and inorganic scaffolds with antibacterial properties could provide advantages for bone regeneration. In this study, we obtained scaffolds of polycaprolactone (PCL) charged with calcium phosphates nanoparticles and impregnated with extracts of Colombian plants as an alternative for potential bone regeneration. Calcium phosphate nanoparticles were obtained via auto-combustion synthesis. The nanoparticles were incorporated into the PCL with a chemical dissolution-disperse process. The composite obtained was used to produce a filament to print Triply Periodic Minimal Surface (TPMS) based scaffolds. Such geometry facilitates cellular growth thanks to its interconnected porosity. The scaffolds were impregnated with extracts of Justicia cf colorifera (Acanthaceae), and Billia rosea (Sapindaceae) due to their ancestral medical applications. A physical and biological characterization was conducted. The process to print scaffolds with an enhanced geometry to facilitate the flux of biological fluids was successful. The scaffolds loaded with B. rosea showed strong antibacterial behavior, suggesting the presence of reported terpenoids with antibacterial properties. The approach used in this study evidenced promising prospects for bone defect repair.

Translucency of a Dental Porcelain Mixed by Two Ceramic Slurry Methods: A Bayesian Comparison.

Background: The ceramics industry produces porcelain pastes using a controlled ratio of water and porcelain powder. Two methods are used to produce a dental porcelain paste: one-step mixing or incremental mixing. Objective: To evaluate the optical properties of a feldspathic dental ceramic using two different ceramic paste preparation methods using a Bayesian approach. Materials and Methods: Two groups of feldspathic porcelain discs, an incremental mixing group (n = 40) and a one-step mixing group (n = 40), were assessed. Groups were evaluated using spectrophotometry, and the translucency parameter (TP) of each sample was calculated. Surfaces were characterized by AFM and SEM. Statistical analysis was performed using a Bayesian approach. Results: Translucency parameter values of the incremental mixing group ranged from 1.65 to 3.41, while values for the one-step mixing group ranged from 3.62 to 5.74, this difference being statistically significant. The lowest roughness was obtained on the surface of discs in the one-step mixing group. Conclusions: Feldspathic porcelain with lower translucency and higher roughness was obtained using the incremental mixture method.

Chemical, structural and mechanical characterization of bovine enamel.

OBJECTIVE: The purpose of this investigation was to establish microstructure, microhardness, fracture toughness, chemical composition, and crack repair of bovine enamel and to compare these features with their human counterparts. DESIGN: Bovine enamel fragments were prepared and optical microscopy and atomic force microscopy were used to establish microstructure; Raman spectroscopy was used to estimate composition and microindentation using Vickers testing was performed to evaluate hardness. RESULTS: A strong dependence between indentation load and microhardness values was observed, as was the case in human enamel. Similar microstructure and chemical composition between bovine and human enamel, 7.89% lower microhardness and 40% higher fracture toughness values for bovine enamel were found. CONCLUSION: From a structural and mechanical standpoint, bovine enamel is a suitable alternative to human enamel for in vitro testing of dental products.

A novel approach to create an antibacterial surface using titanium dioxide and a combination of dip-pen nanolithography and soft lithography.

Soft lithography and Dip-Pen Nanolithography (DPN) are techniques that have been used to modify the surface of biomaterials. Modified surfaces play a role in reducing bacterial adhesion and biofilm formation. Also, titanium dioxide has been reported as an antibacterial substance due to its photocatalytic effect. This work aimed at creating patterns on model surfaces using DPN and soft lithography combined with titanium dioxide to create functional antibacterial micropatterned surfaces, which were tested against Streptococcus mutans. DPN was used to create a master pattern onto a model surface and microstamping was performed to duplicate and transfer such patterns to medical-grade stainless steel 316L using a suspension of TiO2. Modified SS316L plates were subjected to UVA black light as photocatalytic activator. Patterns were characterized by atomic force microscopy and biologically evaluated using S. mutans. A significant reduction of up to 60% in bacterial adhesion to TiO2 -coated and -micropatterned surfaces was observed. Moreover, both TiO2 surfaces reduced the viability of adhered bacteria after UV exposure. TiO2 micropatterned demonstrated a synergic effect between physical and chemical modification against S. mutans. This dual effect was enhanced by increasing TiO2 concentration. This novel approach may be a promising alternative to reduce bacterial adhesion to surfaces.

Self-Assembled Monolayers for Dental Implants.

Implant-based therapy is a mature approach to recover the health conditions of patients affected by edentulism. Thousands of dental implants are placed each year since their introduction in the 80s. However, implantology faces challenges that require more research strategies such as new support therapies for a world population with a continuous increase of life expectancy, to control periodontal status and new bioactive surfaces for implants. The present review is focused on self-assembled monolayers (SAMs) for dental implant materials as a nanoscale-processing approach to modify titanium surfaces. SAMs represent an easy, accurate, and precise approach to modify surface properties. These are stable, well-defined, and well-organized organic structures that allow to control the chemical properties of the interface at the molecular scale. The ability to control the composition and properties of SAMs precisely through synthesis (i.e., the synthetic chemistry of organic compounds with a wide range of functional groups is well established and in general very simple, being commercially available), combined with the simple methods to pattern their functional groups on complex geometry appliances, makes them a good system for fundamental studies regarding the interaction between surfaces, proteins, and cells, as well as to engineering surfaces in order to develop new biomaterials.

Soft Lithography and Minimally Human Invasive Technique for Rapid Screening of Oral Biofilm Formation on New Microfabricated Dental Material Surfaces.

INTRODUCTION: Microfabrication offers opportunities to study surface concepts focused to reduce bacterial adhesion on implants using human minimally invasive rapid screening (hMIRS). Wide information is available about cell/biomaterial interactions using eukaryotic and prokaryotic cells on surfaces of dental materials with different topographies, but studies using human being are still limited. OBJECTIVE: To evaluate a synergy of microfabrication and hMIRS to study the bacterial adhesion on micropatterned surfaces for dental materials. MATERIALS AND METHODS: Micropatterned and flat surfaces on biomedical PDMS disks were produced by soft lithography. The hMIRS approach was used to evaluate the total oral bacterial adhesion on PDMS surfaces placed in the oral cavity of five volunteers (the study was approved by the University Ethical Committee). After 24 h, the disks were analyzed using MTT assay and light microscopy. RESULTS: In the present pilot study, microwell structures were microfabricated on the PDMS surface via soft lithography with a spacing of 5 µm. Overall, bacterial adhesion did not significantly differ between the flat and micropatterned surfaces. However, individual analysis of two subjects showed greater bacterial adhesion on the micropatterned surfaces than on the flat surfaces. SIGNIFICANCE: Microfabrication and hMIRS might be implemented to study the cell/biomaterial interactions for dental materials.

Effects of Line and Pillar Array Microengineered SiO2 Thin Films on the Osteogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells.

A primary goal in bone tissue engineering is the design of implants that induce controlled, guided, and rapid healing. The events that normally lead to the integration of an implant into bone and determine the performance of the device occur mainly at the tissue-implant interface. Topographical surface modification of a biomaterial might be an efficient tool for inducing stem cell osteogenic differentiation and replace the use of biochemical stimuli. The main goal of this work was to develop micropatterned bioactive silica thin films to induce the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) only through topographical stimuli. Line and pillar micropatterns were developed by a combination of sol-gel/soft lithography and characterized by scanning electron microscopy, atomic force microscopy, and contact angle measurements. hMSCs were cultured onto the microfabricated thin films and flat control for up to 21 days under basal conditions. The micropatterned groups induced levels of osteogenic differentiation and expression of osteoblast-associated markers higher than those of the flat controls. Via comparison of the micropatterns, the pillars caused a stronger response of the osteogenic differentiation of hMSCs with a higher level of expression of osteoblast-associated markers, ALP activity, and extracellular matrix mineralization after the cells had been cultured for 21 days. These findings suggest that specific microtopographic cues can direct hMSCs toward osteogenic differentiation.

Modulation of human dermal microvascular endothelial cell and human gingival fibroblast behavior by micropatterned silica coating surfaces for zirconia dental implant applications.

Dental ceramic implants have shown superior esthetic behavior and the absence of induced allergic disorders when compared to titanium implants. Zirconia may become a potential candidate to be used as an alternative to titanium dental implants if surface modifications are introduced. In this work, bioactive micropatterned silica coatings were produced on zirconia substrates, using a combined methodology of sol-gel processing and soft lithography. The aim of the work was to compare the in vitro behavior of human gingival fibroblasts (HGFs) and human dermal microvascular endothelial cells (HDMECs) on three types of silica-coated zirconia surfaces: flat and micropatterned (with pillars and with parallel grooves). Our results showed that cells had a higher metabolic activity (HGF, HDMEC) and increased gene expression levels of fibroblast-specific protein-1 (FSP-1) and collagen type I (COL I) on surfaces with pillars. Nevertheless, parallel grooved surfaces were able to guide cell growth. Even capillary tube-like networks of HDMEC were oriented according to the surface geometry. Zirconia and silica with different topographies have shown to be blood compatible and silica coating reduced bacteria adhesion. All together, the results indicated that microstructured bioactive coating seems to be an efficient strategy to improve soft tissue integration on zirconia implants, protecting implants from peri-implant inflammation and improving long-term implant stabilization. This new approach of micropatterned silica coating on zirconia substrates can generate promising novel dental implants, with surfaces that provide physical cues to guide cells and enhance their behavior.

Effects of density of anisotropic microstamped silica thin films on guided bone tissue regeneration--in vitro study.

The growing demand for better implant aesthetics has led to increased research on the development of all-ceramic dental implants. The use of microtextured coatings with enhanced properties has been presented as a viable way to improve tissue integrability of all-ceramic implants. The aim of this study was to evaluate the effects of different densities of anisotropic microtextured silica thin films, which served as a model coating, on the behavior of human osteoblast-like cells. The differential responses of human osteoblast-like cells to anisotropic silica microtextures with varying densities, produced via a combination of sol-gel and soft lithography processing, were evaluated in terms of alignment, elongation (using fluorescence microscopy), overall cellular activity, and the expression/activity levels of alkaline phosphatase (ALP). Statistical analysis was conducted using one-way ANOVA/Tukey HSD post hoc test. The thin films were thoroughly characterized via scanning electron microscopy/energy dispersive spectroscopy, Fourier transform infrared, and contact angle measurements. Thin film characterization revealed increased nanoscale roughness and reduced wettability on the micropatterned surfaces. Cell culture experiments indicated that the microtextures induced cell alignment, elongation, and guided colonization on the surface. Cells cultured on denser micropatterns exhibited increased metabolic activity (t = 14-21 days). The early expression/activity levels of ALP released into the medium were found to be significantly higher only on the least dense micropattern. These results suggest the possibility that microstructured silica thin films could be used to guide and enhance peri-implant cell/tissue responses, potentially improving tissue integration for metallic and all-ceramic dental implants.

Reinforced Portland cement porous scaffolds for load-bearing bone tissue engineering applications.

Modified Portland cement porous scaffolds with suitable characteristics for load-bearing bone tissue engineering applications were manufactured by combining the particulate leaching and foaming methods. Non-crosslinked polydimethylsiloxane was evaluated as a potential reinforcing material. The scaffolds presented average porosities between 70 and 80% with mean pore sizes ranging from 300 µm up to 5.0 mm. Non-reinforced scaffolds presented compressive strengths and elastic modulus values of 2.6 and 245 MPa, respectively, whereas reinforced scaffolds exhibited 4.2 and 443 MPa, respectively, an increase of ∼62 and 80%. Portland cement scaffolds supported human osteoblast-like cell adhesion, spreading, and propagation (t = 1-28 days). Cell metabolism and alkaline phosphatase activity were found to be enhanced at longer culture intervals (t ≥ 14 days). These results suggest the possibility of obtaining strong and biocompatible scaffolds for bone repair applications from inexpensive, yet technologically advanced materials such as Portland cement.

The effect of slurry preparation methods on biaxial flexural strength of dental porcelain.

STATEMENT OF PROBLEM: One-step and incremental mixing procedures are currently used to produce dental ceramic pastes. In the ceramic industry, high quality is obtained using one-step mixing, but in dentistry, the best method has not been yet determined. PURPOSE: The purpose of this study is to evaluate the effects of 2 mixing techniques on the biaxial flexural strength and microstructure of dental porcelain. MATERIAL AND METHODS: Feldspathic porcelain discs (2 × 15 mm in diameter) were produced and divided according to the ceramic paste preparation method, powder-liquid incremental mixing group (n=50) or one-step mixing, as a control group (n=50). Specimens were tested for biaxial flexural strength and characterized using porosimetry, relative humidity, SEM/EDS, XRD, and FT-IR analyses. Statistical analysis was conducted using Weibull statistics. The Weibull modulus, characteristic strength and relative humidity were compared between groups, using Student's t-test and Mann-Whitney U test (α=.05). RESULTS: The powder-liquid incremental mixing group showed significantly higher values (SD) of Weibull modulus (6.74 (0.70), P<.001) and characteristic strength (79.87 (2.01) MPa, P<.001) when compared to the one-step mixing group (4.94 (0.94) and 75.95 (2.61) MPa). Significantly lower mean (SD) relative humidity values (P=.009) were found for powder-liquid incremental mixing group (20% (0.5%)) compared to one-step mixing group (22% (1%)). XRD spectra showed that the one-step mixing group produced higher amounts of the amorphous phase. CONCLUSIONS: Specimens produced by the incremental mixing technique showed higher biaxial flexural strength than one-step mixing.

Evaluación de la fricción en arcos ortodóncicos de acero inoxidable con y sin recubrimiento vítreo aplicado por el método Sol-Gel / Friction evaluation in stainless steel arches with and withouth glass coating using the Sol-Gel method

Introducción: el propósito de este estudio in vitro fue comparar la fuerza de fricción estática y dinámica generada entre brackets y alambres de acero inoxidable con y sin recubrimiento vítreo aplicado por el método Sol-Gel. Métodos: en todas las pruebas de fricción fueron utilizados brackets (0,018 x 0,025”), alambres de acero inoxidable (0,016 x 0,016”) y ligaduras elásticas. Se realizó una caracterización con microscopia óptica y microscopia electrónica de barrido (SE M). La fuerza friccional fue evaluada utilizando una máquina de pruebas Testresources® en medio seco. Resultados: los resultados mostraron que el grupo de alambres de acero inoxidable sin modificación (grupo control) presentaron los valores más bajos de fuerza de fricción estática, seguido del grupo de alambres recubiertos por el método Sol-Gel (grupo Sol-Gel) y el grupo de alambres con tratamiento térmico (grupo térmico). Para la fricción dinámica, el grupo Sol-Gel mostró los valores más bajos, seguido del grupo control y el grupo térmico. Conclusión: los recubrimientos evaluados no mostraron mejor comportamiento friccional sobre brackets de acero inoxidable cuando son comparados con el grupo control.

Introduction: the aim of this in vitro study was to compare the static and dynamic frictional force generated between surfaces of metallic brackets and glass coated applied by the Sol-Gel method, and non coated wires. Methods: metallic brackets (0,018 x 0,025″), stainless steel wires (0,016 x 0,016″) and elastic ligatures were used in all frictional tests. All components were characterized using SEM and optical microscopy. The frictional force was evaluated using a machine of tests Testresources® in dry environment. Results: the results showed that the stainless steel wires without modification (control group) showed the lowest values of static friction force followed by the stainless steel wires group coated by Sol-Gel method and the wires group with thermic treatment (thermic group). For dynamic friction force, the Sol-Gel group showed the smallest values, followed by the control group and the thermal group. Conclusion: the evaluated coating did not show a better frictional performance applied on stainless steel brackets in comparison with the control group.

Evaluación in vitro de la resistencia friccional entre brackets cerámicos y arcos de acero inoxidable con y sin recubrimiento vítreo aplicado por el metodo sol-gel / In vitro evaluation of frictional resistance between ceramic brackets and orthodontic steel arches with and without glass coatings applied by sol-gel method

Introducción: comparar la resistencia friccional estática y dinámica in vitro entre brackets cerámicos y alambres de acero inoxidable con recubrimiento vítreo aplicado por el método Sol-Gel y sin él. Métodos: se prepararon 58 alambres de acero inoxidable AISI 304 de 0.016 x 0.016 con recubrimiento vítreo aplicado por Sol-Gel y sin él. Posteriormente se evaluó la resistencia a la fricción estática y dinámica in vitro de los alambres sobre brackets cerámicos de zafiro monocristalino y se caracterizaron las superficies en contacto por microscopia óptica y electrónica de barrido (SEM). Resultados: se encontraron diferencias estadísticamente significativas entre ambos grupos tanto para la fuerza de fricción estática (p = 0,000) como dinámica (p = 0,001). El grupo de los alambres recubiertos presentó una fuerza de fricción estática y dinámica mayor (estática: 1,78 ± 0,44 N, dinámica: 1,75 ± 0,49 N) que el grupo sin recubrimientos (estática: 1,37 ± 0,31 N, dinámica: 1,41 ± 0,27 N). La caracterización por SEM mostró que se producen defectos superficiales en los recubrimientos después de las pruebas de fricción. Conclusión: los recubrimientos evaluados no mostraron mejor comportamiento friccional sobre brackets de zafiro monocristalino cuando son comparados con el grupo control.

Introduction: to compare the in vitro static and dynamic frictional resistance between ceramic brackets and stainless steel wires with and without glass coatings applied by sol-gel method. Methods: 58 commercial stainless steel orthodontic wires AISI 304 (0.016 x 0.016 inch) were prepared with and without vitreous coating applied by Sol- Gel method. The in vitro static and dynamic frictional resistance of the wires on the mono-crystalline ceramic brackets were evaluated; also, the wire surfaces were characterized by means of Optical Microscopy and scanning electronic microscopy (SEM). Results: statistically significant differences were found between both groups under static (p = 0.000) as well as dynamic (p = 0.001) friction test. The friction values found in the coated group were higher (Static friction: 1.78 ± 0.44 N, Dynamic friction: 1.75 ± 0.49 N) than the group with no coating (Static friction: 1.37 ± 0.31 N, Dynamic friction: 1.41 ± 0.27 N). Characterization by SEM showed surface defects in both groups after the friction tests. Conclusion: the evaluated coatings did not perform better in terms of frictional behavior on sapphire mono-crystalline ceramic brackets when compared with the control group.

Dientes de bovino como sustituto de dientes humanos para su uso en la odontología. Revisión de literatura / Use of bovine teeth as replacement of missing human teeth. A review of literature

Los dientes humanos son similares morfológica e histológicamente a los de algunos mamíferos, pero los dientes bovinos presentan algunas características especiales como son: la composición histológica y su forma anatómica, que entre otras características, los hacen ideales para su utilización como sustitutos de los dientes humanos en investigaciones sobre materiales dentales...

Computación evolutiva: una herramienta de modelamiento en ciencias de la salud / Evolutive computing: a modeling tool in health sciences

Este artículo presenta una revisión de la computación evolutiva como una alternativa en la generación de conocimiento, se exploran los conceptos básicos de la te´cnica y algunas aplicaciones en ciencias de la salud. Se presentan los aspectos más importantes en la modelación de sistemas y procesos biológicos. Estos modelos pueden ser utilizados para la toma de decisiones en la vida real.

Comparación de la reproductibilidad de dos materiales de impresión de hidrocoloide irreversible. Estudio “in Vitro” / Comparision of the reproducibility of two irreversible hydrocolloid

El hidrocoloide irreversible (alginato) es el material de impresión mas comúnmente utilizado es la elaboración de modelos diagnósticos.Este estudio comparo la seguridad en la reproductibilidad de dos alginatos: Jeltrate (Caulk, Co., USA) y Olympic (New Stetic Ltda., Colombia). Para ello se utilizó un modelo maxilar ideal con 12 dientes, al cual se le tomaron 12 impresiones con cada uno de los alginatos y luego se hizo el vaciado en yeso tipo IV. Sobre estos modelos se tomaron 8 mediciones con un microscopio de taller de indicación digital con una precisión de lectura de 0.001 mm.Los resultados mostraron que no hay diferencia significativa entre los troqueles obtenidos de los dos tipos de alginato evaluados; aunque una diferencia significativa se encontró cuando se comparo la distancia intermolar entre el modelo maestro y los modelos de yeso. Los modelos vaciados fueron de dimensiones mayores que el modelo maestro...