Ensayo estructural no destructivo utilizando microtomografía de rayos X para estimación de diferencias de densidad másica en muestras óseas de conejo / Non-destructive structural assay using X-ray micro-tomography to estimate mass density differences in rabbit bone samples

Al realizarse estudios sobre muestras óseas para analizar características como dureza, densidad y salud, se suelen utilizar equipamientos que permiten la cuantificación de la densidad electrónica, proporcional a la densidad másica, que se relaciona directamente con la densidad mineral ósea. El test conocido como densitometría ósea se suele realizar con equipos de rayos X, ultrasonido o por medio de la utilización de isótopos radioactivos. Este estudio cuantifica la cantidad mineral ósea por superficie y suele ser utilizado para evaluar, entre otros, riesgos de fracturas o estado de osteoporosis. La técnica de tomografía computada utiliza imágenes bidimensionales de rayos X y métodos de reconstrucción tomográfica implementados en algoritmos computacionales para obtener información de la estructura interna de un objeto, de forma no destructiva. Equipamientos especialmente desarrollados logran obtener imágenes con resolución sub-milimétrica, dando lugar a la técnica conocida como micro-tomografía. La posibilidad de estudiar estructuras óseas con este grado de resolución y obtener imágenes morfológicas tridimensionales con información de la densidad electrónica, presenta una importante opción para estudios específicos sobre, entre otros, crecimiento de hueso y estudios de nuevos componentes que permiten acelerar el crecimiento de tejidos dañados. En el presente trabajo se analizan muestras óseas del cráneo de conejos donde se han dañado determinadas zonas y se han injertado diferentes sustancias tendientes a evaluar respuestas de reparación de tejido óseo. El análisis se realiza a los fines de estudiar la performance de la técnica de micro-tomografía desarrollada en laboratorio con el objetivo de observar su potencialidad en este tipo de estudios y la capacidad de estos análisis en la caracterización de las propiedades físicas de este tipo de muestras.

When performing studies on bone samples aiming at analyzing its physical characteristics such as hardness, density and health, typically it is used to utilize different equipment for the quantification of electron density, which results proportional to mass density, which is directly related to bone mineral density. The test known as bone densitometry is usually done using X-ray equipment, ultrasound or through the utilization of radioactive isotopes. This analysis quantifies the amount of mineral bone on a surface and is usually implemented to assess, among others, risks of fractures or the osteoporosis state in a patient. The computed tomography technique uses two-dimensional X-ray images and tomographic reconstruction methods implemented on computational algorithms to obtain information about the internal structure of an object in a nondestructively way. Specially developed equipment able to obtain images with sub-millimeter resolution, results in the technique known as micro-tomography. The ability to study bone structures at sub-millimeter levels and obtain three-dimensional morphological images with electron density information, presents an important option for specific studies on bone growth and studies on new components that allow the growth of damaged tissues. In this paper rabbits cranium bone samples where certain areas have been damaged and have been filled with different substances specially designed to evaluate repair responses on bone tissue are analyzed. The analysis is performed in order to study the performance of the micro-tomography technique developed in the laboratory in order to observe its potentiality in this type of studies and the ability of these analysis in the characterization of the physical properties of such samples.

Ortodoncia y periodoncia / Orthodontics and periontics

El paciente periodontal se puede beneficiar con un tratamiento combinado de ortodoncia y periodoncia, ya que determinados movimientos dentarios como la extrusión, la intrusión, la rotación, el enderezamiento, etc pueden ser favorables para el periodonto enfermo. Lo que es fundamental antes de empezar el tratamiento de ortodoncia de un paciente periodontal es eliminarla inflamación activa de los tejidos (AU)

Periodontal patients can benefit from a combined treatment of orthodontics and periodontics, because certain tooth movements as extrusion, intrusion, rotation, straightening, etc. may be favourable for the periodontal patient. Which is essential before starting orthodontic treatment of a periodontal patient is to eliminate active inflammation of the tissues (AU)

Restauraciones estéticas de porcelana pura. Sistema Cercon / Aesthetic all-ceramic restorations. Cercon System

La estética en odontología está orientada a imitar la naturaleza, a tratar de conservar las proporciones, las formas, el color, la simetría. La tecnología ha desarrollado materiales cerámicos libres de metal que han reemplazado a los materiales tradicionales, capaces de imitar mejor a la naturaleza. El óxido de circonio parcialmente estabilizado con itrio, no solo es extremadamente resistente, sino que posee la ventaja de ser altamente translucido. Su translucidez de aproximadamente el 50% de la luz incidente, permite la elaboración de restauraciones con apariencia natural. La duración del proceso de escaneado y fresado dependerá del tamaño del objeto, del número de objetos procesados y de los pasos seleccionados (CAM o CAD/CAM). La estructura de óxido de circonio densamente sinterizado con su preciso ajuste, se cubre con la cerámica de recubrimiento que ha sido especialmente desarrollada para este propósito. En casi todos los casos que se nos plantean hay un solo diagnóstico, pero distintas alternativas de plantear el tratamiento. El éxito de estas restauraciones será predecible siempre que se fundamente en el conocimiento de los principios biológicos que la sustentan. El objetivo de esta publicación es exponer de manera concisa las bases teóricas a modo esquemático y las imágenes de la secuencia del tratamiento clínico (AU)

Aesthetic dentistry is dedicated to imitate nature by maintaining the size, shape, colour and symmetry. Technology has developed metal-free ceramic materials so capable of reproducing a natural appearance, that traditional materials have been replaced by them. The yttrium partially-stabilized zirconium oxide does not only have the advantage of being extremelly resistant, but it is also highly translucent. It has a translucency that allows about 50% of the incident light to pass through, a characteristic that is vital for providing a more natural appearance to restorations. The duration of scanning and milling procedures will depend on the size of the object, the number of objects proccessed and the steps selected (CAM or CAD/CAM). The framework of the densely sintered zirconium oxide with its precise fit is veneered with the veneering ceramic developed especially for this purpose. Almost in all cases, there are several treatment alternatives for the same diagnosis. The success of these restorations will be predicted as long as it is founded on sustaining biological principles. The aim of this paper is to concisely present the sequences for a clinical treatment in a schematic and illustrative manner (AU)

[Study of traction and effect of bonding agents on etched porcelain]. / Estudio de tracción y efecto de los agentes de acoplamiento sobre porcelana grabada.

Nowadays many authors suggest the use of porcelain laminate veneer that has come to play an important role in the solution of many esthetic and functional problems. At the moment, it is the alternative treatment to solve some cases with the least dental reduction, the highest fitting and a low cost. To evaluate the tractional resistance done on the porcelain veneer, in which acid etching and connecting agents were applied, I suggest: 1. The resistance of traction carried out on etched porcelain laminate to which an agent of silane join and a resin of connection were applied, was the one that had the best conduct. 2. The tractional resistance carried out on the laminate fronts where a treatment of only silane and resin of connection was applied, was greater where the treatment of silane was employed. 3. The etched with acid both in the adamantine surface and in that of well depurated porcelain, is an important factor to obtain a good retention.

[Analysis of enamel thickness of anterior teeth and its relation to preparation for porcelain veneers]. / Análisis de los espesores del esmalte en elementos anteriores y su relación con el tallado para colocar carillas de porcelana.

The development of porcelain, acrylic and mixed crowns is not under discussion. In the same way, it should not be discussed now the evolution of silicate cements, the acrylics, the glass ionomer and the composite resins in their different techniques. We only want to analyze concisely the actual condition of the investigation and of the clinic, as regards the reconstruction with lamellas of the front part of the mouth. Lit can be deduce from the researches that the measurement of the vestibular thickness of y the enamel upon the incisives, laterals and canines specifies that: 1. As regards form, the most suitable elements for the laying of the porcelain laminate are the square, then the ovoid and finally the triangular ones. 2. The central incisives are the best; secondly the canines and then the laterals (this is directly related to the convexity of the fronts and to the amount of residual enamel). 3. It is advisable to finish the peripheric edge of the cavity 1 mm, above the anatomic neck to assure an adequate thickness of enamel in order to obtain a good adherence of the porcelain laminate veneers. 4. It is convenient to use appropriate techniques during the adamantine preparation in order to control its depth (for example diamond-like stones with ends).

[Different types of tooth preparation for placement of ceramic veneers]. / Diferentes tipos de tallado de los elementos dentarios para la colocación de carillas cerámicas.

Lately the porcelain laminate veneer in the fore-upper sector of the mouth, has gained popularity due to the multiple advantages that it has shown, therefrom the purpose of describing the different reduction techniques according to the function of the laminate restauration. We describe the instruments that will be used and the sequence that should be carried on during the different types of reduction, classifying them in three large groups according to the anomaly presented by the elements to be restored.

[Repositioning splints or bite guards: their use]. / Placas reposicionadoras o guardas oclusales: su uso.

It is well known that organic and organized occlusion should be according to the patterns of mandibular motions, which are determined for T.M.J. Presence of syntomatolojy either muscular or articular must be analysed before making any definite procedure. Knowledge and application of splints is essential to odontologist of general practice, to solve that syntomatolojy.

[Acid etching of prefabricated porcelain veneers]. / Estudio sobre grabado ácido de carillas de porcelana prefabricada.

The aim of the present work is to study on standard porcelain teeth the acid concentration to produce the micromechanic retention with the cemented resin and then to enamel. Teeth were beater-up following the described technique, the application of two different types of etch solutions: hydrochloric acid and fluorhidric acid, in a lack of application time between 10 to 20 minutes. With the purpose of determine the type of etch solution that produce the best amount of micropores in standed porcelain laminates veneers we can conclude that: to the internal etched of the standard porcelain laminates veneer, the utilization of fluorhidric acid is the most convenient, also is necessary the previons stand blaster with aluminum oxide of 25 um to increase the retentive capacity over the etch surface.

Estudio sobre grabado ácido de carillas de porcelana prefabricada / [Acid etching of prefabricated porcelain veneers]

The aim of the present work is to study on standard porcelain teeth the acid concentration to produce the micromechanic retention with the cemented resin and then to enamel. Teeth were beater-up following the described technique, the application of two different types of etch solutions: hydrochloric acid and fluorhidric acid, in a lack of application time between 10 to 20 minutes. With the purpose of determine the type of etch solution that produce the best amount of micropores in standed porcelain laminates veneers we can conclude that: to the internal etched of the standard porcelain laminates veneer, the utilization of fluorhidric acid is the most convenient, also is necessary the previons stand blaster with aluminum oxide of 25 um to increase the retentive capacity over the etch surface.

Placas reposicionadoras o guardas oclusales: su uso. / [Repositioning splints or bite guards: their use]

It is well known that organic and organized occlusion should be according to the patterns of mandibular motions, which are determined for T.M.J. Presence of syntomatolojy either muscular or articular must be analysed before making any definite procedure. Knowledge and application of splints is essential to odontologist of general practice, to solve that syntomatolojy.

Estudio sobre grabado ácido de carillas de porcelana prefabricada. / [Acid etching of prefabricated porcelain veneers]

The aim of the present work is to study on standard porcelain teeth the acid concentration to produce the micromechanic retention with the cemented resin and then to enamel. Teeth were beater-up following the described technique, the application of two different types of etch solutions: hydrochloric acid and fluorhidric acid, in a lack of application time between 10 to 20 minutes. With the purpose of determine the type of etch solution that produce the best amount of micropores in standed porcelain laminates veneers we can conclude that: to the internal etched of the standard porcelain laminates veneer, the utilization of fluorhidric acid is the most convenient, also is necessary the previons stand blaster with aluminum oxide of 25 um to increase the retentive capacity over the etch surface.

[Ceramometal rehabilitation on gnathological principles]. / Rehabilitacion metaloceramica con principios gnatologicos.

We suggest a technique in which the rules of the Gnatology are strictly followed and an organic occlusion is entirely made of metal, it is checked its function, appropriate alignment, phonation, aesthetics, gingival adaptation, contact, relations, etc., as if it were a final rehabilitation. Then, on the original model, each crown, future ceramic carrier, is made and the necessary space for the porcelain and its adaptation is tested into the mouth. In the same way, the following steps are carried out till the biscuit and all the relations with the elements, that are to be imitated, are strictly established, when the biscuit has been finished, the whole is tested into the mouth. Finally, the crowns and bridges are made up and shade but this will not alter the function that has been obtained, due to the meticulous technique that has been suggested.

[Porcelain veneers: 4 application technics]. / Carillas de porcelana: cuatro técnicas para su aplicación.

The present paper describes the different techniques currently employed for the use of porcelain laminate veneer, from the simplest stock teeth to the most complex casting system. Advantages and disadvantages of each are described herein.