Caracterização microestrutural de um esmalte dentário submetido à radiação ionizante e ensaio de desgaste antagonizados por uma cerâmica híbrida / Microstructural characterization of a gamma irradiated dental enamel and wear performance antagonized by a hybrid ceramic

A radioterapia de cabeça e pescoço pode alterar e causar danos à estrutura dentária. Anteriormente a radioterapia, estes pacientes devem passar por consultas e tratamento odontológico orais, sugerindo a cerâmica híbrida como escolha para reabilitações orais, uma vez que esta cerâmica apresenta a característica de menor desgaste do dente. O presente estudo objetivou avaliar o efeito de diferentes doses de radiação ionizante sobre: o comportamento mecânico e estrutural da cerâmica híbrida; as propriedades mecânicas e químicas do esmalte dentário; o desempenho do esmalte dentário irradiado e dois materiais antagonistas distintos (Enamic e Esteatita). Para isto, discos de Enamic e os fragmentos dentais foram submetidos às doses diárias de 2 Gy; totalizando as doses: 0, 20, 40 e 70 Gy (esmalte e Enamic), e, 50 Gy e 60 Gy (esmalte). Após a radiação, as cerâmicas foram analisadas mecanicamente pelos testes de: dureza e flexão biaxial, e, quimicamente pelo FT-IR. Enquanto, os fragmentos de dentes (n = 60) foram observados: a degradação estrutural por FT-IR e DR-X (n=5), a nanodureza e módulo elástico (n = 10), teste de riscamento (n = 3) e desgaste antagonizados por Enamic e Esteatita (n = 10). Os dados foram submetidos aos testes ANOVA (1 e 2 fatores) e Tukey. Mediante os resultados observados, conclui-se que a radiação ionizante não alterou as propriedades da cerâmica híbrida e as propriedades cristalinas do esmalte dentário, porém, alterou a dureza, o módulo elástico, a resistência ao riscamento, a composição química (degradação do colágeno) e desgaste do esmalte dentário(AU)

The head and neck radiotherapy treatment can change and damage the dental structure. Before the radiotherapy treatment, the patients should have a dental consultation and to submit to dentistry treatments, suggesting the hybrid ceramics material are suggested as the choice to oral rehabilitations, for this material shows the characteristic of less damage of the tooth. This study aimed to evaluate the effects of different doses of gamma irradiation on: mechanical and structural behavior of hybrid ceramics; mechanical and chemical properties of dental enamel; the wear performance of irradiated dental enamel and two distinct antagonist materials (Enamic and Steatite). For that, Enamic discs (ISO 6872) and dental fragments were submitted to daily irradiation doses of 2 Gy; about the doses adding up to: 0, 20, 40 and 70 Gy (enamel and Enamic), and, 50 Gy and 60 Gy (enamel only). Then Following that procedure, ceramics were analyzed for: hardness (n = 4), biaxial flexural (n = 10) and chemically by FT-IR (n = 2). While In the meantime, 60 fragments of third molars were observed about: structural degradation by FT-IR and DR-X (n = 5), nano hardness and elastic modulus (n = 10), scratch test (n = 3), chewing simulator test antagonized by: Enamic and steatite (n = 10). The data were submitted to ANOVA- 1Way, and ANOVA-Two Way and Tukey's Test. It is This study concluded that: gamma irradiation did not affect the properties of the hybrid ceramics and the crystalline properties of the dental enamel; however, composition and mechanical properties were affected, such as: hardness, elastic modulus, scratch resistance, chemical composition (collagen degradation) and tooth enamel wear(AU)

Do sanitary ceramic workers have a worse presentation of chest radiographs or pulmonary function tests than other ceramic workers?

BACKGROUND/PURPOSE: Silicosis remains the most prevalent occupational disease worldwide. There have been no specific studies focusing on the association between exposure settings at work and the clinical severity in silicosis patients. In this study, we describe and compare the clinical characteristics and silicosis-associated exposure history at work among workers from several types of ceramic production facilities in Taiwan. METHODS: We reviewed the medical records of 221 patients who were first diagnosed with silicosis at the Occupational Medicine Clinic of Northern Taiwan in 2012. For each patient, we collected data on demographic characteristics, smoking habits, working history, duration of exposure, and years on the first relevant job. We also retrieved clinical reports of the pulmonary function test and the baseline chest radiography used for silicosis staging. RESULTS: As compared to other ceramic workers, sanitary ceramic workers had a worse X-ray type (p=0.044), more advanced age (p<0.001), longer working duration (p=0.029), and a higher proportion of starting the first relevant job prior to the year 1975 (p=0.003). However, after adjusting for age, work duration, and an initial occupational exposure prior to 1975, sanitary ceramic workers showed a comparable risk for worse X-ray findings to other ceramic workers (adjusted odds ratio=1.18, p=0.704). Results of multivariable regression models on individual lung function parameter also suggested comparably impaired lung function tests between sanitary and other ceramic workers (p>0.05). CONCLUSION: In this study, we found that sanitary ceramic workers were at a similar risk to other ceramic workers for moderate to severe silicosis when older age and longer working duration were accounted for.

Tiempo de vida de las restauraciones dentales libres de metal: revisión sistemática / Lifetime of metal-free dental restorations: a systematic review

En la actualidad existen muchos materiales dentales para la restauraciónestética, sin embargo, su tiempo de vida clínico no se conoce ampliamente. Objetivo: Identificar las publicaciones recientes de los materiales de restauración libre de metal que incluyan estudios clínicos. Metodología: La búsqueda sistemática de la literatura se realizó en bases de datos de PubMed y SciELO; se consideraron publicacionesdel 2010-2015 y que fueran investigaciones clínicas exclusivamente.Las palabras clave utilizadas fueron: Veneer crowns, dental restorationsfree metal, metal free crowns, aesthetic crowns y restauraciones libres de metal, coronas de silicato de litio, tipos de cerámicas. Resultados: Se revisaron 40 artículos y 20 cumplieron con los criterios de selección para la revisión bibliográfica. Todas las restauraciones protésicas libres de metal muestran un desempeño clínico muy similar a los tres años. Las restauraciones de zirconia y disilicato de litio por CAD mostraronel mejor éxito clínico. Conclusión: El éxito clínico de las restauracioneslibres de metal de esta revisión de la literatura muestra que van de un92.7 al 100 por ciento a tres o más años de seguimiento...

Hybrid materials offer new perspectives.

Dental materials, especially in restorative dentistry, must not only be cost-effective, they must also meet many other requirements: biocompatibility, durability, excellent shade and light effects, abrasion resistance, hardness, mechanical strength under pressure, chemical resistance, surface density, ease of manufacture, and easy intraoral maintenance.

Updating Classifications of Ceramic Dental Materials: A Guide to Material Selection.

The indications for and composition of today's dental ceramic materials serve as the basis for determining the appropriate class of ceramics to use for a given case. By understanding the classifications, composition, and characteristics of the latest all-ceramic materials, which are presented in this article in order of most to least conservative, dentists and laboratory technicians can best determine the ideal material for a particular treatment.

A new classification system for all-ceramic and ceramic-like restorative materials.

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

Polishing for glass ceramics: which protocol?

PURPOSE: The execution of adjustments on ceramic restorations is sometimes necessary for either correction of occlusion and/or inadequate contours or esthetical improvements. Clinically, the surfaces undergo weariness through fine grinding diamond burs which remove the superficial glazing layer. Several materials for ceramic polishing have been used in an attempt to reach a satisfactory surface smoothness. The aim of this study was to perform a literature review on different polishing protocols of several dental ceramics. STUDY SELECTION: This is a literature review performed through scientific articles published between 2004 and 2012, indexed in MEDLINE, PubMed and Scielo databases. The study selected and analyzed a total of 20 relevant articles that evaluated different types of ceramics, polishing treatment and surface roughness. RESULTS: After an extensive literature review, this study observed: 1 - after the rupture of the glazing layer due to the adjustments of the restorations, the best choice for the polishing of the surface will depend on the type of ceramics used; 2 - glazing procedure provide excellent results regarding to the superficial smoothness; however, if reglazing is impossible, either abrasive rubber cups/points or sandpaper discs followed by the use of diamond polishing pastes results in a satisfactory superficial smoothness; 3 - clinical studies that take into account the behavior of the protocols polishing are scarce and should be encouraged; 4 - the large number of variables influence the final outcome of polishing should be considered. CONCLUSIONS: The necessity in standardization of methodologies to enable a comparison among researches.

Clasificación y significado clínico de las diferentes formulaciones de las cerámicas para restauraciones dentales / Classification and clinical significance of different formulations of ceramics for dental restorations

Durante los últimos 40 años las cerámicas dentales han presentado significativos avances tecnológicos, desde la porcelana feldespática a las cerámicas basadas en zirconio, mejorando sus propiedades mecánicas aumentando aproximadamente en casi 10 veces la resistencia a la flexión y a la fractura. Característica importante, común a todos los sistemas cerámicos es la proporción de la fase vítrea y cristalina y el grado de porosidad dado que ambas afectan las propiedades ópticas y mecánicas de la restauración. Para la mejor comprensión de la diversidad de cerámicas desarrolladas durante los últimos años se proponen dos clasificaciones, una basada en su composición, que permite relacionar el material con sus propiedades físicas y otra basada en el método de fabricación que define las opciones de manejo y que adicionalmente, permite conocer con mayor facilidad las ventajas y limitaciones de las cerámicas dentales además de ayudar a definir la selección del material más indicado para cada requerimiento clínico.

During the last 40 years, dental ceramics had showed significant technological advances, from feldsphatics porcelain to ceramics based on zirconio, improving mechanicals properties, reaching close to 10 foils of flexural and fracture strength. Important characteristics, common to all ceramic systems, are glass phase and crystalline phase proportion, and the amount of porosity, because both affect the mechanicals and optical properties of the final restorations. For better understanding of the wide ceramics options, we propose two ceramics classifications based on composition, which associate the material with their physical properties and the fabrication method, which define the laboratory options and give information related to ceramics advantages and limitations, those information help to make the ceramic selection for each especial clinical requirement.

How and when does fabrication damage adversely affect the clinical performance of ceramic restorations?

OBJECTIVES: As compared to factory-processed ceramic parts, one unique trait of all-ceramic dental restorations is that they are custom-fabricated, which implies a greater susceptibility to fabrication defects. A variety of processing techniques is now available for the custom fabrication of all-ceramic single and multi-unit restorations, these include sintering, heat-pressing, slip-casting, hard machining and soft machining, all in combination with a final staining or veneering step. All these fabrication techniques, from shaping to firing, are associated with the production of flaws of various shapes and sizes, in conjunction with thermal residual stresses, all of which are capable of inducing failure. METHODS: This review will examine the various types of fabrication damage inherent to each technique and attempt to establish a relationship between fabrication defects and clinical performance of all-ceramic dental restorations with particular attention to their longevity in vivo. RESULTS: Failure mechanisms in dental ceramics can be very complex and often involve the combination of physical factors, to which are added patient and clinician-related variables such as restoration design and in vivo conditions. SIGNIFICANCE: Tremendous progress has been made in understanding the failure mechanisms of all-ceramic dental restorations over the past thirty years. It remains that there is still a need for laboratory tests that usefully simulate clinical conditions.

Porcelanas dentales / Dental porcelains

Las restauraciones elaboradas con porcelana ocupan un lugar central en la odontología restauradora y rehabilitadora estética. Las propiedades físicas y estéticas, las indicaciones clínicas y la técnica de trabajo de las porcelanas dentales están íntimamente relacionads con su composición y estructura. Su comprensión se convierte en decisiva para el exitoso trabajo del clínico.

Porcelanas dentales / Dental porcelains

Las restauraciones elaboradas con porcelana ocupan un lugar central en la odontología restauradora y rehabilitadora estética. Las propiedades físicas y estéticas, las indicaciones clínicas y la técnica de trabajo de las porcelanas dentales están íntimamente relacionads con su composición y estructura. Su comprensión se convierte en decisiva para el exitoso trabajo del clínico. (AU)

Cementing all-ceramic restorations: recommendations for success.

BACKGROUND: Several all-ceramic restorative systems of various compositions, properties and indications are available to the dental practitioner. Because of the large number of systems, the dental team faces questions and decisions when choosing the appropriate system and the appropriate means of cementation. OVERVIEW: The authors present a brief overview of the cementation options for various types of all-ceramic restorations. In this article, they discuss the cementation of current all-ceramic restorations and make clinical recommendations tailored to each type of ceramic. CONCLUSION AND CLINICAL IMPLICATIONS: The clinician must have a good understanding of the ceramic type to determine whether a restoration should be cemented adhesively or nonadhesively. Other variables, such as isolation and preparation design, also influence the cementation choice. Various ceramic types demand different surface treatments before cementation. Choosing and applying the appropriate surface treatment and cementation procedure will contribute to long-lasting restorations. The literature is lacking in clinical trial results that validate current in vitro data regarding cementation of all-ceramic restorations.

Recomendaciones para la selección del material cerámico libre de metal, de acuerdo a la ubicación de la restauración en la arcada / Recommendations for the selection of metal-free ceramic material, according to the location of the restoration in the arcade

El siguiente artículo es una revisión de la literatura donde se abordan aspectos clínicos, clasificación, indicaciones de estos materiales para la elección más adecuada de la restauración. Para realizar la búsqueda bibliográfica se seleccionaron investigaciones clínicas y artículos dedicados a la difusión de resultados de investigaciones in vitro. Este trabajo servirá de guía para seleccionar una cerámica libre de metal para coronas completas con base a las características y propiedades presentadas de acuerdo a las necesidades estético-funcionales específicas de cada paciente.

The following article is a review of the dental literature available, which mentions some clinical aspects, classification, indications of the materials selected for restorations. During the literature search, the articles of clinical research were selected, as well as articles dedicated to publish the results in vitro. This article is intended to be a guide in order to select a metal-free system for complete crowns based on physical properties and according to the specific esthetic and functional needs of each patient.

Cerámicas dentales: clasificación y criterios de selección / Dental ceramics: Classification and selection criteria

Hoy en día, hablar de restauraciones estéticas implica hablar de cerámica sin metal. Han sido tan importantes y revolucionarios los cambios y aportaciones en este campo en los últimos años que en la actualidad existen multitud de sistemas cerámicos. Todos ellos buscan el equilibrio entre los factores estéticos, biológicos, mecánicos y funcionales. Sin embargo, existen diferencias considerables entre ellos. Por lo tanto, para seleccionar la cerámica más adecuada en cada caso, es necesario conocer las principales características de estos materiales y de sus técnicas de confección. Esta elección no debe ser delegada al técnico de laboratorio, sino que debe ser responsabilidad del odontoestomatólogo porque él es quien conoce y controla las variables que condicionan el éxito de la restauración a largo plazo. En este artículo, se revisan los principales sistemas cerámicos disponibles actualmente y se analiza su comportamiento clínico. Por último, se exponen unas pautas para orientar al profesional en la toma de decisiónes

At the present time, to speak about aesthetic restorations implies speaking about alloy free ceramics. This field has experienced important changes and revolutionary contributions. This has led to the introduction of a multitude of all-ceramic systems. All of these quest for a balance between the aesthetic, biological, mechanical and functional factors. However, considerable differences exist among them. Therefore, to select the most suitable ceramic in every case, it is necessary to know the main features of these materials and the laboratory procedures. Porcelain selection should not be left up to the laboratory technician. Material selection should be the responsibility of the clinician because he knows and controls the variables that determine the long-term success of the restoration. This article reviews the all-ceramic systems now available and its clinical performance. Lastly, decision making guidelines for the clinician are detailed

[The classification of ceramics according to its chemical nature and its method of production]. / Classification des céramiques selon la nature chimique et le procédé de mise en oeuvre.

Nowadays, we find on the market a huge amount of design and manufactured system that allows the realisation of all-ceramics restorations, using different ceramics. The purpose of this article is suggesting a classification of mostly used ceramics and a few laboratory process used in our university.

Comparison between the in vitro surface transformations of AP40 and RKKP bioactive glasses.

Two bioactive silica-phosphate glasses, AP40 and RKKP, were compared in their behaviour in simulated biological environment. Their chemical composition is practically identical, except that RKKP contains small amounts of amphoteric network-former oxides Ta2O5 and La2O3 (composition in wt% for AP40: beta-Ca3(PO4)2 24.50, SiO2 44.30, CaO 18.60, Na2O 4.60, K2O 0.19, MgO 2.82, CaF2 4.99; RKKP: beta-Ca3(PO4)2 24.23, SiO2 43.82, CaO 18.40, Na2O 4.55, K2O 0.19, MgO 2.79, CaF2 4.94, Ta2O5 0.99, La2O3 0.09). Previous investigations showed a better performance in osteopenic bone for RKKP. To gain more insight into these differences in biological behaviour, the in vitro bioactivity of the glasses was studied by treatment with a continuously replenished Hanks' Balanced Salt Solution (HBSS). The glasses were examined before and after HBSS treatment for 20 and 40 days by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Energy Dispersion (EDX), Raman and IR vibrational spectroscopies. Some slight but notable differences between the two glasses were observed after HBSS treatment. IR and EDX analyses showed that deposits formed on both glasses were composed of a calcium deficient carbonate-apatite; however, the layer formed on RKKP glass was found to be slightly more calcium deficient and thinner. EDX analysis evidenced the presence of a small percentage of F- ions only in the layers formed on the RKKP samples. The differences disclosed, although slight, can contribute to the understanding of the different biological behaviour previously observed.