Parámetros para la evaluación visual e instrumental del color dental en estudios in-vitro. Revisión de la literatura / Parameters for visual and instrumental assessment of tooth colour in in-vitro studies. Literature review

Objetivo: establecer los parámetros para la evaluación visual e instrumental del color dental en estudios in-vitro a partir de la literatura científca publicada entre 2015 y 2021. Métodos: se realizó la búsqueda en las bases de datos: PubMed, Web of Science, Science Direct, Scopus, Scielo y Lilacs; también en el motor de búsqueda Google Académico y las bibliotecas de las editoriales Wiley y Springer. Las palabras clave utilizadas fueron tooth, color, in-vitro, color perception, shade matching, thresholds, appearance, surrounding, "CIELAB" y "CIEDE2000". Teniendo en cuenta los criterios de elegibilidad, se seleccionaron los estudios de acuerdo al título, resumen y texto completo. Resultados: la búsqueda arrojó un total de 37 publicaciones que se agruparon en tres tópicos: 1. toma de color visual: condiciones ambientales, observadores y nivelación; 2. toma de color instrumental: instrumentos; y 3. procesamiento de datos: cálculo de la diferencia de color y umbrales de perceptibilidad (PT) y aceptabilidad (AT). Conclusiones: los aspectos más importantes en la evaluación visual son la iluminación, el ambiente para registro (sitio, entorno y fondo alrededor de la muestra), las condiciones geométricas de visualización, los observadores y el uso de guías. En la evaluación instrumental es relevante elegir el aparato apropiado de acuerdo con su precisión y reproducibilidad, como los espectroradiómetros y los espectrofotómetros de uso clínico. Se presenta el procesamiento de datos para establecer las variaciones de cada coordenada, las diferencias de color (ΔE): CIELAB y CIEDE2000, los umbrales y los lineamientos.

Objective: To establish the parameters for the visual and instrumental evaluation of tooth color in in-vitro studies based on the scientifc literature published between 2015 and 2021. Methods: The search was carried out in the databases of PubMed, Web of Science, Science Direct, Scopus, Scielo, Lilacs; search engine Google Scholar and publishers' library of Wiley and Scielo, using the keywords "tooth", "color", "in vitro", "color perception", "shade matching", "thresholds", "appearance", "surrounding", "CIELAB", and "CIEDE2000". The literature was selected according to the title, abstract and full text taking into the eligibility criteria. Results: It yielded a total of 37 publications, which were grouped into three topics: 1. visual color acquisition: environmental conditions for color acquisition, observers and levelling. 2. instrumental color sampling: instruments. 3. Data processing: Calculation of color diference and perception thresholds (PT) and acceptability thresholds (AT). Conclusions: The most important aspects in the visual assessment are lighting, the environment for color registration (site, environment and background around the sample), the geometric conditions of visualization, the observers and the use of guides. Regarding the instrumental assessment of color, the appropriate devices must be chosen according to its precision and reproducibility, being the spectrophotometers and spectroradiometers the most precise ones. It is presented how the data processing is carried out to establish the variations of each coordinate, the color diferences (ΔE): CIELAB and CIEDE2000, thresholds and guidelines.

Medios de almacenamiento de dientes para estudios de color / Teeth storage media for color studies / Meios de armazenamento de dentes para estudos de cor

Resumen Todos los medios de almacenamiento usados para ensayos de investigación alteran las propiedades físicas y/o químicas de los dientes, especialmente el color dental. El objetivo de este trabajo es establecer cual es el medio de almacenamiento más indicado para dientes que van a ser usados en estudios de color, basados en una revisión sistematizada y proponer un protocolo específico. Mediante las palabras clave ¨storage, medium¨, ¨teeth¨, ¨color¨, ¨stability¨, ¨saliva¨, ¨formalin¨, ¨thymol¨, ¨ethanol¨ conectadas por AND o OR y consultando las bases de datos PubMed, ScienceDirect, Embase, Scopus, Scielo, Lilacs y Google Scholar, se seleccionaron artículos con nueve criterios de evaluación a tres niveles de evidencia (alto, medio y bajo). Se realizó la síntesis y el análisis de la literatura, y como producto se establecieron los parámetros para el protocolo de almacenamiento. El resultado final arrojó 8 artículos, dos con nivel de evidencia alto para la saliva natural y/o saliva artificial sin carboximetilcelulosa. Tres con nivel de evidencia medio para el timol 0,1%, cloramina T 0,5%, glutaraldehido 2% y formalina 10%. Tres con nivel de evidencia bajo para el etanol, óxido de etileno o hidróxido de potasio. El medio de almacenamiento más indicado es saliva humana seguida por saliva sintética sin carboximetilcelulosa y se estableció con estos parámetros el protocolo del almacenamiento.

Abstract All storage media used in research assays alter some of the physical and/ or chemical properties of the teeth, especially tooth color. The objective was to establish which is the most appropriate medium for storing teeth for color studies based a systematized review, and to propose a specific protocol. Using as keywords ¨storage¨, ¨medium¨, ¨teeth¨, ¨color¨, ¨sta- bility¨, ¨saliva¨, ¨formalin¨, ¨thymol¨, ¨ethanol¨ connected by AND o OR and consulting PubMed, ScienceDirect, Embase, Scopus, Scielo, Lilacs and Google Scholar databases, articles were selected to provide information on storage media with eight criteria for evaluating at three levels of high, medium and low evidence. An analysis and synthesis of the literature led to the results and the storage protocol. The search yielded eight articles, two with a high level of evidence for natural saliva and / or artificial saliva without carboxymethylcellulose. Three with a medium level of evidence for 0.1% thymol, 0.5% chloramine T, 2% glutaraldehyde and 10% formalin. Three with low evidence level for ethanol, ethylene oxide or potassium hydroxide. Storage medium most indicate is human saliva, followed by synthetic saliva without carboxymethylcellulose and so a storage protocol was established.

Resumo Todos os meios de armazenamento utilizados para ensaios de pesquisa alteram as propriedades físicas e/ou químicas dos dentes, especialmente a cor dos dentes. O objetivo é estabelecer qual meio de armazenamento é mais adequado para os dentes serem usados em estudos de cores com base em uma revisão sistemática, e propor um protocolo específico. Usando as palavras-chave "storage medium¨, ¨teeth¨, ¨color¨, ¨stability¨, ¨saliva¨, ¨formalin¨, ¨thymol¨, ¨ethanol " conectados por AND ou OR e consultando as bases de dados PubMed, ScienceDirect, Embase, Scopus, Scielo, Lilacs e Google Scholar, os artigos foram selecionado com nove critérios de avaliação em três níveis de evidência (alto, médio e baixo). Foi feita a análise, síntese da literatura e como produto foram estabelecidos os parâmetros para o protocolo de armazenamento. O resultado final rendeu 8 artigos, dois com alto nível de evidência para saliva natural e/ou saliva artificial sem carboximetilcelulose. Três com nível médio de evidência para timol 0,1%, cloramina T 0,5%, glutaraldeído 2% e formalina 10%. Três com baixo nível de evidência de etanol, óxido de etileno ou hidróxido de potássio. O meio de armazenamento mais indicado é a saliva humana, seguida pela saliva sintética sem carboximetilcelulose e o protocolo de armazenamento foi estabelecido com esses parâmetros

Método químico simplificado de desmineralización del esmalte dental humano / Simplified chemical method of demineralization in human dental enamel

Introducción: Se requieren métodos experimentales abreviados para simular las lesiones de desmineralización temprana de forma controlada y reproducible. Objetivo: Realizar una evaluación in vitro de un método simple de desmineralización incipiente del esmalte. Métodos: Estudio experimental aleatorizado con doble diseño factorial de réplicas. Se seleccionaron 12 terceros molares de sujetos humanos saludables para su desmineralización en solución de ácido láctico racémico. Las muestras se distribuyeron aleatoriamente: Grupo 1 (G1) (n= 6) ácido láctico a pH 2,4 y Grupo 2 (G2) (n= 6) ácido láctico a pH 5,4. A continuación, cada grupo se subdividió (n = 2) para evaluar el efecto de las soluciones a tres tiempos de exposición (7, 15 y 30 días) a 37 °C. La evaluación se llevó a cabo con estereomicroscopios, equipo de radiografía digital con un software de análisis digital de imágenes y microscopía de polarización. Se formuló una integración de los índices de respuesta y se realizó un ANOVA. Resultados: Los hallazgos visuales, radiográficos e histológicos mostraron que en el G1 en los tiempos 1 a 3, la desmineralización se caracterizó por una gran pérdida de la integridad del esmalte (80 por ciento a 100 por ciento). Visualmente, el G2 a los 7 días mostró opacidad y pérdida de brillo (16 por ciento) con preservación de la estructura superficial del esmalte. Conclusiones: Se demuestra que el empleo de ácido láctico durante 7 días a pH 5,4 produce una lesión clínica, radiográfica e histológica similar a una lesión temprana del esmalte(AU)

Introduction: Abridged experimental methods are required to simulate early demineralizing lesions in a controlled and reproducible way. Objective: Perform an in vitro evaluation of a simple method of incipient enamel demineralization. Methods: Randomized experimental study with a double factorial replication design. Twelve third molars from healthy human subjects were selected for demineralization in a racemic lactic acid solution. Samples were then distributed randomly: Group 1 (G1) (n= 6) lactic acid at pH 2.4 and Group 2 (G2) (n= 6) lactic acid at pH 5.4. Each group was then subdivided (n = 2) to evaluate the effect of the solutions at three exposure times (7, 15 and 30 days) at 37°C. The evaluation used stereomicroscopes, a digital x-rays apparatus with software for the digital analysis of images, and polarization microscopy. An integration of the response indices was formulated and ANOVA was performed. Results: Visual, radiographic and histological findings showed that G1 at time 1 through 3 displayed demineralization characterized by extensive loss (80 percent to 100 percent) of enamel integrity. Visually, G2 at 7 days exhibited opacity and loss of brightness (16 percent), with preservation of the surface structure of the enamel. Conclusions: It was shown that employing lactic acid for 7 days at pH 5.4 develops a clinical, radiographic and histological injury similar to an early enamel lesion(AU)

Efecto de agentes blanqueadores libres de peróxido sobre el color dental. Revisión sistemática / Effect of Peroxide-Free Dental Bleaching Agents on Dental Color. Systematic Review

Antecedentes: Los agentes blanqueadores oxidantes tales como los peróxidos generan daños irreversibles en el esmalte dental y afectan químicamente el componente orgánico e inorgánico del esmalte. Se reportan en la literatura sustancias alternativas que pueden mejorar el color del esmalte, sin causarle daño. Objetivo: Identificar las sustancias blanqueadoras tipo remineralizante reportadas en la literatura y su efecto en el color del esmalte dental. Métodos: Se consultaron las bases de datos PubMed, ScienceDirect, Embase, Scielo, Lilacs y Scopus, las palabras clave empleadas para la búsqueda fueron dental enamel, tooth bleaching, bleaching, calcium phosphate, hidroxyapatite, apatite, biomimetic, biomimetics, conectadas por el operador booleano AND y OR de diferentes maneras. Los criterios de elegibilidad de los artículos que harían parte de la revisión fueron que no incluyeran peróxidos de hidrógeno y carbamida con adición fluoruros y fosfatos de calcio y adicionalmente que emplearan un método de medición de color. Resultados: El resultado de la búsqueda arrojó 7 artículos, las sustancias encontradas de tipo remineralizante fueron hidroxiapatita sintética, fosfatos de calcio y el hexametafosfato de sodio. Según los criterios de evaluación definidos solo 4 de ellos tuvieron un nivel de evidencia alto, uno nivel medio y dos bajos. Todos los estudios reportan con los tratamientos probados, la capacidad de generar cambios en el color del esmalte dental. Conclusión: Las sustancias blanqueadoras remineralizantes encontradas, tienen la capacidad de producir cambios en el color del esmalte dental, lo cual se evidencia con modificación en las diferentes escalas de medición empleadas.

Background: Oxidizing bleaching agents such as peroxides generate irreversible damage to dental enamel and chemically affect the organic and inorganic component of the enamel. Alternative substances that can improve the color of the enamel without damaging it are reported in the literature. Purpose: To identify the remineralizing bleaching substances reported in the literature and their effect on the color of the dental enamel. Methods: The databases PubMed, ScienceDirect, Embase, SciELO, Lilacs and Scopus were consulted, the keywords used for the search were dental enamel, tooth bleaching, bleaching, calcium phosphate, hydroxyapatite, apatite, biomimetic, biomimetics, connected by the Boolean operator AND and OR in different ways. The eligibility criteria of the articles that would be part of the review were not to include hydrogen peroxide and carbamide peroxides with addition of fluorides and calcium phosphates and additionally using a color measurement method. Results: The result of the search yielded 7 articles, the substances found of remineralizing type were synthetic hydroxyapatite, calcium phosphates and sodium hexametaphosphate. According to the evaluation criteria defined, only 4 of them had a high level of evidence, one medium level and two low. All studies report with proven treatments the ability to generate changes in tooth enamel color. Conclusions: The remineralizing whitening substances found have the ability to produce changes in the color of the dental enamel, which is evidenced with modification in the different measurement scales used.

Evaluation of an experimental remineralizing agent for repairing enamel surfaces.

The best material for repairing enamel surface defects is one very similar to the original enamel and which interacts with natural remineralization mechanisms. It does not repair extensive damage, so in order to fill large defects, external help is required using phosphocalcic ceramic composites that activate salivary remineralization efficiently though on smaller in scale. Effective adhesion of the repair may depend on the amount of aqueous fluids present in the enamel, which apparently enable nucleation and growth of new minerals to ensure adhesion and stability. The amount of fluids is governed by osmotic pressure. This study evaluated the influence of two osmotic pressure values of isotonic and hypotonic saliva and two modified remineralizing agent compositions: combinations of "conditioner" and "remineralizing agent" in proportions of 90%: 10% (A) and 50%: 50%(B), on filling artificial cracks. Results were evaluated by profilometer, stereomicroscope and confocal laser microscope. A 22 factorial design and a logistic model for statistical analysis were used. Only the composition of the mineralizing agent had a significant effect on efficiency in repairing defects. Compositions A and B both repaired dental enamel defects, but composition B presented higher levels of repair and more compact deposits as observed under stereomicroscope.

El mejor material para reparar defectos superficiales del esmalte es uno muy similar al original y que este interactúe con los mecanismos naturales de remineralización. Este no arregla danos extensos por lo que se requiere de una ayuda externa para rellenar defectos grandes con un material que active la remineralización salivar que sea eficiente pero de menor alcance. Para esto se emplearon cerámicas compuestas principalmente fosfocálcicas. La adhesión efectiva de la reparación puede depender de la cantidad de fluidos acuosos existentes en la porosidad del esmalte pues aparentemente permiten la nucleación y crecimiento de nuevos minerales para asegurar adhesión y estabilidad. La cantidad de fluidos está gobernada por la presión osmótica. En este estudio se evaluó la influencia que tienen dos valores de presión osmótica de la saliva isotónica y hipotónica y dos composiciones de agente remineralizante modificado: condicionador y agente remineralizante en composiciones de 90%/10% (A) y 50%/50%(B) respectivamente, sobre el llenado de grietas artificiales por perfilometría, estereomicroscopio y microscopía confocal láser. Se trabajó con un diseño factorial 22 y tratamiento estadístico: modelo logístico. Solamente la composición de la sustancia remineralizante tuvo efecto significativo en la eficiencia para reparar defectos. La composición tiene un efecto reparador sobre los defectos del esmalte dental en sus dos composiciones, no obstante, la composición 50%/50% presenta niveles más altos de reparación y forma depósitos que al estereomicroscopio se observan más compactos.

Evaluation of an experimental remineralizing agent for repairing enamel surfaces / Evaluación de un agente remineralizante experimental reparador de superficie de esmalte

The best material for repairing enamel surface defects is one very similar to the original enamel and which interacts with natural remineralization mechanisms. It does not repair extensive damage, so in order to fill large defects,external help is required using phosphocalcic ceramic composites that activate salivary remineralization efficiently though on smaller in scale. Effective adhesion of the repair may depend on the amount of aqueous fluids present in the enamel, which apparently enable nucleation and growth of new minerals to ensure adhesion and stability. The amount of fluids is governed by osmotic pressure. This study evaluated the influence of two osmotic pressure values of isotonic and hypotonic saliva and two modified remineralizing agent compositions: combinations of "conditioner" and "remineralizing agent" in proportions of 90%: 10% (A) and 50%: 50%(B), on filling artificial cracks. Results were evaluated by profilometer, stereomicroscope and confocal laser microscope. A 22 factorial design and a logistic model for statistical analysis were used. Only the composition of the mineralizing agent had a significant effect on efficiency in repairing defects. Compositions A and B both repaired dental enamel defects, but composition B presented higher levels of repair and more compact deposits as observed under stereomicroscope (AU)

El mejor material para reparar defectos superficiales del esmalte es uno muy similar al original y que este interactúe con los mecanismos naturales de remineralización. Este no arregla daños extensos por lo que se requiere de una ayuda externa para rellenar defectos grandes con un material que active la remineralización salivar que sea eficiente pero de menor alcance. Para esto se emplearon cerámicas compuestas principalmente fosfocálcicas. La adhesión efectiva de la reparación puede depender de la cantidad de fluidos acuosos existentes en la porosidad del esmalte pues aparentemente permiten la nucleación y crecimiento de nuevos minerales para asegurar adhesión y estabilidad. La cantidad de fluidos está gobernada por la presión osmótica. En este estudio se evaluó la influencia que tienen dos valores de presión osmótica de la saliva isotónica y hipotónica y dos composiciones de agente remineralizante modificado: condicionador y agente remineralizante en composiciones de 90%/10% (A) y 50%/50%(B) respectivamente, sobre el llenado de grietas artificiales por perfilometría, estereomicroscopio y microscopía confocal láser. Se trabajó con un diseño factorial 22 y tratamiento estadístico: modelo logístico. Solamente la composición de la sustancia remineralizante tuvo efecto significativo en la eficiencia para reparar defectos. La composición tiene un efecto reparador sobre los defectos del esmalte dental en sus dos composiciones, no obstante, la composición 50%/50% presenta niveles más altos de reparación y forma depósitos que al estereomicroscopio se observan más compactos (AU)

An intramembranous ossification model for the in silico analysis of bone tissue formation in tooth extraction sites.

The accurate modeling of biological processes allows us to predict the spatiotemporal behavior of living tissues by computer-aided (in silico) testing, a useful tool for the development of medical strategies, avoiding the expenses and potential ethical implications of in vivo experimentation. A model for bone healing in mouth would be useful for selecting proper surgical techniques in dental procedures. In this paper, the formulation and implementation of a model for Intramembranous Ossification is presented aiming to describe the complex process of bone tissue formation in tooth extraction sites. The model consists in a mathematical description of the mechanisms in which different types of cells interact, synthesize and degrade extracellular matrices under the influence of biochemical factors. Special attention is given to angiogenesis, oxygen-dependent effects and growth factor-induced apoptosis of fibroblasts. Furthermore, considering the depth-dependent vascularization of mandibular bone and its influence on bone healing, a functional description of the cell distribution on the severed periodontal ligament (PDL) is proposed. The developed model was implemented using the finite element method (FEM) and successfully validated by simulating an animal in vivo experiment on dogs reported in the literature. A good fit between model outcome and experimental data was obtained with a mean absolute error of 3.04%. The mathematical framework presented here may represent an important tool for the design of future in vitro and in vivo tests, as well as a precedent for future in silico studies on osseointegration and mechanobiology.

Effects of bleaching on osteoclast activity and their modulation by osteostatin and fibroblast growth factor 2.

HYPOTHESIS: Dental bleaching with H2O2 is a common daily practice in dentistry to correct discoloration of anterior teeth. The aim of this study has been to determine whether this treatment of human teeth affects growth, differentiation and activity of osteoclast-like cells, as well as the putative modulatory action of osteostatin and fibroblast growth factor 2 (FGF-2). EXPERIMENTS: Previously to the in vitro assays, structural, physical-chemical and morphological features of teeth after bleaching were studied. Osteoclast-like cells were cultured on human dentin disks, pre-treated or not with 38% H2O2 bleaching gel, in the presence or absence of osteostatin (100 nM) or FGF-2 (1 ng/ml). Cell proliferation and viability, intracellular content of reactive oxygen species (ROS), pro-inflammatory cytokine (IL-6 and TNFα) secretion and resorption activity were evaluated. FINDINGS: Bleaching treatment failed to affect either the structural or the chemical features of both enamel and dentin, except for slight morphological changes, increased porosity in the most superficial parts (enamel), and a moderate increase in the wettability degree. In this scenario, bleaching produced an increased osteoclast-like cell proliferation but decreased cell viability and cytokine secretion, while it augmented resorption activity on dentin. The presence of either osteostatin or FGF-2 reduced the osteoclast-like cell proliferation induced by bleaching. FGF-2 enhanced ROS content, whereas osteostatin decreased ROS but increased TNFα secretion. The bleaching effect on resorption activity was increased by osteostatin, but this effect was less evident with FGF-2. CONCLUSIONS: These findings further confirm the deleterious effects of tooth bleaching by affecting osteoclast growth and function as well as different modulatory actions of osteostatin and FGF-2.

Effect of 30 % hydrogen peroxide on mineral chemical composition and surface morphology of bovine enamel.

A combination of atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and gas adsorption techniques was used to characterize the effect of 30 % hydrogen peroxide (HP) on enamel surface. To perform the analyses of AAS, 1 ml of 30 % HP was added to 30 mg of a bovine enamel powder sample (150-200 µm fractions) for times of 5, 20, 60, 90, and 120 min; then 5 ml of the solution was withdrawn after each time period to measure [Ca(2+)] ions. The remaining powder was recovered and analyzed by FTIR. For SEM and gas adsorption tests, 4 × 4 mm(2) enamel sectioned samples were polished and 30 % HP was applied on the surface for the same time periods. AAS data show that 30 % HP treatment mobilized calcium from the enamel at all times studied. FTIR spectra showed that the total amount of phosphate and carbonate mineral contents such as amide I decreased significantly. SEM revealed that randomly distributed areas throughout the smooth enamel surface treatment became rougher and more irregular. These alterations indicate that surface damage increases with increasing durations of HP treatment. Gas adsorption analysis proved that bleached enamel is a typically non-porous material with a small specific surface area which decreases slightly with the 30 % HP treatment. In sum, 30 % HP induced a significant alteration of the organic and mineral part of the enamel, leading to the release of calcium and a rougher, more irregular enamel surface on randomly distributed areas.

Effect of a new remineralizing biomaterial on the color of dental enamel.

The aim of this research was to describe the effects of altering the composition of a modified remineralizing agent (MRA) and the osmotic pressure on tooth color by using spectrophotometric analysis. One hundred and four (104) human premolars and molars were randomly divided into 2 groups of 52 specimens each. Group 1 was treated with the remineralizing agent MRA 55, (remineralizing agent 1), a 50% - 50% by weight mixture of coarse-grain and fine-grain generating minerals, and group 2 was treated with the remineralizing agent MRA 91 (remineralizing agent 2), containing the same minerals in a 90% - 10% proportion. Each group was divided into 2 subgroups with 26 specimens each, which were stored as follows: subgroups A were stored in synthetic saliva with isotonic osmotic pressure (IP), and subgroups B in hypotonic osmotic pressure saliva (HP). The initial and final readings were taken with a Vita Easy Shade spectrophotometer. Color parameters (L*, a*, b*) and whiteness indices (WIC, WIO, W) were calculated from the readings. The color changes (deltaL, deltaA, deltaB, and deltaE) and whiteness indices were compared and analyzed with descriptive analyses. The variables deltaL, deltaA, deltaB, deltaE, and the whiteness index W were analyzed with an analysis of variance (ANOVA), and the indices WIC and WIO were analyzed with a nonparametric Kruskal-Wallis ANOVA. The results indicate that combination A2 (MRA 91 and IP) affected variables deltaB and deltaE, while combination B1 (MRA 55 and HP) affected variables deltaA, deltaB and the whiteness index WIO. Only MRA 91 affected the variable deltaL. The osmotic pressure of saliva and the remineralizing agent used affect the color of dental enamel.

Effect of a new remineralizing biomaterial on the color of dental enamel

El objetivo de este trabajo fue describir el efecto de la composición de una sustancia remineralizante (SRM) y de la presión osmótica sobre el color dental mediante espectrofotometría. Se tomaron 104 premolares y molares humanos repartidos aleatoriamente en 2 grupos, cada uno de 52 especímenes. El grupo 1 se trató con la sustancia remineralizante SRM 55 (agente remineralizante 1) mezcla de 50 por ciento - 50 por ciento de mineral de grano fino y otro mineral de grano grueso y el grupo 2 se trató con la sustancia remineralizante SRM 91(agente remineralizante 2) contienen los mismos minerales en proporción 90 por ciento - 10 por ciento. A su vez cada grupo se dividió en 2 subgrupos, cada uno de 26 especímenes que se almacenaron así: Un subgrupo en saliva sintética con presión osmótica isotónica (PI) y el otro con presión osmótica hipotónica (PH). Se tomaron registros iniciales y finales con el espectrofotómetro Vita Easy Shade®. Con las lecturas se calcularon losparámetros de color (L*; a*; b*) y los índices de blanqueamiento (WIC; WIO; W). Los cambios de color (ΔL; ΔA; ΔB; yΔE) y los índices de blanqueamiento se compararon y se trataron todos mediante un análisis descriptivo. Las variables ΔA, ΔL, ΔB, ΔE e índice de blanqueamiento W se trataron con ANOVA y los índices WIC y WIO con un análisis de varianza no paramétrico Kruskal Wallis. Los resultados indican que la combinación A2 (SRM 91 y PI) afectó las variables ΔB y ΔE. La combinación B1 (SRM 55 Y PH) afectó las variables ΔA, ΔB y el índice de blanqueamiento WIO. Solamente SRM 91afectó la variable ΔL. La presión osmótica de la saliva y la sustancia remineralizante afectan el color del esmalte dental...

Caracterización de la dentina tratada endodónticamente / Characterization of endodontically treated dentin

INTRODUCCIÓN: restaurar dientes tratados endodónticamente implica tratar la dentina con sustancias desinfectantes y ácidas que mejoran la adhesión, pero generan cambios estructurales e irreversibles en la misma. El objetivo de este artículo fue detallar y analizar los cambios en la estructura y las propiedades mecánicas, descritas en la literatura, que producen el hipoclorito de sodio al 5,25%, ácido etilendiaminotetraacético, (EDTA), al 17% y la clorhexidina al 2% sobre la dentina tratada endodónticamente. MÉTODOS: se buscó en las bases de datos: Scient Direct, Pubmed, Scielo y EbscoHost las palabras clave "Human Dentin"and "Root Canal" and "Human Dentin and Change, "Dentin Treated" y "Treated dentin and Chlorhexidine", seleccionando 67 artículos que cumplieron con describir y detallar los cambios en la dentina cuando es irrigada con hipoclorito de sodio al 5,25% y ácido etilendiaminotetraacético,(edta), al 17% y clorhexidina al 2% en diferentes momentos del tratamiento. RESULTADOS Y CONCLUSIONES: se encontró que la dentina tratada presenta cambios, como pérdida de la arquitectura dentinal, el contenido iónico y la matriz orgánica, reducción en la microdureza, la nanodureza, y la resistencia tensil, y compresiva. La dentina tratada endodónticamente, es un sustrato alterado químicamente que repercute en sus propiedades y en la durabilidad de la adhesión.

INTRODUCTION: restoring endodontically treated teeth involves treating dentin with disinfectants and acidic substances that improve adhesion but generate structural irreversible changes. The objective of this article was to describe and analyze the changes in structure and mechanical properties produced by 5.25% sodium hypochlorite, 17% ethylenediaminetetraacetic acid (EDTA), and 2% chlorhexidine on endodontically treated dentin, as described in the literature. METHODS: the following databases were consulted: Scient Direct, Pubmed, Scielo, and EbscoHost, using these keywords: "Human Dentin" and "Root Canal" and "Human Dentin and Change", "Dentin Treated" and "Treated dentin and Chlorhexidine". We selected 67 articles that met these criteria: thoroughly describe dentin changes when it is irrigated with 5.25% sodium hypochlorite and 17% ethylenediaminetetraacetic acid (EDTA), and 2% chlorhexidine at different treatment stages. RESULTS AND CONCLUSIONS: : we found out that treated dentin suffers changes in terms of dentinal architecture loss, ionic content and organic matrix, and reduction in microhardness, nanohardness, and compressive and tensile strength. Endodontically treated dentin is a chemically altered substrate with affected properties and poor adhesion durability.

Selective removal of mineral and organic components of bovine enamel by phosphoric acid.

PURPOSE: To follow the chemical composition of bovine enamel during phosphoric acid-induced demineralization. MATERIALS AND METHODS: Enamel samples were ground into a fine powder, selecting the 150- and 200-µm fractions in order to obtain a more homogeneous study material. They were immersed in diluted phosphoric acid (0.1%) for increasing durations ranging from 1 to 1440 min. The chemical composition of the solution and enamel powder was determined after each sequential treatment by means of atomic absorption (AA) and Fourier transform infrared (FTIR) spectroscopy. RESULTS: AA data revealed that the amount of calcium mobilized to the solution by the acid treatment was higher at shorter exposure times. However, FTIR data showed that the degree of mineralization of the enamel remained constant during the treatment, indicating that the mineral and organic components were lost at the same rate. Interestingly, poorly crystalline phosphate and carbonate-rich mineral components were preferentially removed and were presumably the main source of calcium released by the acid exposure. FTIR results also demonstrated that organic components rich in hydrophobic groups were preferentially removed during acid treatment. CONCLUSION: Etching with phosphoric acid produces a nonhomogeneous demineralization of bovine enamel, with the selective removal of poorly crystalline mineral and hydrophobic organic components.

Demineralization effects of phosphoric acid on surface and subsurface bovine enamel bleached with in-office hydrogen peroxide.

PURPOSE: To measure the demineralization capacity of 37% phosphoric acid on surface and subsurface bovine enamel after bleaching with hydrogen peroxide (H2O2). MATERIALS AND METHODS: Three equally-sized sections with 16 mm2 of exposed enamel surface were obtained from the enamel of 10 bovine incisors. One specimen sample from each crown was assigned to one of three groups (n = 10): group I, no bleaching agent; group II, bleached with 38% H202 for 20 min; or group III, 30% H202 for 60 min. After 24 h, the thickness of specimens was measured and they were immersed in 37% phosphoric acid solution, of which 5-ml aliquots were collected at 30 s and 60 s. Specimens were then ground to a depth of 25 µm and again immersed in 37% phosphoric acid solution. This procedure was repeated for enamel depths of 50 and 100 µm. Ca2+ concentrations in the phosphoric acid aliquots were measured by atomic absorption spectroscopy. RESULTS: No significant differences were found in the total amounts of extracted Ca2+ between bleached and unbleached specimens (F = 0.142; p = 0.869). The amount of Ca2+ extracted was similar among the four depth levels in the unbleached and in the 30% H202 bleached specimens. A significantly larger amount of Ca2+ was obtained at 25 µm depth (subsurface) from specimens treated with 38% H202. CONCLUSIONS: Pre-bleaching with 38% H202 significantly increased the decalcifying effect of phosphoric acid on subsurface enamel at a depth of 25 µm compared to 100 µm, whereas pre-bleaching with 30% H202 did not modify this effect at any level.