Clinical implementation of comprehending dentin on a microscopic level

SUMMARY: The aim of the present in vitro study is to visualize dentin to get an in-depth knowledge of the nature of dentin that could provide useful information regarding conditioning dentinal substrate when treating dentinal lesions. Forty-nine extracted human third molars were obtained and prepared to produce artificial dentinal lesions through demineralizing with acetic acid for 7 and 14 days, or lactic acid for 7 days. The teeth were divided into groups and treated with either NaOCl, pepsin, trypsin, or phosphoric acid. To obtain information on the morphology of the treated dentinal surfaces, all samples were visualized under high resolution field emission scanning electron microscope. With high magnification reaching x50000 dentin was clearly visualized together with its constitutes. The effect of various demineralization approaches and various treatment protocols were demonstrated clearly. The relationship between the conditioning procedure steps and the subsequent bond strength was discussed. To our best knowledge, there is no previous clear highly magnified scanning electron microscope images for dentin, and dentinal components and constitutes with and without various treatments. The current in vitro study suggests the complexity nature of dentin as a substrate that should be treated carefully especially with technique sensitive procedures such as adhesive restorations.

El objetivo del presente estudio in vitro fue visualizar la dentina para obtener un conocimiento completo de la naturaleza de ella lo que podría proporcionar información útil sobre el acondicionamiento del sustrato dentinario en el tratamiento de lesiones dentinarias. Se obtuvieron 49 terceros molares humanos extraídos y se prepararon para producir lesiones dentinales artificiales mediante desmineralización con ácido acético por 7 y 14 días, o ácido láctico por 7 días. Los dientes se dividieron en grupos y se trataron con NaOCl, pepsina, tripsina o ácido fosfórico. Para obtener información sobre la morfología de las superficies dentinarias tratadas, todas las muestras se visualizaron bajo un microscopio electrónico de barrido de emisión de campo de alta resolución. Con un gran aumento que alcanzó x50000, la dentina se visualizó claramente junto con sus componentes. Se demostró el efecto de varios enfoques de desmineralización y varios protocolos de tratamiento. Se discutió la relación entre los pasos del procedimiento de acondicionamiento y la subsiguiente fuerza de unión. Hasta donde sabemos, no hay imágenes claras previas de microscopio electrónico de barrido altamente ampliadas para la dentina y los componentes y constituyentes de la dentina con y sin diferentes tratamientos. El estudio in vitro actual sugiere la naturaleza compleja de la dentina como sustrato que debe tratarse con cuidado, especialmente en los procedimientos sensibles a la técnica, tal como las restauraciones adhesivas.

Effects of using different root canal sealers and protocols for cleaning intraradicular dentin on the bond strength of a composite resin used to reinforce weakened roots / Efectos del uso de diferentes selladores de conductos radiculares y protocolos para limpiar la dentina intrarradicular sobre la fuerza de unión de una resina compuesta utilizada para reforzar raíces debilitadas

Background: This study evaluated the effects of using different root canal sealers and protocols for cleaning intraradicular dentin on the bond strength of a composite resin used to reinforce weakened roots. Material and Methods: Sixty-four roots of extracted human maxillary canines were weakened, prepared and filled with two different endodontic sealers (Endofill and AH Plus). In half of the sample, set aside for each respective sealer, excess filling material was cleaned. In the other half, the weakened areas were not cleaned, and the excess of sealer was spread on the intraradicular dentin. Intentionally worn areas inside each root were restored with a microhybrid light-cure composite resin (Z100) to reinforce them, with and without acid etching. Prefabricated metal posts were fixed with a dual resin cement (RelyX ARC), and the specimens were submitted to a pull-out test. Statistical analysis was performed by means of Shapiro-Wilk, analysis of variance (one-way ANOVA) and Tukey-Kramer tests (p<0.05). Results: The groups filled with Endofill (GI, GII, GIII, GIV) had the lowest bond strength values, which were similar among each other (p>0.05).The greatest bond strength values were observed in roots filled with AH Plus (GV, GVI, GVII, GVIII), mainly without cleaning of the weakened areas, and followed by acid etching (GVII), and also with cleaning of the weakened areas, however, with no acid etching (GVI) (p<0.05). Conclusion: The greatest bond strength values were observed in roots filled with AH Plus; (1) without cleaning of the weakened areas and with acid etching, and; (2) with cleaning of the weakened areas, but without acid etching.

Antecedentes: este estudio evaluó los efectos del uso de diferentes selladores de conductos radiculares y protocolos para limpiar la dentina intrarradicular sobre la fuerza de unión de una resina compuesta utilizada para reforzar las raíces debilitadas. Material y Métodos: Sesenta y cuatro raíces de caninos maxilares humanos extraídos fueron debilitadas, preparadas y rellenadas con dos selladores endodónticos diferentes (Endofill y AH Plus). En la mitad de la muestra, reservada para cada sellador respectivo, se limpió el exceso de material de relleno. En la otra mitad, las áreas debilitadas no se limpiaron y el exceso de sellador se esparció sobre la dentina intrarradicular. Las áreas desgastadas intencionalmente dentro de cada raíz se restauraron con una resina compuesta fotopolimerizable microhíbrida (Z100) para reforzarlas, con y sin grabado ácido. Los postes metálicos prefabricados se fijaron con un cemento de resina dual (RelyX ARC) y los especímenes se sometieron a una prueba de extracción. El análisis estadístico se realizó mediante Shapiro-Wilk, análisis de varianza (ANOVA de una vía) y pruebas de Tukey-Kramer (p<0,05). Resultados: Los grupos rellenos con Endofill (GI, GII, GIII, GIV) presentaron los valores más bajos de fuerza de unión, los cuales fueron similares entre sí (p>0,05). Los mayores valores de fuerza de unión se observaron en raíces rellenas con AH Plus (GV, GVI, GVII, GVIII), principalmente sin limpieza de las áreas debilitadas, seguido de grabado ácido (GVII), y también con limpieza de las áreas debilitadas aunque sin grabado ácido (GVI) (p<0.05). Conclusión: Los mayores valores de fuerza de unión se observaron en las raíces rellenas con AH Plus; (1) sin limpieza de las áreas debilitadas y con grabado ácido, y; (2) con limpieza de las áreas debilitadas, pero sin grabado ácido.

Uso efectivo de los adhesivos de octava generación / Effective use of eighth generation adhesives

Introducción: se realizó una revisión bibliográfica con el objetivo de conocer, analizar y comparar los diferentes tipos de adhesivos de octava generación que se encuentran en el mercado y la diferencia que existe entre cada uno. Los adhesivos universales han demostrado mejoras en su resistencia, sobre todo en las técnicas de aplicación y en las propiedades de estos materiales, al mejorar la fuerza adhesiva para que el odontólogo pueda brindar tratamientos restaurativos exitosos. Objetivo: conocer, analizar y comparar los diferentes tipos de adhe- sivos de la octava generación empleados en odontología. Material y métodos: se realizó una búsqueda en las bases de datos electrónicas PubMed, BVS, Redalyc y ScienceDirect. Se utilizaron 32 artículos que cumplieron con los criterios predeterminados y la especificidad reque- rida para la pregunta de investigación. Conclusiones: se demostró que la tecnología cada día avanza, sobre todo en el área de los adhesivos, ya que éstos son de mucha utilidad en el día a día del odontólogo; es importante conocer cada uno de éstos, puesto que es un poco complejo seleccionar el correcto, mas no el uso. En la actualidad, existen diversas opciones por las que el odontólogo puede optar, es por ello que el pro- fesional debe estar capacitado sobre cada una de las diferentes marcas existentes y, de acuerdo al tratamiento, debe elegir cuál es mejor utilizar en una rehabilitación. Es importante para el odontólogo conocer estos materiales, ya que esto lo beneficiará al momento de llevar un plan de tratamiento restaurador (AU)

Introduction: a bibliographic review was carried out to learn about, analyze, and compare the different types of eighth-generation adhesives on the market and the difference between each one. Universal adhesives have demonstrated improvements in their resistance, especially in the application techniques and properties of these materials, improving the adhesive strength so that the dentist can provide successful restorative treatments. Objective: to know, analyze and compare the different types of eighth-generation adhesives used in dentistry. Material and methods: a search was made of the following electronic databases: PubMed, BVS, Redalyc, ScienceDirect. Finally, 32 articles that met the predetermined criteria and the specificity required for the research question were used. Conclusions: it was demonstrated that technology is advancing every day, especially in the area of adhesives since these are very useful in the daily life of the dentist. It is important to know each one of these since it is a little complex at the moment of selecting the correct one, but not the use. Currently, there are several options that the dentist can choose, which is why the professional must be trained on each of the various existing brands and according to the treatment which is the best to use at the time of rehabilitation. The dentist needs to know these materials since they will benefit him/her when carrying out a restorative treatment plan (AU)

Potencial remineralizante del fluoruro diamino de plata al 38% en dentina de dientes temporales afectada por caries / Remineralizing potential of 38% silver diamine fluoride in dentin affected by dental caries

Introducción: la caries es una enfermedad compleja que afecta a cualquier edad. La prevalencia es mayor en la primera dentición, sobre todo en población con baja percepción económica. El fluoruro diamino de plata (FDP) al 38% ha sido utilizado como una alter- nativa de tratamiento para esta enfermedad. Funciona como una solución remineralizante y cariostática. Objetivo: evaluar el efecto remineralizante del FDP al 38% en dentina afectada por lesiones de caries en molares temporales. Material y métodos: estudio clínico, epidemiológico, descriptivo, longitudinal y experimental. Se llevó a cabo en molares de primera dentición de niños de tres a cinco años de edad. Los niños seleccionados tenían molares con lesiones cariosas dentinarias, Pitts las denomina D3. No se incluyeron niños con dientes que presentaron patologías pulpares irreversibles. La aplicación del FDP al 38% la efectuó un operador entrenado para esta finalidad. Se utilizaron los criterios de Nyvad para determinar el grado de dureza de la dentina y con ello deducir su remineraliza- ción. Se observó la permanencia de la remineralización efectuada por un periodo de cinco meses. Resultado y conclusión: el FDP es un compuesto eficaz en 91% de los casos en un periodo de cinco meses o más (AU)

Introduction: dental caries is a complex disease that affects any age. The prevalence is higher in primary dentition, especially in a population with low economic perception. 38% silver diamine fluoride (FDP) has been used as an alternative treatment for this disease. It works as a remineralizing and cariostatic solution. Objective: to evaluate the remineralizing effect of 38% FDP on dentin affected by dental caries, in temporary molars. Material and methods: clinical, epidemiological, descriptive, longitudinal and experimental study. It was carried out in temporary molars of children between three and five years of age. The selected children presented molars with dental carious lesions, Pitts calls them D3. Children with teeth that presented irreversible pulp pathologies were not included. The application of the FDP to 38% was carried out by an operator trained for this purpose. The Nyvad criteria were used to determine the degree of hardness of the dentin and thereby deduce its remineralization. The permanence of the remineralization carried out was observed for a period of five months. Result and conclusion: the FDP is an effective compound in 91% of the cases, in a period of five months or more (AU)

Influence of violet LED associated or not with peroxide gel on inflammation, mineralization, and collagen fiber maturation in dentin and pulp tissue.

OBJECTIVES: To evaluate the influence of violet LED, associated or not with a 17.5% hydrogen peroxide (HP) bleaching gel, on inflammation, mineralization in pulp tissue, and collagen fiber maturation in dentin and pulp tissue. MATERIALS AND METHODS: The maxillary molars of eighty Wistar rats were distributed into four groups (n = 10): CONT - without treatment; HP - 30 min application of 17.5% HP; LED - 20 min application of violet LED; and HP+LED - application of PH and violet LED. Rats were euthanized and jaws were processed for histologic and immunohistochemical evaluation (IL-17, IL-23, and osteocalcin) and picrosirius red immediately after (T0), and at 7 (T1), 15 (T2), and 30 days (T3) post-treatment, with Wilcoxon, Mann-Whitney, paired T-test, and T-test (α = 0.05). RESULTS: HP and HP+LED presented necrosis and severe inflammatory infiltrate. When compared to CONT group, LED presented severe osteocalcin (OCN) immunostaining in T2 and less immature fibers in T2 and T3. CONCLUSION: The violet LED caused no severe damage to the pulp tissue, increased IL-17 and IL-23 expression in T0 when associated with HP, and had no influence on pulp tissue mineralization, besides accelerating the maturation of collagen fibers of dentin. CLINICAL RELEVANCE: Violet LED therapy induced no inflammation in the pulp tissue of rats and played no role in pulp tissue fibrosis, besides accelerating the maturation of dentin collagen fibers.

Comparación de la fuerza de adhesión a dentina de cementos de autograbado vs grabado total / Comparison of bond strength to dentin of self-etching cements vs total etching

Los sistemas cementantes han mejorado notablemente, los objetivos que persiguen los nuevos cementos es que la adhesión sea duradera y conseguir siempre que sea posible una interface cerrada con un sellado perfecto. Se han podido desarrollar nuevas técnicas y nuevos materiales de cementación que han ido perfeccionando la unión del material restaurador al diente. En el presente estudio se compara la fuerza de adhesión a dentina de cementos de autograbado y cementos de grabado total para comprobar los efectos positivos en el grabado de la dentina. Para el estudio se utilizaron dos cementos a base de resina (RelyX U200 Clicker 3M y RelyX Ultimate 3M). Se encapsularon 40 molares en acrílico en dos grupos de 20 muestras para la aplicación de dos sistemas cementantes de autograbado (grupo 1) y de grabado total (grupo 2), respectivamente, se desgastaron hasta descubrir la dentina; siguiendo las especificaciones del fabricante se colocó el cemento en cada grupo, y después se sometieron a pruebas de cizalla en una máquina de ensayo universal Instron. La medida expresada en megapascales (MPa) fue: grupo 1 = 7.5569 y grupo 2 = 12.6444. En este caso fueron analizados dos grupos, tomándose la primera significancia bilateral. Se realiza la prueba en t de Student, con 95% de intervalo de confianza en la diferencia, demostrando así que el cemento RelyX Ultimate 3M tiene mayor fuerza de adhesión que el cemento RelyX U200 Clicker 3M. Nuestra investigación fue factible y llegamos a nuestro propósito, en el cual comprobamos la mayor adhesión de cementos de grabado total, los cuales son sometidos a un previo tratamiento del diente (AU)

Materiais inteligentes na odontologia minimamente invasiva: remoção, recuperação e restauração da dentina / Smart materials in minimally invasive dentistry: dentin removal, recovery and restoration

O objetivo da presente tese foi analisar as características das interações de materiais inteligentes quando aplicados em dentina, avaliando as técnicas de remoção, a recuperação e a restauração do tecido cariado. Para isso, foram realizados 6 estudos englobando os conceitos atuais da odontologia de mínima intervenção. O primeiro estudo consiste em uma revisão bibliométrica, que realizou um levantamento nas bases de dados MEDLINE, Scopus, Web of Science, Cochrane Library, Lilacs/BBO e Embase, evidenciando o potencial bioativo dos materiais estudados e a necessidade de testá-los em dentina totalmente ou parcialmente desmineralizada através de estudos laboratoriais. O segundo estudo visou comparar in vitro diferentes técnicas para remoção de cárie artificialmente produzidas: o uso de broca, cureta e dois agentes químico-mecânicos (Papacárie Duo Gel®, Fórmula e Ação e Brix3000®, Brix Medical Science). Para isso, foram realizados escaneamentos em micro-CT antes e após a remoção de cárie com o intuito de comparar o volume e a densidade mineral da dentina, demonstrando que não houve diferença entre as técnicas quanto a quantidade de tecido removido (p>0,05). Além disso, nesse mesmo estudo, foi avaliado o potencial de cimentos de polialquenoato (Poly Zinc®, Prevest DenPro e Ketac Molar®, 3M ESPE) na recuperação da densidade mineral da dentina remanescente, mostrando que o cimento de policarboxilato de zinco apresentou um desempenho melhor (33,6%) quando comparado ao cimento de ionômero de vidro (6%; p<0,01). Quanto à seletividade in vitro dos agentes químico-mecânicos à base de papaína, um terceiro estudo foi conduzido, testando as alterações na morfologia e rugosidade superficial da dentina hígida antes e após a aplicação dos géis, comprovando que esses géis são específicos e seguros, sendo que os valores da rugosidade superficial não apresentaram diferenças estatísticas (p>0,05). No quarto estudo foi avaliado in vitro a interação de materiais restauradores liberadores de íons aplicados sobre a dentina artificialmente cariada. Excetuando o compósito resinoso testado (Aura®, SDI), tanto o cimento de ionômero de vidro (Fuji IX®, GC) quanto os cimentos a base de silicato de cálcio (Endo-pass®, DEI e Theracal®, Bisco) provocaram precipitação mineral na interface com a dentina. Esses resultados foram confirmados através de análises quantitativas (α = 5%) e qualitativas. O quinto estudo analisou in vitro dois cimentos de ionômero de vidro modificados por resina (CIVMR; Ionolux®, VOCO e ACTIVA®, Pulpdent) quando aplicados sobre sistemas adesivos universais simplificados (Futurabond®, VOCO e Scotchbond®, 3M) com o objetivo de comparar a força de união a longo prazo desses materiais aplicados sobre dentina. Foi possível constatar que a composição dos sistemas adesivos influencia mais do que o protocolo de aplicação, seja a aplicação convencional ou autocondicionante. Entretanto, quando bem empregados, os CIVMR, podem melhorar a longevidade de adesão desses sistemas adesivos (p<0,05). O sexto estudo consiste em uma revisão de literatura narrativa que apresenta os materiais liberadores de íons disponíveis no mercado, seus mecanismos ação e suas indicações clínicas. Com isso, pode-se concluir que grande parte dos estudos sobre materiais bioativos ainda são limitados a experimentos in vitro e que, apesar de apresentarem resultados positivos quanto a sua bioatividade em recuperar densidade e promover precipitação mineral, esses resultados ainda não podem ser extrapolados clinicamente. Quanto as técnicas de remoção seletiva de cárie, talvez conhecer os conceitos biológicos, fisiológicos e químicos dos processos seja mais importante do que a técnica aplicada em si. Isso também serve no emprego dos materiais bioativos já disponíveis no mercado, que de acordo com a sua composição, a indicação clínica pode variar. (AU)

The aim of the present study was to analyze the type of interactions between smart materials and dentin by studying the techniques for carious tissue removal, dentin recovery and tissue restoration. In order to do this, 6 studies were carried out, involving the current concepts of minimally invasive dentistry. The first study consisted of a bibliometric review, in which we carried out a survey in MEDLINE, Scopus, Web of Science, Cochrane Library, Lilacs/BBO and Embase databases, on the bioactive potential of restorative materials and their effect in sound, completely or partially demineralized dentin through laboratory studies. The second study aimed to compare in vitro different techniques for dentin caries removal: drill, hand excavator and two chemical-mechanical agents (Papacárie Duo Gel®, Fórmula e Ação and Brix3000®, Brix Medical Sciences). In order to do this, micro-CT scans were performed before and after caries removal to compare the volume and mineral density of dentin, and the results showed no difference among the techniques regarding the amount of tissue removed (p>0.05). At the same study, the potential of polyalkenoate cements (Poly Zinc®, Prevest DenPro and Ketac Molar®, 3M ESPE) to recover mineral density of the remaining dentin was evaluated, showing that the zinc polycarboxylate cement presented higher performance (33.6%) compared to the glass ionomer cement (6%; p<0.01). To test the in vitro selectivity of the chemical-mechanical agents based on papain, a third study was conducted to test the changes in the morphology and surface roughness of sound dentin before and after the application of papain gels. The results showed that they are specific and safe, as the surface roughness values after application were not statistically significant different (p>0.05). The fourth study evaluated in vitro the interaction of ion-releasing restorative materials applied on artificially carious dentin. With the exception of the resin composite (Aura®, SDI), both glass ionomer cement (Fuji IX®, GC) and calcium silicate-based cements (Endo-pass®, DEI and Theracal®, Bisco) resulted in mineral precipitation at the interface with dentin. These results were confirmed through quantitative (α= 5%) and qualitative analyses. The fifth study analyzed in vitro two resin-modified glass ionomer cements (RMGIC; Ionolux®, VOCO and ACTIVA®, Pulpdent) when applied with simplified universal adhesive systems (Futurabond®, VOCO and Scotchbond®, 3M) with the aim to compare the long-term bond strength between these materials and dentin. It was possible to verify that the composition of the adhesive systems influenced more than the application protocol (conventional or self-etch mode). However, RMGIC can improve the longevity of adhesion of these adhesive systems (p<0.05). The sixth study consisted of a narrative critical literature review presenting the ion-releasing materials available on the market, their mechanisms of action and their clinical indications. It can be thus concluded that most studies on bioactive materials are still limited to in vitro experiments and, despite showing positive results regarding bioactivity in recovering density and promoting mineral precipitation, these results still can not be extrapolated to clinical applications. Regarding the selective potential of caries removal techniques, the knowledge of biological, physiological and chemical concepts of the processes is more important than the technique used. This can be also applied to the use of bioactive materials available on the market, which according to their composition, may present different clinical indications and applications. (AU)

El objetivo de la presente tesis fue analizar las características de las interacciones de los materiales inteligentes cuando se aplican a la dentina para estudiar las técnicas de remoción, recuperación y restauración del tejido. Para ello se realizaron 6 estudios que engloban los conceptos actuales de la odontología de mínima intervención. El primer estudio consiste en una revisión bibliométrica, que realizó una revisión en las bases de datos MEDLINE, Scopus, Web of Science, Cochrane Library, Lilacs/BBO y Embase, evidenciando el potencial bioactivo de los materiales estudiados y la necesidad de probarlos en dentina totalmente o parcialmente desmineralizada a través de estudios de laboratorio. El segundo estudio tuvo como objetivo comparar in vitro diferentes técnicas para la remoción de caries producidas artificialmente: el uso de material rotatorio, cureta y dos agentes químico-mecánicos (Papacárie Duo Gel® y Brix3000®). Para ello, se realizaron análisis en micro-CT antes y después de la remoción de caries con el fin de comparar el volumen y la densidad mineral de la dentina, demostrando que no hubo diferencia entre las técnicas en la cantidad de tejido removido (p>0,05). Además, en el mismo estudio se evaluó el potencial de los cementos de polialquenoato (Poly Zinc®, Prevest DenPro y Ketac Molar®, 3M ESPE) en la recuperación de la densidad mineral de la dentina remanente, demostrando que el cemento de policarboxilato de zinc presentó un comportamiento mejor (33,6%) en comparación con el cemento de ionómero de vidrio (6%; p<0,01). Con relación la selectividad in vitro de los agentes químico-mecánicos a base de papaína, se realizó un tercer estudio probando los cambios en la morfología y rugosidad superficial de la dentina sana antes y después de la aplicación de los geles, demostrando que estos geles son específicos y seguros, siendo que los valores de rugosidad superficial no presentaron diferencias estadísticas (p>0.05). El cuarto estudio evaluó in vitro la interacción de materiales restauradores liberadores de iones aplicados sobre dentina cariada artificialmente. Excepto por el compuesto de resina (Aura®, SDI), tanto el cemento de ionómero de vidrio (Fuji IX®, GC) como los cementos a base de silicato de calcio (Endo-pass®, DEI y Theracal®, Bisco) causaron precipitación mineral en la interfaz con la dentina. Estos resultados se confirmaron mediante análisis cuantitativos (α = 5%) y cualitativos. El quinto estudio analizó in vitro dos cementos de ionómero de vidrio modificados con resina (CIVMR; Ionolux®, VOCO y ACTIVA®, Pulpdent) aplicados sobre sistemas adhesivos universales simplificados (Futurabond®, VOCO y Scotchbond®, 3M) con el objetivo de comparar la fuerza de unión a largo plazo de estos materiales aplicados a la dentina. Se pudo verificar que la composición de los sistemas adhesivos influye más que el protocolo de aplicación, sea la aplicación convencional o el autograbado. Sin embargo, el CICMR puede mejorar la longevidad de la adhesión de estos sistemas adhesivos (p<0.05). El sexto estudio consiste en una revisión narrativa de la literatura que presenta los materiales liberadores de iones disponibles en el mercado, sus mecanismos de acción y sus indicaciones clínicas. Con esto, se puede concluir que la mayoría de los estudios sobre materiales bioactivos aún se limitan a experimentos in vitro y que, a pesar de mostrar resultados positivos con relación a su bioactividad para recuperar densidad y promover la precipitación mineral, estos resultados aún no son extrapolables clínicamente. En cuanto a las técnicas de eliminación selectiva de caries, quizás sea más importante conocer los conceptos biológicos, fisiológicos y químicos de los procesos que la técnica elegida. Esto también sirve para el uso de materiales bioactivos disponibles en el mercado, que, según su composición, la indicación clínica puede variar. (AU)

Adhesión a dentina parte I: características del sustrato y sistemas adhesivos / Dentin bonding part I: substrate characteristics and bonding systems

La Odontología Restauradora contemporánea no puede concebirse sin la adhesión de los materiales restauradores a las estructuras dentarias. En mu-chos procedimientos restauradores, no sólo el esmal-te sino también la dentina se encuentra involucrada, por lo tanto, la adhesión a esta última juega un rol cla-ve en el éxito clínico. No obstante, todavía supone un gran desafío lograr una adhesión estable y predeci-ble en el tiempo. El propósito del presente artículo es analizar las características principales de la dentina como sustrato adhesivo y describir los sistemas ad-hesivos actuales y sus mecanismos de acción (AU)

Contemporary Restorative Dentistry cannot be conceived without the adhesion of restorative materials to dental structures. In many restorative procedures not only the enamel, but also the dentin is involved, therefore dentin bonding plays a key role in their success. However, it is still a great challenge to achieve stable and predictable dentin bonding over time. The aim of this article is to analyze the main characteristics of dentin as an adhesive substrate and to describe current adhesive systems and their bonding mechanisms (AU)

Adhesión a dentina part II: estrategias para optimizar la adhesión a dentina y protocolos adhesivos / Dentin bonding part II: strategies to optimize dentin bonding and adhesive protocols

La adhesión a dentina con sistemas adhesivos polimé-ricos representa un desafío que surge de la necesi-dad de vincular un sustrato dentario heterogéneo y variable con materiales que presentan todavía cier-tos aspectos a atender para poder conseguir el máxi-mo desempeño. El propósito del presente artículo es evaluar algunas de las estrategias propuestas para mejorar la adhesión a dentina, y sugerir un protocolo de trabajo con los diferentes tipos de sistemas adhesivos (AU)

Dentin bonding with polymeric adhesive systems represents a challenge that arises from the need to link a heterogeneous and variable dental substrate with materials that still have certain aspects to be addressed in order to achieve maximum performance. The aim of this article is to evaluate some of the proposed strategies to improve dentin bonding and to suggest a protocol for each different type of bonding systems (AU)

Novel Bioactive Adhesive Monomer CMET Promotes Odontogenic Differentiation and Dentin Regeneration.

This study aimed to evaluate the in vitro effect of the novel bioactive adhesive monomer CMET, a calcium salt of 4-methacryloxyethyl trimellitate acid (4-MET), on human dental pulp stem cells (hDPSCs) and its capacity to induce tertiary dentin formation in a rat pulp injury model. Aqueous solutions of four tested materials [4-MET, CMET, Ca(OH)2, and mineral trioxide aggregate (MTA)] were added to the culture medium upon confluence, and solvent (dH2O) was used as a control. Cell proliferation was assessed using the Cell Counting Kit-8 assay, and cell differentiation was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. The mineralization-inducing capacity was evaluated using alizarin red S staining and an alkaline phosphatase activity assay. For an in vivo experiment, a mechanical pulp exposure model was prepared on Wistar rats; damaged pulp was capped with Ca(OH)2 or CMET. Cavities were sealed with composite resin, and specimens were assessed after 14 and 28 days. The in vitro results showed that CMET exhibited the lowest cytotoxicity and highest odontogenic differentiation capacity among all tested materials. The favorable outcome on cell mineralization after treatment with CMET involved p38 and c-Jun N-terminal kinases signaling. The nuclear factor kappa B pathway was involved in the CMET-induced mRNA expression of odontogenic markers. Similar to Ca(OH)2, CMET produced a continuous hard tissue bridge at the pulp exposure site, but treatment with only CMET produced a regular dentinal tubule pattern. The findings suggest that (1) the evaluated novel bioactive adhesive monomer provides favorable biocompatibility and odontogenic induction capacity and that (2) CMET might be a very promising adjunctive for pulp-capping materials.

Hydroxypropylmethylcellulose as a film and hydrogel carrier for ACP nanoprecursors to deliver biomimetic mineralization.

Demineralization of hard tooth tissues leads to dental caries, which cause health problems and economic burdens throughout the world. A biomimetic mineralization strategy is expected to reverse early dental caries. Commercially available anti-carious mineralizing products lead to inconclusive clinical results because they cannot continuously replenish the required calcium and phosphate resources. Herein, we prepared a mineralizing film consisting of hydroxypropylmethylcellulose (HPMC) and polyaspartic acid-stabilized amorphous calcium phosphate (PAsp-ACP) nanoparticles. HPMC which contains multiple hydroxyl groups is a film-forming material that can be desiccated to form a dry film. In a moist environment, this film gradually changes into a gel. HPMC was used as the carrier of PAsp-ACP nanoparticles to deliver biomimetic mineralization. Our results indicated that the hydroxyl and methoxyl groups of HPMC could assist the stability of PAsp-ACP nanoparticles and maintain their biomimetic mineralization activity. The results further demonstrated that the bioinspired mineralizing film induced the early mineralization of demineralized dentin after 24 h with increasing mineralization of the whole demineralized dentin (3-4 µm) after 72-96 h. Furthermore, these results were achieved without any cytotoxicity or mucosa irritation. Therefore, this mineralizing film shows promise for use in preventive dentistry due to its efficient mineralization capability.

Reconstruction of a Demineralized Dentin Matrix via Rapid Deposition of CaF2 Nanoparticles In Situ Promotes Dentin Bonding.

Dentin bonding based on a wet-bonding technique is the fundamental technique used daily in clinics for tooth-restoration fixation and clinical treatment of tooth-related diseases. Limited bonding durability led by insufficient adhesive infiltration in the demineralized dentin (DD) matrix is the biggest concern in contemporary adhesive dentistry. This study proposes that the highly hydrated noncollagenous protein (NCP)-formed interfacial microenvironment of the DD matrix is the root cause of this problem. Meanwhile, the endogenous phosphate groups of the NCPs are used as pseudonuclei to rapidly induce the formation of amorphous CaF2 nanoparticles in situ in the interfacial microenvironment. The DD matrix is thus reconstructed into a novel porous structure. It markedly facilitates the infiltration of dentin adhesives in the DD matrix and also endows the DD matrix with anticollapsing capability when water evaporates. Whether using a wet-bonding or air-drying mode, the bonding effectiveness is greatly promoted, with the 12 month bonding strength being about twice that of the corresponding control groups. This suggests that the nanoreinforced DD matrix eliminates the dependence of bonding effectiveness on the moisture status of the DD surface controlled only by experiences of dentists. Consequently, this bonding strategy not only greatly improves bonding durability but also overcomes the technical sensitivity of bonding operations of the total-etched bonding pattern. This exhibits the potential to promote dentin bonding and is of great significance to dentistry.

Multifunctional Ca-Zn-Si-based micro-nano spheres with anti-infective, anti-inflammatory, and dentin regenerative properties for pulp capping application.

While pulp capping using a variety of materials has been applied clinically to preserve the health and vitality of the dental pulp and induce dentin repair no material meets all the anti-infection, anti-inflammation, and promoting pulp tissue regeneration criteria. Micro-nano materials of bioactive glasses (BG) with the biocompatibility and osteogenesis-promoting properties were developed for this study using Zn-doped bioactive glass (BGz) micro-nano spheres for dental pulp capping to control infection and inflammation and promote tissue regeneration. Of three key findings, the co-culture of Porphyromonas gingivalis showed that the BGz had an excellent antibacterial effect, and after being stimulated with BGz in vitro, macrophages showed a significant decrease of pro-inflammatory M1 markers compared with the undoped BG group. It is also noted that the conditioned medium derived from BGz-stimulated macrophages could significantly promote mineralized dentin formation of dental pulp cells (DPCs). In rats, acute pulp restoration experiments proved that BGz used as a pulp capping agent had excellent dentin regenerative properties. This work may provide a novel strategy to promote osteo/dentinogenic differentiation through regulating early inflammation, with potential applications in pulp capping.

Endogenous Enzymatic Activity in Dentin Treated with a Chitosan Primer.

The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth (n = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups (p < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time.

Biomateriales que inducen la remineralización del esmalte dental y dentina / Biomaterials that induce remineralization of the dentin and enamel surface

Desde los sesentas, con la invención del vidrio bioactivo, los tratamientos de remineralización se han popularizado entre los cirujanos dentistas y su utilización es cada vez mayor; la remineralización, en conjunto con las adecuadas medidas de higiene preventiva, representa uno de los mejores abordajes mínimamente invasivos y a un costo comparativamente bajo. Este estudio documental tiene por objetivo establecer una mejor comprensión del uso clínico de los biomateriales que inducen la remineralización de la superficie del esmalte dental y dentina. Se realizó una exploración utilizando motores de búsqueda (bases de datos en PubMed, Medigraphic, y Science Direct). El proceso de localización de los estudios relevantes se efectuó introduciendo palabras clave como: silicatos de calcio, fosfopéptidos de caseína-fosfato de calcio amorfo, remineralización, esmalte y dentina, incluyéndose en el procedimiento artículos de antigüedad no superior a siete años, en español e inglés, publicados en revistas científicas aprobadas por pares.Actualmente, no es posible remineralizar del todo la estructura dentaria, por lo cual, en un futuro cercano, los esfuerzos de la odontología de remineralización deben apuntar al desarrollo de agentes biomiméticos inteligentes que restauren al cien por ciento la estructura dental perdida (AU)

Since the sixties, with the invention of bioactive glass, remineralization treatments have become popular among dental surgeons. Their usage is increasing; remineralization, in conjunction with appropriate preventive hygiene measures, represents one of the best minimally invasive treatments at a relatively low cost. This documentary study aims to establish a better understanding of the clinical use of biomaterials that induce remineralization of the surface of teeth enamel and dentin. A search was conducted using search engines (PubMed and Medigraphic databases, and Science Direct). The search process for the relevant studies was carried out by introducing keywords such as calcium silicates, phosphopeptides of amorphous calcium casein-phosphate, remineralization, enamel and dentin, including in the search articles no older than seven years in Spanish and English published in scientific reviewed journals. Currently, it is not possible to completely remineralize the dentary structure so, in the near future, remineralization dentistry efforts should aim to develop (AU)

Compromised dental cells viability following teeth-whitening exposure.

This study aimed to assess the viability of dental cells following time-dependent carbamide peroxide teeth-whitening treatments using an in-vitro dentin perfusion assay model. 30 teeth were exposed to 5% or 16% CP gel (4 h daily) for 2-weeks. The enamel organic content was measured with thermogravimetry. The time-dependent viability of human dental pulp stem cells (HDPSCs) and gingival fibroblast cells (HGFCs) following either indirect exposure to 3 commercially available concentrations of CP gel using an in-vitro dentin perfusion assay or direct exposure to 5% H2O2 were investigated by evaluating change in cell morphology and by hemocytometry. The 5% and 16% CP produced a significantly lower (p < 0.001) enamel protein content (by weight) when compared to the control. The organic content in enamel varied accordingly to the CP treatment: for the 16% and 5% CP treatment groups, a variation of 4.0% and 5.4%, respectively, was observed with no significant difference. The cell viability of HDPSCs decreased exponentially over time for all groups. Within the limitation of this in-vitro study, we conclude that even low concentrations of H2O2 and CP result in a deleterious change in enamel protein content and compromise the viability of HGFCs and HDPSCs. These effects should be observed in-vivo.

Sodium Hypochlorite and Chlorhexidine Downregulate MMP Expression on Radicular Dentin.

OBJECTIVE: Matrix metalloproteinases (MMPs) are present in radicular dentin and can convert structural matrix proteins into signaling molecules; thus, these enzymes play an essential role in dentin biomineralization and tissue regeneration therapies. Their expression on radicular dentin may be affected by the irrigation solutions used during root canal treatments. This study aimed to evaluate the effects of the most common irrigants on radicular dentin MMP expression. MATERIALS AND METHODS: The experimental solutions were distilled water (control), 5% sodium hypochlorite (NaOCl), 18% ethylenediaminetetraacetic acid (EDTA), and 2% chlorhexidine (CHX). Samples were prepared from extracted human teeth. For zymography analysis, root sections were powderized, and dentin proteins were extracted to observe gelatinolytic activity. Root dentin slices were treated with the experimental solutions for immunohistochemical analysis using anti-MMP-2 and anti-MMP-9 antibodies. ANOVA and the Tukey test were performed. RESULTS: Zymograms revealed the presence of MMP-2, MMP-8, and MMP-20 in the control group and the EDTA-treated group. Immunohistochemistry confirmed the presence of MMP-2 and MMP-9 mainly associated with the dentinal tubule lumens and occasionally with intertubular dentin. NaOCl- and CHX-treated groups showed lower expression of MMPs than the control group. Immuno-staining for both proteinases in the EDTA-treated group showed higher expression compared to the other experimental groups. CONCLUSION: Our results showed that most common irrigants affect MMP expression on radicular dentin. Treatment with NaOCl and chlorhexidine resulted in lower expression of MMPs, while EDTA increased their expression in root canal dentin.

Evaluation of Anti-Biofilm Activity of Mouthrinses Containing Tannic Acid or Chitosan on Dentin In Situ.

In contrast to enamel, dentin surfaces have been rarely used as substrates for studies evaluating the effects of experimental rinsing solutions on oral biofilm formation. The aim of the present in situ study was to investigate the effects of tannic acid and chitosan on 48-h biofilm formation on dentin surfaces. Biofilm was formed intraorally on dentin specimens, while six subjects rinsed with experimental solutions containing tannic acid, chitosan and water as negative or chlorhexidine as positive control. After 48 h of biofilm formation, specimens were evaluated for biofilm coverage and for viability of bacteria by fluorescence and scanning electron microscopy. In addition, saliva samples were collected after rinsing and analyzed by fluorescence (five subjects) and transmission electron microscopy (two subjects) in order to investigate the antibacterial effect on bacteria in a planktonic state and to visualize effects of the rinsing agents on salivary proteins. After rinsing with water, dentin specimens were covered by a multiple-layered biofilm with predominantly vital bacteria. In contrast, chlorhexidine led to dentin surfaces covered only by few and avital bacteria. By rinsing with tannic acid both strong anti-adherent and antibacterial effects were observed, but the effects declined in a time-dependent manner. Transmission electron micrographs of salivary samples indicated that aggregation of proteins and bacteria might explain the antiadhesion effects of tannic acid. Chitosan showed antibacterial effects on bacteria in saliva, while biofilm viability was only slightly reduced and no effects on bacterial adherence on dentin were observed, despite proteins being aggregated in saliva after rinsing with chitosan. Tannic acid is a promising anti-biofilm agent even on dentin surfaces, while rinsing with chitosan could not sufficiently prevent biofilm formation on dentin.

Effect of Root Canal Filling Materials and Pretreatment with Solvents on the Shear Bond Strength of Composite Resin with Primary Tooth Dentin.

AIM: Root canal filling materials have the tendency to inhibit adhesion of resin-based composites. This study was aimed at evaluating the effect of root canal filling materials and their solvents on the shear bond strength (SBS) of resin composite with the primary tooth dentin. METHODS AND MATERIALS: Seventy-two intact anterior primary teeth were selected. Smooth dentinal surfaces were prepared to a minimum diameter of 3 mm and thickness of 1.5-2.0 mm. The samples were equally divided into six groups (n = 12). In group 1: control group, no root filling material; in group 2: Metapex, no solvent; in group 3: Metapex+ethanol solvent; in group 4: ZOE, no solvent; in group 5: ZOE+ethanol solvent; and in group 6: ZOE+orange oil solvent were applied. Then, dentin surfaces were etched, and composite restorations were placed and cured. The specimens were stored in distilled water at 37°C for 24 hours. SBS values were determined using a universal testing machine. RESULTS: The SBS values of composite to dentin in groups 2 and 4 were significantly lower than those in the control group (P < 0.001). Cleansing of the specimens with 96% ethanol after removal of Metapex significantly increased the composite-dentin bond (P < 0.001). Applying ZOE, only orange oil solvent significantly increased the SBS of the composite to the primary tooth dentin (P = 0.01). CONCLUSION: To reduce the negative effects of endodontic root filling materials on the SBS of composite and primary tooth dentin, ethanol is a suitable solvent when Metapex is used, while orange oil might be a better choice than ethanol when applying ZOE.

Xenogeneic dentin matrix as a scaffold for biomineralization and induced odontogenesis.

Commonly recognized mechanisms of the xenogeneic-extracellular matrix-based regenerative medicine include timely degradation, release of bioactive molecules, induced differentiation of stem cells, and well-controlled inflammation. This process is most feasible for stromal tissue reconstruction, yet unsuitable for non-degradable scaffold and prefabricated-shaped tissue regeneration, like odontogenesis. Treated dentin matrix (TDM) has been identified as a bioactive scaffold for dentin regeneration. This study explored xenogeneic porcine TDM (pTDM) for induced odontogenesis. The biological characteristics of pTDM were compared with human TDM (hTDM). To investigate its bioinductive capacities on allogeneic dental follicle cells (DFCs) in the inflammation microenvironment, pTDM populated with human DFCs were co-cultured with human peripheral blood mononuclear cells (hPBMCs), and pTDM populated with rat DFCs were transplanted into rat subcutaneous model. The results showed pTDM possessed similar mineral phases and bioactive molecules with hTDM. hDFCs, under the induction of pTDM and hTDM, expressed similar col-I, osteopontin and alkaline phosphatase (ALP) (all expressed by odontoblasts). Whereas, the expression of col-I, dentin matrix protein-1 (DMP-1) and bone sialoprotein (BSP) were down-regulated when cocultured with hPBMCs. The xenogeneic implants inevitably initiated Th1 inflammation (up-regulated CD8, TNF-α, IL-1ß, etc)in vivo. However, the biomineralization of pre-dentin and cementum were still processed, and collagen fibrils, odontoblast-like cells, fibroblasts contributed to odontogenesis. Although partially absorbed at 3 weeks, the implants were positively expressed odontogenesis-related-proteins like col-I and DMP-1. Taken together, xenogeneic TDM conserved ultrastructure and molecules for introducing allogeneic DFCs to odontogenic differentiation, and promoting odontogenesis and biomineralizationin vivo. Yet effective immunomodulation methods warrant further explorations.