Effect of Water and Chlorhexidine with Different Pressures of Oral Irrigation Device on the Surface Roughness and Topography of Giomer

Abstract Objective: To evaluate the effect of different pressures of an oral irrigation device (OID) and the irrigation solution type on the surface roughness of the giomer restorative material. Material and Methods: In this in vitro study, disk-shaped giomer samples were fabricated and assigned to 5 groups (n=23): Group 1, storage in distilled water (control); Group 2, OID #7 pressure/ water; Group 3, OID #10 pressure/ water; Group 4, OID #7 pressure/ 0.05% CHX; Group 5, OID #10 pressure/ 0.05% CHX. The samples' treatment simulated a one-year application of OID. Surface roughness (Ra) and topography of the giomer were evaluated using profilometry and scanning electron microscopy. The data were analyzed with Paired t-test, Tukey, and ANOVA tests (α=0.05). Results: The Ra of the samples increased significantly after treatment with OID (p<0.001). The roughness increase in groups with a pressure of 10 was higher than those with a pressure of 7 (p<0.001). The effect of pressure on surface changes was significant (p<0.001). However, the solution type and the cumulative effect of these two factors were insignificant (p=0.08 and p=0.43, respectively). Conclusion: Oral irrigation device with both solutions significantly increased the surface roughness and topographic changes of the giomer. The severity of these changes was related to the device's pressure.

Avaliação in vitro da microdureza e porosidade de duas resinas compostas fotopolimerizáveis / Evaluación in vitro de la microdureza y porosidad de dos resinas compuestas fotopolimerizables / In vitro evaluation of the microhardness and porosity of two photopolymerizable composite resins

RESUMO Introdução: Os estudos científicos acerca das propriedades físicas e mecânicas apresentadas pelas resinas compostas são cada vez mais necessários diante da grande variedade de produtos disponíveis no mercado atual, resultante do aumento de sua demanda dentro da odontologia que preza por preparos minimamente invasivos com a devolução das características estéticas e funcionais do elemento dentário. Objetivo: Avaliar e comparar a microdureza e porosidade das resinas compostas fotopolimerizavéis Filtek Z350 XT 3M e Zirconfill Technew. Métodos: Foram confeccionados 10 corpos de prova por amostra (n= 10) submetidos a teste microdureza Vickers e porosidade por microtomografia computadorizada. Resultados: Com relação à presença de porosidades, dada em porcentagem, o grupo da Filtek apresentou os menores valores médios. Quando comparado estatisticamente, os grupos apresentaram diferença estatística (p= 0,019), com uma magnitude de efeito alta. Com relação aos valores de microdureza, o grupo da Filtek apresentou os maiores valores médios. Quando comparados estatisticamente, os grupos não apresentaram diferença estatística (p > 0,05). Conclusões: A porosidade foi significativamente diferente entre os grupos estudados, sendo o grupo Filtek Z350XT de menor percentual. No entanto, os grupos não apresentaram diferença estatística para microdureza, apesar do grupo Filtek Z350XT ter apresentado maior valor médio(AU)

RESUMEN Introducción: Los estudios científicos sobre las propiedades físicas y mecánicas presentadas por las resinas compuestas son cada vez más necesarios ante la gran variedad de productos disponibles en el mercado actual, resultante del aumento de su demanda dentro de la odontología que aprecia por preparaciones mínimamente invasivas con la devolución de las características estéticas y funcionales del elemento dental. Objetivo: Evaluar y comparar la microdureza y porosidad de las resinas compuestas fotopolimerizables Filtek Z350 XT 3M y Zirconfill Technew. Métodos: Se han confeccionado 10 cuerpos de prueba por muestra (n= 10) sometidos a prueba de microdureza Vickers y porosidad por microtomografía computarizada. Resultados: Con respecto a la presencia de porosidades, dada en porcentaje, el grupo de Filtek presentó los menores valores medios. Cuando se comparó estadísticamente, los grupos presentaron una diferencia estadística (p= 0,019), con una magnitud de efecto alto. Con respecto a los valores de microdureza, el grupo de Filtek presentó los mayores valores medios. Cuando se comparó estadísticamente, los grupos no presentaron una diferencia estadística (p> 0,05). Conclusiones: La porosidad fue significativamente diferente entre los grupos estudiados, siendo el grupo Filtek Z350XT de menor porcentaje. Sin embargo, los grupos no presentaron diferencia estadística para microdureza, a pesar de que el grupo Filtek Z350XT presentó un valor medio más alto(AU)

ABSTRACT Introduction: Scientific studies about the physical and mechanical properties of composite resins are increasingly needed in view of the wide variety of products available in the market today, resulting from the increase in their demand for dental care purposes, with a preference for minimally invasive preparations aimed at restoring the esthetic and functional characteristics of the treated element. Objective: Evaluate and compare the microhardness and porosity of the photopolymerizable composite resins Filtek Z350 XT and Zirconfill Technew. Methods: Ten test bodies were developed per sample (n= 10) and subjected to Vickers microhardness and porosity testing by computerized microtomography. Results: With respect to the presence of porosity, expressed in percentages, the Filtek group had the lowest mean values. When compared statistically, the two groups showed a statistical difference (p= 0.019) with a high effect magnitude. Regarding microhardness, the Filtek group had the highest mean values. Statistical comparison did not find any difference between the groups (p> 0.05). Conclusions: Porosity was significantly different in the groups studied, the Filtek Z350XT group exhibiting the lowest percentage. However, the groups did not show any statistical difference concerning microhardness, despite the fact that the Filtek Z350XT group had a higher mean value(AU)

The Impact of Radiotherapy in the in Vitro Remineralization of Demineralized Enamel

Objective: To evaluate the impact of radiotherapy on enamel around restorations of glass ionomer cement (GIC) and fluoride tooth paste (FTP). Material and Methods: Eighty enamel blocks were made and randomly distributed into two groups, according to the fluoride therapy, non-fluoride tooth paste (NFTP) and FTP (n=40) and in subgroups in conformity with radiation dose (0, 10, 30 and 60 Gy). Roughness and microhardness enamel analyses were conducted before radiotherapy. Enamel cavities were made and restored with two GIC (Ketac Molar Easy Mix or Vitremer). Enamel blocks were submitted to 10, 30 and 60 Gy. Then, artificial enamel caries lesions were created by a pH-cycling procedure and FTP or NFTP were used as treatment. The restored enamel blocks were submitted to final roughness and microhardness analyses. Roughness increase (ΔR) and hardness loss (ΔH) values of enamel were submitted to ANOVA and Tukey test (p=0.05). Results: The irradiated enamel group showed statistically higher ΔR (0.44 ±0.2) and ΔH (99.26±7.0) values compared to non-irradiated group (ΔR = 0.051±0.02; ΔH=66.16±12.7) when a resin-modified GIC and NFTP were used. Conclusion: Higher radiation dose increased dissolution of bovine enamel. The use of GIC associated with FTP decreased roughness and increased enamel hardness after radiotherapy.

Erosive potential of sports beverages on human enamel "in vitro" / Potencial erosivo de bebidas esportivas no esmalte humano "in vitro" / Potencial erosivo de bebidas deportivas en el esmalte humano "in vitro"

INTRODUCTION: The low pH of sports drinks may cause tooth enamel demineralization. Objective: To measure Vickers hardness of human enamel exposed to sports drinks. METHODS: Human molars were used to collect the enamel samples. Each sample had a test surface (exposed to the drinks) and a control surface (unexposed). The samples were exposed to isotonic drinks Gatorade and Powerade, and to maltodextrin drinks Malto Advanced and Malto Active, for 10 minutes every 12 hours over 30 days. The Vickers microhardness test was conducted with three indentations on each surface. The mean of the indentations within each group was considered in the statistical analysis. Sports drinks variables were analyzed with ANOVA/Tukey (p≤0.01). The independent t-test was used in the comparison between the control and test surfaces of each drink (p ≤ 0.05). RESULTS: Enamel exposure to Gatorade (p = 0.000) Malto Advanced (p = 0.000) and Malto Active (p = 0.000) was seen to significantly reduce microhardness, while the isotonic drink Powerade had no significant effect on enamel (p = 0.248). CONCLUSION: It was concluded that with the exception of the isotonic drink Powerade, all the sports drinks tested caused a reduction in the microhardness of human enamel. Evidence Level III; Therapeutic studies - Investigating the Results of Treatment.

INTRODUÇÃO: O baixo pH de bebidas esportivas pode promover perda mineral do esmalte dental. OBJETIVO: Avaliar a microdureza Vickers do esmalte humano exposto a bebidas esportivas. MÉTODOS: Dentes molares humanos foram usados para coletar as amostras de esmalte. Cada amostra apresentou uma superfície de teste (exposta às bebidas) e uma superfície de controle (não exposta). As amostras foram expostas aos isotônicos Gatorade e Powerade e às maltodextrinas Advanced Series e Malto Active durante 10 minutos de 12/12 horas, durante 30 dias. O teste de microdureza Vickers foi realizado com três indentações em cada superfície. Na análise estatística, foi considerada a média das indentações dentro de cada grupo. As variáveis bebidas esportivas foram avaliadas com ANOVA/Tukey (p ≤ 0,01). Na comparação entre a superfície controle e teste de cada bebida foi utilizado o Teste t para amostras independentes (p ≤ 0,05). RESULTADO: Observou-se que a exposição do esmalte a Gatorade (p = 0,000), Malto Advanced (p = 0,000) e Malto Active (p = 0,000) reduz significativamente a microdureza, enquanto que o isotônico Powerade não produziu efeito significativo sobre o esmalte (p = 0,248). CONCLUSÃO: Concluiu-se que com exceção do isotônico Powerade, todas as bebidas esportivas testadas provocaram redução na microdureza do esmalte dental humano. Nível de Evidência III; Estudos terapêuticos ­ investiga o resultado de um tratamento.

INTRODUCCIÓN: El bajo pH de bebidas deportivas puede favorecer la pérdida mineral del esmalte dental. OBJETIVO: Evaluar el esmalte dureza Vickers humano expuesto a las bebidas deportivas. MÉTODOS: Se utilizaron los dientes molares para la toma de las muestras de esmalte. Cada muestra tenía una superficie de prueba (expuestos a las bebidas) y una superficie de control (no ex-puesta). Las muestras fueron expuestas en isotónica Gatorade y Powerade, y maltodextrinas, y la serie Advanced activo Malto durante 10 minutos 12/12 horas durante 30 días. La prueba de dureza Vickers se realizó con tres muescas en cada superficie. El análisis estadístico fue la media de las muescas dentro de cada grupo. variables de bebidas deportivas se analizaron con ANOVA / Tukey (p≤0,01). La comparación entre la superficie de control y prueba de cada bebida se utilizó la prueba t para muestras independientes (p ≤ 0,05). RESULTADOS: Se observó que la exposición del esmalte Gatorade (p = 0,000) Malto avanzada (p = 0,000) y Malto activo (p = 0,000) reduce significativamente la dureza, mientras que Powerade isotónica ningún efecto significativo sobre el esmalte (p = 0,248). CONCLUSIÓN: Se concluye que con la excepción de Powerade isotónica, todas las bebidas deportivas probados causó una reducción en la dureza del esmalte humano. Nivel de Evidencia; Estudios terapéuticos - Investigación de los resultados del tratamento.

Milk Reverts the Effects of an Enamel Erosive but Healthy Diet

Objective: To determine the erosive effects of popular fruits and vegetables on enamel, and the potential counter effects of milks. Material and Methods: Ten popular fruits and vegetables were individually blended in a juicer to form a fruit or vegetable juice. The labial surfaces (three for each treatment group) were then immersed for thirty minutes in a fresh juice of one of ten products: strawberry, spinach, pineapple, grapefruit, green pepper, pickle, orange, apple, tomato, and carrot. In a second experiment, human enamel was treated with Coca-Cola for 30 minutes, followed by a variety of milks: Skim, 2%, Whole, Chocolate, Lactaid, Almond, and Silk Soy. Three teeth were used for each treatments and enamel microhardness of each sample was measured at baseline, after erosive exposure, and after the 30-minute variable treatment. Results: All fruits and vegetables showed differences between the pre- and posttreatment microhardness values. For the second experiment, tested milks result in significant increases (p<0.05) in enamel microhardness. Paired-t test was used for all comparisons. A thirty-minute exposure to the juices of all fruits and vegetables examined in the study significantly changed the microhardness of enamel, with grapefruit and pickle having potentially the most erosive effect on enamel. Diets that are high in fruits and vegetables can predispose to enamel erosion. For the second experiment, filtered water, ACT fluoride rinse, and varying milks all result in remineralization of enamel. Conclusion: Eroded enamel exposed to milk demonstrated a significant greater gain of enamel microhardness as compared to filtered water.

Evaluación de la microdureza superficial de resinascompuestas: revisión de la literatura / Evaluation of the surface microhardness of composite resins: literature review

En la actualidad, ha aumentado considerablemente el uso de resinas compuestas, llegando a convertirse en el principal material restaurador utilizado por los odontólogos, tanto para el sector anterior como el posterior. Dentro de sus propiedades, encontramos la dureza, la cual forma parte muy importante para determinar su durabilidad en boca. Esta propiedad está determinada por la cantidad de relleno que presente la resina, por ende, a mayor cantidad de relleno, mayor será su dureza y menores cambios dimensionales. A pesar de todas las mejoras en tecnología y propiedades de las resinas compuestas, aún no se encuentra un material que posea características ideales que lo hagan indestructible al paso de los años. El objetivo de este artículo es revisar las principales características de las resinas compuestas, especialmente la microdureza superficial. La dureza es una condición de la superficie de un material determinado, no representa ninguna propiedad de la materia y está relacionada con las propiedades elásticas y plásticas de cada material. Existen en la actualidad muchos sistemas para medir la dureza, por ejemplo, sistema Brinell, Rockwell, Vickers y Knoop

At present, the use of composite resins has increased considerably, becoming the main restorative material used by dentists, both for the anterior and posterior sectors. Among its properties, we find the hardness, which is a very important part to determine its durability in the mouth. This property is determined by the amount of filler that the resin presents, therefore, the greater the amount of filler, the greater its hardness and smaller dimensional changes. Despite all the improvements in technology and properties of composite resins, there is still no material that has ideal characteristics that make it indestructible over the years. The objective of this article is to review the main characteristics of composite resins, especially surface microhardness. Hardness is a condition of the surface of a given material, it does not represent any property of the material and is related to the elastic and plastic properties of each material. There are currently many systems to measure hardness, for example, Brinell, Rockwell, Vickers and Knoop systems.

Comparison of the indentation strength and single-edge-v-notched beam methods for dental ceramic fracture toughness testing

Aim: To study influence of the cooling rate after sintering a veneering porcelain (Vita VM9) on fracture toughness by indentation strength (IS) and single-edge-v-notched beam (SEVNB) methods. Methods: Vita VM9 bars were sintered according to the manufacturer's recommendation and cooled under three conditions: Slow (inside the furnace from sintering temperature to room temperature); Normal (inside the furnace from sintering temperature to 500 ºC and outside the furnace from 500 ºC to room temperature); and Fast (outside the furnace from sintering temperature to room temperature). Fracture toughness was measured by IS (n=10) and SEVNB (n=10) methods. Data were analyzed by two-way ANOVA (α=0.05). Results: The fracture toughness obtained from SEVNB (slow - 1.02±0.10; normal - 1.09±0.13; and fast - 1,02±0.18 MPa.m1/2 cooling techniques) was significantly lower than IS (slow - 1.19±0.13; normal - 1.17±0.07; and fast - 1.16±0.06 MPa. m1/2 cooling techniques). There was no significant influence of the cooling technique (p=0.012). Conclusions: The measurement technique influenced the fracture toughness values . IS method overestimated the fracture toughness values. Irrespective of the measuring method, cooling rate did not influence the Vita VM9 veneering porcelain fracture toughness (Au)

In vitro Effect of Erosive Challenge on Surface Microhardness of Orthodontic Composites

Objective: To evaluate in vitro the effect of erosive challenge and continuous immersion in cola drink on surface microhardness of orthodontic composites. Material and Methods: Forty samples of three composites (Transbond XT, Quick Cure and Ortho Cem) were prepared (4 x 2 mm) and distributed into 4 groups (n=10): erosive challenge, artificial saliva immersion (control 1), continuous cola immersion and artificial saliva immersion (control 2). Erosive challenge was performed 4 times per day (5 min) in cola drink for 2 h in artificial saliva for 7 days. Samples of continuous cola immersion group were soaked in cola drink for 5 weeks and the beverage was renewed every two days. Control samples were immersed in artificial saliva for 7 days (control 1) and 5 weeks (control 2). Vickers microhardness (VHN) measurements were performed before and after erosive challenge and continuous immersion. Data were evaluated by paired Student's T-test, ANOVA one-way and Tukey tests (α = 0.05). Results: After 7 days of erosive challenge, there was no statistical difference between VHN values before and after erosive challenge and artificial saliva immersion. However, after 5 weeks of cola drink and artificial saliva immersion, significant reduction in VHN values was observed for all composites when compared to baseline values, and specimens immersed in cola drink showed lower VHN compared to those immersed in saliva, regardless of composite composition. Conclusion: After 7 days of erosive challenge, there was no alteration in superficial VHN of orthodontic composites. However, after 5 weeks of immersion in cola drink, significant reduction of VHN values was observed for all composites.

Surface Hardness of Glass Ionomer Cements used in Atraumatic Restorative Treatment

Objective: To evaluate the surface hardness of a national glass ionomer cement with increased powder / liquid ratio, suitable for the atraumatic restorative treatment technique. Material and Methods: This is a study of the quantitative experimental type, in which 30 specimens were made and divided equally into 03 experimental groups (glass ionomer cement restorative Vitro Molar -DFL in the proportion specified by the manufacturer; glass ionomer cement restorative Vitro molar ratio -DFL modified with incorporation of 50% powder; and Gold Label 9 - GC Corporation in the proportion specified by the manufacturer). After handling, the materials were placed in a Teflon mold for manufacturing the cylindrical samples (5mm x 2 mm), with the aid of a Centrix syringe (Centrix, Shelton, CT, USA). Specimens were stored in liquid petroleum jelly at a temperature 37 ° ± 1 for up to 7 days. The specimens were evaluated by Vickers hardness test at time intervals of 24 hours and 7 days after manufacture. The data were subjected to the Independent Student's-t tests and analysis of variance (ANOVA), and subsequently by Tukey's test at 95% level of significance. Results: The setting time positively influenced the hardness of the two glass ionomer cements (p<0,001). Cement Gold Label 9 showed higher hardness values than cement Vitro Molar (p<0,001), irrespective of the evaluation time interval. The latter in turn, showed improved values when manipulated with the modified powder / liquid ratio (3: 2) (p<0,001). Conclusion: Vitro Molar glass ionomer cement showed higher hardness values when manipulated with the modified powder/liquid ratio.

Dental bleaching with ozone: effects on color and enamel microhardness / Clareamento dental com ozônio: efeitos na cor e na microdureza do esmalte

The aim of this in vitro study was to evaluate the effects of dentalbleaching with ozone (O3) on color change and enamelmicrohardness. Enamel blocks (3 x 3 x 3mm) were randomlydistributed for treatments (n=10). Color change (ΔE) and Knoopmicrohardness of the enamel blocks were evaluated before andafter the following treatments: C – deionized water (control); HP– 37.5% hydrogen peroxide (Pola Office+/ SDI); PLA – placebogel; O3– ozone; and O2– oxygen. Four 8-minute applicationswere used for HP and PLA, and one 19-minute application for O3and O2.One-way ANOVA revealed that ΔE was not significantlyinfluenced by the treatment (p = 0.112). For the treatments withHP, PLA, O3 and O2, ΔE was greater than 3.3. The paired t testshowed significant decrease in microhardness after treatments (p< 0.001) but no significant difference between treatments(ANOVA; p = 0.313). Dental bleaching treatments with O3, HP,O2and PLA induced enamel color changes that may be clinicallydiscernible, although enamel microhardeness decreased.

O objetivo deste estudo in vitro foi avaliar os efeitos doclareamento dental com ozônio (O3) quanto à alteração de core microdureza do esmalte. Blocos de esmalte (3 x 3 x 3mm)foram aleatoriamente distribuídos entre os tratamentos(n=10). Alteração de cor (ΔE) e microdureza Knoop foramavaliados antes e após cada um dos seguintes tratamentos: C– água deionizada (controle); PH – peróxido de hidrogênio a37,5% (Pola Office+/ SDI); PLA – gel placebo; O3– ozônio;O2– oxigênio. Quatro aplicações de PH e PLA foramrealizadas por 8 minutos cada e uma aplicação de O3e O2foram realizados por 19 minutos em cada bloco de esmalte.ANOVA a um critério mostrou que os valores de ΔE não foramsignificativamente influenciados pelo tratamento (p = 0,112).Para os tratamentos com PH, PLA, O3 e O2, o ΔE foi maior que3,3. O teste t pareado mostrou diminução significativa dosvalores de microdureza no final do tratamento quandocomparado com o tempo baseline (p < 0,001), mas não houvediferença significativa entre os tratamentos (ANOVA; p =0,313). O tratamento com O3, PH, O2e PLA levou a alteraçãode cor do esmalte clinicamente perceptível, embora tenha sidoobservada diminuição da microdureza do esmalte com arealização dos tratamentos.

A nanodureza e o módulo de elasticidade versus resistência de união da resina com a dentina / The nanohardness and elastic modulus versus bond strength of resin to dentin

Objetivo: Avaliar a nanodureza (Nn) e o módulo de elasticidade (ME) da região de adesão quando utilizados diferentes sistemas adesivos e correlacionar com a resistência adesiva (RA) à dentina. Método: Foram medidos a nanodureza e o módulo de elasticidade da resina composta junto à área de união, da camada de adesivo (Ad), da camada híbrida (Ch), e da dentina adjacente utilizando testes de nanoendentação. Quarenta molares (n=10) foram preparados de modo a obterem-se superfícies planas em dentina, sobre as quais os sistemas adesivos foram aplicados (Adper Scotchbond Multiuso, Adper Single Bond 2, Adper SE Plus e Clearfil SE Bond). Sobre essas superfícies foi inserida a resina composta. Os dentes restaurados foram seccionados para obterem-se corpos-de-prova com área aderida de 1mm2. Um palito de cada dente foi selecionado para análise da nanodureza e do módulo de elasticidade da interface adesiva. Os demais tiveram a resistência de união testada através do teste de microtração. Resultados: O teste ANOVA detectou diferença estatística entre todos os grupos, exceto para a variável nanodureza da camada híbrida. O teste de correlação de Pearson detectou significância para o módulo de elasticidade. Conclusões: Pôde-se concluir que as propriedades mecânicas (resistência adesiva, módulo de elasticidade e nanodureza do sistema adesivo e da camada híbrida) variam dependendo do sistema adesivo. Quanto maior o módulo de elasticidade da camada híbrida de um sistema adesivo maior é sua resistência adesiva e menor o módulo de elasticidade da camada de adesivo. Pôde observar que não houve correlação entre nanodureza e a resistência adesiva.

To evaluate the nanohardness (Nn) and the modulus of elasticity (ME) in the region of adhesion when used different adhesive systems and correlate with the bond strength to dentin (RA). We measured the nanohardness and the modulus of elasticity of the resin composed with the area of bond of the adhesive layer (Ad), hybrid layer (Ch) and adjacent dentin using nanodentition tests. Forty molars (n = 10) were prepared in order to obtain flat dentin surfaces on which the adhesive systems were applied (Adper Scotchbond Multipurpose, Single Bond 2, Adper SE Plus and Clearfil SE Bond). On these surfaces was inserted a composite resin. The restored teeth were sectioned to obtain body-of-proof with adhered area of 1mm2. A stick of each teeth was selected for the nanohardness analysis and the modulus of elasticity of the adhesive interface. The others had the bond strength tested using the microtensile test. The ANOVA detected statistical difference between all groups, except for the variable nanohardness of the hybrid layer. The Pearson’s correlation test found significance for the modulus of elasticity. It was concluded that the mechanical properties (bond strength, the modulus of elasticity and nanohardness of the adhesive system and the hybrid layer) vary depending on the adhesive system. The higher the modulus of elasticity of the hybrid layer of an adhesive system a greater adhesive strength will be and lower the modulus of elasticity of the adhesive layer. It can be observed that there was no correlation between nanohardness and bond strength.

Transmissão de luz através de cerâmicas e desenvolvimento de equipamento determinante do tempo de fotoativação

O objetivo deste estudo foi avaliar a quantidade de luz transmitida (LT) em cerâmicas (com diferentes composições e associações, espessuras e cores), a microdureza Vickers (VNH) de um cimento de dupla polimerização e desenvolver um equipamento para determinação da intensidade luminosa e do tempo para a fotoativação de cimentos de restaurações odontológicas indiretas. Foram utilizados discos de cerâmica reforçadas com leucita, dissilicato de lítio, à base de zircônia e feldspáticas, com dimensões de 10 mm de diâmetro e espessuras de 2 e 5 mm nas cores A2 e A4. Associções entre os quatro tipos, duas cores e duas espessuras dessas cerâmicas totalizaram dezesseis grupos testes para LT e dezesseis grupos testes e um controle para VHN. O medidor de potência utilizado para as leituras de LT foi o Thorlabs PM 30 (Thorlabs Gmbh, Alemanha). O aparelho fotoativador utilizado foi um Radii-Cal (SDI)...

Efeito da espessura, cor e translucidez de uma cerâmica de dissilicato de lítio sobre a transmissão da luz halógena e de diodo emissor de luz, o grau de conversão e a microdureza de diferentes cimentos resinosos / Effect of thickness, shade and translucency of a lithium disilicate glass-ceramic on the light transmission of halogen or light emitting diode, degree of conversion and microhardness of different resin cements

Avaliou-se o efeito da espessura, cor e translucidez de uma cerâmica vítrea sobre a transmissão da luz halógena (HAL) e diodo emissor de luz (LED) e sobre o grau de conversão e microdureza de diferentes cimentos resinosos. Quarenta bloco da cerâmica IPS e.max CAD (Ivoclar Vivadent) de translucidez (alta-HT e baixa-LT) cores A1, A2, A3.5, foram cortados (1, 2, 3, 4 e 5mm) e cristalizados (200 corpos de prova). Os espectros de emissão de HAL (Demetron LC) e LED (Bluephase, Ivoclar Vivadent) foram determinados. A intensidade da luz (mW/cm2) incidente sobre o detector e da luz transmitida através da cerâmica foram medidas em triplicata para cada fonte de luz. Os coeficientes de absorção de luz...

Evaluation of Fluoride Release, pH and Microhardness of Glass Ionomer Cements

To evaluate fluoride release, pH and microhardness of glass ionomer cements (GIC). Material and Methods:Four different cements: Vidrion ® R (G1), Vitro Fil ® (G2), Maxxion ® (G3) and Magic Glass ® (G4) and a composite resin (G5 -control group) comprised the sample. Thirty specimens were manufactured (10 mm x 3 mm) and stored in deionized water. Analyses were performed after 24 hours, 7 days and 28 days. The following devices were used for measurements: fluorometer, pH meter and microhardness tester. Data were analyzed by Kruskal-Wallis, Mann-Whitney, Friedman and Wilcoxon tests (α= 0.05) using the SPSS ® software (Statistical Package for Social Sciences) version 17. Results:GICs were able to release fluoride; however, the amount released decreased with increasing immersion time (p <0.002). The pH of all products increased over time, the lowest value was identified for Magic Glass (5.93) and the highest for Maxxion (6.94) at time of 24 h. Materials showed significant decrease in surface microhardness, especially G4 for presenting the lowest recorded values (p <0.05). Conclusion:GICs arefluoride-releasing restorative materials with pH favorable to oral homeostasis and good mechanical behavior...

Changes in microhardness and morphology of the adamantine structure as a function of the exposure time to different drugs

To investigate the in vitro effect of four pediatric liquid medicines on the microhardness and morphology of the enamel of permanent teeth after different exposure times. Material and Methods:Claritin, Celestone, Amplictil and Vick syrup honey flavor were tested. Seventy tooth fragments were obtained, 50 embedded in acrylic resin and submitted to Knoop Hardness test (50 gf, 15 s, and 5 indentations) before and after immersion in drugs. The specimens were randomly divided into five groups (n = 10), four experimental and one control group (distilled water). The immersion cycle consisted of a single exposure in times of 5 and 15 minutes. Other 20 dental specimens were divided between groups and analyzed by Scanning Electron Microscopy. The level of statistical significance was set at 5% with a confidence interval of 95%. Results:The microhardness analysis showed no statistically significant difference between experimental groups (p > 0.05), although there was statistically significant difference within each group at different times (p < 0.05). The SEM micrographs showed distinct changes in the enamel morphology. Conclusion:The decreased in microhardness was dependent on the time of the immersion cycle and morphological changes were influenced by the type of drug and by the exposure time...

Influência do pH de bebidas isotônicas sobre a microdureza de resinas compostas / pH influence of isotonic drinks on composite microhardness

Objetivo: Este estudo experimental in vitro teve como objetivo a análise da influência do pH de bebidas isotônicas sobre a microdureza de resinas compostas. Material e Métodos: A avaliação do pH endógeno foi realizada através de leitura com o pH - metro Tecnal pH Meter TEC-2®. Para a avaliação da microdureza, foram confeccionados corpos de prova, com dois tipos de resina diferentes. Para cada tipo de resina foram confeccionados 7 corpos de prova, distribuídos de acordo com a solução de armazenamento (bebidas isotônicas das marcas Gatorade® e Powerade®, nos sabores limão, tangerina e laranja e água destilada- controle). A análise da microdureza dos corpos de prova foi realizada após um ciclo de imersão de 21 dias, por 1 hora diária, seguindo às 23 horas restantes em repouso na água destilada. Foi utilizado o microdurômetro (MicrohardnessTester Fm-700; Futuretech, Tokyo, Japan) com penetrador diamantado piramidal tipo Vickers aplicando-se uma carga de 50g de 30 segundos. Os dados foram apresentados por meio de estatística descritiva e utilizou-se os testes ANOVA e t pareado, com p < 0,05. Resultados: Todas as bebidas analisadas apresentaram pH inferior ao considerado crítico para a dissolução do esmalte dental (5,5), sendo o Powerade Limão a bebida com menor pH (2,98). Observou-se que os corpos de prova que ficaram imersos nas bebidas isotônicas, obtiveram valores de microdureza estatísticamente menores quando comparados ao grupo controle. Conclusão: Todas as bebidas avaliadas apresentaram pH ácido e alteraram a microdureza das resinas compostas estudadas.Descritores: pH. Testes de dureza. Resinas compostas. Bebidas energéticas.

Análise comparativa da microdureza superficial e profunda entre uma resina composta microhíbrida e uma resina composta de nanopartículas / Comparative analysis of superficial and deep microhardness between microhybrid and nanoparticle composite resins

Objetivo: Comparar, in vitro, a microdureza Vickers superficial e profunda entre uma resina composta microhíbrida e uma resina composta de nanopartículas.Método: Foram confeccionados 40 corpos-de-prova, distribuídos em 4 grupos (n=10/grupo) de acordo com o tipo e a superfície da resina avaliada: Z100TM (topo e base) com partículas microhíbridas; FiltekTM Z350 XT (topo e base) o compósito resinoso de nanopartículas, ambas na cor A2. A fotoativação dos espécimes foi realizada pelo tempo de 40s utilizando o aparelho Ultraled® (Dabi Atlante ? Brasil) com comprimento de onda de 450 a 490nm. As amostras foram armazenadas num recipiente à prova de luz, em ambiente seco, a uma temperatura de 37oC por 24 horas. Cada superfície testada (topo ou base) foi delimitada em quadrantes, realizando, em cada um, três aferições de microdureza Vickers e aplicando uma carga de 50gf, por 45s com o emprego do aparelho Shimadzu HMV-2T. O cálculo de microdureza de cada espécime foi obtido considerando-se a média das 12 endentações realizadas. Os dados obtidos em MPa foram submetidos aos testes estastísticos ANOVA e Tukey (significância de 5%). Resultados: Os valores médios e desvio padrão obtidos pelos grupos testados foram: G1 ? Z100TM topo ? 94,99 (+/- 2,70); G2 ? Z100TM base - 74,84 (+/- 1,42); G3 ? FiltekTM Z350 XT topo ? 57,53 (+/- 1,13); G4 ? FiltekTM Z350 XT base - 35,37 (+/- 4,19). Observou-se diferença estatística significativa entre os valores de microdureza de ambas as resinas quando avaliada as superfícies Topo e Base, a um nível de significância padrão de 5%. Conclusão: Os maiores valores de microdureza foram os obtidos pela resina microhíbrida Z100TM, demonstrando um melhor desempenho dessa propriedade mecânica para a resina microhíbrida em relação à resina composta nanoparticulada FiltekTM Z350 XT.

Objective: To compare, in vitro, the superficial and deep Vickers microhardness between a microhybrid composite resin and a nanoparticle composite resin. Method: Forty specimens were prepared and distributed in 4 groups (n=10/group) according to the type of resin and surface evaluated: Z100TM (top and bottom) with microhybrid particles and FiltekTM Z350 XT (top and bottom) with nanoparticles, both resins with shade A2. Photoactivation of specimens was done for 40 s using the Ultraled® unit (Dabi Atlante, Brazil) with 450 to 490nm wavelength. The specimens were stored in a light-proof receptacle in a dry environment with temperature of 37oC for 24 h. Each test surface (top or bottom) was divided into quadrants. In each quadrant, three Vickers microhardness measurements were made with 50 gf load for 45 s using a Shimadzu HMV-2T hardness tester. The microhardness value of each specimen was obtained considering the mean of the 12 indentations. Data (in MPa) were analyzed statistically by ANOVA and Tukey?s test at 5% significance level. Results: Means and standard deviations in the groups were as follows: G1 - Z100TM top - 94.99 (± 2.70); G2 - Z100TM bottom - 74.84 (±1.42); G3 - FiltekTM Z350 XT top - 57.53 (± 1.13); G4 - FiltekTM Z350 XT bottom - 35.37 (± 4.19). There was statistically significant difference between the microhardness values of both resins when comparing the top and bottom surfaces (p less than 0.05). Conclusion: The highest microhardness values were obtained with the microhybrid resin (Z100TM), demonstrating a better performance for this mechanical property compared with FiltekTM Z350 XT nanoparticle composite resin.

Chitosan: effect of a new chelating agent on the microhardness of root dentin

The effect of solutions of 0.2% chitosan, 15% EDTA and 10% citric acid on the microhardness of root dentin was evaluated comparatively in this study. Thirteen sound human maxillary central incisors were selected and decoronated at the cementoenamel junction. Ten roots were set into rapid polymerization acrylic resin and the root/resin block was fitted to the cutting machine to obtain slices from the cervical third. The first slice was discarded and the second slice was divided into four quadrants. Each quadrant was used to construct a sample, so that 4 specimens were obtained from each root slice, being one for each chelating solution to be tested: 15% EDTA, 10% citric acid, 0.2% chitosan and distilled water (control). The specimens were exposed to 50 μL of the solution for 5 min, and then washed in distilled water. A microhardness tester (Knoop hardness) with a 10 g load was used for 15 s. Data were analyzed statistically by one-way ANOVA and Tukey-Kramer test (α=0.05). The other 3 roots had the canals instrumented and irrigated at the end of the biomechanical preparation with the test solutions, and then examined by scanning electron microscopy (SEM) for qualitative analysis. All solutions reduced the microhardness of root dentin in a way that was statistically similar to each other (p>0.05) but significantly different from the control (p>0.05). The SEM micrographs showed that the three solutions removed smear layer from the middle third of the root canal. In conclusion, 0.2% chitosan, 15% EDTA and 10% citric acid showed similar effects in reducing dentin microhardness.

Avaliou-se o efeito das soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% sobre a microdureza da dentina radicular. Foram utilizados 13 incisivos centrais superiores humanos, os quais tiveram suas coroas seccionadas transversalmente e desprezadas. Dez raízes foram incluídas em resina acrílica de rápida polimerização e o bloco formado raiz/resina adaptado à maquina de corte. Desprezou-se o primeiro corte transversal da porção cervical e dividiu-se o segundo, em 4 quadrantes. Cada quarto foi destinado à confecção do corpo-de-prova obtendo-se 4 espécimes para cada raiz, um para cada solução (n=10): EDTA a 15%, ácido cítrico a 10%, quitosana a 0,2% e água destilada (controle). Os espécimes receberam 50 μ L da solução por 5 min, sendo em seguida, lavados com água destilada. Utilizou-se um microdurômetro (dureza Knoop) com carga de 10 g durante 15 s. Os dados foram avaliados por meio do teste ANOVA e Tukey-Kramer (α=0,05). Três incisivos centrais superiores foram instrumentados e irrigados, ao final da biomecânica, com uma das soluções estudadas. Os espécimes foram levados para MEV e posterior análise qualitativa. Todas as soluções avaliadas reduziram a microdureza da dentina radicular de forma semelhante entre si (p>0,05) e estatisticamente diferente do controle (p<0,01). As fotomicrografias mostraram que as 3 soluções removeram a smear layer do terço médio do canal radicular. Concluiu-se que as soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% apresentam efeito semelhante na redução da microdureza dentinária.

Associação entre fluorescência vermelha emitida pela placa bacteriana e atividade de cárie: estudo in situ / Association between red fluorescence emitted by bacterial plaque and caries activity: in situ study

O objetivo desse estudo in situ cruzado de duas fases foi avaliar a influência da presença de placa dentária fluorescente no vermelho na indução de lesões cariosas. Foram utilizados 272 blocos de esmalte bovino, que foram avaliados inicialmente em relação à microdureza superficial e quantificação da fluorescência verde com o QLF (Quantitative light-induced fluorescence). Dezessete voluntários utilizaram dispositivos palatais removíveis, com oito amostras cobertas com uma rede plástica para favorecer maior acúmulo de placa. No grupo experimental foi gotejada solução de sacarose a 20%, 8 X ao dia e no grupo controle, água destilada. Cada fase durou 14 dias com 7 dias de wash-out. Os blocos foram avaliados após 4, 7, 10 e 14 dias. Após cada período, a placa bacteriana presente sobre a superfície dos blocos foi analisada utilizando o QLF para a quantificação de fluorescência vermelha. Após cuidadosa limpeza da superfície, o bloco foi novamente avaliado para a perda de fluorescência verde (QLF) e perda de microdureza superficial. Foram realizadas análises de multinível para comparação entre os grupos, bem como análises de regressão linear de multinível entre as medidas de fluorescência vermelha e os desfechos relacionados à desmineralização. Em relação à microdureza de superfície, pode-se observar uma tendência de aumento da perda de dureza entre os diferentes períodos apenas no grupo experimental. Quanto à fluorescência vermelha da placa, houve aumento gradual de acordo com os diferentes períodos em ambos os grupos, sendo esse aumento mais pronunciado no grupo experimental. Houve associação significativa entre as medidas da fluorescência da placa e perda de dureza, independente dos grupos. Em conclusão, a fluorescência vermelha da placa bacteriana está relacionada à placa madura, independente da sua cariogenicidade.

The aim of this two-phase crossover in situ study was to evaluate the influence of presence of red bacterial plaque on the induction of carious lesions. We used 272 bovine enamel blocks, which were initially evaluated in relation to surface microhardness and quantification of green fluorescence using the QLF (Quantitative light-induced fluorescence). Seventeen volunteers to use removable intra-oral appliances were selected, containing eight specimens covered by a plastic net to promote plaque accumulation. 20% sucrose solution, 8 times per day, was dripped in the experimental group, and distilled water was dripped in the control group. Each phase lasted 14 days, with seven days of wash-out. The specimens were assessed after 4, 7, 10 and 14 days. After each period, bacterial plaque present on the blocks surface was analyzed using the QLF to quantify the red fluorescence. After careful cleanness, the block was evaluated again with QLF to assess the loss of green fluorescence and surface microhardness loss. Multilevel analyses were carried out to compare the groups, as well as multilevel linear regression analyses among the red fluorescence and outcomes related to the demineralization. With regard to the surface microhardness, we could observe a trend of hardness loss among the different periods only at the experimental group. In relation to the red fluorescence of plaque, there was a gradual increase according to the different periods in both experimental and control groups, being this increase more relevant in the experimental group. There was significantly association between red fluorescence measurements and microhardness loss, independently of the groups. In conclusion, the red fluorescence of bacterial plaque is related to the mature plaque, independently of its cariogenicity.

Efecto de la unidad de luz y de la profundidad de polimerización sobre la microdureza de un composite / Effect of light unit and depth on curing a composite microhardness

El objetivo de este estudio fue evaluar a través de test de microdureza el efecto de la profundidad de polimerización de un composite utilizando diferentes unidades de luz. Fueron preparados cuerpos de prueba utilizando un composite microhíbrido - Filtek Z250 (3M) en matrices de teflón con dos profundidades diferentes: 2 mm y 3 mm, conteniendo un orificio central de 2 mm de diámetro. Los valores de dureza fueron medidos en la región de superficie y en la de fondo. Fueron utilizadas tres unidades de luz, dos a base de Luz Emitida por Diodo - LED: Optilight CL (Gnatus) y Radii (SDI) y una a base de luz halógena: Ultralux (Dabialtante). Después de la fotoactivación durante 40 segundos, los cuerpos de prueba fueron almacenados en recipiente oscuro, durante 24 horas. El test de dureza Vickers fue realizado con el equipo de dureza Shimadzu Micro Hardness Testers, utilizando una carga de 300 gramos por 15 segundos. Fueron realizadas tres identaciones en cada región (superficie y fondo) de los cuerpos de prueba. Los valores de dureza fueron sometidos a análisis de variancia (ANOVA) y al test de Tukey-Kramer (p<0,05).No fue observada diferencia estadísticamente significativa entre los equipos fotoactivadores, sin embargo, el equipo Ultralux proporcionó mayores valores de dureza al composite de que los otros equipos. Considerando el tipo de equipo evaluados, no hubo diferencia estadísticamente significativa en relación a la microdureza del composite en las profundidades de 2mm e 3mm en ninguna de las regiones. Comparando las regiones de los cuerpos de prueba analizadas, (superficial y fondo), fue observada diferencia estadísticamente significativa en ambas profundidades y con todos los equipos, siendo los valores dureza Vickers mayores en la región de fondo de los cuerpos de prueba. Concluyese que entre los equipos utilizados, el Ultralux proporcionó mayor dureza al composite siendo estadísticamente significativa, sin embargo, no hubo diferencia significativa...

The aim of this study was to evaluate the influence of different depths of cure on the microhardness of a composite resin when using three different types of light units. Test specimens with a 2-mm diameter centered orifice were prepared with a microhybrid composite - Filtek Z250 (3M) using teflon matrices with two different depths: 2 mm and 3 mm. Hardness values were assessed both in superficial and deep areas. Three light units were compared: two light-emitting diode units - Optilight CL (Gnatus) and Radii (SDI), and one halogen-based light unit - Ultralux (Dabialtante). After light curing for 40 minutes, the specimens were stored in a lightproof container for 24 hours. The Vickers hardness test was carried out by the Shimadzu Micro Hardness Tester at a load f 300 grams for 15 seconds. Three test indentations were made in each area (superficial and deep) of the specimens. Mean values of hardness were compared by the analysis of variance (ANOVA), and by the Tukey-Kramer test at 5%. They demonstrated a statistically significant difference between the three light units. The Ultralux device yielded the highest values of hardness regardless the depth of the specimens. It was also observed no statistically significant difference in terms of hardness when comparing the two thicknesses of composite resin within each studied group.