Can surface protection prevent the loss of hardness on dentin and composite resin surfaces exposed to erosive challenges? / ¿Puede la protección de la superficie prevenir la pérdida de dureza en las superficies de dentina y resina compuesta expuestas a erosión?

Objective: This study investigated the effect of endogenous erosion on the microhardness of dentine and a nanofilled composite resin. Procedures for preventing erosion were also studied. Materials and Methods: 90 bovine dentine specimens were divided into three groups in accordance with the method for preventing: negative control, topical application of fluoride and resin-modified glass ionomer varnish. 120 composite resin specimens were distributed into four groups, which also included a resin sealant, among the preventive procedures. Specimens were then randomly divided into three sub-groups according to the exposure to simulate gastric acid solution and subsequent remineralization: negative control, 9 and 18 cycles. Surface analysis was carried out by measuring the Knoop hardness. The data obtained were statistically analyzed using 2-way ANOVA and Tukey test. Result: The mean hardness of dentine and of the composite specimens resin exhibited lower hardness after 18 cycles. However, the resin-modified glass ionomer varnish resulted in greater values compared to the other preventive procedures. Conclusion: A resin-modified glass ionomer varnish seems to be a promising method for minimizing the damage caused by endogenous acid, but its protection can be reduced depending on the intensity of the erosive challenge.

Objetivo: Este estudio investigó el efecto de la erosión endógena sobre la microdureza de la dentina y una resina compuesta de nanorrelleno. También se estudiaron los procedimientos para prevenir la erosión. Materiales and Métodos:90 muestras de dentina bovina se dividieron en tres grupos de acuerdo con el método para prevenir: control negativo, aplicación tópica de fluoruro y barniz de ionómero de vidrio modificado con resina. Se distribuyeron 120 muestras de resina compuesta en cuatro grupos, que también incluían un sellador de resina, entre los procedimientos preventivos. Las muestras se dividieron al azar en tres subgrupos de acuerdo con la exposición para simular la solución de ácido gástrico y la remineralización posterior: control negativo, 9 y 18 ciclos. El análisis de la superficie se realizó midiendo la dureza Knoop. Los datos obtenidos se analizaron estadísticamente mediante ANOVA de 2 vías y prueba de Tukey. Resultados: La dureza media de la dentina y de la resina de muestras compuestas exhibió una dureza más baja después de 18 ciclos. Sin embargo, el barniz de ionómero de vidrio modificado con resina resultó en valores mayores en comparación con los otros procedimientos preventivos. Conclusión: Un barniz de ionómero de vidrio modificado con resina parece ser un método prometedor para minimizar el daño causado por el ácido endógeno, pero su protección puede reducirse dependiendo de la intensidad del desafío erosivo.

In vitro study of marginal, internal and proximal adaptation of implant-supported single-crown CAD/CAM restorations

Aim: This study evaluated the precision of a CAD/CAM system by measuring marginal, internal and proximal fits in implant-supported single-crown restorations. Methods: Ten models of the upper arch were made in which implants replaced the upper left premolars. For fabrication of the zirconia infrastructures, titanium bases (TiBase) were coded and scanned using a scan body. A second digital impression was made for the fabrication of prostheses. Silicone impression material was used to determine the internal clearance between the TiBase and infrastructure and between the infrastructure and crown, whose thickness was measured at three points [P1 (cervical), P2 (middle) and P3 (occlusal)] with a stereoscopic microscope at 70x and 100x magnification. One-way ANOVA for repeated measures and the Student t-test were used for the analysis of internal and marginal adaptation. Proximal contacts were analyzed qualitatively. Results: There was no significant difference between the teeth evaluated (Student's t-test; p>0.05) or between the corresponding points evaluated in either tooth (one-way ANOVA; p>0.05). Analysis of the internal clearance between the infrastructure and crown demonstrated that all points were significantly different compared to the reference standardized at 100 µm (Student's t-test p<0.0001). There was no significant difference between P1 and P2, with the thickness at these two points being lower than that obtained at P3 (one-way ANOVA, p<0.05). The proximal contacts did not coincide with the quality defined by the device. Conclusion: The system tested was unable to produce implant-supported single-crown ceramic restorations with marginal, internal and proximal fits matching the digital workflow, with the inferior fits requiring adjustment prior to cementation

Effect of the ceramic translucency on the long-term water sorption and solubility of resin cements

Aim: The aim of this study was to evaluate the influence of the translucency of ceramic on water sorption and solubility of resin cements over time. Methods: Lithium disilicate ceramic slides (15x15x1 mm), A1 in color and with different translucencies (high-medium-low) were manufactured; and a glass slide with similar dimension was used as control. Under every slide, 15 specimens (8x0.5 mm) from each resin cement were prepared: light-cured (RelyX Veneer); conventional dual-cured (RelyX ARC); and self-adhesive dual-cured (Rely-X U200). The specimens were then sub-divided according to the period of evaluation (immediately, after 6 and 12 months of storage) (n=5). To evaluate the loss or gain of mass, the specimens were dried until a constant mass was reached. Subsequently, they were divided according to the respective period of storage at 37°C in distilled water and weighed immediately following removal from water. After each period, specimens underwent a new dehydration. Values from water sorption and solubility were calculated and statistically analyzed (Anova 3-way/Tukey test). Results: The lower translucency resulted in greater water sorption and solubility for all cements, regardless of the experimental period. The self-adhesive dual-cured cement showed higher water sorption under all experimental periods and had worse values after 1 year aging. Differences among solubility could only be detected after aging, and the light-cured material had higher values after 6 and 12 months. Conclusions: It could be concluded that the low degree of translucency can negatively influence the passage of light and interfere on the durability of the resin cement. The conventional dual-cured resinous agent seemed to be less affected by such condition

Effect of Dental Erosion and Methods for its Control on the Marginal and Internal Adaptation of Restorations with Different Adhesive Systems / Efeito da Erosão Dental e de Métodos para seu Controle na Adaptação Marginal e Interna de Restaurações Confeccionadas com Diferentes Sistemas Adesivos

The dentin exposed to erosive challenges is often superficially protected to prevent progression of the lesion. This study investigated the marginal and internal adaptation of composite resin restorations made on surfaces that had first been treated with different methods for controlling erosion. Cavities with margins in dentin were prepared in bovine incisors (n=360) and were divided into three groups according to the method for controlling the erosive challenge: negative control, topical application of fluoride and resin-modified glass ionomer varnish. The specimens were then randomly divided into three sub-groups according to the exposure to simulated gastric acid solution (DES) (5% HCl, pH=2.2) and subsequent remineralization (RE): negative control, 9 and 18 cycles of DES-RE. Finally, teeth were divided into four groups, depending on the bonding agent used for composite resin restoration (n=10): conventional etch-and-rinse adhesive system (2 and 3 steps) and self-etching (1 and 2 steps). Front and internal images of the interface tooth/restoration were recorded in stereoscopic microscope (15x) to quantify the percentage of adhesive failures. Despite the promising results of the resin-modified glass ionomer varnish after 9 cycles; no protective material prevented increased internal defects after 18 erosive cycles. More continuous internal margins were noted with etch-andrinse acid systems after more intense erosion. The maintenance of internal margins in eroded substrates was positively influenced by the resinmodified glass ionomer varnish and, under the most aggressive challenge, by the use of etch-and-rinse adhesives systems. (AU)

A dentina exposta a desafios erosivos é muitas vezes superficialmente protegida para prevenir a progressão da lesão. Este estudo investigou a adaptação marginal e interna de restaurações de resina composta realizadas em superfícies que foram previamente tratadas com diferentes métodos para controlar a erosão. Cavidades com margens em dentina foram preparadas em dentes incisivos bovinos (n=360) e divididas em três grupos de acordo com o método de controle do desafio erosivo: controle negativo, aplicação tópica de flúor e verniz de ionômero de vidro modificado por resina. Os espécimes foram então divididos aleatoriamente em três subgrupos de acordo com a exposição à solução de ácido gástrico simulada (DES) (HCl a 5%, pH = 2,2) e posterior remineralização (RE): controle negativo, 9 e 18 ciclos de DES-RE. Por fim, os dentes foram divididos em quatro grupos, de acordo com o agente de união utilizado para a restauração da resina composta (n=10): sistema adesivo convencional (2 e 3 passos) e autocondicionante (1 e 2 passos). Imagens frontais e internas da interface dente/restauração foram registradas em microscópio estereoscópico (15x) para quantificar a porcentagem de falhas adesivas. Apesar dos resultados promissores do verniz de ionômero de vidro modificado por resina após 9 ciclos; nenhum material de proteção impediu o aumento de defeitos internos após 18 ciclos erosivos. Margens internas mais contínuas foram observadas com sistemas adesivos convencionais após erosão mais intensa. A manutenção das margens internas em substratos erodidos foi influenciada positivamente pelo verniz de ionômero de vidro modificado por resina e, sob o desafio mais agressivo, pelo uso de sistemas de adesivos convencionais. (AU)

Análise da influência do posicionamento do fotopolimerizador sobre a rugosidade superficial da resina composta ­ estudo in vitro / Analysis of the influence of the photopolymerizer on the surface roughness of the composite resin ­ in vitro study

Introdução: uma adequada polimerização da resina composta proporciona um bom desempenho clínico e propriedades físicas satisfatórias na restauração. A conversão de monômeros em polímeros depende não só da luz visível emitida pelo fotopolimerizador e do sistema fotoiniciador presente na resina composta, como também da quantidade de energia que alcança a resina composta e que está na dependência de como essa luz é aplicada sobre a resina. Objetivo: verificar a influência do posicionamento da ponta de um fotopolimerizador de amplo espectro sobre a rugosidade de duas resinas compostas. Metodologia: previamente à confecção dos corpos de prova, foi realizada a randomização de quatro grupos experimentais (n=10) para locação dos corpos de prova, da resina Vittra APS (FGM) em duas apresentações (Vittra APS Esmalte-bleach e a Vittra APS Dentina A0) e duas variações do posicionamento da ponta do fotopolimerizador (0º e 20º). Foram confeccionados quarenta corpos de prova cilíndricos em resina composta, na dimensão 6 x 1,5 mm. Valores da Ra foram registrados usando-se um rugosímetro e analisados estatisticamente (Shapiro-Wilk/ ANOVA). A rugosidade superficial (Ra) de topo de cada corpo de prova foi individualmente avaliada, sendo realizadas três leituras por superfície em posições diferentes. Resultados: não foi verificada significância estatística da interação entre os fatores, nem foram notadas diferenças estatisticamente significativas entre os fatores isolados. Dentre os posicionamentos analisados, constatou-se que o fotopolimerizador a 20º não alterou a rugosidade das resinas utilizadas. Conclusão: a variação da angulação da ponta do fotopolimerizador em 20o não alterou a rugosidade superficial das resinas testadas.

Introduction: proper polymerization of the composite resin provides good clinical performance and satisfactory physical properties of the restoration. The conversion of monomers to polymers depends not only on the visible light emitted by the curing light and the photoinitiating system present in the composite resin, but also on the amount of energy that the composite resin reaches and is dependent on how that light is applied to the resin. Objective: to verify the influence of the tip positioning of a broad spectrum curing light on the roughness of two composite resins. Metodology: prior to the preparation of the specimens, four experimental groups (n = 10) were randomized to locate the specimens, Vittra APS resin (FGM) in two presentations (Vittra APS Enamel-bleach and Vittra APS Dentin A0) and two variations of the curing tip positioning (0º and 20º). Forty 6 x 1.5 mm composite resin cylindrical specimens were made. Ra values were recorded using a roughness meter and statistically analyzed (Shapiro-Wilk/ANOVA). The top surface roughness (Ra) of each specimen was individually evaluated and three surface readings were taken at different positions. Results: no statistical significance of the interaction between the factors was verified, nor were statistically significant differences observed between the isolated factors. Among the positions analyzed, it was found that the curing light at 20º did not change the roughness of the resins used. Conclusion: variation of the curing angle of the curing light tip at 20o did not change the surface roughness of the resins tested.

Comparação do efeito de diferentes protocolos de polimento na rugosidade superficial de restaurações de resina composta / Comparison of the effect of different polishing protocols on surface rugosity of composite resin restorations

Objetivo: o objetivo do presente estudo foi comparar a influência de diferentes protocolos de polimento sobre a rugosidade superficial de uma resina composta nanoparticulada. Metodologia: foram confeccionados 30 corpos de prova (1,5 mm espessura e 6 mm diâmetro), divididos em 3 grupos (n=10), de acordo com o tipo de polimento realizado: 1. Grupo controle; 2. Borrachas abrasivas em 3 granulações (grossa, média, fina); 3 Borracha abrasiva de granulação única. Todos os grupos receberam acabamento com lixa d'água, simulando uma ponta diamantada fina, sendo que o grupo controle não recebeu o polimento com borracha, após esse acabamento. Após o polimento dos grupos 2 e 3, a rugosidade superficial de cada corpo de prova, dos três grupos, foi avaliada em 3 medidas, através de rugosímetro, sendo calculada a média aritmética dos 3 valores picos e vales. A análise estatística inferencial foi feita por meio da ANOVA a 1-critério e teste de Tukey, para comparações múltiplas, com nível de significância de 5%. Resultados: observaram-se maiores valores de rugosidade no grupo controle (3,31µm), seguido do polimento de 1 passo (1,53µm) e 3 passos (0,48µm). Conclusão: diante disso, observa-se alta rugosidade superficial no acabamento com pontas diamantadas, simulado pelo grupo controle, e sua redução após o polimento. Entretanto, apenas o sistema de 3 passos foi capaz de produzir uma lisura superficial clinicamente aceitável.

Aim: the aim of the present study was to compare the influence of different polishing protocols on the surface roughness of a nanoparticulate composite resin. Methodology: Thirty specimens (1.5 mm thickness and 6 mm diameter) were made and divided into 3 groups (n = 10), according to the type of polishing performed: 1. Control group; 2. 3 grit abrasive rubs (thick, medium, thin); 3 Single grain abrasive rubber. All groups were finished with sandpaper, simulating a fine diamond tip, and the control group did not receive rubber polishing after this finish. After groups 2 and 3 polishing, the surface roughness of each specimen of the three groups were evaluated in 3 measurements by means of roughness, and the arithmetic mean of the 3 peaks and valleys (Ra) values were calculated. Inferential statistical analysis was performed using one-way ANOVA and Tukey test for multiple comparisons, with a significance level of 5%. Results: higher roughness values were observed in the control group (3.31µm), followed by 1-step (1.53µm) and 3-step (0.48µm) polishing. Conclusion: therefore, it is noticed a high surface roughness in the diamond-tipped finish, simulated by the control group, which was reduced after polishing. However, only the 3-step system was able to produce a clinically acceptable surface smoothness.

Water sorption and solubility of a nanofilled composite resin protected against erosive challenges / Sorção de água e solubilidade de uma resina composta nanoparticulada protegida contra desafios erosivos

Objective: Erosive challenges are capable of demineralizing dentin and promote physical and mechanical changes in restorative materials. The present study investigates the water sorption and solubility of one nanofilled composite resin submitted to erosive challenges. It also studies procedures that can protect these surfaces. Material and Methods: 120 specimens were used. It was divided into four experimental groups according to the type of surface protection used (negative control, topical application of fluoride, resin-modified glass ionomer varnish and resin-based sealant). Subsequently, they were randomly assigned to three subgroups (n = 10), (negative control, 9 and 18 cycles of DES-RE). According to the exposure to the simulated solution of gastric acid (DES) (5% HCl, pH = 2.2) and subsequent remineralization (RE). The specimens were dehydrated until a constant mass was obtained and immersed in deionized water for 7 days, when they were weighed and submitted to a new dehydration. The values of water sorption and solubility were calculated according to the ISO 4049:2000 specifications and analyzed statistically (2-way ANOVA / Tukey, alpha = 5%). Results: The water sorption and solubility averages after 18 cycles of DES-RE were statistically higher than negative control. Independently of the erosive challenge received, the specimens protected with the resin-modified glass ionomer varnish presented a significant increase in the values of loss and mass gain in relation to the other groups. Conclusion: No control method presented promising surface protection capacity of composite resin against to erosive challenges (AU)

Objetivo: Os desafios erosivos capazes de desmineralizar o esmalte também podem promover alterações físicas e mecânicas nos materiais restauradores. O presente trabalho investigou a sorção de água e solubilidade de uma resina composta nanoparticulada submetida a desafios erosivos. Também estudou procedimentos que possam proteger estas superfícies. Material e Métodos: Foram confeccionados 120 corpos de prova. Foram divididos em quatro grupos experimentais, de acordo com o tipo de proteção superficial empregada (controle negativo, aplicação tópica de flúor, verniz de ionômero de vidro modificado por resina e selante resinoso). Após, foram aleatoriamente distribuídos em três subgrupos (n=10) (controle negativo, 9 e 18 ciclos DES-RE). De acordo com a exposição à solução simulada de ácido gástrico (DES) (HCl a 5%, pH=2,2) e posterior remineralização (RE). Os espécimes foram desidratados até obtenção de massa constante e imersos em água destilada por 7 dias, quando foram pesados, e submetidos à nova desidratação. Os valores de sorção e solubilidade foram calculados de acordo as ISSO 4049:2000 e analisados estatisticamente (2-way ANOVA /Tukey, alfa = 5%). Resultados: Independentemente do desafio erosivo recebido, os corpos de prova protegidos com o verniz de ionômero de vidro modificado por resina, apresentaram aumento significativo dos valores de perda e ganho de massa em relação aos demais grupos. Conclusão: Nenhum método de controle apresentou promissora capacidade de proteção superficial da resina composta frente aos desafios erosivos(AU)

Can surface protection prevent damage in margins of composite resin restorations after simulated endogenous erosion?

Aim: The study investigated the effect of using surface protection agents in the adaptation of external and internal margins of restorations subjected to simulated erosion. Methods: Cavities with margins in dentin were prepared in bovine incisors (n=120). Adhesive restorations were placed using a three-step etch&rinse adhesive system and nanofilled composite resin. The specimens were divided into four groups, according to the surface protection: negative control, topical application of fluoride (TAF), resin sealant and resin-modified glass ionomer varnish (RMGI varnish). Afterwards, they were divided into three sub-groups, according to the exposure to a simulated solution of gastric acid (DES) (5% HCl, pH=2,2) and subsequent remineralization (RE): negative control, 9 and 18 cycles of DES-RE. The evaluation of the tooth-restoration interface was performed on the internal and frontal images with the aid of a stereoscopic microscope (15x), and the percentage of continuous margins without adhesive failures was quantified. Results: In the external margins, only those groups with surface protection using sealants (resin and glass-ionomer) did not exhibit a significant decrease in the percentage of continuous margins after the erosive challenges. After 18 cycles of DES-RE, the use of resin-modified glass ionomer varnish resulted in the highest percentage of continuous margins. Conclusion: It was concluded that physically covering the surfaces with a sealing agent preserved the marginal adaptation of composite resin restorations exposed to endogenous erosive challenges

Mass change of a sodium bicarbonate air-polished nanocomposite exposed to cigarette smoke, coffee, and red wine / Perda de massa de nanocompósito jateado com bicarbonato de sódio e exposto à fumaça de cigarro, café e vinho tinto

Introdução: As resinas compostas estão sujeitas à desafios na cavidade oral relacionados aos hábitos dos pacientes, que podem comprometer a integridade e longevidade das restaurações. As consequências da associação do consumo de bebidas e o uso de cigarros à profilaxia profissional precisam ser estudadas. Objetivo: O objetivo desse estudo foi avaliar como o jateamento com bicarbonato de sódio afeta a mudança de massa (sorção e solubilidade) de uma resina composta exposta à fumaça de cigarro, vinho tinto e café. Material e método: Oitenta corpos-de-prova de resina composta (FiltekZ350 XT - 3M/ESPE) foram preparados e distribuídos em 8 grupos (n=10): G1 (jateamento + água destilada), G2 (jateamento + café), G3 (jateamento + vinho tinto), G4 (jateamento + fumaça de cigarro), G5 (água destilada), G6 (café), G7 (vinho tinto) e G8 (fumaça de cigarro). Os corpos-de-prova de resina composta foram pesados em três tempos diferentes para obter M1 (massa inicial), M2 (massa após 30 dias de armazenamento nas soluções testadas e exposição ao agente) e M3 (após dessecação). Os valores de sorção e solubilidade foram calculados e analisados usando ANOVA 2-fatores e teste Tukey (5%). Resultado: Os grupos experimentais tiveram maior sorção e solubilidade comparado ao grupo controle, independentemente do uso do jateamento. Não houve diferença estatística na sorção para o fator jateamento. Porém, a solubilidade foi maior nos grupos jateados. Conclusão: O jateamento com bicarbonato de sódio foi capaz de intensificar a solubilidade da resina testada, embora não tenha aumentado significativamente os valores de sorção.

Introduction: Composite resins are subject to challenges in the oral cavity that are related to patients' habits, which can compromise the restorations' integrity and longevity. Therefore, it is necessary to study how consuming beverages and smoking cigarettes affects professional prophylaxis. Objective: The aim of this study was to evaluate how the sodium bicarbonate air-polishing affects the mass change (sorption and solubility) of a composite resin exposed to cigarette smoke, red wine, or coffee solution. Material and method: Eighty composite resin samples (FiltekZ350 XT - 3M/ESPE) were prepared and distributed into 8 groups (n=10): G1 (air-polishing + distilled water), G2 (air-polishing + coffee), G3 (air-polishing + red wine), G4 (air-polishing + cigarette smoke), G5 (distilled water), G6 (coffee), G7 (red wine), or G8 (cigarette smoke). The composite resin samples were weighed in triplicate to obtain M1 (initial mass), M2 (mass after 30 days of storage in the tested solutions), and M3 (after desiccation) values. The sorption and solubility values were calculated and analyzed using 2-way ANOVA and Tukey's test (5%). Result: The experimental groups had higher sorption and solubility values than the control groups, regardless of whether air-polishing was used. There was no statistically significant difference in the sorption between the air-polished and non-air-polished groups; however, the solubility was higher in the air-polished groups. Conclusion: Air-polishing using sodium bicarbonate powder was able to intensify the solubility process of the tested resins but did not significantly increase the sorption values.

Effect of air-polishing on properties of nanocomposite submitted to coffee, red wine and cigarette smoke

AIM: The aim of this study was to evaluate the surface roughness and the color stability of nanocomposite exposed to the sodium bicarbonate air-polishing (SBAP) followed by red wine, coffee and cigarette smoke exposure. MATERIALS AND METHODS: 64 nanocomposite specimens were prepared and allocated in 8 groups: G1 (SBAP + distilled water), G2 (SBAP + coffee), G3 (SBAP + red wine), G4 (SBAP + cigarette smoke), G5 (distilled water), G6 (coffee), G7 (red wine) and G8 (cigarette smoke). The surface roughness was evaluated in three periods: before and after SBAP and after exposuring to agents tested. The color was evaluated according to CIEL*a*b* parameters using reflection spectrophotometer in two moments: initial and 30 days after the exposure to staining agents. Data were subjected to three-way repeated measures ANOVA and Tukey's test (5%). RESULTS: The results showed a higher surface roughness of the nanocomposite submitted only to the SBAP and those exposed to the SBAP followed by exposure to the coffee or wine solution. The previous application of SBAP followed by cigarette smoke exposure did not increase the roughness of nanocomposite. The SBAP procedure just increased the staining for cigarette smoke group. CONCLUSION: The SBAP increases resin surface roughness, which worsens when there is exposure to coffee and red wine solution. In addition, SBAP may also provide increased staining of nanocomposites exposed to cigarette smoke

Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin

Abstract The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Alteração de cor em simulação de dente escurecido, utilizando duas resinas compostas de mesma cor com diferentes opacidades / Colour change in a simulation of discolored tooth using two composite resins of the same colour but different opacities

Introdução: o tratamento estético de dentes escurecidos é desafiador, especialmente quando o escurecimento ocorre de maneira pontual. Para alcançar bons resultados, é imprescindível, além do domínio da técnica restauradora, o conhecimento sobre a composição e características ópticas dos materiais restauradores. Objetivo: avaliar a cor resultante da sobreposição de duas resinas compostas, quando utilizadas sobre um substrato escurecido. Metodologia: na confecção dos corpos de prova, foram utilizadas duas matrizes metálicas e as resinas compostas Charisma A2 e OA2 e Opallis DA4 (simulando o substrato escurecido), perfazendo um total de 30 corpos de prova. As mensurações de cor foram realizadas em espectrofotômetro de reflexão (UV-2600; Shimadzu) e as leituras colorimétricas foram realizadas no programa Color Analysis, seguindo os parâmetros do sistema CIEL*a*b*. A análise estatística inferencial foi realizada pela ANOVA 1-critério. Para as comparações múltiplas, utilizou-se o teste Tukey (significância de 5%). Resultados: entre as três variáveis, apenas na variável a* houve diferença estatística (p<0,0001). Conclusão: os resultados permitiram a observação de alteração colorimétrica após o uso de ambas as resinas, porém com melhores resultados para o grupo da resina AO2, quando em comparação com o grupo da A2.

Introduction: the aesthetic treatment of darkened teeth is challenging, especially when darkening occurs in a timely manner. Besides mastering the restorative technique, knowledge about the composition and optical characteristics of restorative materials are essential in order to achieve good results. Objective: to evaluate the colour resulting from the overlapping of two composite resins when used on a darkened substrate. In the preparation of the test specimens, two metal matrices and the Charisma A2 and OA2 and Opallis DA4 composite resins (simulating the darkened substrate) were used, making a total of 30 specimens. The color measurements were performed in a spectrophotometer (UV-2600; Shimadzu) and the colorimetric readings were performed in the Color Analysis program, following the CIEL * a * b * system parameters. Inferential statistical analysis was carried out by ANOVA 1-criterion. The Tukey test (5% significance) was used for the multiple comparisons. Results: among the three variables, only in variable a * there was a statistical difference (p <0.0001). Conclusion: the results allowed the observation of colorimetric alteration after the use of both resins, but with better results for the AO2 resin group in comparison to the A2 group.

Avaliação do efeito da água de piscina sobre a rugosidade superficial de resinas compostas de esmalte / Evaluation of the pool water effect on the surface roughness of enamel composite resins

Introdução: a estabilidade de cor e a durabilidade de uma restauração em resina composta são influenciadas por sua lisura superficial. Características inerentes ao material, procedimentos de acabamento e polimento, dieta e hábitos dos indivíduos podem interferir nas suas propriedades superficiais. Objetivo: avaliar a rugosidade superficial de resinas compostas de esmalte submetidas ao contato com água de piscina clorada e estimar se o uso de uma proteção mecânica limitaria esse contato e seus efeitos. Metodologia: duzentos corpos de prova, de cinco diferentes resinas foram preparados e distribuídos, aleatoriamente, em quatro grupos (n=10), de acordo com o desafio a que foram submetidos: imersão em água destilada sem e com proteção de moldeira de acetato; imersão em água clorada sem e com proteção de moldeira de acetato. Os corpos ficaram imersos por 30 dias, sendo as respectivas águas trocadas diariamente. Para avaliação da rugosidade superficial, utilizou-se um rugosímetro. Procedeu-se à análise estatística inferencial por meio da análise de variância a 3-critérios, avaliando-se a comparação múltipla dessas médias com auxílio do teste de Tukey (nível de significância de 5%). Resultados: observou-se: interação significativa entre os fatores água e condição experimental (p<0,0001) e maior rugosidade superficial para a resina Esthet-X HD, quando exposta à água clorada. O uso da moldeira resultou em maiores valores de rugosidade superficial para todas as resinas testadas quando expostas à água clorada. Conclusão: o efeito da água de piscina foi material dependente. O uso da proteção mecânica pareceu aumentar a rugosidade superficial das resinas compostas expostas à água clorada.

Introduction: the color stability and durability of a composite resin restoration are influenced by its surface smoothness. Characteristics inherent to the material, finishing and polishing procedures, diet and habits of individuals may interfere with their surface properties. Objective: to evaluate the surface roughness of enamel composite resins submitted to contact with chlorinated pool water and to estimate if the use of a mechanical protection would limit this contact and its effects. Methodology: two hundred specimens of five different resins were prepared and randomly distributed into four groups (n = 10), according to the challenge they were subjected to: immersion in distilled water, without and with acetate tray protection; immersion in chlorinated water, without and with acetate tray protection. The bodies were immersed for 30 days, and their waters were changed daily. To evaluate the surface roughness, a rugosimeter was used. Inferential statistical analysis was performed using 3-criteria analysis of variance, and a multiple comparison of these means was evaluated using Tukey's test (significance level of 5%). Results: it was observed a significant interaction between water and experimental conditions (p <0.0001) and greater surface roughness for Esthet-X HD resin when exposed to chlorinated water. The use of the tray resulted in higher surface roughness values for all the resins tested when exposed to chlorinated water. Conclusion: the effect of pool water was dependent material. The use of mechanical protection appeared to increase the surface roughness of composite resins exposed to chlorinated water.

Effect of a desensitizing dentifrice on the bond strength of different adhesive systems

Aim: This in vitro study evaluated the effect of using a dental hypersensitivity treatment on thebond strength to dentin of etch-and-rinse and self-etching simplified adhesive systems. Methods:40 healthy molars were used. The crowns of teeth were removed at the dentinoenamel junction,and remaining roots were sectioned in the mesiodistal direction along their long axis, separatingthe buccal and lingual/palatal halves. The segments obtained were ground, keeping the buccalor lingual/palatal face turned downwards in order to flatten the surface and produce a standardizedsmear layer. Prepared specimens were randomly distributed into 4 groups (n=10), according tothe combination of surface treatment with the desensitizing dentifrice Colgate Sensitive Pro-Relief(Colgate Palmolive®) (test group - with dentifrice and control group - without dentifrice) and typeof simplified bonding agent (etch-and-rinse and self-etching agents). Resin composite blockswere fabricated on the dentin surfaces, after application of bonding agents, and specimens weresectioned into rectangular stick-shaped specimens with cross-sectional area of approximately0.8mm2. For microtensile bond strength tests, 4 sticks were randomly selected from the centralregion of specimens, and fixed to a universal test machine. Data were analyzed statistically by theMann-Whitney U test (a=0.05). Results: The bond strength obtained in the group withoutdesensitizer (control) + etch-and-rinse agent was significantly higher compared with the othergroups. Under both experimental conditions, the self-etching agent showed weak bond strengthto dentin. Conclusions: Change in the dentin substrate by obliteration of tubules in the processof relieving dentinal sensitivity could reduce the bond strength of simplified etch-and-rinse andself-etching bonding agents.

Influence of different shades and LED irradiance on the degree of conversion of composite resins

The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm ' 2 mm) were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE) or microhybrid resin (Opallis - A2E, A2D, and EBleach Low) and were randomly divided into 12 groups (n = 5 each) according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/cm²; Ultralume 5, 850 mW/cm²). After 24 h, the DC was measured on two surfaces (top and bottom) with Fourier Transform infrared spectroscopy (FTIR). Data were statistically analyzed with two-way ANOVA and Tukey test (a = 0.05). Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.

Efeito da aplicação de primers para metal na resistência de união de cimentos resinosos à zircônia / Effect of application of metal primers on the bond strength of resin cements to zirconia

O objetivo deste estudo foi avaliar o efeito da aplicação de primers para estruturas à base de ligas metálicas na resistência de união (RU) de um cimento convencional e de um cimento autoadesivo à zircônia, utilizando o teste de microcisalhamento. Foram preparadas 60 placas de óxido de zircônia (Cercon), com dimensões de 13 x 5 x 1 mm (comprimento x largura x espessura). Essas placas foram jateadas com óxido de alumínio e divididas em seis grupos experimentais, segundo o tratamento utilizado (n = 10). Os primers e cimentos foram aplicados de acordo com as recomendações dos fabricantes e grupos experimentais. Após o tratamento da zircônia, cilindros de cimento resinoso foram construídos na superfície das placas, utilizando matrizes (Tygon) com 0,7 x 1 mm (diâmetro x altura). As amostras foram armazenadas em água destilada por 24 h à 37ºC e submetidas ao ensaio de microcisalhamento (0,5 mm/min, Instron 4411). Os valores obtidos foram analisados pela ANOVA (2 fatores) e teste Tukey (α = 0.05). Somente a utilização do Metal Primer II aumentou a RU dos dois cimentos resinosos à zircônia. O cimento autoadesivo RelyX U-100 obteve as maiores médias de RU quando comparado ao cimento convencional Bistite II DC, para todos os tratamentos de superfície utilizados. Para se obter maior RU à zircônia Cercon deve ser utilizado o Metal Primer II e o cimento autoadesivo RelyX U-100.

The aim of this study was to evaluate the effect of alloy primers on the bond strength (BS) of conventional resin cement and self-adhesive cement to zirconia using the microshear bond strength test. Sixty ceramic plates, with dimensions of 13 x 5 x 1 mm (length x width x thickness), were prepared . The ceramic plates were air-abraded with aluminum oxide and divided into six experimental groups, according to the treatment used (n = 10). The primers and resin cements were applied according to manufacturers' recommendations and experimental groups. After treatment of the zirconia, resin cement cylinders were constructed on their surfaces by using matrix (Tygon) with 0.7 x 1 mm (diameter x height). The samples were stored in distilled water for 24 hours at 37°C and tested in a universal testing machine (0.5 mm/min, Instron 4411). The data were analyzed by ANOVA (two factors) and Tukey test (α = 0.05). Only the use of Metal Primer II increased the bond strength of all resin cements to zirconia. The self-adhesive RelyX U-100 cement promoted higher bond strength values than Bistite II DC, for all surface treatments. To obtain the highest bond strength to zirconia, it must be used the Metal Primer II and the self-adhesive RelyX U-100 resin cement.

Effect of chemical degradation followed by toothbrushing on the surface roughness of restorative composites

OBJECTIVES: The aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram). Material and METHODS: Twenty cylinders (5 mm diameter and 4 mm height) of each composite were randomly allocated to 4 groups (n=5), according to the food-simulating liquid in which they were immersed for 7 days at 37°C: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load). Measurements of the surface roughness (Ra, »m) were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM). RESULTS: The statistical analysis (ANOVA with cofactor / Tukey's test, α=5 percent) detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. CONCLUSIONS: The surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media.

Statistical results on restorative dentistry experiments: effect of the interaction between main variables

Statistical analysis interpretation is a critical field in scientifc research. When there is more than one main variable being studied in a research, the effect of the interaction between those variables is fundamental on experiments discussion. However, some doubts can occur when the p-value of the interaction is greater than the signifcance level. OBJECTIVE: To determine the most adequate interpretation for factorial experiments with p-values of the interaction nearly higher than the signifcance level. MATERIALS AND METHODS: The p-values of the interactions found in two restorative dentistry experiments (0.053 and 0.068) were interpreted in two distinct ways: considering the interaction as not signifcant and as signifcant. RESULTS: Different findings were observed between the two analyses, and studies results became more coherent when the signifcant interaction was used. CONCLUSION: The p-value of the interaction between main variables must be analyzed with caution because it can change the outcomes of research studies. Researchers are strongly advised to interpret carefully the results of their statistical analysis in order to discuss the findings of their experiments properly.

Efeito dos períodos de armazenamento na resistência de união de um sistema adesivo autocondicionante à dentina bovina / Effect of the storage periods on the bond strength of a self-etch system to bovine dentin

O objetivo do presente estudo foi avaliar o efeito do armazenamento de dentes bovinos, em diferentes períodos, na resistência de união de um sistema adesivo autocondicionante de dois passos. Para essa avaliação, 40 incisivos bovinos (n = 10) foram armazenados em solução de timol 0,10 g.mL 1(um negativo) durante os seguintes períodos: 24 horas (controle), 15 dias, um mês e seis meses. Após esses períodos de armazenamento, cada dente foi desgastado até a exposição da dentina superfcial, um sistema adesivo autocondicionante (Clearfl SE Bond/Kuraray) foi aplicado e um bloco de resina composta (TPH Spectrum, Dentsply DeTrey) foi confeccionado sobre o substrato dentinário. Os materiais restauradores foram aplicados segundo as instruções do fabricante. Os espécimes foram seccionados a fim de se obterem fatias de 1 mm de espessura e constrições foram realizadas para obtenção do formato de ampulheta com área adesiva de 1 mm2. As fatias foram testadas sob tensão em uma máquina de ensaio universal a uma velocidade de 0,5 mm.min 1(um negativo) e o padrão de fratura foi analisado em microscopia eletrônica de varredura (MEV). Os seguintes resultados foram obtidos (MPa): 24 horas - 11,73 ± 5,2; 15 dias - 9,66 ± 3,6; 1 mês - 11,01 ± 6,7, e 6 meses - 9,43 ± 4,7. Não foi observada nenhuma diferença estatística signifcante (ANOVA, p = 0,79). Falhas na interface adesiva foram mais frequentemente observadas. Pode-se concluir que os períodos de armazenamento avaliados não infuenciaram a união do sistema adesivo autocondicionante à dentina bovina.

The aim of this study was evaluate the effect of the storage of bovine teeth in different periods on the microtensile bond strength of a two-step self-etch system. For this, forty bovine incisors (n = 10) were stored in 0.10 g.mL 1(one negative) thymol solution during the following periods: 24 hours (control), 15 days, 1 month, and 6 months. After these storage periods, each tooth was fattened until superfcial dentin exposure, the bonding system (Clearfl SE Bond/Kuraray) was applied and a composite block (TPH Spectrum, Dentsply DeTrey) was built over the dentin substrate. Restorative materials were used following manufacturer's instructions. The specimens were sectioned to obtain 1 mm thick slabs, which were trimmed to an hour-glass shape with cross sectional area of 1 mm2. Slabs were tested under tension in a universal testing machine at 0.5 mm.min 1(one negative) and their failure mode was analyzed with scanning electron microscopy (SEM). The following results were obtained (MPa): 24 hours - 11.73/5.2; 15 days - 9.66/3.6; 1 month - 11.01/6.7, 6 months - 9.43/4.7. Signifcant differences among experimental groups were not observed (ANOVA, p = 0.79). Failures within the adhesive interface were the most frequently observed. May be concluded that the storage periods did not infuence the bonding of the two-step self-etch system to dentin.

Influência de colutórios bucais na dureza de resinas compostas / Influence of mouthrinses on the hardness of composite resin materials

O objetivo deste trabalho foi avaliar o efeito de colutórios bucais na dureza de três resinas compostas (Filtek Supreme® A2B – nanoparticulada [SUP], Filtek Z250® A2 – híbrida [Z25], Filtek Flow® A2 – híbrida de consistência fluida [FLO]). Três colutórios foram selecionados (Listerine® [LIS], PerioGard® [PER] e Cepacol® [CEP]) e a água destilada [AD] foi utilizada como solução de controle. Setenta e duas matrizes de um polímero de náilon, com 3 mm de diâmetro e 3 mm de espessura, foramconfeccionadas. As resinas foram inseridas nas matrizes em dois incrementos, os quais foram fotoativados por 20s cada. Os corpos-de-prova (cps) foram aplainados em lixas d’água e armazenados em água destilada por 24h. Cada tipo de resina composta foi dividido em quatro grupos (n = 6) de acordo com as soluções estudadas, as quais foram utilizadas sob o seguinte regime: três imersões por dia de 10min cada, durante trinta dias.Durante o período do estudo, os cps foram individualmente armazenados em água destilada. Cinco leiturasde dureza foram realizadas em cada cp e a média do número de dureza Knoop (KHN) dessas leituras foi utilizadapara a realização da análise estatística. Os resultados e desvios-padrão (DP) foram: SUP + LIS = 63,3(5,2) Bb; SUP + PER = 70,0(3,6)Ab; SUP + CEP = 67,8(3,6)ABb; SUP + AD = 64,3(3,8)Bb; Z25 + LIS = (2,4)88,4Aa; Z25 + PER = 77,1(5,4)Ba; Z25 + CEP = 83,8(3,9)Aa; Z25 + AD = 83,7(4,1)Aa; FLO + LIS = 44,3(4,1)Ac; FLO + PER = 46,5(1,6)Ac; FLO + CEP = 48,7(2,0)Ac; FLO + AD = 44,2(0,8)Ac. Após a análise de variância e o teste de Tukey (5 por cento), observou-se diferença estatística significativa entre a dureza Knoop das resinas testadas, sendoZ25 > SUP > FLO. Conclui-se que as resinas compostas comportaram-se de maneira diferente para cada tipo desolução utilizada