Abstract INTRODUCTION Rio de Janeiro has hardly experienced coronavirus disease. METHODS Here, 87,442 reverse transcription polymerase chain reaction (RT-PCR) test results for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were reported among Rio de Janeiro residents (March to September 2020). RESULTS Overall, RT-PCR positivity of 44.6% decreased over time towards 20%. Positivity was greater among males (OR=1.22; 95%CI:1.19-1.26); Black (OR=1.10; 95%CI:1.02-1.19), Brown (OR=1.16; 95%CI:1.10-1.22), and indigenous people (OR=2.11; 95%CI:0.88-5.03) compared to Whites and increased with age; with epidemic spread from the capital to inland regions. CONCLUSIONS SARS-CoV-2 keeps spreading in Rio de Janeiro, and reopening of activities may fuel the epidemic.

RESUMO Este estudo avaliou o conteúdo mineral do esmalte e a microdureza superficial antes e após o tratamento clareador, utilizando peróxido de carbamida 10% (PC) contendo cálcio (Ca) ou fosfato de cálcio amorfo (ACP) em sua composigao. Trinta e seis espécimes de esmalte bovino foram alocados aleatoriamente em 3 grupos (n = 12) de acordo com os tratamentos clareadores: G1 - Opalescence PF 10% (CP), G2 -NiteWhite (CP+ACP); e G3 - Opalescence PF (10%) com cálcio (CP + CA). O agente clareador foi aplicado na superficie do esmalte por 6 h/dia por um periodo de 21 dias. A superficie do esmalte foi avaliada por microdureza Knoop (KNH) e espectrometria de fluorescencia de raios X micro-dispersiva (p-EDXRF) no inicio e após o tratamento clareador. Os dados foram analisados estatisticamente pelo teste ANOVA de medidas repetidas e Tukey (a = 0,05). Houve uma diminuigao significativa da microdureza após os tratamentos clareadores para todos os grupos estudados, mas nao houve diferenga entre os diferentes géis. Nao houve diferenga da relagao Ca/P mensurada por p-EDXRF para todos os grupos nos tempos estudados; no entanto, o grupo CP+CA apresentou menor valor comparado ao grupo CP+ACP. O grupo CP foi similar aos grupos CP+ACP e CP+CA. Portanto, pode-se concluir que houve redugao significativa da microdureza do esmalte após o clareamento, independente da presenga de cálcio ou APC na composigao dos géis, embora nao tenha havido alteragao significando na relagao Ca/P do esmalte após o clareamento. Isto indica um potencial erosivo dos géis clareadores, causando o amolecimento sem perda da estrutura do esmalte, independente da presenga dos íons cálcio e ACP.

ABSTRACT This study evaluated enamel mineral content and surface microhardness before and after bleaching treatment using 10% carbamide peroxide (CP) containing calcium (Ca) or amorphous calcium phosphate (ACP). Thirty-six bovine slabs were randomly allocated into 3 groups (n = 12) according to bleaching treatment: G1 - Opalescence PF 10% (CP), G2 -NiteWhite ACP (CP+ACP), and G3 - Opalescence PF (10%) with calcium (CP+CA). The bleaching agent was applied on enamel surface for 6 h/day over a period of 21 days. Enamel surface was evaluated by Knoop microhardness (KNH) and micro energy-dispersive X-ray fluorescence spectrometry (p-EDXRF) at baseline and at after bleaching treatment. Data were statistically analyzed by repeated measures ANOVA and Tukey's test (a = 0.05). There was a significant decrease in microhardness after bleaching treatments for all study groups, but no difference between bleaching gels. There was no difference in the Ca/P ratio measured by p-EDXRF for all groups at the study times, but the mean value was lower in group CP+CA than in group CP+ACP. Group CP was similar to both CP+ACP and CP+CA. It can be concluded that enamel microhardness decreased after the bleaching process, regardless of the presence of calcium or ACP, but there was no significant change in the Ca/P ratio of enamel after bleaching for each tested gel. This indicates that the bleaching gels have erosive potential, causing softening of enamel without promoting surface loss, regardless of the presence of calcium of ACP ions.

Abstract 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.

Resumo 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.

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.

AIM: This in vitro study evaluated the effect of using a dental hypersensitivity treatment on the bond 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, separating the buccal and lingual/palatal halves. The segments obtained were ground, keeping the buccal or lingual/palatal face turned downwards in order to flatten the surface and produce a standardized smear layer. Prepared specimens were randomly distributed into 4 groups (n=10), according to the combination of surface treatment with the desensitizing dentifrice Colgate Sensitive Pro-Relief (Colgate Palmolive®) (test group - with dentifrice and control group - without dentifrice) and type of simplified bonding agent (etch-and-rinse and self-etching agents). Resin composite blocks were fabricated on the dentin surfaces, after application of bonding agents, and specimens were sectioned into rectangular stick-shaped specimens with cross-sectional area of approximately 0.8mm². For microtensile bond strength tests, 4 sticks were randomly selected from the central region of specimens, and fixed to a universal test machine. Data were analyzed statistically by the Mann-Whitney U test (a=0.05). RESULTS: The bond strength obtained in the group without desensitizer (control) + etch-and-rinse agent was significantly higher compared with the other groups. Under both experimental conditions, the self-etching agent showed weak bond strength to dentin. CONCLUSIONS: Change in the dentin substrate by obliteration of tubules in the process of relieving dentinal sensitivity could reduce the bond strength of simplified etch-and-rinse and self-etching bonding agents.

Background: Photodynamic therapy (PDT) is a method of microbial reduction which can benefit periodontal treatment in areas of difficult access, such as deep pockets and furcations. The aim of this randomized controlled clinical trial was to evaluate the effects of PDT as an adjunct to full-mouth ultrasonic debridement in the treatment of severe chronic periodontitis. Material and Methods: Twenty-two patients with at least one pocket with a probing depth (PD) of ≥7 mm and one pocket with a PD of ≥5 mm and bleeding on probing (BOP) on each side of the mouth were included, characterizing a split mouth design. The control group underwent full-mouth ultrasonic debridement and the test group received the same treatment associated with PDT. The PDT was performed on only one side of the mouth and the initial step consisted of subgingival irrigation with 0.005% methylene blue dye. Two minutes after applying the photosensitizer, the low power laser – AsGaAl (Photon Lase III – PL7336, DMC, São Carlos -São Paulo, Brazil) was applied (660 nm, 100 mW, 9 J, 90 seconds per site, 320 J/cm 2 , diameter tip 600 µm). The following clinical parameters were evaluated: plaque index, gingival index, BOP, gingival recession (GR), PD, and clinical attachment level (CAL). All parameters were collected before, 1, 3 and 6 months after treatment. Results: An improvement in BOP, PD and CAL was observed after treatment, in both groups, but without any difference between them. After 6 months, the PD decreased from 5.11±0.56 mm to 2.83±0.47 mm in the test group (p<0.05) and from 5.15±0.46 mm to 2.83±0.40 mm in the control group (p<0.05). The CAL changed, after 6 months, from 5.49±0.76 mm to 3.41±0.84 mm in the test group (p<0.05) and from 5.53±0.54 to 3.39±0.51 mm in the control group (p<0.05). Conclusion: Both approaches resulted in significant clinical improvements in the treatment of severe chronic periodontits, however, the PDT did not provide any additional benefit to those obtained with full-mouth ultrasonic debridement used alone.

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.

Este estudo avaliou a influência do tempo de espera entre a aplicação do adesivo e a polimerização na resistência de união à dentina e no grau de conversão (GC) de um sistema à base de etanol. Superfícies vestibular e lingual de 15 terceiros molares foram desgastadas até a exposição da dentina e aleatoriamente distribuídas em 3 grupos (n=10), segundo a forma de aplicação do sistema adesivo (Single Bond 2, 3M ESPE): G1 (controle) - uso seguindo recomendações do fabricante; G2 e G3 (experimental) - aguardou-se tempo de espera de 30 e 60 segundos, respectivamente, entre a aplicação das camadas do adesivo e a fotoativação. Dois cilindros (1,4 x 1 mm) de resina composta (Filtek Flow, 3M ESPE) foram aderidos à cada superfície; e submetidos ao ensaio de micro-cisalhamento 24h após a polimerização. Semelhante procedimento adesivo foi utilizado para a avaliação do grau de conversão por meio de um espectrômetro de infra-vermelho transformado de Fourrier (FTIR). Diferenças significativas nos valores de resistência de união (p=0,0003) e GC foram observados (p=0,0004). A resistência de união do grupo 3 (espera de 60 segundos) foi estatisticamente maior que a dos demais grupos. Os grupos 1 (protocolo do fabricante) e 2 (espera de 30 segundos) apresentaram resultados estatisticamente semelhantes entre si. O resultado do GC indicou que tanto o tempo de espera de 30 segundos quanto o de 60 segundos apresentam semelhança estatística. De acordo com os achados obtidos, verifica-se que a utilização do tempo de espera prolongado (60 segundos) traz benefícios uma vez que permite melhor infiltração do agente de união e volatilização do solvente.

This study evaluated the influence of the prolonged setting time of an ethanol-based adhesive system on the dentin bond strength and degree of conversion. Labial and lingual surfaces of fifteen human third molars were flattened until the dentin was exposed and randomly allocated to 3 groups (n=10), according to the dwell time between the application of two consecutive layers of the adhesive system (Adper Single Bond Plus, 3M ESPE) and light activation: G1 - control (no extra dwell time); G2 and G3 - dwell time of 30 seconds and 60 seconds, respectively. After light curing, two cylinders (1.4 x 1 mm) of composite resin (Filtek Flow, 3M ESPE) were bonded to each surface and submitted to micro-shear testing, 24 hours after light curing. A similar adhesive procedure was used for the degree of conversion evaluation using Fourier transform infrared spectroscopy (FTIR). Significant differences between bond strength values (p=0.0003) and degrees of conversion (p=0.0004) were detected. The bond strength of G3 (60-second dwell time) was statistically higher than that of other groups. G1 (control) and G2 (30-second dwell time) presented similar results. Values of degree of conversion indicated that both the 30-second and 60-second dwell times resulted in similar and greater percentages of conversion. The use of a longer dwell time (60 seconds) might provide better solvent volatilization and monomer infiltration; bringing benefits to dentin bonding using simplified etch & rinse adhesive systems.

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, ¼m) 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%) 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.

Este estudo avaliou as alteracoes dimensionais de silicones de condensacao e adicao usados em duas tecnicas como resultado de areas retentivas de preparos do tipo onlay. Um modelo padrao foi feito e vinte e cinco moldagens realizadas com os dois materiais, atraves da tecnica de dupla impressao ou impressao simultanea, e cada material resultou em 50 modelos de gesso. Imagens digitais foram feitas com um microscopio de luz e as distancias entre os pontos de referencia criados no modelo de gesso foram comparados aos pontos de referencia no modelo padrao. Nos segmentos oclusais, medio-mesial e cervico-mesial, a tecnica de dupla impressao (DI) com silicone de condensacao apresentou valores similares comparados ao modelo padrao. Os valores do silicone de adicao com DI foram similares ao modelo padrao somente no segmento mesio-oclusal. Nos outros segmentos (disto-cervical, medio-distal e disto-oclusal), todos os grupos foram estatisticamente diferentes do controle. Pode- se concluir que moldagens com silicone de adicao e condensacao conferem modelos de gesso com alteracoes dimensionais significativas na maioria das areas avaliadas, quando comparadas ao modelo padrao. As areas retentivas relacionadas ao preparo de onlay influenciaram na estabilidade dimensional das moldagens atraves dos silicones de condensacao e adicao.

This study evaluated the effect of retentive areas on onlay preparations on the dimensional alterations in condensation and addition silicone materials. A standard model with an onlay preparation was made. Each impression material was used through the double or simultaneous impression technique (n=25), resulting in a hundred impressions of the same model. Impressions were poured with type IV dental stone. Digital images were taken with a light microscope and the distances between the reference points created on the plaster dies were compared with the ones on the standard model. In the occlusal, mesial-medium and mesial-cervical segments, the double impression (DI) with condensation silicone presented similar values compared to the standard model. The values of the addition silicone with DI were similar to the standard model only in the mesial-occlusal segment. In the other segments (distal-cervical, distal-medium and distal-occlusal), all groups were statistically different from the control. It could be concluded that addition and condensation silicone impressions provided plaster dies with significant dimensional alterations in most of the evaluated areas when compared to the standard model. The retentive areas related to the onlay preparation influenced the dimensional stability of the addition and condensation silicone impressions.

A selecao de cor na regiao dos incisivos superiores (RIS) e muito dificil quando se utiliza isolamento absoluto durante o procedimento restaurador. O objetivo deste trabalho foi mensurar os parametros de temperatura e umidade relativa na RIS e avaliar a influencia do ciclo de inspiracao e expiracao na microinfiltracao de restauracoes em resina composta realizadas na RIS, utilizando tres sistemas adesivos. Sessenta incisivos bovinos higidos foram distribuidos, aleatoriamente, em seis grupos (n=10) de acordo com as condicoes ambientais (laboratorial ou condicao intraoral) e um dos tres sistemas adesivos testados (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). Os especimes restaurados com resina composta foram termociclados (800 ciclos, 5-55°C), imersos em solucao de azul de metileno a 2% e seccionados longitudinalmente. A penetracao de corante ao longo da margem da restauracao foi mensurada e analisada estatisticamente usando testes nao parametricos. Os parametros de temperatura e umidade relativa em RIS foram significativamente diferentes quando comparados aos encontrados em condicoes laboratoriais. As restauracoes realizadas em RIS nao apresentaram aumento na infiltracao marginal, quando comparadas as restauracoes executadas em laboratorio. Como as condicoes de temperatura e umidade intraoral nao apresentaram efeito negativo no selamento marginal de restauracoes em resina composta, a nao utilizacao do uso de isolamento absoluto pode ser considerada quando restauracoes esteticas em dentes anteriores forem realizadas.

Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/ downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55°C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally. The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/ humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

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.

Este estudo avaliou a compatibilidade de uniao entre cimentos resinosos de dupla polimerizacao e sistemas adesivos simplificados (adesivo autocondicionante - 1 passo- e adesivo total-each - 2 passos), apos 24h e 3 meses. A superficie oclusal de 24 terceiros molares humanos foi exposta e planificada. Os dentes foram aleatoriamente divididos em 3 grupos usados de acordo a seguinte combinacao entre sistema adesivo/cimento resinoso [G1 - Single Bond/Rely X ARC (SB/RX); G2 - Excite DSC/Variolink II (EX/VR); G3-Adper Prompt/Rely X ARC (AD/RX)]. Restauracoes indiretas em resina composta foram cimentadas na superficie dentinaria, e seccionados em multiplos palitos para a realizacao do teste de resistencia de uniao atraves do ensaio de microtracao. Os palitos obtidos por dente foram submetidos ao teste apos 24 horas e 3 meses (ANOVA/ Tukey test, α=5%). O padrao de fratura foi observado no microscopio eletronico de varredura. Apos 24 horas, AD/RX apresentou menor valor medio de resistencia de uniao. Os corpos-de-prova do grupo AD/RX nao resistiram ao armazenamento de 3 meses. SB/RX e EX/VR demonstraram similar resistencia de uniao em ambos os periodos avaliados. A associacao AD/RX resultou em menores valores medios de resistencia de uniao, especialmente apos o armazenamento. A cimentacao de restauracoes indiretas utilizando sistemas autocondicionantes (1 passo) e cimentos resinosos de dupla polimerizacao nao foi considerada clinicamente confiavel.

This study evaluated the bonding compatibility between dualcured resin cements and simplified adhesive systems (one-step self-etch and two-step etch & rinse), measured after 24 hours and 3 months. The occlusal dentin surfaces of 24 human third molars were exposed and flattened. Teeth were randomly assigned to 3 groups and treated with different combinations of adhesive system and resin cement [G1 - Single Bond/Rely X ARC (SB/RX); G2 - Excite DSC/Variolink II (EX/VR); G3 - Adper Prompt/Rely X ARC (AD/RX)]. Indirect composite restorations were cemented on flattened surfaces, and sectioned to obtain multiple bonded beams for the microtensile bond strength test. The beams from each tooth were tested under tension after 24 hours and 3 months (ANOVA/ Tukey’s test, α=5%). Failure patterns were evaluated with scanning electron microscopy. After 24h, AD/RX presented the lowest bond strength mean values. AD/RX specimens did not withstand three months storage. SB/RX and EX/VR presented similar bond strengths in both periods tested. The association AD/RX resulted in low bond strength mean values, especially after storage. Cementing indirect restorations using one-step self-etch adhesive systems and dual-cured resin cements would be clinically unreliable.

O objetivo do presente estudo foi avaliar o efeito de diferentes sistemas adesivos sobre a microinfiltração na interface de reparos em resina composta. Corpos-de-prova do compósito Filtek Z250 (3M-ESPE) foram divididos aleatoriamente em cinco grupos (n=20) de acordo com a forma de confecção do reparo: C - controle - condicionamento com ácido fosfórico a 35%; SB1 - condicionamento ácido e aplicação de uma camada do agente de união Single Bond (3M-ESPE); SB2 - condicionamento ácido e aplicação de duas camadas de Single Bond; SMP1 - condicionamento ácido, aplicação do primer e do adesivo do sistema Scotchbond Multipurpose Plus (3M-ESPE) e SMP2 - condicionamento ácido e aplicação apenas do adesivo do ultimo sistema. O reparo foi finalizado com a inserção de nova camada do compósito restaurador. As amostras foram termocicladas (500 ciclos / 5-55°C [±2]) e imersas por 4h em solução tamponada de azul de metileno 2% (pH 7,0). A penetração do corante na interface do reparo foi avaliada em lupa estereoscópica (40x) por três examinadores utilizando quatro escores representativos. A análise estatística não encontrou diferenças entre os grupos experimentais (Kruskal-Wallis / p > 0.05). Dessa maneira, os diferentes sistemas adesivos mostraram comportamento semelhante sobre a microinfiltração na interface do reparo.

The purpose of the present study was to evaluate the microleakage at the composite-repair interface using different bonding systems. Composite resin specimens (Filtek Z250 - 3M-ESPE) were divided into five groups (n=20) according to the following bonding mechanism: C - control - etching with 35% phosphoric acid; SB1 - etching and application of one coat of Single Bond (3M-ESPE); SB2 - etching and application of two coats of Single Bond (3M-ESPE); SMP1 - etching, application of Scotchbond Multi-Purpose primer (3M-ESPE) followed by the adhesive and, SMP2 - etching, application of Scotchbond Multi-Purpose adhesive (3M-ESPE) without the primer. Thereafter, all groups received new resin application. Samples were thermocycled (500 cycles / 5ºC - 55ºC [±2]) and immersed for 4h in 2% methylene blue buffered dye solution (7.0 pH). Three examiners measured the extent of microleakage in a stereoscope microscope, using four representative scores. For all experimental groups, no significant difference in microleakage at the repair was identified by Kruskal-Wallis test (p > 0.05). Therefore, different types of bonding systems presented the same effect on the dye penetration along the repair interface.

O grau e a morfologia da degradação do colágeno foram comparativamente analisados em ratos com fibrose hepática recente (tratamento de oito semanas com tetracloreto de carbono) e tardia (igual tratamento por 12 semanas), e acompanhados após a suspensão da administração da droga. O desaparecimento da fibrose (quando quantitativamente avaliada) foi gradual e semelhante para ambos os grupos. As modificações vistas à microscopia de luz e ao microscópio eletrônico foram também semelhantes. Estes resultados inesperadamente negativos diferem de outros modelos de fibrose hepática e sugerem que o grau de agressão ao parênquima hepático seja um fator limitante da degradação da fibrose que se segue à remoção do agente causal. Assim sendo, não apenas a idade da fibrose, mas o estado geral de alteração do órgão atingido influenciam a degradação e remoção do colágeno.

The rate and morphology of collagen degradation were comparatively analyzed in rats with "early" and "late" carbon tetrachloride-induced hepatic fibrosis, during three different periods after discontinuation of the drug. Treatment with CCl4 lasted for eight weeks for the group of early fibrosis and 12 weeks for the late fibrosis group. Fibrosis gradually disappeared, but when quantitative methods were applied, the amount of collagen degradation and removal in early and late fibrosis did not reach statistical significance. The light microscope and ultrastructural changes were also qualitatively similar in both cases. Probably some long-lasting effects to the liver, induced by the drug, prevented early hepatic fibrosis from undergoing the characteristic ultrastructural changes seen during "acute" collagen degradation, as compared to other experimental models of hepatic fibrosis, after the causal agent is totally removed. Present findings suggest that not only the age of fibrosis but also the overall damage inflicted to the organ are limiting factors in the process of collagen degradation and removal.