Abstract The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Resumo O objetivo desse estudo foi avaliar o grau de conversão, estabilidade de cor, composição química e resistência de união de um cimento resinoso fotoativado contaminado com três soluções hemostáticas diferentes. Foram preparadas amostras para o grupo controle (cimento não contaminado) e grupos experimentais (cimento contaminado com uma das soluções hemostáticas) de acordo com os testes. Para o grau de conversão e análise de cor (n=10), as amostras (3 mm de diâmetro e 2 mm de espessura) foram avaliadas por espectroscopia de infravermelho com transformação de Fourier (FTIR) e espectrofotometria CIELAB (L*, A*, B*), respectivamente. Para a análise química elementar (n=1), os espécimes (2 mm de espessura e 6 mm de diâmetro) foram avaliados por espectroscopia de energia dispersiva de raios-x (EDS). As resistências de união dos grupos foram avaliadas pelo ensaio de microcisalhamento (n=20) em um substrato cerâmico de vidro reforçado com leucita, seguida da análise de modo de falha por microscopia eletrônica de varredura (MEV). Os valores médios, com exceção da avaliação química e do modo de falha, foram avaliados por ANOVA e pelo teste de Tukey. A estabilidade de cor foi influenciada pelo tempo de armazenagem (p<0,001) e interação entre a contaminação e o tempo (p<0,001). A contaminação pelo Hemostop e Viscostat Clear não influenciaram no GC, porém a contaminação com Viscostat aumentou o GC. A resistência de união do cimento a cerâmica foi negativamente afetada pelos contaminantes (p<0,001). A contaminação por agentes hemostáticos afetou a resistência de união, o grau de conversão e a estabilidade de cor do cimento resinoso fotoativado testado.

Abstract The aim of this study was to evaluate the degree of conversion, color stability, chemical composition, and bond strength of a light-cured resin cement contaminated with three different hemostatic solutions. Specimens were prepared for the control (uncontaminated resin cement) and experimental groups (resin cement contaminated with one of the hemostatic solutions) according to the tests. For degree of conversion, DC (n = 5) and color analyses (n = 10), specimens (3 mm in diameter and 2 mm thick) were evaluated by Fourier transform infrared spectroscopy (FTIR) and CIELAB spectrophotometry (L*, a*, b*), respectively. For elemental chemical analysis (n = 1), specimens (2 mm thick and 6 mm in diameter) were evaluated by x-ray energy-dispersive spectroscopy (EDS). The bond strengths of the groups were assessed by the microshear test (n = 20) in a leucite-reinforced glass ceramic substrate, followed by failure mode analysis by scanning electron microscopy (SEM). The mean values, except for the elemental chemical evaluation and failure mode, were evaluated by ANOVA and Tukey’s HSD test. The color stability was influenced by storage time (p<0.001) and interaction between contamination and storage time (p<0.001). Hemostop and Viscostat Clear contamination did not affect the DC, however Viscostat increased the DC. Bond strength of the resin cement to ceramic was negatively affected by the contaminants (p<0.001). Contamination by hemostatic agents affected the bond strength, degree of conversion, and color stability of the light-cured resin cement tested.

Resumo O objetivo neste estudo foi avaliar a resistência de união à microtração (RUµT) de um sistema adesivo convencional (Adper Single Bond 2 - SB) em diferentes substratos dentinários e períodos de armazenagem. Vinte e quatro blocos de dentina foram obtidos de terceiros molares hígidos e separados aleatoriamente em 3 grupos (n=8): dentina sadia (Ds), dentina afetada (Da) e dentina infectada (Di). A Da e a Di foram submetidas ao desenvolvimento biológico artificial de cárie (S. mutans). O tecido cariado amolecido foi removido usando broca esférica sob inspeção visual com a solução Caries Detector (grupo Da). Considerou-se como Di a dentina amolecida e fortemente pigmentada de vermelho e como Da, a dentina hígida e levemente pigmentada de vermelho. O sistema adesivo SB foi aplicado de acordo com as recomendações do fabricante e blocos da resina composta Z350 foram construídos (6 mm de altura). O conjunto (dente/bloco de resina) foi armazenado em água deionizada por 24 horas a 37 °C. Estes foram seccionados em palitos (1,0 mm2 de área), que foram separados aleatoriamente em 3 períodos de armazenagem: 24 horas, 6 meses e 1 ano. Os palitos foram submetidos ao ensaio de resistência de união à microtração na máquina EZ teste a uma velocidade de 1,0 mm/min. Dados de RUµT foram submetidos à Análise de Variância 2 fatores em esquema de parcela subdividida e ao teste de Tukey (a=0,05). Os valores de resistência (MPa) da Ds (41,2) foram significativamente maiores do que os da Da (32,4) e Di (27,2), independente do tempo de armazenagem. Di e Da, 6 meses e 1ano, apresentaram valores similares de resistência de união. As falhas adesivas e mistas foram predominantes para todos os grupos. Em conclusão, os maiores valores de RUµT (48,1±9,1) foram verificados para a Ds e 24 h de armazenagem. A armazenagem diminuiu os valores de RUµT para todas as condições.

Abstract The aim of this study was to evaluate the μTBS in different dentin substrates and water-storage periods. Twenty-four dentin blocks obtained from sound third molars were randomly divided into 3 groups: Sound dentin (Sd), Caries-affected dentin (Ca) and Caries-infected dentin (Ci). Dentin blocks from Ca and Ci groups were subjected to artificial caries development (S. mutans biofilm). The softest carious tissue was removed using spherical drills under visual inspection with Caries Detector solution (Ca group). It was considered as Ci (softer and deeply red stained dentin) and Ca (harder and slightly red stained dentin). The Adper Single Bond 2 adhesive system was applied and Z350 composite blocks were built in all groups. Teeth were stored in deionized water for 24 h at 37 ºC and sectioned into beams (1.0 mm2 section area). The beams from each tooth were randomly divided into three storages periods: 24 h, 6 months or 1 year. Specimens were submitted to µTBS using EZ test machine at a crosshead speed of 1.0 mm/min. Failure mode was examined by SEM. Data from µTBS were submitted to split plot two-way ANOVA and Tukey’s HSD tests (a=0.05). The µTBS (MPa) of Sd (41.2) was significantly higher than Ca (32.4) and Ci (27.2), regardless of storage. Ca and Ci after 6 months and 1 year, presented similar µTBS. Mixed and adhesive failures predominated in all groups. The highest µTBS values (48.1±9.1) were found for Sd at 24 h storage. Storage of specimens decreased the µTBS values for all conditions.

Abstract Resin cements have led to great advances in dental ceramic restoration techniques because of their ability to bond to both dental structures and restorative materials. Objective The aim of this study was to assess the performance of resin cements when different curing modes are used, by evaluating the degree of conversion and bond strength to a ceramic substrate. Material and Methods Three resin cements were evaluated, two dual-cured (Variolink II and RelyX ARC) and one light-cured (Variolink Veneer). The dual-cured resin cements were tested by using the dual activation mode (base and catalyst) and light-activation mode (base paste only). For degree of conversion (DC) (n=5), a 1.0 mm thick feldspathic ceramic disc was placed over the resin cement specimens and the set was light activated with a QTH unit. After 24 h storage, the DC was measured with Fourier transform infrared spectroscopy (FTIR). For microshear bond strength testing, five feldspathic ceramic discs were submitted to surface treatment, and three cylindrical resin cement specimens were bonded to each ceramic surface according to the experimental groups. After 24 h, microshear bond testing was performed at 0.5 mm/min crosshead speed until the failure. Data were submitted to one-way ANOVA followed by Tukey test (p<0.05). Scanning electron microscopy (SEM) was used for classifying the failure modes. Results Higher DC and bond strength values were shown by the resin cements cured by using the dual activation mode. The Variolink II group presented higher DC and bond strength values when using light-activation only when compared with the Variolink Veneer group. Conclusion The base paste of dual-cured resin cements in light-activation mode can be used for bonding translucent ceramic restorations of up to or less than 1.0 mm thick.

Fundamento: Menos complicações hemorrágicas e deambulação precoce fazem do acesso radial uma via privilegiada para cateterismo cardíaco. Entretanto, a abordagem transradial (TR) nem sempre é bem-sucedida, sendo necessária a sua conversão em acesso femoral. Objetivo: Avaliar a taxa de conversão do acesso radial em femoral no cateterismo cardíaco e identificar seus fatores preditivos. Métodos: Registro prospectivo de dois centros, incluindo 7.632 pacientes consecutivos submetidos a cateterização via acesso radial entre janeiro de 2009 e outubro de 2012. Avaliou-se a incidência de conversão em acesso femoral e seus fatores preditivos através de análise de regressão logística. Resultados: A idade média dos pacientes foi de 66 ± 11 anos, sendo 32% deles mulheres. Houve 2.969 (38.4%) intervenções coronarianas percutâneas (ICP),sendo a artéria radial direita a primeira escolha mais usada (97,6%). A taxa de insucesso do acesso radial foi de 5,8%. Fatores preditivos independentes da conversão do acesso radial em femoral foram o uso de bainhas introdutoras curtas (OR 3,047; IC: 2,380-3,902; p < 0,001), ICP (OR 1,729; IC: 1,375-2,173; p < 0,001), sexo feminino (OR 1,569;IC: 1,234-1,996; p < 0,001), doença multiarterial (OR 1,457; IC: 1,167-1,819; p = 0,001), área de superfície corporal(ASC) ≤ 1,938 (OR 1,448; IC: 1,120-1,871; p = 0,005) e idade > 66 anos (OR 1,354; IC: 1,088-1,684; p = 0,007). Conclusão: A abordagem transradial para cateterismo cardíaco tem alta taxa de sucesso e a necessidade de sua conversão em acesso femoral nesta coorte foi baixa. Os fatores preditivos independentes de sua conversão em acesso femoral foram: sexo feminino; idade mais avançada; menor ASC; uso de bainhas introdutoras curtas; doença multiarterial; e ICP.

Background: Fewer bleeding complications and early ambulation make radial access a privileged route for cardiac catheterization. However, transradial (TR) approach is not always successful, requiring its conversion into femoral access. Objectives: To evaluate the rate of conversion from radial into femoral access in cardiac catheterization and to identify its predictors. Methods: Prospective dual-center registry, including 7632 consecutive patients undergoing catheterization via the radial access between Jan/2009 and Oct/2012. We evaluated the incidence of conversion into femoral access and its predictors by logistic regression analysis. Results: The patients’ mean age was 66 ± 11 years, and 32% were women. A total of 2969 procedures (38.4%) were percutaneous coronary interventions (PCI), and the most used first intention arterial access was the right radial artery (97.6%). Radial access failure rate was 5.8%. Independent predictors of conversion from radial into femoral access were the use of short introducer sheaths (OR 3.047, CI: 2.380-3.902; p < 0.001), PCI (OR 1.729, CI: 1.375-2.173; p < 0.001), female sex (OR 1.569, CI: 1.234-1.996; p < 0.001), multivessel disease (OR 1.457, CI: 1.167-1.819; p = 0.001), body surface area (BSA) ≤ 1.938 (OR 1.448, CI: 1.120-1.871; p = 0.005) and age > 66 years (OR 1.354, CI: 1.088-1.684; p = 0.007). Conclusion: Transradial approach for cardiac catheterization has a high success rate and the need for its conversion into femoral access in this cohort was low. Female sex, older age, smaller BSA, the use of short introducer sheaths, multivessel disease and PCI were independent predictors of conversion into femoral access.

This study aimed to guide the planning of anticurvature filing using pre-determined anatomical points on teeth to establish directions for proper implementation of the technique. Two hundred digital periapical radiographs of human molar teeth were selected and divided into two groups (n = 100): MX (maxillary) and MD (mandibular) molars. Mesiobuccal roots were considered for the MX group and mesial roots for the MD group. Pre-determined anatomical points required for planning the anticurvature filing on the root canal path were located, and the distances between these points obtained. The anticurvature filing was simulated in two different protocols for each group, and the region of dentin removal and the remaining dentin thickness were measured in the safety and danger zones of the root canals. Statistical analysis was carried out at a significance level of 5%. The distances between the anatomical points and the thickness of remaining dentin showed significant differences when the two groups were compared (p < 0.001). No significant differences were found between the two experimental groups regarding the area of dentin removal at the root region, but differences were detected in comparison with dentin removal at the crown (p < 0.001). In terms of wear produced after simulation of both anticurvature filing protocols, significant differences were verified for all regions, except for the dentin remaining at the danger zone. The radiographic location of anatomical points allows for planning and implementation of controlled and efficient anticurvature filing and can be performed in the same manner for maxillary and mandibular molars.

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm2 from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Este estudo avaliou a anatomia do canal radicular de incisivos inferiores, antes e após a instrumentação endodôntica, identificando regiões inacessíveis à ação das limas (Área Crítica de instrumentação - AC), em uma perspectiva tridimensional. Trinta incisivos centrais inferiores humanos foram selecionados, divididos em dois grupos (n=15), e instrumentados usando limas rotatórias ProTaper Universal. No grupo RX, imagens longitudinais foram obtidas em duas incidências, vestíbulo-lingual (VL) e mésio-distal (MD), por meio de radiografias digitais. No grupo CT, imagens transversais foram obtidas por meio de microtomografia computadorizada (μTC), em secções localizadas a 3 mm, 9 mm, e 15 mm do ápice. A área do canal das amostras foi avaliada antes e após a instrumentação usando as imagens digitais de cada grupo. Os dados foram analisados por meio do teste t, ANOVA a um critério com parcela subdividida e ao teste de Tukey (α=0,05). A área de canal encontrada nas radiografias MD foi maior do que nas radiografias VL, o que também foi confirmado nas imagens transversais (p<0,01). A Área Crítica de instrumentação só foi detectada nas radiografias MD e nas seções de μTC. Na configuração de canal, a redução contínua na conicidade do canal foi observada nas radiografias VL, enquanto na incidência MD, houve uma constrição no terço cervical e um subsequente aumento no terço médio (p<0,01). A forma cônica do canal radicular foi observada somente na visão VL. O alargamento do canal verificado nas radiografias VL não foi indicativo de instrumentação homogênea, uma vez que áreas não instrumentadas (AC) foram observadas nas paredes vestibular e lingual em visões distintas.

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukey's test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images

FUNDAMENTO: O benefício clínico de intervenção coronária percutânea (ICP) para lesões coronárias longas é incerto; além disso, foram levantadas dúvidas questões sobre a sua segurança. OBJETIVO: Avaliar os preditores de eventos cardíacos adversos maiores (ECAM) associados à ICP utilizando Full Metal Jacket (FMJ), definido como a sobreposição de stents farmacológicos (SF) medindo >60 mm de comprimento, para lesões muito longas. MÉTODOS: Foram incluídos 136 pacientes consecutivos com lesões coronárias longas, requerendo FMJ em nosso cadastro de centro único. O desfecho primário incluiu a ocorrência combinada de todas as causas de morte, infarto do miocárdio (IM) e revascularização do vaso alvo (RVA). Variáveis demográficas, clínicas, angiográficas e de procedimento foram avaliadas por meio de análise de regressão de Cox para determinar os preditores independentes de desfecho. RESULTADOS: O comprimento médio do stent por lesão foi de 73,2 ± 12,3 mm e o diâmetro médio do vaso de referência foi de 2,9 ± 0,6 mm. O sucesso angiográfico foi de 96,3%. A ausência de ECAM foi de 94,9% em 30 dias e 85,3% em um ano. No acompanhamento de um ano, a taxa de mortalidade por todas as causas foi de 3,7% (1,5% por mortes cardíacas), a taxa de IM foi de 3,7%, e a incidência de trombose de stent (TS) definitiva ou provável foi de 2,9%. O gênero feminino [risco relativo (RR), 4,40; intervalo de confiança de 95% (IC), 1,81-10,66, p = 0,001) e ICP de artéria coronária não direita (RR, 3,49; p = 0,006; IC 95%, 1,42-8,59) foram preditores independentes de ECAM em um ano. A ausência de eventos adversos em um ano foi maior em pacientes com angina estável submetidos à ICP (RR, 0,33; IC 95% 0,13-0,80, p = 0,014). CONCLUSÕES: A ICP utilizando FMJ com SF para lesões muito longas foi eficaz, mas associada a uma alta taxa de TS em acompanhamento de um ano. No entanto, a taxa de mortalidade cardíaca, IM não relacionado a procedimento, e ECAM foi relativamente baixa. ICP de vaso coronário alvo, apresentação clínica, e gênero feminino são novos fatores clínicos contemporâneos que parecem apresentar efeitos adversos sobre o resultado da ICP utilizando FMJ para lesões longas.

BACKGROUND: The clinical benefit of percutaneous coronary intervention (PCI) for long coronary lesions is unclear; furthermore, concerns have been raised about its safety. OBJECTIVES: To evaluate the predictors of major adverse cardiac events (MACE) associated with PCI using a full metal jacket (FMJ), defined as overlapping drug-eluting stents (DES) measuring >60 mm in length, for very long lesions. METHODS: We enrolled 136 consecutive patients with long coronary lesions requiring FMJ in our single-center registry. The primary endpoint included the combined occurrence of all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR). Demographic, clinical, angiographic, and procedural variables were evaluated using stepwise Cox regression analysis to determine independent predictors of outcome. RESULTS: The mean length of stent per lesion was 73.2 ± 12.3 mm and the mean reference vessel diameter was 2.9 ± 0.6 mm. Angiographic success was 96.3%. Freedom from MACE was 94.9% at 30 days and 85.3% at one year. At the one-year follow-up, the all-cause mortality rate was 3.7% (1.5% cardiac deaths), the MI rate was 3.7%, and the incidence of definite or probable stent thrombosis (ST) was 2.9%. Female gender [hazard ratio (HR), 4.40; 95% confidence interval (CI), 1.81-10.66; p = 0.001) and non-right coronary artery PCI (HR, 3.49; 95%CI, 1.42-8.59; p = 0,006) were independent predictors of MACE at one year. Freedom from adverse events at one year was higher in patients with stable angina who underwent PCI (HR, 0.33; 95%CI, 0.13-0.80; p = 0.014). CONCLUSIONS: PCI using FMJ with DES for very long lesions was efficacious but associated with a high rate of ST at the one-year follow-up. However, the rate of cardiac mortality, nonprocedure-related MI, and MACE was relatively low. Target coronary vessel PCI, clinical presentation, and female gender are new contemporary clinical factors that appear to have adverse effects on the outcome of PCI using FMJ for long lesions.

O tempo de presa de cimentos endodônticos pode afetar a resistência de união de pinos de fibra de vidro à dentina radicular. Quarenta dentes foram selecionados e tratados endodonticamente com cimento à base de hidróxido de cálcio. Em seguida, os mesmos foram divididos em dois grupos de acordo com o tempo decorrido entre o tratamento endodôntico e a cimentação definitiva (n=20): Imediato - pinos de fibra de vidro cimentados após o tratamento endodôntico; e Mediato - cimentação do pino realizada 7 dias após o tratamento endodôntico. As raízes foram subdivididas de acordo com o cimento resinoso (RelyX ARC e RelyX Unicem). As amostras foram armazenadas a 37 °C durante 24 h e seccionadas em seis fatias de 1 mm de espessura relacionadas com terços cervical, médio e apical. Os espécimes foram submetidos a teste de push-out a uma velocidade de 0,5 mm/min e os valores de resistência de união obtidos (MPa) foram submetidos à análise de variância em esquema de parcelas subdivididas e teste de Tukey (α=0,05). Para os cimentos RelyX ARC e Unicem, a resistência de união foi maior quando os pinos foram cimentados 7 dias após o tratamento endodôntico. RelyX Unicem apresentou valores de resistência de união superiores ao RelyX ARC para os períodos de cimentação. Concluiu-se que a cimentação do pino de fibra de vidro deve ser feita após o completo tempo de presa do cimento endodôntico. Cimentos resinosos auto-adesivos devem ser preferidos para cimentação de pinos de fibra.

The cure time of endodontic sealers may influence the bond strength of fiber posts to root dentin. Forty teeth were selected and endodontically filled using calcium hydroxide cement and then divided into 2 groups according to the time elapsed between endodontic filling and post luting (n = 20): Immediately - glass fiber post luting immediately after endodontic filling; and Delayed - post luting performed 7 days after endodontic filling. The roots were also subdivided according to resin cement used for post luting (RelyX ARC and RelyX Unicem). The specimens were stored at 37°C for 24 h and sectioned in six 1-mm-thick slices from cervical, middle and apical thirds. The slice specimens were submitted to a push-out test at a crosshead speed of 0.5 mm/min, and the bond strength values obtained (MPa) were submitted to two-way ANOVA in a split-plot arrangement and Tukey's test (α=0.05). For both RelyX ARC and Unicem, the bond strength was significantly higher when the posts were cemented 7 days after the endodontic treatment. RelyX Unicem showed significantly higher bond strength values than RelyX ARC for both cementation periods. It was concluded that post luting should be made after the complete setting of the root canal sealer. Self-adhesive resin cement should be preferred for fiber post luting.

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.

O objetivo deste estudo foi avaliar o efeito de diferentes parâmetros de solda a plasma verificando a resistência flexural de barras de liga de titânio (Ti-6Al-4V). Quarenta espécimes de Ti-6AL-4V e dez espécimes de liga de NiCr foram preparados (40 mm de altura e 3,18 mm de diâmetro) e divididos em 5 grupos (n=10). As barras de liga titânio do grupo controle não foram seccionadas e nem submetidas a processo de soldagem. Os grupos PL10, PL12 e PL14, continham barras de titânio seccionadas e soldadas com uma corrente de 3 A por períodos de 10,12 e 14 ms, respectivamente. O grupo NCB consistiu de barras de liga de NiCr soldadas pelo método de brasagem convencional. Em seguida as barras foram submetidas ao teste de flexão de três pontos e os valores obtidos foram transformados em resistência flexural (MPa). Análise estatística foi realizada usando ANOVA de fator único e o teste Tukey com o nível de significância de 0,05. Diferença estatística foi verificada entre os grupos avaliados (p<0,001), com os maiores valores pra o grupo controle. Não foram encontradas diferenças entre os grupos de solda plasma (p>0,05). O grupo NCB apresentou os menores valores de resistência flexural embora tenha sido estatisticamente semelhante ao grupo PL14. Não houve diferença significante na profundidade de penetração entre os grupos de solda plasma (p=0,05). Três espécimes representativos foram aleatoriamente selecionados para serem avaliados por meio de microscopia eletrônica de varredura. A composição das regiões soldadas foi verificada por meio de espectroscopia por energia dispersiva. Este estudo fornece informações iniciais de parâmetros para permitir a utilização de soldagem plasma durante a fabricação de estruturas em liga de titânio.

The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10). The titanium alloy beams for the control group were not sectioned or subjected to welding. Groups PL10, PL12, and PL14 contained titanium beams sectioned and welded at current 3 A for 10, 12 or 14 ms, respectively. Group NCB consisted of NiCr alloy beams welded using conventional torch brazing. After, the beams were subjected to a three-point bending test and the values obtained were analyzed to assess the flexural strength (MPa). Statistical analysis was carried out by one-way ANOVA and Tukey's HSD test at 0.05 confidence level. Significant difference was verified among the evaluated groups (p<0.001), with higher flexural strength for the control group (p<0.05). No significant differences was observed among the plasma welded groups (p>0.05). The NCB group showed the lowest flexural strength, although it was statistically similar to the PL 14 group (p>0.05). The weld depth penetration was not significantly different among the plasma welded groups (p=0.05). Three representative specimens were randomly selected to be evaluated under scanning electron microcopy. The composition of the welded regions was analyzed by energy dispersive X-ray spectroscopy. This study provides an initial set of parameters supporting the use of plasma welding during fabrication of titanium alloy dental frameworks.

The esthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good esthetics. However, fracture can occur in some cases due to their brittle behavior. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost. In this paper, two cases are presented, in which fractures occurred in extensive metal-ceramic fixed partial dentures, and their replacement was not possible. Ceramic repair was chosen and the sequences of treatment with and without presence of the ceramic fragment are also discussed. The cases illustrate that, in some situations, fractured metal-ceramic partial dentures can be successfully repaired when prosthetic replacement is not a choice. Prosthodontists must use alternatives that allow a reliable repair to extensive metal-ceramic fixed partial dentures. Surface preparation of the ceramic with hydrofluoric acid in conjunction with a silane coupling agent is essential for a predictable bonding of composite resin. The repair performed with composite resin is an esthetic and functional alternative when extensive fixed partial dentures cannot be replaced.