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Aim: To evaluate the marginal fit of protocol bars milled from digital models obtained by conventional molding followed by bench scanning or digital molding with an intraoral scanner. Methods: Four morse-cone implants and the mini-pillars were installed in a 3D printed mandible model (master model). Digital models of the master model were obtained by (n=10): (Group A - Conventional) conventional (analog) molding of the master model followed by bench scanning or (Group B - Digital) molding of the master model with an intraoral scanner. All-on-four protocol bars were designed and milled from the digital models for both groups and screwed into the master model. Scanning electron microscopy (SEM) images from the distal, central, and mesial regions of each implant were obtained and the implant-protocol bar marginal fit was measured in an image software (Image J). The mean misfit of each region was analyzed by two-factor ANOVA, Tukey test, and Student's t-test (0,05 = 0.05). Results: The digital approach (B) showed higher misadaptation than the conventional approach (A, p < 0.05), regardless of the region evaluated. In group A, the central region showed higher maladjustment than the mesial region (p<0.05), however, there were no differences among regions of group B (p>0.05). Conclusion: The conventional method of acquiring digital models using the bench scanner produced bars for the All-On-Four protocol with better marginal fit than the digital models obtained with an intraoral scanner

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BACKGROUND: This experimental study assessed reverse torque of indexed and nonindexed (NI) abutments in Morse Taper (MT) implants in a mechanical fatigue test. MATERIALS AND METHODS: In this experimental study It was used 37 implants MT and over them installed Pilar Flex abutments (4.8 mm × 6 mm × 1.5 mm). The groups were as follows: Group A used 19 MT implants with a NI Pilar Flex abutment loaded with 32 N/cm and Group B used 18 MT implants with an indexed (IN) Pilar Flex abutment loaded with 20 N/cm. The abutments were tested according to ISO standard 14801/2007. The specimens were installed at 30° from the axial axis and underwent a 133 N load, 4 Hz frequency, and 1,000,000 cycles. Once the test was completed, the reverse torque was provided by an electronic torque meter. Data were submitted to statistical analysis using the t-test for independent samples and paired t-test. The significance level was considered P < 0.05. RESULTS: Results obtained showed that the indexed Pilar Flex abutment had a percentage of torque loss from the initial torque of 49% and the NI Pilar Flex abutment lost 14%. Paired Student's t-tests revealed that for both NI (P < 0.001) and indexed (P < 0.001) abutments, the counter torque values were significantly lower than those applied at the initial torque. CONCLUSION: According on the methodology used, the NI Pilar Flex abutment was more effective regarding the reverse torque in single-unit implant prostheses versus the indexed Pilar Flex abutment. A greater loosening in the indexed Pilar Flex abutment retaining screw was noted in the reverse torque test, and the Pilar Flex abutment failed to show good outcomes related to the cold welding effect.

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AIM AND OBJECTIVES: This study assessed, through finite element analysis, the biomechanical behavior of an implant system using the All-on-Four® technique with nickel-chromium (M1) and polyether ether ketone (PEEK) bars (M2). MATERIALS AND METHODS: Implants and components were represented in three-dimensional (3D) geometric models and submitted to three types of load: axial, oblique, and load on all teeth. The 3D models were exported to a computer-aided design-like software such as Solidworks 2016 (Dassault Systemes, Solidworks Corps, USA) for editing and Nonuniform Rational Basis Splines parametrization. RESULTS: Data were analyzed according to system's areas of action: peri-implant bone, implant, intermediates, intermediates' screws, prostheses' screws, and bars. Largest peak stress was shown in M2. CONCLUSION: PEEK is a promising material for use in dentistry; however, further studies are necessary to evaluate its performance.

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A variedade de materiais de moldagem, bem como o tempo decorrido entre o ato da moldagem e o vazamento do molde podem ser causas de alterações dimensionais nos modelos de trabalho e também falhas na fidelidade de cópia dos preparos protéticos. Objetivo: avaliar in vitro a variação dimensional de modelos de gesso vazados em diferentes tempos, produzidos por 4 materiais de moldagem. Materiais e métodos: os materiais de moldagem foram divididos em 4 grupos: (A) experimentais, sendo A1 e A2 Silicones de Condensação, A3 e A4 Silicones de Adição, os quais reproduziram uma matriz multifuncional. foram obtidos 48 modelos (n=192) pela técnica de moldagem única e vazados nos seguintes tempos 1, 4, 24 e 72 horas com gesso tipo IV. As medidas dos modelos de gesso foram obtidas utilizando-se scanner digital (3Shape, Compass, Brasil). Resultados: Nenhum dos materiais utilizados apresentou variação dimensional estatisticamente significativa (p>0,005) em quaisquer um dos tempos de vazamento. Conclusão: De acordo com a metodologia empregada, o tempo de vazamento não teve influência na variação dimensional observada, nem nos Silicones de Condensação, nem nos Silicones de Adição.

The variety of materials that can be used for dental impression, as well as the time spent between the dental impressions molding and pouring may be responsible for defects such as dimensional discrepancies observed on master casts and also lack of fidelity on the prosthetic work copies. Aim: Evaluate, in vitro, dimensional variation of cast models at different pouring times, considering (4) different impression materials. Materials and methods: The impression materials were divided into 4 groups; (A) experimental, with A1 and A2 condensation silicones, A3 and A4 addition silicones which reproduced a multifunctional matrix. forty-eight models were obtained (n=192) by one step impression technique and poured at the following times 1, 4, 24 and 72 hours with plaster type IV. The plaster models measurements were obtained using digital scanner (3Shape, Compass, Belo horizonte, Minas Gerais, Brazil). Conclusion: According to the used methodology, the molding OU pouring time did not have influence in the dimensional variation observed, neither on condensation silicones nor in addition silicones.

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O objetivo do presente estudo foi avaliar três diferentes tipos de soldagem: Chama Direta a maçarico (convencional\brasagem), Solda Mista representada por fixação de dois pontos (Solda Elétrica Fixator - Kernit, Brasil), e completada com solda convencional, e o método de Solda a Laser (Soldadora Desktop - Sisma LM 500, Itália). Dois implantes plataforma Bränemark 4.1 mm (Neodent, Curitiba/Brasil) foram fixados em uma matriz de alumínio para simular uma ponte fixa implanto-suportada de três elementos. Os espécimes foram obtidos a partir de um bloco de cera CAD-CAM (Ceramill-Amammgirrbarch). Trinta e duas UCLAs hexágono externo foram fresadas e posteriormente unidas a uma barra pré-fabricada em cera com 2,5mm. Os corpos de prova foram fundidos em liga de cobalto-cromo simulando uma prótese fixa de três elementos. Esses espécimes foram divididos aleatoriamente e separados em três grupos (n=6): grupo A (solda chama direta), grupo B (solda mista), grupo C (solda laser). Os espécimes foram seccionados ao meio e unidos com resina acrílica para simular uma soldagem em prótese fixa. Os corpos foram soldados e tratados de acordo com a proposição. Após a soldagem os corpos de prova foram usinados e levados ao teste de flexão na técnica de três pontos. Os dados foram submetidos aos testes estatísticos de Tukey. Os cálculos estatísticos foram conduzidos adotando-se o nível de significância de 5% (α = 0,05). Houve diferença estatisticamente significativa entre os grupos soldados. Os resultados demonstraram valores mais elevados nos grupos A e B, solda convencional e solda mista, e menor valor no grupo C, solda a laser. No entanto, considerando a metodologia aplicada, a solda a laser mostrou uma menor resistência flexural comparada à soldagem convencional e mista, e a fixação prévia de solda elétrica com complemento de solda convencional (solda mista) não alterou a resistência flexural, produzindo resultado semelhante à solda convencional

The objective of this study was to evaluate three different types of welding, blowtorch; (conventional/brazing), welder Joint; represented by securing two points (Arc Welding Fixator - Kernit, Brazil), and supplemented with conventional welding), and Laser welding method (welder Desktop - Sisma LM 500, Italy). Two implants Bränemark 4.1 mm platform (Neodent, Curitiba/Brazil) were fixed in an aluminum matrix. Specimens were obtained from a CAD-CAM wax block (Ceramill - Amammgirrbarch) were milled 32 UCLAs (external hexagon, Bränemark platform), and subsequently joined to a prefabricated bar also wax 2.5 mm, the specimens were casted in cobalt-chromium alloy. These specimens were randomly divided and separated into 3 groups: group A (welding direct flame), Group B (mixed welding), C (laser welding), with 6 samples for each group. The specimens of each group were cut in half to simulate a fixed prosthesis in welding, and put together with acrylic resin. The bodies were welded and treated according to the statement. After the specimens were welded, they were manually grinded and submitted to the 3 points bending test technique. Data were subjected to statistical tests of Tukey. Statistical calculations were performed adopting the significance level of 5% (α = 0.05), using SPSS 20 (SPSS Inc., Chicago, IL, USA). There were differences between the soldered groups. The data showed the highest values obtained in groups A and B, conventional welding and soldering joint, and lower in group C, the laser welding. However, within the applied methodology, the laser welding showed a lower flexural strength compared to conventional and mixed welding, and that the advance fixing of electric welding, conventional welding complement (mixed welding), does not change its flexural strength, producing results similar to conventional welding

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AIM: This work evaluated the mechanical and surface behavior of different die materials. The studied materials are polyurethane resin Exakto-Form (Bredent), Gypsum type IV, Fuji Rock EP (Gc), and Durone (Dentsply). MATERIALS AND METHODS: Two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test. The cylindrical test specimens were submitted to tests of diametral compression strength using a DL2000 universal assay machine, with a load cell of 2000 Kgf and constant speed of 1 mm/min connected to the software. Kruskal-Wallis and Dunn's nonparametric tests were used to analyze the results. The hemispheres were submitted to the surface rugosity assay using a SJ201-P rugosimeter with a sensitivity of 300 µm, speed of 0.5 mm/s, and cut-off of 0.8 mm, and the readings were taken on the convex surface of the test specimens and metallic matrix. Results were analyzed using with Fisher's least significant differences test (LSD) and Dunnett's test. RESULTS: Kruskal-Wallis test showed significant difference between die materials for diametral compression strength (P = 0.002). Dunn's test showed significantly higher values for modified polyurethane resin (Exakto-Form). The gypsum type IV, which did not significantly differ regarding diametral compression strength, showed 34.0% (Durone) and 42.7% (Fuji Rock) lower values in comparison to Exakto-Form. CONCLUSION: Within the parameters adopted in this study, it is possible to conclude that Exakto-Form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity, and, along with the gypsum type IV Durone, showed better reproducibility of details relative to the Fuji Rock.

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O objetivo deste estudo foi avaliar as influências acarretadas pelo tratamento das superfícies das zircônias com primer apropriado na resistência de união entre cimento resinoso e uma cerâmica de Zircônia. foram utilizados 20 corpos de prova em Zircônia VIPI BLOCK ZIRCONN (VIPI, São Paulo, Brasil) divididos em 2 grupos: Grupo 1 ­ tratamento de superfície da zircônia apenas com jateamento de óxido de alumínio e cimento resinoso PanaviaTF 2.0 (Kuraray, Kurashiki, Japão); e Grupo 2 ­ além do jateamento usou-se o primer Ceramic Primer (3M, São Paulo, Brasil). Os espécimes cerâmicos receberam o cimento manipulado na proporção de 1:1 e foram estocados em água destilada a 37ºC por 24 horas antes e após a termociclagem. O ensaio de cisalhamento foi realizado em máquina de ensaios EMIC DL2000 (EMIC, São Paulo, Brasil), os valores de resistência de união foram apresentados em Mpa e analisados através de Análise de Variância (ANOVA) e teste t Student para amostras independentes. Os valores resistência ao cisalhamento entre cimentos e cerâmica à base de zircônia utilizando os primers mencionados não foram estatisticamente diferentes, isto é, nenhuma diferença significativa foi encontrada entre os grupos G1 (8,70 ± 6,31) e G2 (8,18 ± 3,75). Os testes realizados com o primer não mostraram aumento considerável na resistência de união ao cisalhamento entre cimentos e cerâmica à base de zircônia.

The aim of this study was to evaluate the influence of the use of primer to treat zirconia surfaces on the bond strength between resin cement and zirconia ceramics. The 20 specimens were divided into 2 groups: group 1 ­ zirconia surface treatment with sandblasting with aluminum oxide and Panavia T f 2.0 (Kuraray); Group 2 ­ in addition to the sandblasting Ceramic Primer (3M) was used. Each specimen of the ceramic material received manipulated cement in the proportion 1:1. The specimens were stored in distilled water at 37 ° C for 24 hours before and after thermocycling. Shear test was performed in testing EMIC DL2000 (EMIC, São Paulo, Brazil) and the values of bond strength in MPa were analyzed using Analysis of Variance (ANOVA) and Student t test for independent samples machine. There was no significant difference between the values for shear strength between both studied groups: G1 (8.70 ± 6 groups, 31) and G2 (8.18 ± 3.75). The tests performed with the primer used in this study showed no significant increase on shear bond strength between cement and ceramics based on zirconia.

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Este estudo avaliou o comportamento mecânico de uma resina de poliuretano Quartz-die (Zermack - Itália) empregada na modelagem odontológica comparando-a com o gesso tipo IV Durone (Dentsply - Brasil). Uma matriz metálica moldada com silicona de condensação Speedex (Coltène - Suiça) proporcionou corpos de prova com 12mm de altura por 6mm de diâmetro. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV (Durone) foram submetidos a ensaio de compressão na máquina de ensaios universal EMIC DL 2000, com célula de carga de 2000Kgf e velocidade de 0,05mm/min. Oito corpos de prova em resina de poliuretano e oito em gesso tipo IV obtidos a partir de uma matriz metálica hexagonal foram ensaiados noDurômetro Sussen Wolpert tipo Testor HTl, empregando penetrador esférico de 12,7mm, estabelecendo valores para dureza Rockwell. Os valores obtidos foram submetidos ao teste não-paramétrico de Kruskall-Walliscom p<0,05. Dentro dos parâmetros adotados neste estudo pôde-se concluir que a resina de poliuretano Quartz-die apresentou menor resistência à compressão e menor dureza superficial que o gesso tipo IV Durone.

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This laboratory study compared the flexural endurance limits of clinical combinations of dental composite with and without glass ionomer cement (GIC) liners. Using only composite (Filtek Z350), specimens (10 mm long x 2 mm wide x 2 mm thick) in the control group were produced. Two GICs (Vitremer and Vitrebond) were used with the composite to prepare the test groups. Flexural strength and flexural fatigue limit (FFL) tests were performed. The FFL was determined using the staircase method. Data were analyzed by one-way ANOVA and Tukey's test. There was a significant difference in flexural strength values between the composite-only specimens and those produced by composite and GIC (p < 0.05). No statistical difference was observed in the flexural strength values between composite with Vitremer and composite with Vitrebond (p < 0.05). No statistically significant differences were detected in FFL values between composite with Vitremer and composite with Vitrebond; in addition, the mean value of the composite-only specimens differed statistically from those of both composite with Vitremer and composite with Vitrebond (p < 0.05). The FFL was lower than the flexural strength, indicating a decrease in flexural strength of 45 to 50%. Using GICs with composite decreased the mechanical properties (FFL and flexural strength) of the composite.

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Successful restoration depends on the mechanical resistance of dental restorative materials. The occlusal forces from masticatory contacts can affect the durability of restorations and cause fractures. Over time, monomers convert to polymers, leading to degradation of the organic matrix, which can interfere with mechanical resistance. This study sought to assess the effect of artificially accelerated aging on the microhardness of five composite resins: Filtek Z250, Charisma, Durafill VS, Filtek Supreme for body, and Filtek Supreme translucent. Ten test specimens were made of each material, using a 6.0 x 2.0 mm teflon matrix. After 24 hours, five test specimens of each material were submitted to the Vickers microhardness test (control group) for 10 seconds at a load of 300 kgf. The other five test specimens remained in the artificially accelerated aging machine for 196 hours and were submitted to the Vickers microhardness test. Filtek Z250 had the highest values and Durafill the lowest, both at 24 hours and after artificially accelerated aging. Artificially accelerated aging increased the microhardness of the composite resins.

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