Stress distribution around osseointegrated implants with different internal-cone connections: photoelastic and finite element analysis.

The goal of this study was to evaluate the distribution of stresses generated around implants with different internal-cone abutments by photoelastic (PA) and finite element analysis (FEA). For FEA, implant and abutments with different internal-cone connections (H- hexagonal and S- solid) were scanned, 3D meshes were modeled and objects were loaded with computer software. Trabecular and cortical bones and photoelastic resin blocks were simulated. The PA was performed with photoelastic resin blocks where implants were included and different abutments were bolted. Specimens were observed in the circular polariscope with the application device attached, where loads were applied on same conditions as FEA. FEA images showed very similar stress distribution between two models with different abutments. Differences were observed between stress distribution in bone and resin blocks; PA images resembled those obtained on resin block FEA. PA images were also quantitatively analyzed by comparing the values assigned to fringes. It was observed that S abutment distributes loads more evenly to bone adjacent to an implant when compared to H abutment, for both analysis methods used. It was observed that the PA has generated very similar results to those obtained in FEA with the resin block.

CIE L*a*b*: comparison of digital images obtained photographically by manual and automatic modes

The aim of this study was to analyze the color alterations performed by the CIE L*a*b* system in the digital imaging of shade guide tabs, which were obtained photographically according to the automatic and manual modes. This study also sought to examine the observers' agreement in quantifying the coordinates. Four Vita Lumin Vaccum shade guide tabs were used: A3.5, B1, B3 and C4. An EOS Canon digital camera was used to record the digital images of the shade tabs, and the images were processed using Adobe Photoshop software. A total of 80 observations (five replicates of each shade according to two observers in two modes, specifically, automatic and manual) were obtained, leading to color values of L*, a* and b*. The color difference (ΔE) between the modes was calculated and classified as either clinically acceptable or unacceptable. The results indicated that there was agreement between the two observers in obtaining the L*, a* and b* values related to all guides. However, the B1, B3, and C4 shade tabs had ΔE values classified as clinically acceptable (ΔE = 0.44, ΔE = 2.04 and ΔE = 2.69, respectively). The A3.5 shade tab had a ΔE value classified as clinically unacceptable (ΔE = 4.17), as it presented higher values for luminosity in the automatic mode (L* = 54.0) than in the manual mode (L* = 50.6). It was concluded that the B1, B3 and C4 shade tabs can be used at any of the modes in digital camera (manual or automatic), which was a different finding from that observed for the A3.5 shade tab.

CIE L*a*b*: comparison of digital images obtained photographically by manual and automatic modes.

The aim of this study was to analyze the color alterations performed by the CIE L*a*b* system in the digital imaging of shade guide tabs, which were obtained photographically according to the automatic and manual modes. This study also sought to examine the observers' agreement in quantifying the coordinates. Four Vita Lumin Vaccum shade guide tabs were used: A3.5, B1, B3 and C4. An EOS Canon digital camera was used to record the digital images of the shade tabs, and the images were processed using Adobe Photoshop software. A total of 80 observations (five replicates of each shade according to two observers in two modes, specifically, automatic and manual) were obtained, leading to color values of L*, a* and b*. The color difference (ΔE) between the modes was calculated and classified as either clinically acceptable or unacceptable. The results indicated that there was agreement between the two observers in obtaining the L*, a* and b* values related to all guides. However, the B1, B3, and C4 shade tabs had ΔE values classified as clinically acceptable (ΔE = 0.44, ΔE = 2.04 and ΔE = 2.69, respectively). The A3.5 shade tab had a ΔE value classified as clinically unacceptable (ΔE = 4.17), as it presented higher values for luminosity in the automatic mode (L* = 54.0) than in the manual mode (L* = 50.6). It was concluded that the B1, B3 and C4 shade tabs can be used at any of the modes in digital camera (manual or automatic), which was a different finding from that observed for the A3.5 shade tab.

Estabilidade dimensional de modelos obtidos com poliéter e silicone de adição após desinfecção comácido peracético e hipoclorito de sódio / Dimensional stability of casts obtained with polyether and addition reaction silicone after disinfection with sodium hypochlorite and peracetic acid

Este estudo buscou comparar a estabilidade dimensional de modelos após moldagem com poliéter (P), silicone de adição espatulado mecanicamente (SAP) e manualmente (SAM), desinfetados com hipoclorito de sódio 1% (HP), ácido peracético 0,2% (AP) e sem desinfecção. Foram feitas mensurações cruzando o arco posterior (CAP) e anterior (CAA), ântero-posterior direita (APD) e esquerda (APE). A análise estatística (Kruskal-Wallis) mostrou que houve diferença significativa apenas na medida CAP: 1) entre P (0,1203% ± 0,0442) e SAP (0,0350% ± 0,0158) desinfetados com HP; 2) entre P (0,1345% ± 0,1059) e SAP (0,0264%± 0,0302) desinfetados com AP; 3) entre os grupos SAM (0,1054% ± 0,0419) e SAP (0,0264% ± 0,0302). A desinfecção com ácido peracético e hipoclorito de sódio não interferiu negativamente na estabilidade dimensional das moldagens realizadas neste estudo.

This study aimed to compare the dimensional stability of polyether (P), addition silicone auto mixed (ASP) and addition silicone hand mixed (ASM) molds after disinfection with sodium hypochlorite 1% (HP), peracetic acid 0,2% (AP), and no disinfection. Mensurations cross posterior arch (CAP), cross-anterior arch (CAA), and antero-posterior on right (APD) and left sides (APE). Statistical analysis (Kruskall-Wallis) showed significant difference only in measure CAP: 1) between P (0,1203% ± 0,0442) and SAP (0,0350% ± 0,0158) disinfected with HP; 2) between P (0,1345% ± 0,1059) and SAP (0,0264% ± 0,0302) disinfected with AP; and 3) between SAM (0,1054% ± 0,0419) and SAP (0,0264% ± 0,0302). Disinfection with peracetic acid and sodium hypochlorite did not interfere negatively in the dimensional accuracy of the impressions tested in this study. Keywords: impression materials; disinfection; peracetic acid; sodium hypochlorite.

Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva.

OBJECTIVES: To correlate the presence and number of Candida spp. in the saliva of wearers of removable partial dentures retained with precision attachments with the proportion of metal/acrylic resin present in the dentures. METHODS: Saliva samples from 40 removable partial denture wearers (test) and one paired sample of individuals, non-wearers of any type of removable denture (control) were collected, seeded, and the colony forming units of Candida counted and identified. The metal/acrylic resin proportion of each denture was quantified, using silicone plates pressed over each denture. RESULTS: Candida spp. was found in the saliva of 80% of the individuals in the test group and 65% of the control, with C. albicans being the most prevalent species. The test group presented with the highest number of colony forming units of Candida per ml of saliva, and there was weak correlation between this number and the metal and resin area of the denture (Pearson's coefficient of correlation). Greater prevalence and a higher number of colony forming units of Candida per ml of saliva occurred in removable partial denture wearers (p = 0.04) with a weak positive correlation between the metal and resin area and the number of colony forming units of Candida per ml of saliva. However, this correlation was more significant for the area of resin.

Concurrence between interpupillary line and tangent to the incisal edge of the upper central incisor teeth.

OBJECTIVE: Dento-facial harmony is essential to obtain adequate esthetics and a successful treatment. Therefore, the aim of the present study was to analyze the existence of polar symmetry, obtained by two parallel lines, one along the pupils and another along the incisal edge of the upper central incisor teeth of 102 dental students distributed across five Brazilian dental schools. MATERIALS AND METHODS: One hundred and two students with no missing teeth, who had never been subjected to any kind of dental treatment, not even orthodontic treatment, were selected and photographed using a dental eye II camera (Yashica-Kyocera Optics Inc., Somerset, NJ, USA) with a macro-objective lens of 100 mm and using a scale of 1:10 of the natural size. All the individuals were positioned parallel to the plane of Frankfurt and to the ground, and were photographed smiling in order to expose the central incisors. The pictures were transformed into digital images (1,840 x 1,252 pixels) and analyzed later using Microsoft Office Power Point 2007 software. Two lines (along the pupils and another along the maxillary incisive teeth) were drawn, and the inclination obtained was generated by the program itself. Symmetrical cases were classified as "yes" (Y), and the remainder as "no" (N). Cases were also divided according to gender. Results were statistically assessed by analysis of variance and Student's t-test (alpha = 0.05). RESULTS: There was a statistically significant correlation between the line parallel with the pupils and the tangent of the incisal edge of the incisors, irrespective of gender. CONCLUSION: Regardless of gender, there is a correlation between the pupils and the tangent with the incisal edge of the maxillary central incisors. CLINICAL SIGNIFICANCE Despite diversity in individuals, facial and anatomic measurements may aid in the execution and planning of rehabilitation treatments. (J Esthet Restor Dent 21:318-323, 2009).

Concurrence between the maxillary midline and bisector to the interpupillary line.

PURPOSE: Symmetry is one of the factors that contributes to facial harmony, and in oral rehabilitation it determines the success of esthetic treatment. Therefore, the aim of the present study was to analyze the axial symmetry between the bipupillar midline and maxillary central incisors midline of 102 dental students (both genders) distributed across five Brazilian dental schools. MATERIALS AND METHODS: Students with no teeth missing and who had never been subjected to any dental treatment were selected. Photographs were taken with a Dental Eye III camera with a 100-mm macro objective and ratio of 1:10 from natural size, recorded on an Ektachrome ASA/ISO 100 film. The images were developed and applied to Microsoft Office Power Point 2007 software. The results were analyzed by analysis of variance and Student's t-test (alpha = 0.05). RESULTS: There was no significant correlation between bipupillar midline and the maxillary dental midline, irrespective of gender. CONCLUSION: No significant coincidence was observed between the interpupillary and dental midline. However, the interpupillar distance and its relationship with other anatomic structures may be used as a reference in treatment, but measurements must be assessed individually. CLINICAL SIGNIFICANCE: Anatomic measurements and facial proportions can be helpful during the planning of esthetic oral rehabilitation.

Rugosidade superficial de uma porcelana feldspática odontológica após simulação de ajuste oclusal e polimento / Surface roughness of a feldspathic dental porcelain after simulation of occlusal adjustment and polishing

Objetivo: O objetivo desse estudo foi avaliar a rugosidade superficial (Ra) de uma porcelana feldspática glazeada e submetida a dois sistemas de acabamento e polimento após simulação de ajuste oclusal. Metodologia: Vinte corpos-de-prova de porcelana feldspática glazeada (IPS Classic Ivoclar) foram confeccionados em forma de disco de acordo com as recomendações do fabricante e divididos em dois grupos (A e B). A leitura da rugosidade média superficial inicial (Ra 0) foi realizada com um rugosímetro (Surtronic 3+). Os corpos-de-prova foram desgastados com pontas diamantadas (PM82F e 0261PM) e a rugosidade superficial foi novamente aferida (Ra 1). O grupo A foi tratado com pontas de acabamento do sistema Edenta (EXA-Cerapol 352 e 362, Cerapol Super 372) e o grupo B com pontas de acabamento de silicone do sistema Tri Hawk (Universal Fase 1 e Fase 2), sendo realizadas novas leiturasde rugosidade (Ra 2). Os dados foram analisados por ANOVA e teste de Tukey, ao nível de significância de 0,05. Resultados: Os valores médios de Ra e desvio-padrão (em micrometros) foram: Grupo A - Ra 0=0,21±0,07, Ra 1=0,66±0,07, Ra 2=0,23±0,07; e Grupo B - Ra 0=0,20±0,04, Ra 1=0,72±0,06, Ra 2=0,21±0,05. Não houve diferença estatística entre os tratamentos ou entre estes e a porcelana glazeada. Conclusão: Considerando a metodologia empregada, ambos os procedimentos de acabamento e polimento promoveram uma lisura superficial similar à porcelana glazeada original.

Purpose: The aim of this study was to evaluate the surface roughness (Ra) of a feldspathic dental porcelain (IPS Classic Ivoclar) subjected to two polishing systems after simulation of occlusal adjustment. Methods: Twenty disk-shaped feldspathic ceramic (IPS Classic Ivoclar) specimens were fabricated according to the manufacturer instructions and divided into two groups (A and B). The baseline surface roughness (Ra 0) of the glazed specimens was measured using a surface profilometer (Surtronic 3+). The surface was ground with diamond burs (PM82F and 0261PM), and the surface roughness was measured (Ra 1). Group A was treated with the Edenta diamond bur finishing system (EXA-Cerapol #352, #362 and Cerapol Super #372), and Group B was treated with the Tri Hawk silicon tip polishing system (Universal Fase 1 and Fase 2) before the final surface roughness measurement (Ra 2). Data were analyzed by ANOVA and Tukey's test at the 5% significance level. Results: Surface roughness mean and standard deviation values (in micrometer) were: Group A - Ra 0=0.21±0.07, Ra 1=0.66±0.07, Ra 2=0.23±0.07; and Group B - Ra 0=0.20±0.04, Ra 1=0.72±0.06, Ra 2=0.21±0.05). No significant differences were found between the polished groups and the glazed surface. Conclusion: According to the methods used, both polishing systems provided surface roughness similar to that of the original glazed surface.

Resin microtensile bond strength to feldspathic ceramic: hydrofluoric acid etching vs. tribochemical silica coating.

This study aimed to compare the microtensile bond strength of resin cement to alumina-reinforced feldspathic ceramic submitted to acid etching or chairside tribochemical silica coating. Ten blocks of Vitadur-alpha were randomly divided into 2 groups according to conditioning method: (1) etching with 9.6% hydrofluoric acid or (2) chairside tribochemical silica coating. Each ceramic block was luted to the corresponding resin composite block with the resin cement (Panavia F). Next, bar specimens were produced for microtensile testing. No significant difference was observed between the 2 experimental groups (Student ttest, P > .05). Both surface treatments showed similar microtensile bond strength values.

Mechanical properties and microstructural analysis of an AgPd alloy cast under different temperatures

The metal restorations are used in Dentistry a long time ago. Nowadays we have resources that can get casting moreaccurate, with new material and equipments and techniques more precise. The purpose of this study was to evaluate themetallurgical and mechanical aspects of the AgPd dental alloy when it was submitted to different casting temperatures. Itwas used 30 specimens, divided in three groups (n=10): a) control group (no cast); b) casting temperature in accordancewith the manufacturesÆ instructions (T1); b) casting temperature above manufacturesï instructions (like a torch) (T2). Itwas evaluated chemical and metallographic aspects, mechanical properties and Vickers hardness. The results showed amicrostructure similar to T1 and T2 conditions, but with greater amount of light phase and particles in this last one. It wasobserved that the rupture tensile strength for the T1 condition was greater than the T2. The alloy in the no cast conditionpresented greater hardness but there was no statistically significant difference between T1 and T2. Supporting by themetallographic and mechanical results, it may predict that when elevated temperatures was used, above manufactureïsrecommendations, it can occur failures in the prosthesis, like porosities, fissures or cracks.

Avaliação, por microtração, da resistência adesiva entre um cimento resinoso e uma cerâmica aluminizada com e sem o uso de um agente silanizador / Evaluation, by the microtensile test, of the bond strength between a resin cement and a alumina ceramic with and without the use of a silane coupling agent

A resistência adesiva entre uma cerâmica aluminizada (Procera) e um cimento resinoso (Panavia F), com e sem o uso de agente silanizador (Clearfil Porcelain Bond- Sistema Clearfil SE Bond) foi avaliada por ensaio de microtração. Foram confeccionados blocos de cerâmica do sistema Procera (15mmx6mmx6mm). Cada bloco foi dividido em 3 segmentos (5mmx6mmx6mm), os quais constituíram dois grupos: Grupo A- tratamento da superfície cerâmica com jato de Al2O3 e cimentação à um substrato resinoso com o cimento (Panavia F); Grupo B- tratamento da superfície da cerâmica com jato de Al2O3, silanização da mesma (Clearfil Porcelain Bond) e cimentação à um substrato resinoso (Panavia F). Os conjuntos cerâmica/cimento/resina foram armazenados em água destilada à temperatura de 37ºC por sete dias, após o que foram cortados de forma a se obter, para cada grupo, um total de 27 corpos-de-prova medindo 10mmx1mmx1mm e com área de avaliação adesiva de 1mm2 ± 0,1mm . Em seguida foram tracionados em máquina de ensaios universal (EMIC DL 1000) com velocidade de 0,5mm/min até a ruptura. A análise estatística pelo método teste T (Student) dos dados obtidos mostrou que os valores da resistência adesiva (MPa) de GA (média 12,65 ± 2,75) e GB (16,47±3,38) diferiram estatisticamente (p < 5%). Concluímos que o uso do agente silanizador aumentou e resistência de união adesiva entre o cimento resinoso e a cerâmica estudados.

This study evaluated the adhesive bond strength between a alumina ceramic (Procera Allceram) and a resin cement (Panavia F), with and without the use of a silane coupling agent Clearfil SE Bond Sistem), using the microtensile bond strength test. Were made 2 ceramic blocks of Procera (15mmx6mmx6mm) and them they were cute in 3 smaller blocks (5mmx6mmx6mm) that formed two groups: Group A- surface treatment with Al2O3 and cimentation to a composite resin block using Panavia F resin cement; Group B- surface treatment with Al2O3, silanization with Clearfil Porcelain Bond and cimentation to a composite resin block using Panavia F resin cement. The ceramic/cement/resin blocks was stored at 37ºC in distilled water for one week. After this procedure the ceramic/cement/resin blocks was cute in samples. In each group there were 27 samples with the following dimensions: 10mmx1mmx1mm. The adhesive area was 1mm2±0,1mm2. The samples were submitted to a microtensile bond strength test in a universal testing machine (EMIC- DL 1000) with the crosshead speed of 0.5 mm/min until fracture. The statistical analysis using the T test (Student) showed us that Group A (mean 12.65±2.75) and Group B (mean 16.47±3.38) were statistically different (p< 5%). Its possible to conclude that the silane coupling agent increased the bond strength between the resin cement and the ceramic used in this study.

Avaliação dimensional de duas resinas acrílicas utilizadas na obtenção de modelos de remontagem em prótese parcial fixa / Dimensional Evaluation of two acrylic resins used for obtaining cast working in fixed partial denture

Este trabalho teve o propósito de avaliar a precisão de duas resinas quimicamente ativáveis Duralay (EUA) e Cop Clas (Brasil), utilizadas no preenchimento de copings metálicos, durante os procedimentos de moldagem de transferência e obtenção do modelo de remontagem. Foi utilizado um manequim odontológico dentado do arco superior, do qual foram removidos os segundos pré-molares superiores, simulando espaços protéticos bilaterais. Os dentes contíguos aos espaços protéticos foram preparados para receber coroas metalocerâmicas; quatro copings foram adaptados nos preparos do modelo padrão e foram realizadas dez moldagens de transferência utilizando uma silicona de adição. Para cada molde obtido, a superfície interna dos copings foi isolada e preenchida com resina acrílica Duralay vermelha. Desta forma foram obtidos dez modelos de remontagem. O mesmo foi realizado para a obtenção de mais dez modelos de remontagem, preenchendo agora a superfície interna dos copings com resina acrílica Cop Class. Foram obtidas imagens (HP scanjet3750c) da superfície oclusal de todos os modelos; estas foram levadas a um Programa de Análise de Imagens, no qualfoi possível medir as distâncias entre pontos previamente demarcados nos copings. A média dos resultados (P1-P2 =35,680, P2-P3 = 15,530, P3-P4 = 45,315 e P4-P1 = 17,105) foram tratados estatisticamente (teste t de Student, testeF de Fischer e Procedimento de Chauvenet) e mostraram não haver diferenças estatisticamente significantes entre osmateriais ensaiados.

Bond characteristics of porcelain fused to cast and milled titanium

Metalloceramic restorations combine the aesthetic properties of ceramic materials with the high strength of metals. The titanium has excellent biocompatibility, good mechanical properties and low density, and has been recently used for metalloceramic prosthesis. The purpose of this study was to evaluate the shear bond strength of these two materials, and also analyze their bonding interface using Scanning Electron Microscopy (SEM). Thirty-six specimens were prepared and divided in three groups: Group 1- gold alloy (Degudent U-Degussa) + Vita Omega 900 ceramic(Vita) (control group); Group 2 – milled commercially pure titanium (cpTi- Dentaurum) + Titankeramik ceramic (Vita); Group 3 – cast and milled commercially pure titanium (cpTi-Dentaurum) + Titankeramik ceramic(Vita). The shear bond strength mechanical assay was performed in an Instron 4301 machine with capacity for 500Kg. After the test completion, surfaces were evaluated using SEM. The numerical results, put in tables, were: G1= 40,55MPa (+/- 4,8), G2= 63,54 MPA (+/- 1,73) and G3= 68,17 MPA (+/- 1,19). The statistical analysis (ANOVA) showed no significant statistically differences between groups G2 and G3 and the values were larger (significant statiscally) than G1. It is concluded that the titanium alloys is a good alternative to gold alloys to metalloceramic restorations emphasizing that it is cheaper, biocompatible and is has a low density.

Avaliação do monômero residual de resinas acrílicas utilizadas para prótese ocular, polimerizadas convencionalmente e por energia de microondas / Evaluation of residual monomer between conventional and microwave heat-cured acrylic resins used for ocular prostheses

Este trabalho objetivou comparar a quantidade de monômero residual das resinas acrílicas utilizadas para confecção de prótese ocular, termopolimerizável incolor (grupo controle) e Onda-Cryll incolor após a polimerização convencional (MC) e com energia de microondas (MW) respectivamente. Para o experimento foram confeccionados três corpos-de-prova para cada tipo de resina e período de investigação, num total de 30 corpos-de-prova, os quais foram submetidos a ensaios titulométricos nos períodos de 5, 30, 60, 120 e 1.440 minutos (24 horas) após a demuflagem. A resina acrílica termopolimerizável incolor apresentou índices inferiores de concentração de monômero residual em relação à resina acrílica Onda-Cryll incolor. A resina acrílica polimerizada por microondas apresentou baixos índices de concentração de monômero residual, porém um pouco superiores (até 120 minutos) em relação à resina termopolimerizável incolor. Ambos os materiais apresentaram valores numéricos estatisticamente semelhantes de concentração de monômero residual no período de 1440 minutos (24 horas). Uma técnica de confecção de prótese ocular através de forno de microondas é exeqüível, pois os acrílicos apresentam concentrações normais de monômero residual após 120 minutos da sua polimerização, em relação ao grupo controle

Avaliação in vitro da resistência ao desgaste de dentes artificiais / In vitro wear evaluation of denture teeth

O correto restabelecimento da dimensão vertical de oclusão é um dos grandes desafios da odontologia reabilitadora. Por-tanto, a seleção de dentes artificiais com melhores propriedades físicas e mecânicas facilita a manutenção dessa relação. O objetivo deste trabalho foi avaliar a resistência ao desgaste de dentes artificiais de resina por meio de ensaios mecânicos realizados em máquina de escovação. Oito grupos (G I – Postaris, G II – Gnatostar, G III – Vitapan, G IV – Triostat, G V – Trilux, G VI – VipiDent, G VII – Artiplus e G VIII – Biotone), compostos de cinco pré-molares superiores de cada fabricante, foram pesados em balança analítica eletrônica e medidos em sua altura por um micrômetro antes e após os ciclos. Para que os dentes fossem fixados à haste da máquina, foram embutidos em um bloco de resina acrílica de forma que a ponta de cúspide vestibular entre em contato com a amostra do antagonista. Foram realizados 372 ciclos por minuto, num total de 200.000 vezes em uma distância de deslize de 20mm por ciclo em direção vestíbulo-lingual, sob carga axial de 400g. Durante o processo, os dentes foram irrigados com água destilada em ambiente com temperatura controlada pela máquina de 25oC. O material de escolha para o antagonista foi porcelana feldspática de esmalte preparado como uma placa de 24x12x3mm aplicada sobre uma infra-estrutura de liga de níquel-cromo. Os resultados foram submetidos à análise estatística de Tukey com nível de significância p=0,05. Não foram encontradas diferenças significantes entre os grupos para as avaliações de perda de peso e altura.

Thermal curves of acrylic resins in microwave curing / Curvas térmicas de resinas acrílicas polimerizadas por energia de microondas

The use of microwave polymerization on acrylic resins is a clean and easy method to make complete dentures. It is observed that this kind of process may cause a higher porosity when compared to the conventional heated water bath, probably because of the excessive temperature increase. The objective of this study was the qualitative observation of the thermal curves generated on acrylic by the application of microwave energy in different polymerization cycles. Wax model dentures were reproduced, resulting in four specimens, within each one 7 thermocouples were positioned, havingdifferent reading sites of the specimens while the resin was polymerized in a conventional microwave oven. Four cycles were used: 1) three minutes at 475W; 2) 13 minutes at 95W + 1,5 minute at 475W; 3) three minutes at 475W with 150ml of water; and 4) seven minutes at 95W + seven minutes at 95W. The thermocouples were linked to data acquisition equipment, resulting in time-versus-temperature charts. It was concluded that lower power settings led to lower temperature increases. The use of minimum water load caused lower temperature peaks. The used method has a great value for temperature readings when polymerizing microwave acrylic resins

The effect of ceramic surface treatment on bonding to densely sintered alumina ceramic.

STATEMENT OF PROBLEM: Ceramic surface treatment is crucial for bonding to resin. High crystalline ceramics are poorly conditioned using traditional procedures. PURPOSE: The purpose of this study was to evaluate the effect of silica coating on a densely sintered alumina ceramic relative to its bond strength to composite, using a resin luting agent. Material and methods Blocks (6 x 6 x 5 mm) of ceramic and composite were made. The ceramic (Procera AllCeram) surfaces were polished, and the blocks were divided into 3 groups (n = 5): SB, airborne-particle abrasion with 110-microm Al 2 O 3 ; RS, silica coating using Rocatec System; and CS, silica coating using CoJet System. The treated ceramic blocks were luted to the composite (W3D Master) blocks using a resin luting agent (Panavia F). Specimens were stored in distilled water at 37 degrees C for 7 days and then cut in 2 axes, x and y, to obtain specimens with a bonding area of approximately 0.6 mm 2 (n = 30). The specimens were loaded to failure in tension in a universal testing machine, and data were statistically analyzed using a randomized complete block design analysis of variance and Tukey's test (alpha=.05). Fractured surfaces were examined using light microscopy and scanning electron microscopy to determine the type of failure. Energy-dispersive spectroscopy was used for surface compositional analysis. RESULTS: Mean bond strength values (MPa) of Groups RS (17.1 +/- 3.9) ( P =.00015) and CS (18.5 +/- 4.7) ( P =.00012) were significantly higher than the values of Group SB (12.7 +/- 2.6). There was no statistical difference between Groups RS and CS. All failures occurred at the adhesive zone. CONCLUSION: Tribochemical silica coating systems increased the tensile bond strength values between Panavia F and Procera AllCeram ceramic.

Efeito de adesivos na união entre dentes artificiais e resinas acrílicas termopolimerizáveis / Effect of adhesives on the joint between artificial teeth and heat-curing resins

O objetivo deste trabalho foi avaliar o efeito de adesivos na união dente artificial/base de resina acrílica termicamente ativada. Para tanto foram confeccionados 15 corpos-de-prova constituídos por um incisivo central superior artificial (Vipi Dent Plus - Dental Vipi Ltda) jateado com partículas de óxido de aluminio de 110 µm (Micro Etcher - Sanville) e unidos à uma base de resina acrílica termicamente ativada (Vipi Cril - Dental Vipi Ltda), divididos em 3 grupos de cinco elementos cada: G1 - sem adesivo, G2 - com adesivo A e G3 - com adesivo B e submetidos a ensaio de compressão não-axial (resistência transversa). As médias dos resultados obtidos (G1=15,59±0,34, G2=26,30± 0,84 e G3=20,78±1,03) foram submetidos ao teste t Studente e Kolmogorov-Smirnof. Os resultados mostraram que o uso de adesivos efetivou significativamente a união dente/base, não havendo diferenças estatísticas entre os dois adesivos. Desta forma pode-se considerar positivo o uso de adesivos para prensagem de próteses totais e parciais removíveis com dentes artificiais de resina acrílica

Resistência a microtração entre uma cerâmica hidrotérmica e um cimento resinoso, submetidos ou não à ciclagem térmica / Microtensile bond strength between a hidrotermal ceramic and a resin cement, submitted or not to thermal cycling treatment

Objetivou-se, com este trabalho, avaliar por ensaio de microtração, a resistência adesiva entre uma cerâmica (Symbio Ceram, Degussa Dental) e um cimento resinoso (Panavia F, Kuraray), submetidos ou não à ciclagem térmica. Para tanto, foram obtidos três blocos cerâmicos com dimensões de 5mmx6mmx6mm; sua suprefície de colagem (6mm x 5mm) foi polida com lixa (#600), acondicionada com ácido fluorídrico a 10% e silanizada, de acordo com as recomendações do fabricante. A seguir, os blocos foram cimentados a outros de resina composta com as mesmas dimensões, sob carga de 1 Kg. Após isso, foram mantidos em água destilada à temperatura ambiente durante 7 dias e cortados de forma a se obteram 20 corpos-de-prova com dimentsões de 10mmx1mmx1mm, propiciando área adesiva de 1mm²±0,1mm² e dividios em dois grupos submetidos aos seguintes tratamentos: G1 (controle) - manutenção em água destilada a temperatura ambiente durante três dias - e G2 - ciclagem térmica (1500 ciclos) em dois banhos (5ºC e 55ºC), com tempo de permanência de 30 segundos cada, após o que, foram tracionados em máquinas de ensaio universal (EMIC), com célula de carga de 10kgf e velocidade de 0,5mm.min-1. Os resultados númericos (MPa) foram lançados em tabela própria e submetidos à análise estatística Mann-Whitney (alfa=0,05), demonstrando que G1 (27,06±10,59) não diferiu estatisticamente de G2 (22,55±4,81). Considerando a metodologia aplicada e os resultados obtidos, parece-nos lícito concluir que a ciclagem térmica não influenciou a resistência adesiva entre os materiais estudados

Shear bond strengths of a ceramic system to alternative metal alloys.

STATEMENT OF PROBLEM: The success of metal-ceramic restorations is influenced by the compatibility between base metal alloys and porcelains. Although porcelain manufacturers recommend their own metal systems as the most compatible for fabricating metal-ceramic prostheses, a number of alloys have been used. Purpose This study evaluated the shear bond strength between a porcelain system and 4 alternative alloys. MATERIAL AND METHODS: Two Ni-Cr alloys: 4 ALL and Wiron 99, and 2 Co-Cr alloys: IPS d.SIGN 20 and Argeloy NP were selected for this study. The porcelain (IPS d.Sign porcelain system) portion of the cylindrical metal-ceramic specimens was 4 mm thick and 4 mm high; the metal portion was machined to 4x4 mm, with a base that was 5 mm thick and 1 mm high. Forty-four specimens were prepared (n=11). Ten specimens from each group were subjected to a shear load on a universal testing machine using a 1 mm/min crosshead speed. One specimen from each group was observed with a scanning electron microscope. Stress at failure (MPa) was determined. The data were analyzed with a 1-way analysis of variance (alpha=.05). RESULTS: The groups, all including IPS d.Sign porcelain, presented the following mean bond strengths (+/-SD) in MPa: 4 ALL, 54.0+/-20.0; Wiron, 63.0+/-13.5; IPS d.SIGN 20, 71.7+/-19.2; Argeloy NP, 55.2+/-13.5. No significant differences were found among the shear bond strength values for the metal-ceramic specimens tested. CONCLUSION: None of the base metal alloys studied demonstrated superior bond strength to the porcelain tested.