One-step fiber post cementation and core build-up in endodontically treated tooth: A clinical case report.

OBJECTIVE: This clinical case report addresses the step-by-step of the application of a core-and-post system that uses a single resin composite material to fiber post cementation and core build-up in a maxillary left central incisor. CLINICAL CONSIDERATIONS: The literature reports several materials and methods for the restoration of endodontically treated teeth with coronal destruction that require an intra-radicular fiber post for the core build-up. The present case report describes a core-and-post or "monoblock" technique. A dual resin composite (Core-X Flow; Dentsply DeTrey) highly filled material and cement was used for luting the fiber post (Blue X-Post) and build-up the core structure in an easy application. CONCLUSIONS: The "core-and-post" technique that uses a single material system protocol minimizes the material interfaces, steps of procedures, and chair-time in comparison to conventional techniques. CLINICAL SIGNIFICANCE: The use of different materials for post cementation and core build-up requires more steps, which increases the chair-time and number of interfaces among the materials. Since the "monoblock" technique uses only one material, it can streamline the clinical procedures, thus, saving time and materials. Moreover, techniques based on core-and-post systems are easily applied, versatile, and esthetics, and can be applicable to posterior and anterior teeth.

Influence of Particle and Air-Abrasion Moment on Y-TZP Surface Characterization and Bond Strength.

PURPOSE: To evaluate the influence of particle and air-abrasion on the surface characterization and shear bond strength (SBS) of a Y-TZP ceramic with a resin cement. MATERIALS AND METHODS: Y-TZP specimens were air-abraded with 50 µm alumina particles; 120 µm alumina particles; 30 µm silica-coated alumina particles (Rocatec Soft); 110 µm silica-coated alumina particles (Rocatec Plus). Air-abrasion was performed before (BS); after (AS); before and after (BAS) zirconia sintering. Surface characterization included roughness (n = 10), wettability (n = 10), morphology (n = 2), and elemental composition (n = 2). For SBS (n = 11), composite resin discs were bonded to the air-abraded and silane-treated zirconia surface, with the resin cement RelyX ARC. Failure mode was determined. Roughness, wettability, and SBS data were analyzed by two-way ANOVA with pairwise interaction and Tukey's test (α = 0.05). RESULTS: Air-abrasion performed with coarser particles at BS and BAS moments provided the highest roughness values, while the lowest roughness values were observed with particles combined with AS moment (p < 0.01). Rocatec Plus provided lower contact angle than the 120 µm alumina particles (p = 0.013), and BAS exhibited lower contact angle than BS (p = 0.002). The combinations 120 µm/BS and the silica-coated alumina particles/AS and /BAS showed the highest SBS (p < 0.05). The combination of each particle/BAS was statistically similar to the same particle/AS. Failure mode was 100% adhesive for all groups. The interaction particle size/air-abrasion moment determined the morphological pattern. Silicon was observed only in the Rocatec groups. CONCLUSIONS: Roughness was influenced by the particle size and was higher when the zirconia was air-abraded in its green stage. The particle composition played an important role in the wettability and both studied air-abrasion moments provided similar wettability than the one in which air-abrasion is usually performed. The highest SBS values were observed in the three moments, by using certain particles for each moment.

Marginal Fit of Metal-Ceramic Copings: Effect of Luting Cements and Tooth Preparation Design.

PURPOSE: To evaluate the effect of the triad finish line design, axial wall convergence angle, and luting cement on the marginal fit of metal copings used in metal-ceramic crowns. MATERIALS AND METHODS: Schematic dies and their respective copings were cast in NiCr alloy. The dies exhibited the following finish line/convergence angle combinations: sloping shoulder/6°, sloping shoulder/20°, shoulder/6°, shoulder/20°. Marginal fit was evaluated under a stereomicroscope, before and after cementation. Copings were air-abraded with 50 µm Al2 O3 particles and cemented with Cimento de Zinco, RelyX U100, or Panavia F cements (n = 10/group). Data were square-root transformed and analyzed by 3-way factorial random effect model and Tukey's post hoc test (α = 0.05). RESULTS: Statistical analysis showed significance for the interactions finish line and convergence angle (p < 0.05), convergence angle and time (p < 0.001), and luting cement and time (p < 0.001). Sloping shoulder/20° provided the highest marginal discrepancy when compared to the other finish line/convergence angle combinations, which were statistically similar among each other. For both convergence angles and for all luting cements, the marginal discrepancy was significantly higher after cementation. Before and after cementation, 6° provided better marginal fit than 20°. After cementation, Panavia F provided higher marginal discrepancy than Cimento de Zinco. CONCLUSION: Lower convergence angle combined with shoulder and a low-consistency luting cement is preferable to cement metal copings.

Effect of techniques, trays and materials on accuracy of impressions clinically made / Efeito de técnicas, moldeiras e materiais na exatidão de moldagens odontológicas

Abstract Introduction Making accurate and dimensionally stable impressions to duplicate oral conditions and tooth morphology is an essential step of prosthetic dentistry for fabricating well-fitted indirect restorations and, consequently, ensure the longevity and success of the treatment. Several authors describe pros and cons of different impression techniques, although there is no unanimity among them about the best one. Objective This study evaluated casts' accuracy made by different impression techniques, trays and materials. Material and method 10 patients were selected and 20 impressions from teeth #13 to #16 were performed using single-step (SS) and two-step techniques, made with metal stock and customized acrylic resin partial trays, vinyl polysiloxane and condensation silicone rubbers. Type IV gypsum was used to pour the casts. Three photographs of each patient (baseline), as their respective gypsum casts, were taken, measured in their interested buccal surface area. Comparisons of area values among experimental groups and baseline were performed. Data showed adherence to normal curve, being submitted to 3-way ANOVA/Bonferroni test (α=.05). Result Technique produced significant differences (P=0.02). SS technique was more accurate than BUR one (P=0.003; 95=1.22 to 5.98), but both resulted in similar casts to PVC, MOV and NR techniques, which were similar to each other (P>0.05). Conclusion SS technique showed the closest absolute values to baseline.

Resumo Introdução Realizar moldagens precisas e dimensionalmente estáveis que dupliquem a condição oral é um passo essencial para a confecção de restaurações indiretas de qualidade, garantindo seu sucesso e longevidade. Diversos estudos tem demonstrado os prós e contras de diferentes técnicas de moldagem, mas nenhum consenso da melhor técnica ainda foi descrito. Objetivo Este estudo avaliou a exatidão de modelos de gesso confeccionados por diferentes técnicas de moldagem, moldeiras e materiais. Material e método 10 pacientes foram selecionados e 20 moldes dos dentes #13 até #16 foram realizados utilizando técnicas simultânea (SS) e de dois passos, realizados com moldeiras parciais metálicas e individuais de resina acrílica, silicones de adição e condensação. Gesso tipo IV foi usados para os vazamentos. Três fotografias de cada paciente (baseline), assim como dos seus respectivos modelos de gesso foram realizadas e sua área foi então mensurada, na porção vestibular. Comparações de valores de área entre os grupos experimentais e o baseline foram performadas. Os dados mostraram aderência a curva normal, sendo submetidos ao teste 3-way ANOVA/Bonferroni (α=.05). Resultado As técnicas produziram diferenças significativas (P=0.02).Técnica simultânea foi mais precisa que a BUR (P=0.0003; 95=1,22 a 5.98), mas ambas resultaram em modelos similares àqueles feitos por meio das técnicas de PVC, MOV e sem NR, que foram similares entre si (P>0.05). Conclusão Técnica simultânea demonstrou valores absolutos similares àqueles demonstrados pelo baseline.

Comparison of impression techniques and double pouring by dental cast's accuracy. Preliminary clinical-lab trial

Aim: This study compared impression techniques and double pouring by means of cast's accuracy. Methods: For each patient (n=10), impressions from right maxillary canine to first molar were made with acrylic resin trays and vinyl-polysiloxane using one single-step, and four two-steps techniques: relief with poly(vinyl chloride) film; tungsten-carbide bur/scalpel blade; small movements of the tray; non-relief. Total visible buccal surface area of crowns was measured three times using photographs from patients (Baseline) and casts. Mean area values (mm2) between Baseline and casts differences were analyzed by two-way repeated-measures ANOVA (α=.05; 1-ß=85%). Results: No significant differences were observed for Impression Techniques (P=.525), Double Pouring (P=.281), and their interaction (P=.809). Conclusion: All impression techniques and double pouring produced casts with similar accuracy

Fatigue behavior and surface characterization of a Y-TZP after laboratory grinding and regeneration firing.

This study evaluated the effect of grinding and regeneration firing on the flexural fatigue limit and surface characterization of Lava™ Y-TZP ceramic. Forty bar-shaped specimens with 20 × 4.0 × 1.2 mm constituted the as-sintered group (AS = control group), and 80 specimens with 20 × 4.0 × 1.5 mm were ground with cylindrical laboratory stone under water-cooling (WG) or in a dry condition (G) to reach 1.2 mm in thickness. Half of specimens were submitted to regeneration firing (1000 °C, 30 min), forming the groups AS/R, WG/R and G/R. Fatigue limit (500,000 cycles, 10 Hz) was determined by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey HSD tests (α = 0.05). The surface topography (n = 3) and fracture area (n = 3) were evaluated by SEM. Samples were also analyzed by Rietveld refinement from X-ray diffraction data. ANOVA revealed significant differences (P < .001) for grinding protocol, regeneration firing and their interaction. In the groups not submitted to regeneration firing, the mean flexural fatigue limit of WG was higher (P < .05) than that of G and AS, with no statistical difference between each other (P > .05). After regeneration firing the inequality WG>AS>G (P < .05) was observed. The regeneration firing increased the fatigue limit of AS group and decreased those of G and WG groups (P < .05). Grinding protocols created evident grooves on zirconia surface. Failures initiated on tensile side of all specimens. The percentages (wt%) of monoclinic phase before cyclic loading were: AS (7.4), AS/R (6.5), G (2.8), G/R (0.0), WG (4.4), WG/R (0.0); and after cyclic loading: AS (8.6), AS/R (1.2), G (2.4), G/R (5.7), WG (6.3), WG/R (0.0). Wet grinding did not compromise the fatigue limit of zirconia, increasing its mechanical strength. Regeneration firing reduced the fatigue limit of ground samples, despite reducing the amount of monoclinic phase in all experimental conditions.

Influence of Liquid Lubrication on the Screw-Joint Stability of Y-TZP Implant Abutment Systems.

PURPOSE: To evaluate the effectiveness of abutment screws coated with liquid Vaseline on the screw-joint stability of yttria-stabilized tetragonal zirconia (Y-TZP) abutment systems. MATERIALS AND METHODS: Forty Y-TZP prefabricated abutments, 20 Neodent and 20 Bionnovation, were tightened to 20 Ncm on their respective external hexagon implants, and divided into four groups (n = 10) according to the screws: coated with Vaseline or uncoated. The removal torque (RT) value of the abutment screw was measured before and after loading. A cyclic loading (0.5 × 106 cycles; 15 Hz) between 11 and 211 N was applied. Means were compared using a repeated-measures ANOVA (α = 0.05). RESULTS: There was no significant difference between coated and uncoated screws (p = 0.822). Significant differences were found between the abutment systems (p < 0.001). There was a significant effect of cyclic loading (p < 0.001). CONCLUSIONS: Coated and uncoated screws presented similar effectiveness in maintaining preload. CLINICAL RELEVANCE: The liquid lubricant used in this study does not influence the stability of Y-TZP single-implant restorations.

Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring.

This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-speed tungsten carbide bur and scalpel blade, (4) small movements of the tray and (5) without relief-negative control. The impressions were disinfected with 0.5% sodium hypochlorite for 10 minutes and stored during 110 and 230 minutes for the first and second pouring, respectively, with type IV gypsum. Three intra-oral lateral photographs of each patient were taken using a tripod and a customized radiographic positioner. The images were imported into ImageJ software and the total area of the buccal surface from teeth #13 to #16 was measured. A 4.0% coefficient of variance was criterion for using these measurements as Baseline values. The casts were photographed and analyzed using the same standardization for the clinical images. The area (mm2) obtained from the difference between the measurements of each gypsum cast and the Baseline value of the respective patient were calculated and analyzed by repeated-measures two way-ANOVA and Mauchly's Sphericity test (α = 0.05). No significant effect was observed for Impression technique (P = 0.23), Second pouring (P = 0.99) and their interaction (P = 0.25). The impression techniques and double pouring did not influence the accuracy of the gypsum casts.

Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic.

This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic

Abstract This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

Resumo Este estudo avaliou o efeito de protocolos de desgaste e ressinterização no limite de fadiga flexural e na caracterização da superfície da zircônia LavaTM. Corpos-de-prova em forma de barra (20×4,0×1,2 mm, n=40; 20×4,0×1,5 mm, n=80) foram obtidos. Metade das barras com menor altura (1,2 mm) constituiu o grupo controle (AS), enquanto as de maior altura (1,5 mm) foram desgastadas com fresas diamantadas com (WG) ou sem (G) irrigação. A outra metade dos corpos-de-prova de menor altura e metade dos desgastados foram ressinterizadas (1000 °C, 30 min), obtendo-se os grupos ASR, WGR e GR. O limite de fadiga (500.000 ciclos, 10 Hz) foi avaliado pelo método de escada em dispositivo de flexão em 4 pontos. Os dados foram analisados pelos testes ANOVA a dois fatores e Tukey (α=0,05). A topografia de superfície (n=3) e área de fratura (n=3) foram avaliadas por MEV. Os dados de difração de raios-X (n=1) foram analisados pelo refinamento de Rietveld. ANOVA revelou diferenças significantes (p<0,001) para desgaste, ressinterização e interação entre os fatores. O desgaste aumentou o limite de fadiga para os grupos não ressinterizados. Não houve diferença significante entre os grupos ressinterizados. A ressinterização aumentou o limite de fadiga somente para o grupo AS. Ambos os protocolos criaram riscos evidentes na superfície da zircônia. As falhas iniciaram sempre no lado de tração. A porcentagem de fase monoclínica foi: AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) antes e AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) após a ciclagem. O desgaste aumentou o limite de fadiga da zircônia não ressinterizada e formou ranhuras evidentes na sua superfície. A ressinterização promoveu aumento significativo no limite de fadiga somente para o grupo controle. Em geral, o desgaste e a ressinterização diminuíram ou anularam o conteúdo de fase monoclínica.

Sistema Cone Morse e utilização de pilares com plataforma switching / Morse Taper System and platform switching abutment application

Os implantes cone morse associados a pilares com plataforma switching têm proporcionado resultados promissores com relação à estabilidade dos tecidos peri-implantares. Isso se deve ao perfil cônico do componente protético, à íntima adaptação na interface implante/pilar e ao menor acúmulo de biofilme bacteriano. Para isso, deve-se levar em consideração o posicionamento infraósseo do implante. Essa configuração implante/pilar possui resistência à fratura superior em relação aos sistemas convencionais e, além disso, devido à manutenção da crista óssea e da diversidade de pilares e componentes protéticos, possibilita reabilitações orais estéticas e biocompatíveis.

Morse taper implants associated with platform switching abutments have provided promising results with respect to the stability of peri-implant tissues. This is due to the conical profile of the abutment, the intimate adaptation at the implant/abutment interface, and to the lower accumulation of bacterial biofilm. For this, it has been proposed the insertion of the implants below the crestal bone level. This implant/ abutment configuration presents higher fracture strength compared to the conventional systems and, in addition, because of the maintenance of crestal bone and the diversity of abutments and prosthetic components, provides aesthetic and biocompatible oral rehabilitations.

Effect of surface and heat treatments on the biaxial flexural strength and phase transformation of a Y-TZP ceramic.

PURPOSE: To evaluate the effect of grinding and airborne-particle abrasion on the biaxial flexural strength (BFS) and phase transformation of a Y-TZP ceramic, and examine whether sintering the veneering porcelain renders the previous heat treatment recommended by the manufacturer unnecessary. MATERIALS AND METHODS: Lava zirconia specimens (N = 108) were obtained with the following dimensions: 14.0 mm diameter × 1.3 mm thickness (n = 36) and 14.0 mm × 1.6 mm (n = 72). The thicker specimens were ground with diamond burs under irrigation and received (heat-treated groups) or not (non-heat-treated groups) a heat treatment (1000°C for 30 min) prior to the four firing cycles applied to simulate the sintering of the veneering porcelain. All specimens were air abraded as follows (n = 12): 1) 30-µm silica-modified Al2O3particles (Rocatec Soft); 2) 110-µm silica-modified Al2O3particles (Rocatec Plus); and 3) 120-µm Al2O3particles, followed by Rocatec Plus. Three specimens of each group were analyzed by x-ray diffraction (XRD) to assess the monoclinic phase content (%). The BFS test was performed in a mechanical testing machine (Instron 8874). Data (MPa) were analyzed by two-way ANOVA (grinding × airborne-particle abrasion and heat treatment × airborne-particle abrasion) and Tukey's post-hoc test (α = 0.05). The strength reliability was analyzed using the Weibull distribution. RESULTS: Grinding significantly decreased the BFS of the non-heat-treated groups (p < 0.01). Within the ground groups, the previous heat treatment did not influence the BFS (p > 0.05). Air abrasion only influenced the BFS of the ground/heat-treated groups (p < 0.01). For the non-heat-treated groups, the grinding did not decrease the Weibull modulus (m), but it did decrease the characteristic strength (σ0). For Rocatec Soft and 120-µm Al2O3particles + Rocatec Plus, the heat-treated groups presented lower m and higher σ0 than the ground/non-heat-treated groups. The independent variables did not seem to influence phase transformation. Air-abraded surfaces presented higher monoclinic zirconia content than the as-sintered and ground surfaces, which exhibited similar content. CONCLUSION: Even under irrigation, grinding compromised the Y-TZP ceramic strength. The sintering of the veneering porcelain rendered the previous heat treatment recommended by the manufacturer unnecessary. Airborneparticle abrasion influenced the strength of heat-treated zirconia.

Modified indexing technique for the immediate interim restoration of a dental implant.

Because of the functional and esthetic requirements of patients, different techniques have been proposed to reduce the time between dental implant placement and interim restoration fabrication. This article describes a modified indexing technique by using a surgical template for open-tray impression and definitive cast development during immediate loading procedures. This technique does not use a complete impression of the oral cavity and, therefore, is more comfortable, less time consuming, and less expensive. It also allows the fabrication of interim restorations with the optimal shape for developing an adequate emergence profile.

Caracterização de superfície, adesiva e mecânica de uma zircônia parcialmente estabilizada por ítria em função da partícula ou do momento do jateamento / Surface, adhesive and mechanical characterization of an yttria partially stabilized tetragonal zirconia according to the particle or the moment of air-abrasion

A retenção mecânica e a longevidade das restaurações indiretas com infraestrutura de zircônia podem ser favorecidas pela cimentação adesiva. No entanto, como a zircônia é uma cerâmica cristalina, tratamentos de superfície alternativos aos convencionais (ácido fluorídrico e silanização) devem ser utilizados com o objetivo de estabelecer união mecânica e química na interface cimento resinoso/restauração. Dentre os tratamentos promotores de retenção micromecânica, o jateamento é ainda um dos métodos mais eficazes e fáceis. Esse procedimento pode ser realizado com partículas de óxido de alumínio/alumina (Al2O3) convencionais e/ou revestidas por sílica de diferentes tamanhos e, portanto, diferentes comportamentos quanto à rugosidade e à área de superfície disponível para adesão, bem como ao molhamento por agentes de união, podem ser observados. Apesar do seu papel benéfico na resistência de união da interface cimento resinoso/zircônia e até mesmo na resistência mecânica imediata da zircônia, sabe-se que o jateamento favorece a criação de microtrincas superficiais, as quais, em longo prazo, sob as condições adversas da cavidade oral, tendem a se propagar pelo corpo do material, reduzindo sua resistência mecânica ou até mesmo promovendo sua falha catastrófica. Considerando que o protocolo convencional preconiza o jateamento da zircônia sinterizada, uma alternativa seria realizá-lo na zircônia previamente à sua sinterização, uma vez que ela seria mais propícia à criação de retenções micromecânicas e, possivelmente, os efeitos da severidade do jateamento e seus danos na resistência mecânica do material, em longo prazo, seriam minimizados. Levando-se em consideração os aspectos ressaltados, este estudo teve como objetivos: 1) Avaliar o efeito da partícula empregada no jateamento na rugosidade de superfície, molhamento e padrão morfológico de uma zircônia parcialmente estabilizada por ítria, bem como verificar a existência de correlação entre as variáveis dependentes rugosidade e molhamento; 2) Avaliar o efeito do momento do jateamento na caracterização de superfície (rugosidade, morfologia e transformação de fase) e resistência à flexão de uma zircônia parcialmente estabilizada por ítria, sua resistência de união ao cisalhamento com um cimento resinoso e o modo de fratura predominante na área adesiva. Também verificou-se a existência de correlação entre as variáveis dependentes rugosidade e resistência de união. No primeiro estudo, espécimes (14 × 14 × 1,4 mm) da zircônia Lava (3M ESPE AG) foram obtidos e, com exceção do grupo controle (n=20), jateados com uma das seguintes partículas (n=20): 1) Al2O3 de 50 µm; 2) Al2O3 de 120 µm; 3) Al2O3 de 250 µm; 4) Al2O3 de 30 µm revestida por sílica (Rocatec Soft); 5) Al2O3 de 110 µm revestida por sílica (Rocatec Plus); 6) Al2O3 de 120 µm e Rocatec Plus. As análises de rugosidade (Ra) e molhamento (pelo silano RelyX Ceramic Primer) foram realizadas nos mesmos espécimes. Para a análise da morfologia de superfície por microscopia eletrônica de varredura (MEV), foram preparados dois espécimes adicionais (6,0 × 6,0 × 1,0 mm) para cada grupo. Os dados de Ra (µm) foram analisados por ANOVA a 1 critério e teste Dunnett C (α=0,05), e os dados de molhamento por ANOVA a 1 critério (α=0,05). O teste de correlação de Spearman foi aplicado para verificar uma possível correlação entre rugosidade e molhamento. Com exceção dos grupos jateados com Al2O3 de 120 µm, os demais apresentaram valores de rugosidade estatisticamente diferentes. Com relação ao molhamento, não houve diferença estatística entre os grupos. Não foi observada correlação (rs=-0,09, P=0,27) entre rugosidade e molhamento. A partícula influenciou a morfologia de superfície da zircônia. O aumento da rugosidade pareceu acompanhar o aumento do tamanho das partículas. A análise de MEV mostrou que diferentes partículas promoveram diferenças nos padrões morfológicos. No segundo estudo, espécimes da zircônia Lava foram jateados com Al2O3 de 50 µm depois (DS); antes (AS); ou antes e depois (ADS) da sinterização da zircônia. Para a rugosidade (Ra), trinta espécimes (10 × 10 × 3,0 mm) (n=10) foram analisados em rugosímetro. Discos de resina composta (n=30) foram cimentados com RelyX ARC (3M ESPE) sobre estes espécimes e armazenados em água destilada a 37 ºC por 24 horas previamente ao ensaio de resistência de união ao cisalhamento (RC). O modo de fratura foi avaliado em estereomicroscópio (×20). A morfologia de superfície (n=2) foi avaliada por MEV (×500). Para o ensaio de resistência à flexão (RF) 4 pontos (EMIC DL2000), trinta e nove espécimes em formato de barra (20 × 4,0 × 1,2 mm) (n=13) foram jateados de acordo com os três momentos propostos, e um grupo adicional (não jateado) foi avaliado (n=13). A transformação de fase (n=1) foi analisada pelo refinamento de Rietveld com os dados da difração de raios X. Os dados de Ra (µm) e RC (MPa) foram analisados por ANOVA a 1 critério e teste de Tukey (α=0,05). O teste de correlação de Pearson determinou se havia correlação entre rugosidade e RC. Para os dados de RF (MPa), foram utilizados ANOVA a 1 critério e teste Dunnett C (α=0,05). O momento do jateamento foi significante (P<0,001) para os dados de Ra, RC e RF. Os grupos AS e DS apresentaram a maior (1,3 µm) e menor (0,7 µm) Ra. A maior RC (7,0 MPa) foi observada no grupo DAS, seguido pelo grupo DS (5,4 MPa) e, finalmente, pelo grupo AS (2,6 MPa). Todos os grupos apresentaram 100% de falha adesiva. Uma fraca correlação (r=-0,45, P<0,05) foi encontrada entre rugosidade e RC. A morfologia de superfície foi influenciada pelo momento do jateamento. Os grupos não jateado (926,8 MPa) e AS (816,3 MPa) apresentaram valores de RF estatisticamente semelhantes, porém valores menores que os grupos DS (1249,1 MPa) e DAS (1181,4 MPa), sem diferença estatisticamente significante entre eles. Os grupos não jateado, DS, AS e DAS mostraram, respectivamente, percentuais em massa de fase monoclínica de 0,0%, 12,2%, 0,0% e 8,6%. A superfície muito rugosa promovida pelo jateamento antes da sinterização da zircônia prejudicou a união com o cimento resinoso. Os padrões morfológicos após os diferentes momentos do jateamento foram condizentes com a rugosidade de superfície. Considerando a RC e a RF imediatas, o grupo DAS exibiu o melhor desempenho. O jateamento, independentemente do momento, promove transformação de fase tetragonal para monoclínica, enquanto a sinterização tende a zerar o conteúdo de fase monoclínica

The mechanical retention and longevity of indirect restorations with zirconia framework can be favored by the adhesive cementation. However, as zirconia is a crystalline ceramic, alternative surface treatments to the conventional ones (hydrofluoric acid and silanization) should be used with the aim of establishing mechanical and chemical bonding at the resin cement/restoration interface. Among the treatments that promote micromechanical retention, the air-abrasion is still one of the most effective and easy-to-use methods. This procedure can be performed with conventional and/or silica-coated aluminum oxide/alumina (Al2O3) particles of different sizes and, therefore, different behaviors regards roughness and available surface area for bonding, and also wettability by bonding agents, may be observed. Despite its beneficial role on the bond strength of the resin cement/zirconia interface and even on the short-term mechanical strength of zirconia, it is known that the air-abrasion favors the creation of surface microcracks, which, in the long term, under the adverse conditions of the oral cavity, tend to propagate towards the bulk of the material, decreasing its mechanical strength or even promoting its catastrophic failure. Whereas the conventional protocol recommends the air-abrasion of the sintered zirconia, one alternative would be to perform it on the zirconia before sintering, since it would be more favorable for the formation of micromechanical retentions and, possibly, the effects of the severity of the air-abrasion and its damage on the mechanical strength of the material, in the long term, would be minimized. Taking into account the highlighted aspects, the objectives of this study was: 1) To evaluate the effect of the particle used for air-abrasion on the surface roughness, wettability and morphological pattern of an yttria partially stabilized tetragonal zirconia, as well as to verify the correlation between the dependent variables roughness and wettability; 2) To evaluate the effect of air-abrasion moment on the yttria partially stabilized tetragonal zirconia surface characterization (roughness, morphology and phase transformation) and flexural strength, its shear bond strength to a resin cement and the predominant failure mode in the adhesive area. The correlation between the dependent variables roughness and bond strength was also verified. In the first study, specimens (14 × 14 × 1.4 mm) were obtained from Lava (3M ESPE AG) and, except for the control group (n=20), air-abraded with one of the following particles (n=20): 1) 50 µm Al2O3; 2) 120 µm Al2O3; 3) 250 µm Al2O3; 4) 30 µm silica-coated Al2O3 (Rocatec Soft); 5) 110 µm silica-coated Al2O3 (Rocatec Plus); 6) 120 µm Al2O3 and Rocatec Plus. The roughness (Ra) and wettability (by the silane RelyX Ceramic Primer) analyses were performed on the same specimens. For the surface morphology analysis by scanning electron microscopy (SEM), two additional specimens (6.0 × 6.0 × 1.0 mm) per group were prepared. The Ra (µm) data were analyzed by one-way ANOVA and Dunnett C test (α=0.05), and the wettability data by oneway ANOVA (α=0.05). Spearman correlation analysis was applied to test for a possible correlation between roughness and wettability. With the exception of the groups abraded with 120 µm Al2O3, the other ones presented statistically different roughness values. Concerning wettability, there was no significant difference among the groups. No correlation (rs=-0.09, P=0.27) was found between roughness and wettability. The particle influenced the surface morphology of the zirconia. The roughness increase seemed to have followed the size enlargement of the particles. The SEM analysis indicated that different particles provided differences in the morphological patterns. In the second study, specimens from Lava zirconia were air-abraded with 50 µm Al2O3 particles after (AS); before (BS); or before and after (BAS) zirconia sintering. For roughness (Ra), thirty specimens (10 × 10 × 3.0 mm) (n=10) were analyzed by a profilometer. Composite resin discs (n=30) were bonded with RelyX ARC (3M ESPE) on these specimens and stored in distilled water at 37 ºC for 24 h before the shear bond strength (SBS) test. Failure mode was determined with a stereomicroscope (×20). The surface morphology (n=2) was evaluated by SEM (×500). For the 4-point flexural strength (FS) test (EMIC DL2000), thirty-nine bar-shaped specimens (20 × 4.0 × 1.2 mm) (n=13) were air-abraded according to the three moments proposed, and an additional group (non-abraded) was evaluated (n=13). The phase transformation (n=1) was analyzed by Rietveld refinement with X-ray diffraction data. The Ra (µm) and SBS (MPa) data were analyzed by one-way ANOVA and Tukey's test (α=0.05). Pearson correlation analysis determined if there was correlation between roughness and SBS. For FS (MPa) data, one-way ANOVA and Dunnett C test (α=0.05) were used. Air-abrasion moment was significant (P<0.001) for Ra, SBS and FS data. The BS and AS groups presented the highest (1.3 µm) and the lowest (0.7 µm) Ra. The highest SBS (7.0 MPa) was observed for the BAS group, followed by the AS group (5.4 MPa) and, finally, by the BS group (2.6 MPa). All groups presented 100% adhesive failure. A weak correlation (r=-0.45, P<0.05) was found between roughness and SBS. The surface morphology was influenced by the air-abrasion moment. The non-abraded (926.8 MPa) and BS (816.3 MPa) groups exhibited statistically similar FS values, but lower values than the AS (1249.1 MPa) and BAS (1181.4 MPa) groups, with no significant difference between them. The non-abraded, AS, BS, and BAS groups exhibited, respectively, percentages in weight of monoclinic phase of 0.0%, 12.2%, 0.0%, and 8.6%. The very rough surface provided by the air-abrasion before zirconia sintering impaired the bonding with the resin cement. The morphological patterns after the different air-abrasion moments were consistent with the surface roughness. Considering the short-term SBS and FS, the BAS group exhibited the best performance. Air-abrasion, regardless of its performance moment, provides tetragonal to monoclinic transformation, while sintering tends to zero the monoclinic phase content.

Effect of carbamide peroxide bleaching gel on composite resin flexural strength and microhardness.

This study investigated the effect of 16% carbamide peroxide (Whiteness Perfect/FGM) on the Vickers microhardness and flexural strength of the restorative composites Filtek Z100 (hybrid), Filtek Z350 (nanofill), Brilliant (micro-hybrid) and Opallis (micro-hybrid). Disc-shaped (4x2 mm; n=5) and bar-shaped (12x2x1 mm; n=10) specimens of each restorative material were randomly divided into 2 groups: (G1) 16 weeks stored in distilled water; (G2) 16 weeks stored in distilled water, with 16% carbamide peroxide application during 6 h per day for the last 4 weeks. The mechanical properties were evaluated using a Vickers microhardness tester and a mechanical testing machine. Data were analyzed by two-way ANOVA and Tukey's (HSD) post-hoc test (α=0.05). Filtek Z100 presented the highest microhardness value, followed by Filtek Z350 and finally by Brilliant and Opallis (p=0.00). Filtek Z100 and Brilliant exhibited the highest flexural strength value, followed by Filtek Z350 and Opallis (p=0.00). Bleaching treatment decreased significantly microhardness of Brilliant and Opallis (p=0.00). The flexural strength of all studied materials was not affected by the home bleaching (p=0.28).

Próteses parciais removíveis associadas a encaixes: implicações clínicas e laboratoriais / Removable partial dentures associated to attachments: clinical and laboratory implications

Atualmente, a utilização de próteses fixas e/ou implantes osseointegrados é o tratamento almejado pela maioria dos pacientes parcialmente edêntulos. No entanto, dependendo da condição periodontal dos dentes remanescentes, bem como da condição óssea do espaço protético, a reabilitação oral com esses tratamentos torna-se limitada ou contraindicada. Nesses casos, a utilização de próteses parciais removíveis com encaixes torna-se importante alternativa para a reabilitação estética e funcional. Os encaixes são dispositivos mecânicos compostos por duas partes (macho-fêmea), uma situada internamente em relação à outra, que atuam como retentor direto, propiciando retenção, suporte e estabilidade às próteses dentárias. Esses dispositivos podem ser classificados como intra ou extracoronários, considerando o seu posicionamento em relação ao dente pilar. No entanto, independentemente do tipo de encaixe selecionado, a associação entre as próteses parciais fixa e removível deve ser realizada respeitando-se os princípios biomecânicos de ambas. Sendo assim, o objetivo deste estudo foi revisar e discutir a literatura quanto às implicações clínicas e laboratoriais da associação entre próteses parciais fixas e removíveis por intermédio de encaixes

Nowadays, the fixed partial dentures and/or dental implants is the most requested treatmentby the majority of partially edentulous patients. However, depending on the periodontal condition of the remaining teeth, as well as the bone condition of the prosthetic space, the oral rehabilitation with these treatments may be limited or even contraindicated. In such cases, the use of removable partial dentures associated to attachments becomes an important alternative for aesthetic and functional rehabilitation. Attachments are mechanical devices consisted of two parts (patrix-matrix), one placed inside another, which act as direct retainer, providing retention, support and stability to the dentures. These devices can be classified as intra or extracoronal attachments, considering their position in relation to the abutment tooth. However, regardless the type of attachment, the association between fixed and removable partial dentures should be performed respecting the biomechanical principles of both. Therefore, the purpose of this study was to review and discuss the literature about the clinical and laboratory implications of the association between fixed and removable partial dentures by means of attachments

Resistência à flexão em porcelana feldspática: efeito da ciclagem mecânica e limite de fadiga pelo método escada / Flexural strength of feldspathic porcelain: effect of mechanical cycling and fatigue limit by the staircase method

Este estudo avaliou o limite de fadiga (LF), determinado pelo método escada, e o efeito da ciclagem mecânica sobre a resistência à flexão (RF) da porcelana feldspática Duceragold. Corpos de prova (25 x 5 x 2 mm) foram confeccionados de acordo com as instruções do fabricante e submetidos ao ensaio de RF (n = 10), em três pontos. Para determinação do LF (n = 30), foram utilizados carregamento inicial de 60% da RF, tensão incremental de 3% da RF, 10.000 ciclos e 2 Hz. Os dados foram submetidos à Anova e teste de Tukey (p < 0,05). Embora os ciclos propostos não tenham reduzido estatisticamente a RF, análises fractográficas evidenciaram estrias, sinais característicos de fadiga mecânica.

This study evaluated the fatigue limit (FL) by the staircase method and the effect of mechanical cycling on the flexural strength (FS) of Duceragold feldspathic porcelain. Specimens (25 x 5 x 2 mm) were made according to manufacturer’s directions and submitted to t hree-point fl exural s trength t est (n = 10). To d etermine FL (n = 30; 10,000 cycles; 2 Hz), an initial loading of 60% of the FS and an incremental loading (step) of 3% of the FS were used. Data were analyzed by Anova and Tukey´s test (p < 0.05). Although the proposed cycles have not reduced FS significantly, fractography analysis showed striation, characteristic signs of mechanical fatigue.

Effect of Carbamide Peroxide Bleaching Gel on Composite Resin Flexural Strength and Microhardness

This study investigated the effect of 16% carbamide peroxide (Whiteness Perfect/FGM) on the Vickers microhardness and flexural strength of the restorative composites Filtek Z100 (hybrid), Filtek Z350 (nanofill), Brilliant (micro-hybrid) and Opallis (micro-hybrid). Disc-shaped (4x2 mm; n=5) and bar-shaped (12x2x1 mm; n=10) specimens of each restorative material were randomly divided into 2 groups: (G1) 16 weeks stored in distilled water; (G2) 16 weeks stored in distilled water, with 16% carbamide peroxide application during 6 h per day for the last 4 weeks. The mechanical properties were evaluated using a Vickers microhardness tester and a mechanical testing machine. Data were analyzed by two-way ANOVA and Tukey's (HSD) post-hoc test (α=0.05). Filtek Z100 presented the highest microhardness value, followed by Filtek Z350 and finally by Brilliant and Opallis (p=0.00). Filtek Z100 and Brilliant exhibited the highest flexural strength value, followed by Filtek Z350 and Opallis (p=0.00). Bleaching treatment decreased significantly microhardness of Brilliant and Opallis (p=0.00). The flexural strength of all studied materials was not affected by the home bleaching (p=0.28).

Este estudo investigou o efeito do peróxido de carbamida a 16% (Whiteness Perfect/FGM) na dureza Vickers e resistência à flexão dos compósitos restauradores Filtek Z100 (híbrida), Filtek Z350 (nanoparticulada), Brilliant (micro-híbrida) e Opallis (micro-híbrida). Espécimes em forma de disco (4x2 mm; n=5) e de barra (12x2x1 mm; n=10) de cada material restaurador foram distribuídos aleatoriamente em 2 grupos: (G1) 16 semanas em água destilada; (G2) armazenamento em água destilada durante 16 semanas, com aplicação do peróxido de carbamida a 16% por 6 h diárias nas últimas 4 semanas. As propriedades mecânicas foram avaliadas em microdurômetro Vickers e máquina de ensaios mecânicos. Os dados foram analisados por ANOVA a 2 critérios e teste de Tukey (α=0,05). Filtek Z100 apresentou o maior valor de dureza, seguido por Filtek Z350 e, finalmente, por Brilliant e Opallis (p=0,00). Filtek Z100 e Brilliant mostraram o maior valor de resistência à flexão, seguido por Filtek Z350 e Opallis (p=0,00). O clareamento diminuiu significantemente a dureza das resinas Brilliant e Opallis (p=0,00). A resistência à flexão dos materiais estudados não foi afetada pelo clareamento caseiro (p=0,28).

The effect of different surface treatments on the shear bond strength of luting cements to titanium.

STATEMENT OF PROBLEM: Although titanium presents attractive physical and mechanical properties, there is a need for improving the bond at the titanium/luting cement interface for the longevity of metal ceramic restorations. PURPOSE: The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of resin-modified glass ionomer and resin cements to commercially pure titanium (CP Ti). MATERIAL AND METHODS: Two hundred and forty CP Ti cast disks (9.0 × 3.0 mm) were divided into 8 surface treatment groups (n=30): 1) 50 µm Al(2)O(3) particles; 2) 120 µm Al(2)O(3) particles; 3) 250 µm Al(2)O(3) particles; 4) 50 µm Al(2)O(3) particles + silane (RelyX Ceramic Primer); 5) 120 µm Al(2)O(3) particles + silane; 6) 250 µm Al(2)O(3) particles + silane; 7) 30 µm silica-modified Al(2)O(3) particles (Cojet Sand) + silane; and 8) 120 µm Al(2)O(3) particles, followed by 110 µm silica-modified Al(2)O(3) particles (Rocatec). The luting cements 1) RelyX Luting 2; 2) RelyX ARC; or 3) RelyX U100 were applied to the treated CP Ti surfaces (n=10). Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5°C to 55°C). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey HSD post hoc test (α=.05). Failure mode was determined with a stereomicroscope (×20). RESULTS: The surface treatments, cements, and their interaction significantly affected the SBS (P<.001). RelyX Luting 2 and RelyX U100 exhibited similar behavior for all surface treatments. For both cements, only the group abraded with 50 µm Al(2)O(3) particles had lower SBS than the other groups (P<.05). For RelyX ARC, regardless of silane application, abrasion with 50 µm Al(2)O(3) particles resulted in significantly lower SBS than abrasion with 120 µm and 250 µm particles, which exhibited statistically similar SBS values to each other. Rocatec + silane promoted the highest SBS for RelyX ARC. RelyX U100 presented the highest SBS mean values (P<.001). All groups showed a predominance of adhesive failure mode. CONCLUSIONS: The adhesive capability of RelyX Luting 2 and RelyX U100 on the SBS was decisive, while for RelyX ARC, mechanical and chemical factors were more influential.