Bonding to densely sintered alumina- and glass infiltrated aluminum / zirconium-based ceramics.

The objective of this study was to test two hypotheses: (1) silica coating affects the bond strength between ceramics and a resin cement; (2) bond strength is affected by the type of ceramic. Twelve blocks 5 x 6 x 8 mm of In-Ceram Zirconia (ZR) and twelve Procera AllCeram (PR) ceramics were made and duplicated in composite. Five blocks of each ceramic were treated as follows: (1) ZR + GB (laboratorial airborne particles abrasion with Al2O3 particles) + silane; (2) ZR + SC (chairside tribochemical silica coating system, Cojet); (3) PR + GB; (4) PR + SC. Two treated samples of ceramic were analyzed under SEM. The ceramic-composite blocks were cemented with Panavia F and stored in 37ºC distilled water for 7 days. They were then cut to produce bar specimens (n=30) with a bonding area of 0.6±0.1mm². Specimens were loaded to failure under tension in a universal testing machine (1 mm/min). Bond strength (sigma) values were statistically analyzed using ANOVA (Two-way) and Tukey (alpha = 0.05). Mean sigma (MPa) and standard deviation were as follows: 1) 15.1 ± 5.3; 2) 26.8 ± 7.4; 3) 12.7 ± 2.6; 4) 18.5 ± 4.7. Silica coated surfaces showed statistically higher sigma than the same substrate treated with GB only. In addition, ZR (with vitreous phase) showed higher ó than PR (without vitreous phase)

Adesão a uma cerâmica aluminizada densamente sinterizada e a uma cerâmica a base de alumina / zircônia infiltrada de vidro

The objective of this study was to test two hypotheses: (1) silica coating affects the bond strength between ceramics and a resin cement; (2) bond strength is affected by the type of ceramic. Twelve blocks 5 x 6 x 8 mm of In-Ceram Zirconia (ZR) and twelve Procera AllCeram (PR) ceramics were made and duplicated in composite. Five blocks of each ceramic were treated as follows: (1) ZR + GB (laboratorial airborne particles abrasion with Al2O3 particles) + silane; (2) ZR + SC (chairside tribochemical silica coating system, Cojet); (3) PR + GB; (4) PR + SC. Two treated samples of ceramic were analyzed under SEM. The ceramic-composite blocks were cemented with Panavia F and stored in 37ºC distilled water for 7 days. They were then cut to produce bar specimens (n=30) with a bonding area of 0.6±0.1mm². Specimens were loaded to failure under tension in a universal testing machine (1 mm/min). Bond strength (sigma) values were statistically analyzed using ANOVA (Two-way) and Tukey (alpha = 0.05). Mean sigma (MPa) and standard deviation were as follows: 1) 15.1 ± 5.3; 2) 26.8 ± 7.4; 3) 12.7 ± 2.6; 4) 18.5 ± 4.7. Silica coated surfaces showed statistically higher sigma than the same substrate treated with GB only. In addition, ZR (with vitreous phase) showed higher ó than PR (without vitreous phase).O objetivo deste estudo foi testar duas hipóteses: (1) a deposição de sílica afeta a resistência adesiva entre cerâmicas e cimento resinoso; (2) a resistência adesiva é afetada pelo tipo de cerâmica. Dez blocos (5 x 6 x 8 mm³) das cerâmicas In-Ceram Zircônia (ZR) e Procera AllCeram (PR) foram confeccionados e duplicados em resina composta. Cinco blocos de cada cerâmica foram assim tratados: (1) ZR + GB (jateamento com partículas de Al2O3) + silano; (2) ZR + SC (deposição de sílica/silanização - Sistema CoJet); (3) PR + GB; (4) PR + SC. Os blocos de cerâmica-compósito foram cimentados com Panavia F e armazenados em água destilada (37ºC / 7 dias). Eles foram então cortados para obter corpos-de-prova em forma de barras (n=30) com uma área adesiva de 0,6 ± 0,1mm². Os cp foram submetidos ao teste de microtração em uma máquina de ensaio universal (1mm.min-1). Os valores de resistência adesiva (sigma) foram submetidos à análise de variância (2 fatores) e ao teste de Tukey (alfa = 0,05). As médias de sigma (MPa) e os desvios padrão foram: 1) 15,1 (5,3); 2) 26,8 (7,4); 3) 12,7 (2,6); 4) 18,5 (4,7). A deposição de sílica na superfície cerâmica apresentou maior que o mesmo substrato tratado com GB. Além disso, ZR (com fase vítrea) apresentou maior sigma que PR (sem fase vítrea)

Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent

Objective The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mm Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (µTBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5°C and 55°C, with a dwell time of 30 s in each bath) and µTBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (α=0.05). Results The µTBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (

Efeito da ciclagem térmica sobre a resistência de união entre uma cerâmica infiltrada com vidro e um cimento resinoso

The aim of the present study was to evaluate the effect of thermocycling on the bond strength between the surface of the glass-infiltrated alumina ceramic In-Ceram (VITA) and the Panavia F resin cement (Kuraray CO.). Four 5x6x6mm In-Ceram blocks were obtained. One of the 6x6mm faces of each block was conditioned with Cojet - System (tribochemical silica coating, ESPE-3M) and then luted under a constant 750g pressure with Panavia F cement to another identical face of a resin composit block (Clearfil AP-X, Kuraray) obtained by reproduction of the ceramic one from Express (3M) addition curing silicone impressions. The four sets so formed by ceramic, luting cement and resin have been each one serially sectioned in 20 sticks so that the adhesive surface in each presented 1mm² of area. The samples were divided in 2 groups (n=10): G1- stored for 7 days in deionized water at 36 ± 2ºC; G2 - thermocycled 1500 times between 5 and 55ºC dwell times. The microtensile tests were accomplished in an universal testing machine (EMIC) at a crosshead speed of 0,5 mm/min. The results showed that the mean tensile bond strength values (MPa) for the group G2: (22,815 ± 5,254) had not statistically differ of the values of group G1: (25,628 ± 3,353) (t = 1,427; gl = 18; p-value = 0,171), at the level of a= 5%. It can be concluded that the thermocycling technique used in the present experiment had not produced statistically significant differences between the bond strength results of the specimens obtained by the two used techniques.O objetivo deste estudo foi avaliar o efeito da ciclagem térmica sobre a resistência de adesão entre a superfície da cerâmica In-Ceram Alumina (VITA) e o cimento resinoso Panavia F (Kuraray). Foram confeccionados quatro blocos de cerâmica In-Ceram com dimensões de 5x6x6mm. Uma das faces com 6x6mm de cada bloco cerâmico, após condicionamento com o sistema Cojet (ESPE-3M) (jateamento com óxido de alumínio/jateamento com óxido de sílica/ silanização) foi cimentada com Panavia F, sob peso constante de 750g, a outro bloco idêntico de resina composta Clearfil AP-X (Kuraray). Os blocos de resina foram obtidos por meio de duplicação daqueles de cerâmica a partir de moldes com silicona de adição Express (3M). Os quatro conjuntos formados por cerâmica, cimento e resina foram seccionados em 20 corpos-de-prova com forma de palitos, de modo que a região adesiva apresentasse 1mm² de área. Dois grupos (n=10) foram constítuidos: G1- estocagem por 7 dias em água deionizada à 36 ± 2ºC; G2- 1500 ciclos entre 5ºC e 55ºC com intervalos de 30 segundos. A seguir, foi realizado o teste de microtração em máquina de ensaio universal (EMIC) com velocidade de 0,5 mm/min. Os resultados mostraram que os valores médios de tensão de ruptura (MPa) para o grupo G2: (22,815 ± 5,254) não tiveram diferenças estatisticamente significantes daqueles do grupo G1: (25,628 ± 3,353) (t= 1,427; gl = 18; p-valor = 0,171), ao nível de significância de 5%. A partir destes resultados, entendemos lícito concluir que o efeito da ciclagem térmica não produziu alterações estatisticamente significantes nos valores da resistência adesiva

Avaliação do efeito da força de aperto de parafusos de retenção na desadaptação marginal de próteses sobre implantes

OBJECTIVES: The present in vitro study was designed to compare the differences in the vertical misfit of implant-supported frameworks using three different forces for tightening the bridge locking screws: fastening by hand until first resistance, and using torque drivers with 10 and 20Ncm. METHODS: The investigation was conducted based on the results given by 9 six-unit nickel-chromium (2 abutments/ 4 pontics) screw-retained implant-supported frameworks. The structures were exposed to simulated porcelain firings. The marginal misfit measurements were made using a traveling measuring microscope at selected screw tightening forces: fastening by hand until first resistance, and using torque drivers with 10 and 20Ncm. The results were submitted to one-way ANOVA with repeated measures on one factor, and post hoc pairwise comparisons using Tukey test (5%). RESULTS: The mean marginal misfit of the frameworks, fastening the screws by hand until first resistance, was 41.56µm (SD±12.45µm). The use of torque driver devices caused a significant reduction in marginal opening (pO presente estudo avaliou o efeito da força de aperto de parafusos de retenção na desadaptação marginal de próteses sobre implantes. A investigação foi conduzida baseada em resultados fornecidos por nove estruturas metálicas implanto-suportadas de seis elementos (02 retentores e 04 pônticos), retidas por parafusos. A mensuração da desadaptação marginal foi realizada com auxílio de microscópio óptico, nos seguintes momentos: M1: aperto com chave manual até a primeira resistência do parafuso; M2: aperto utilizando torquímetro mecânico com 10Ncm e M3: aperto utilizando torquímetro mecânico com 20Ncm. As médias de desadaptação foram submetidas à análise estatística (ANOVA e Tukey). O emprego de torquímetros mecânicos, independente do valor de torque, determinou redução significativa na abertura marginal (

Adhesives with different pHs: effect on the MTBS of chemically activated and light-activated composites to human dentin

PURPOSE: To evaluate the bond strength between human dentin and composites, using two light-activated single-bottle total-etch adhesive systems with different pHs combined with chemically activated and light-activated-composites. The tested hypothesis was that the dentin bond strength is not influenced by an adhesive system of low pH, combined with chemically activated or light-activated composites. MATERIAL AND METHOD: Flat dentin surfaces of twenty-eight human third molars were allocated in 4 groups (n=7), depending on the adhesive system: (One Step Plus-OS and Prime & Bond NT-PB) and composite (light-activated Filtek Z-100 [Z100] and chemically activated Bisfil 2B [B2B]). Each adhesive system was applied on acid-etched dentin and then one of the composites was added to form a 5 mm-high resin block. The specimens were stored in tap water (37ºC/24 h) and sectioned into two axes, x and y. This was done with a diamond disk under coolant irrigation to obtain beams with a cross-section area of approximately 0.8 mm². Each specimen was then attached to a custom-made device and submitted to the microtensile test (1 mm.min-1). Data were analyzed using two-way ANOVA and Tukey's tests (

Grinding of composite cores using diamond burs with different grit sizes

Aim: To evaluate the retention of Y-TZP crowns cemented in aged composite cores ground with burs of different grit sizes. Methods: Sixty composite resin simplified full-crown preparations were scanned, while 60 Y-TZP crowns with occlusal retentions were milled. The composite preparations were stored for 120 days (wet environment-37°C) and randomly distributed into three groups (n=20) according to the type of composite core surface treatment. The groups were defined as: CTRL (control: No treatment), EFB (extra-fine diamond bur [25μm]), and CB (coarse diamond bur [107μm]). The grinding was performed with an adapted surveyor standardizing the speed and pressure of the grinding. The intaglio surfaces on the crowns were air-abraded with silica-coated alumina particles (30 μm) and then a silane was applied. The crowns were cemented with self-adhesive resin cement, thermocycled (12,000 cycles; 5/55°C), stored (120 days) and submitted to aretention test (0.5mm/min). The retentive strength data (MPa) were analyzed using one-way analysis of variance and Tukey test, as well as Weibull analysis. Failures were classified as 50C (above 50% of cement in the crown), 50S (above 50% of cement in the substrate) and COE (composite core cohesive failure). Results: No statistical difference was observed among the retention values (p=0.975). However, a higher Weibull modulus was observed in the CTRL group. The predominant type of failure was 50S (above 50% of cement in the substrate composite). Conclusion: The retention of zirconia crowns was not affected by grinding using diamond burs with different grit sizes (coarse/extra-fine) or when no grinding was performed