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

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 (

Effect of cast rectifiers on the marginal fit of UCLA abutments

OBJECTIVES: This study assessed the effect of cast rectifiers on the marginal misfit of cast UCLA abutments compared to premachined UCLA abutments. The influence of casting and porcelain baking on the marginal misfit of these components was also investigated. METHODS: Two groups were analyzed: test group - 10 cast UCLA abutments, finished with cast rectifier and submitted to ceramic application; control group - 10 premachined UCLA abutments, cast with noble metal alloy and submitted to ceramic application. Vertical misfit measurements were performed under light microscopy. In the test group, measurements were performed before and after the use of cast rectifiers, and after ceramic application. In the control group, measurements were performed before and after casting, and after ceramic application. Data were submitted to statistical analysis by ANOVA and Tukey's test (a= 5%). RESULTS: The use of cast rectifiers significantly reduced the marginal misfit of cast UCLA abutments (from 25.68mm to 14.83mm;

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 (

Estudo do efeito da ciclagem térmica na resistência da união adesiva entre uma cerâmica aluminizada e um cimento resinoso

This study evaluated the effect of thermocycling on the bond strength between Procera AllCeram (Nobel-Biocare) and a resin cement (Panavia F, Kuraray CO). Nine ceramic blocks with dimensions of 5x6x6mm were conditioned at one face with Rocatec System (Espe). After, they were luted with Panavia F to composite resin blocks (Clearfil AP-X, Kuraray CO). The nine groups formed by ceramic, cement and composite resin were split up obtaining 75 samples with dimensions of 12x1x1mm and adhesive surface presenting 1mm²&plusmn;0.1mm² of area. The samples were divided into 3 groups (n=25): G1 - 14 days in distilled water at 37ºC; G2 - 6,000 cycles in water (5ºC - 55ºC - 30s); G3 - 12,000 cycles in water (5ºC - 55ºC - 30s). The samples were tested in a universal testing machine (EMIC) at a crosshead speed of 1mm/min. Data were analyzed by ANOVA and Tukey tests. The results indicated that mean values of rupture tension (MPa) of G1 (10.71 &plusmn; 3.54) did not differ statistically (pEste trabalho avaliou o efeito da ciclagem térmica sobre a resistência adesiva entre a cerâmica aluminizada (Procera AllCeram, Nobel-Biocare) e um cimento resinoso (Panavia F, Kuraray CO). Nove blocos de cerâmica, com dimensões de 5x6x6mm, foram condicionados em uma de suas faces com o Sistema Rocatec (ESPE). A seguir foram cimentados a blocos de resina composta (Clearfil AP-X, Kuraray CO). Os conjuntos cerâmica-cimento-resina foram cortados em 75 corpos-de-prova com formato retangular com dimensões de 12x1x1mm e superfície adesiva apresentando 1mm² &plusmn; 0,1mm². Os corpos-de-prova foram divididos em três grupos (n=25): G1 - 14 dias em água destilada a 37ºC, G2 - 6000 ciclos em água (5ºC e 55ºC) e G3 - 12000 ciclos em água (5ºC e 55ºC). Os corpos-de-prova foram ensaiados sob velocidade de 1mm/min em máquina de ensaio universal (EMIC). Os dados foram tratados estatisticamente com os testes de Anova e Tukey e indicaram que os valores médios de tensão de rupturas (MPa) de G1 (10,71 &plusmn; 3,54) não diferiram estatisticamente (p < 5%) de G2 (9,01 &plusmn; 3,90), porém houve diferença significativa entre G1 e G3 (7,28 &plusmn; 3,00). Concluiu-se que a ciclagem térmica diminuiu a resistência adesiva significativamente quando os corpos-de-prova foram submetidos a 12000 ciclos

Evaluation of shear bond strength and shear stress on zirconia reinforced lithium silicate and high translucency zirconia

This study evaluated the shear stress distribution on the adhesive interface and the bond strength between resin cement and two ceramics. For finite element analysis (FEA), a tridimensional model was made using computer-aided design software. This model consisted of a ceramic slice (10x10x2mm) partially embedded on acrylic resin with a resin cement cylinder (Ø=3.4 mm and h=3mm) cemented on the external surface. Results of maximum principal stress and maximum principal shear were obtained to evaluate the stress generated on the ceramic and the cylinder surfaces. In order to reproduce the in vitro test, similar samples to the computational model were manufactured according to ceramic material (Zirconia reinforced lithium silicate - ZLS and high translucency Zirconia - YZHT), (N=48, n=12). Half of the specimens were submitted to shear bond test after 24h using a universal testing machine (0.5 mm/min, 50kgf) until fracture. The other half was stored (a) (180 days, water, 37ºC) prior to the test. Bond strength was calculated in MPa and submitted to analysis of variance. The results showed that ceramic material influenced bond strength mean values (p=0.002), while aging did not: YZHT (19.80±6.44)a, YZHTa (17.95±7.21)a, ZLS (11.88±5.40)b, ZLSa (11.76±3.32)b. FEA results showed tensile and shear stress on ceramic and cylinder surfaces with more intensity on their periphery. Although the stress distribution was similar for both conditions, YZHT showed higher bond strength values; however, both materials seemed to promote durable bond strengt

In vitro evaluation of the precision of working casts for implant-supported restoration with multiple abutments

OBJECTIVE: The purpose of this study was to compare the accuracy of two working cast fabrication techniques using strain-gauge analysis. METHODS: Two working cast fabrication methods were evaluated. Based on a master model, 20 working casts were fabricated by means of an indirect impression technique using polyether after splinting the square transfer copings with acrylic resin. Specimens were assigned to 2 groups (n=10): Group A (GA): type IV dental stone was poured around the abutment analogs in the conventional way; Group B (GB), the dental stone was poured in two stages. Spacers were used over the abutment analogs (rubber tubes) and type IV dental stone was poured around the abutment analogs in the conventional way. After the stone had hardened completely, the spacers were removed and more stone was inserted in the spaces created. Six strain-gauges (Excel Ltd.), positioned in a cast bar, which was dimensionally accurate (perfect fit) to the master model, recorded the microstrains generated by each specimen. Data were analyzed statistically by the variance analysis (ANOVA) and Tukey's test (α= 5%). RESULTS: The microstrain values (µepsilon) were (mean±SD): GA: 263.7±109.07µepsilon, and GB: 193.73±78.83µepsilon. CONCLUSION: There was no statistical difference between the two methods studied