ABSTRACT
The CAD/CAM technology associated with rapid prototyping (RP) is already widely used in the fabrication of all-ceramic fixed prostheses and in the biomedical area; however, the use of this technology for the manufacture of metal frames for removable dentures is new. This work reports the results of a literature review conducted on the use of CAD/CAM and RP in the manufacture of removable partial dentures.
Subject(s)
Computer-Aided Design , Denture Design , Denture, Partial, Removable , Dental Alloys/chemistry , Humans , Technology, DentalABSTRACT
Polymerization of indirect resin composites (IRC) is carried out in the 'laboratories using special photo-polymerization devices to achieve a higher degree of conversion (DC). Such devices present variation in chambers and light output which may have consequences on the chemical and physical properties of IRCs. This study evaluated the effect of different polymerization devices on the flexural strength, Vickers microhardness and DC of an IRC. Specimens were prepared from an IRC material, Sinfony (3M ESPE), using special molds for flexural strength test (N=30) (25 x 2 x 2 mm, ISO 4049), Vickers microhardness test (N=30) (5 x 4 mm) and for DC (N=30) utilizing Micro-raman Spectroscopy. All specimens were submitted to initial polymerization with a Visio Alpha unit (3M ESPE) and then randomly divided into three groups (n=10/ group). Specimens in Group 1 (control) received additional polymerizations using a Visio Beta Vario device (3M ESPE), and those in Group 2 and Group 3 using Powerlux (EDG) and Strobolux (EDG) devices, respectively. DC and mechanical tests were then conducted. For the mechanical tests, the data were analyzed using ANOVA and Tukey's tests (p < 0.05) and for DC, one-way ANOVA was used. Polymerization in Strobolux (Group 3) resulted in significantly lower flexural strength (MPa) values (134 +/- 27) compared to Visio Beta Vario (165 +/- 20) (Group 1) (p < 0.05). The lowest microhardness values (Kg/mm2) were obtained in Group 3 (30 +/- 1) (p < 0.05). DC was similar in all groups (75 +/- 1, 91 +/- 5, 85 +/- 7% for Visio Beta Vario, Powerlux and Strobolux, respectively) (p = 0.1205). The type of polymerization device may affect the flexural strength and Vickers hardness of the IRC tested. DC also seems to be affected by the type of polymerization device but the results were not significant.
Subject(s)
Composite Resins , Polymerization , Equipment Design , Hardness Tests , Materials TestingABSTRACT
Polymerization of indirect resin composites (IRC) is carried out in the laboratories using special photo-polymerization devices to achieve a higher degree of conversion (DC). Such devices present variation in chambers and light output which may have consequences on the chemical and physical properties of IRCs. This study evaluated the effect of different polymerization devices on the flexural strength, Vickers microhardness and DC of an IRC. Specimens were prepared from an IRC material, Sinfony (3M ESPE), using special molds for flexural strength test (N=30) (25x2x2 mm, ISO 4049), Vickers microhardness test (N=30) (5x4 mm) and for DC (N=30) utilizing Micro-raman Spectroscopy. All specimens were submitted to initial polymerization with a Visio Alpha unit (3M ESPE) and then randomly divided into three groups (n=10/ group). Specimens in Group 1 (control) received additional polymerizations using a Visio Beta Vario device (3M ESPE), and those in Group 2 and Group 3 using Powerlux (EDG) and Strobolux (EDG) devices, respectively. DC and mechanical tests were then conducted. For the mechanical tests, the data were analyzed using ANOVA and Tukey's tests (p<0.05) and for DC, one-way ANOVA was used. Polymerization in Strobolux (Group 3) resulted in significantly lower flexural strength (MPa) values (134±27) compared to Visio Beta Vario (165±20) (Group 1) (p<0.05). The lowest microhardness values (Kg/mm2) were obtained in Group 3 (30±1) (p<0.05). DC was similar in all groups (75±1, 91±5, 85±7 % for Visio Beta Vario, Powerlux and Strobolux, respectively) (p=0.1205). The type of polymerization device may affect the flexural strength and Vickers hardness of the IRC tested. DC also seems to be affected by the type of polymerization device but the results were not significant.
As polimerizacoes de resinas compostas indiretas (RCI) sao realizadas em Laboratorio em dispositivos fotopolimerizadores especiais para que seja alcancado um maior grau de conversao (GC). Estes dispositivos apresentam variacoes nas cameras e nas lampadas polimerizadoras as quais podem gerar consequencias nas propriedades fisicas e quimicas das RCIs. Este estudo avaliou o efeito de diferentes unidades polimerizadoras na resistencia a flexao, dureza Vickers e GC de uma RCI. Amostras da RCI Sinfony (3M ESPE) foram preparadas, utilizando matrizes especiais para o teste de resistencia a flexao (N=30) (25x2x2 mm, ISO 4049), teste de microdureza Vickers (N=30) (5x4 mm) e para o GC (N=30), utilizando a espectroscopia Micro-raman. Todas as amostras foram submetidas a polimerizacao inicial na unidade Visio Alpha (3M ESPE) e em seguida elas foram divididas aleatoriamente em tres grupos (n=10/por grupo). As amostras do Gr1 (controle) tiveram sua polimerizacao final realizada na unidade Visio Beta Vario (3M ESPE), e as do Gr2 e Gr3 nas unidades Powerlux (EDG) e Strobolux (EDG), respectivamente e entao os testes mecanicos e do GC foram conduzidos. Para os testes mecanicos, os dados foram analisados utilizando a analise de Variancia (ANOVA) e o teste de Tukey (p<0.05) e ANOVA 1-fator para o GC. A polimerizacao na unidade Strobolux (Gr3) gerou valores de resistencia a flexao (MPa) significativamente inferiores (134±27) comparado a unidade Visio Beta Vario (165±20) (Gr1) (p<0.05). Os menores valores de microdureza (Kg/mm2) foram obtidos para o Gr3 (30±1) (p<0.05). O GC em todas as unidades polimerizadoras (75±1, 91±5, 85±7 % para Visio Beta Vario, Powerlux e Strobolux, respectivamente) foi semelhante entre os grupos (p=0.1205). O tipo de unidade polimerizadora afetou a resistencia a flexao e a dureza Vickers da RCI testada. O GC tambem foi afetado pelo tipo de unidade polimerizadora, mas a diferenca nao foi significativa.
Subject(s)
Composite Resins , Polymerization , Materials Testing , Equipment Design , Hardness TestsABSTRACT
PURPOSE: This study evaluated the degree of conversion (DC) of four indirect resin composites (IRCs) with various compositions processed in different polymerization units and investigated the effect of thermal aging on the flexural strength and Vicker's microhardness. MATERIALS AND METHODS: Specimens were prepared from four IRC materials, namely Gr 1: Resilab (Wilcos); Gr2: Sinfony (3M ESPE); Gr3: VITA VMLC (VITA Zahnfabrik); Gr4: VITA Zeta (VITA Zahnfabrik) using special molds for flexural strength test (N = 80, n = 10 per group) (25 x 2 x 2 mm(3), ISO 4049), for Vicker's microhardness test (N = 80, n = 10 per group) (5 x 4 mm(2)) and for DC (N = 10) using FT-Raman Spectroscopy. For both flexural strength and microhardness tests, half of the specimens were randomly stored in distilled water at 37 degrees C for 24 hours (Groups 1 to 4), and the other half (Groups 5 to 8) were subjected to thermocycling (5000 cycles, 5 to 55 +/- 1 degree C, dwell time: 30 seconds). Flexural strength was measured in a universal testing machine (crosshead speed: 0.8 mm/min). Microhardness test was performed at 50 g. The data were analyzed using one-way and two-way ANOVA and Tukey's test (alpha= 0.05). The correlation between flexural strength and microhardness was evaluated with Pearson's correlation test (alpha= 0.05). RESULTS: A significant effect for the type of IRC and thermocycling was found (p= 0.001, p= 0.001) on the flexural strength results, but thermocycling did not significantly affect the microhardness results (p= 0.078). The interaction factors were significant for both flexural strength and microhardness parameters (p= 0.001 and 0.002, respectively). Thermocycling decreased the flexural strength of the three IRCs tested significantly (p < 0.05), except for VITA Zeta (106.3 +/- 9.1 to 97.2 +/- 14 MPa) (p > 0.05) when compared with nonthermocycled groups. Microhardness results of only Sinfony were significantly affected by thermocycling (25.1 +/- 2.1 to 31 +/- 3.3 Kg/mm(2)). DC values ranged between 63% and 81%, and were not significantly different between the IRCs (p > 0.05). While a positive correlation was found between flexural strength and microhardness without (r = 0.309) and with thermocycling (r = 0.100) for VITA VMLC, negative correlations were found for Resilab under the same conditions (r =-0.190 and -0.305, respectively) (Pearson's correlation coefficient). CONCLUSION: Although all four IRCs presented nonsignificant DC values, flexural strength and microhardness values varied between materials with and without thermocycling.
Subject(s)
Composite Resins/chemistry , Dental Materials/chemistry , Aluminum Silicates/chemistry , Bisphenol A-Glycidyl Methacrylate/chemistry , Chemical Phenomena , Dental Stress Analysis/instrumentation , Hardness , Humans , Materials Testing , Methacrylates/chemistry , Pliability , Polyethylene Glycols/chemistry , Polymers/chemistry , Polymethacrylic Acids/chemistry , Polyurethanes/chemistry , Silicon Dioxide/chemistry , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Stress, Mechanical , Temperature , Time FactorsABSTRACT
The aim of this study was to evaluate the shear bond strength of Co-Cr and Ni-Cr metal alloys and a specific ceramic, submitted to different thermocycling immersion times. Sixty metal-ceramic specimens were confectioned and standardized in cylindricalformat. Three thermocycling conditions were evaluated: without thermocycling, 3,000 cycles (5 degrees C/55 degrees C+/-1) with 30s of immersion time and 3,000 cycles (5 degrees C/55 degrees C+/-1) with 60s. The shear bond strength was performed in a universal testing machine, using a special device to concentrate the tension at the metal/ceramic interface during the test. The load was applied until fracture of the specimens. The data was statistically analyzed by ANOVA (two-way) and Tukey (p<0.05) test. The results didn't show significant statistic differences between the metal-porcelain combinations. Nevertheless, both metal-ceramic systems submitted to 60s of immersion time showed lower values compared to specimens without thermocycling. It was concluded that the thermocycling immersion time of 1 minute affect the shear bond strength values for the Ni-Cr/porcelain and Cr-Co/porcelain systems.
Subject(s)
Chromium Alloys/chemistry , Dental Bonding , Dental Porcelain/chemistry , Metal Ceramic Alloys/chemistry , Dental Stress Analysis/instrumentation , Humans , Immersion , Materials Testing , Shear Strength , Stress, Mechanical , Temperature , Time FactorsABSTRACT
El objetivo de este estudio fue evaluar la resistencia a cizallamiento de aleaciones metálicas de Co-Cr y Ni-Cr; con un mismo tipo de cerámica, sometidos a diferentes tiempos de inmersión en el termociclaje. Sesenta especímenes fueron confeccionados de forma standarden formato cilindrico. Tres condiciones de termociclaje fueron evaluadas: sin termociclaje, 3000 ciclos (5ºC/55ºC±1) con 30s y 3.000 ciclos (5ºC/55ºC±1) con 60s de tiempo de inmersión. El ensayo de cizallamiento fue realizado en una máquina universal usando un dispositivo para concentrar la tensión en la interfase metalocerámica durante el test. La carga fue aplicada hasta que ocurra la fractura de los especimenes. La información fue estadísticamente analizada por ANOVA(two-way) y el test de Tukey (p<0,05). Los resultados no mostraron diferencia estadísticamente significante entre las combinaciones metal-porcelana. Sin embargo, ambas combinaciones metalocerámicas sometidas a 60s de tiempo de inmersión mostraron valores más bajos en comparación con los especimenes del grupo sin termociclaje. Fue concluido que el tiempo de inmersión de termociclaje de 1 minuto afectó los valores de resistencia de cizallamiento en los grupos de Ni-Cr/porcelana y Cr-Co/porcelana.
