RESUMO
OBJECTIVE: The aim of this study was to evaluate, by means of a fatigue life test, different ceramic materials used in palatal veneers to restore the canine guidance. MATERIALS AND METHODS: Forty-five standardized anatomical preparations were made in extracted healthy human canines with 1.2 uniform thickness. Samples were scanned, restorations were designed and milled in polymer-infiltrated ceramic network (PICN, Vita Enamic), zirconia-reinforced lithium silicate (ZLS, Vita Suprinity), and high translucent yttrium oxide-stabilized tetragonal zirconia (YZHT, Vita YZHT). Dental preparations were etched, restorations were processed according to the manufacturers' recommendations, and adhesively cemented. Then, three samples of each group were tested with load-to-fracture to determine the fatigue parameters. In addition, the palatal veneers stresses were evaluated using numerical models through finite element analysis. RESULTS: The mean of the monotonic test for PICN, ZLS, and YZHT was 674.18 N, 560.5 N, and 918.98 N, respectively. The StepWise test was performed until specimen fracture or until suspension of the test after 1.2 × 106 cycles. Regarding survival, using the Kaplan-Meier method, PICN presented results for the mean and median of 245.21 N and 225 N, respectively; ZLS had an average of 175.76 N and a median of 168 N, and YZHT with an average of 383.30 N and a median of 366 N. Regarding the Weibull method, PICN showed results of 5.43 ß and 264 η for form and scale, respectively; ZLS had 36.14 ß for form and 380.67 η for scale; and YZHT presented 4.95 ß for form and 417.38 η for scale. The highest stress value was calculated for YZHT, ZLS, and PICN, respectively. CONCLUSIONS: It was possible to conclude that all tested materials have the possibility of being used for rehabilitation of upper canines' palatal surface.
RESUMO
BACKGROUND: The objective of this in vitro study was to evaluate the effect of the active application of self-etching ceramic primer (ME&P) on the bond strength of different dental CAD/CAM materials (Lithium Disilicate ceramic (LD), Leucite ceramic (LE), Zirconia reinforced lithium silicate ceramic (ZLS), and Hybrid ceramic (HC)) with thermocycling aging. MATERIAL AND METHODS: The samples were randomly divided into 16 groups (n = 20). Dual resin cement cylinders were made and light cured for 10 s (1.200 mW/cm2) for the shear bond strength test. 3-way ANOVA revealed that the factors were statistically significant (P< 0.05). RESULTS: The aging process had a negative impact on the bond strength for all groups except for Lithium Disilicate, with active application. ZLS and LE showed promising results with high bond strength values for the ME&P active application; however, after aging the bond strength value was significantly reduced. HC showed reduced bond strength values regardless the ME&P application. CONCLUSIONS: In order to obtain a durable bond strength, the recommended protocol of 20 s of active application followed by 40 s of sitting time in the self-etching ceramic primer should be followed when using reinforced-glass ceramics as restorative materials. Key words:Dentistry, dental materials, silane, shear strength, computer-aided design.
RESUMO
O objetivo deste estudo foi comparar, por meio de ensaio de resistência à fadiga, materiais cerâmicos de diferentes graus de dureza para confecção de facetas palatinas no restabelecimento da guia canina em caninos humanos e analisar a tensão superficial por elementos finitos. Foram confeccionados 45 preparos anatômicos padronizados com desgaste uniforme de 1,2 mm de espessura. Os preparos foram escaneados, as restaurações foram desenhadas e fresadas em cerâmica vítrea reforçada por polímero (CVRP, VITA Enamic), cerâmica à base de silicato de lítio reforçado por zircônia (ZLS, VITA Suprinity) ou zircônia tetragonal estabilizada por óxido de ítrio de alta translucidez (YZHT, VITA YZ HT). Os preparos dentais foram condicionados, as restaurações foram tratadas de acordo com as recomendações dos fabricantes, e cimentados adesivamente. Em seguida, 3 espécimes de cada grupo foram testados monotonicamente para determinação dos parâmetros de fadiga. As médias do teste monotônico foram respectivamente para CVRP, ZLS e YZHT os valores de 674,18N, 560,58N e 918,98N. Foi realizado o ensaio de vida acelerado stepwise stress até a fratura dos espécimes ou até a suspensão do ensaio após 1,2 x 106 ciclos. Em relação a sobrevivência, pelo método de Kaplan-Meir, CVRP apresentou resultados para média e mediana de 245,21 e 225, respectivamente; ZLS teve média de 175,76 e mediana de 168 e YZHT com média de 383,30 e mediana de 366. Em relação ao método de Weibull, CVRP apresentou resultados de 5,43 e 264 para forma e escala, respectivamente; ZLS teve 36,14 para forma e 380,67 para escala; e YZHT apresentou 4,95 para forma e 417,38 para escala. As facetas palatinas também foram avaliadas em modelos computacionais por meio da análise de elementos finitos. Sendo calculado maior valor de tensão para YZ HT, ZLS, CVRP respectivamente. É possível concluir que todos os materiais testados apresentam a possibilidade de serem utilizados para reabilitação na face palatina de caninos superiores.
The aim of this study was to compare, by means of a fatigue strength test, ceramic materials with different hardness levels to produce palatal veeners to restore canine guide for protection. Forty-five standardized anatomical preparations were made in healthy human canines with uniform 1.2 mm thickness. The samples were scanned, the restorations were designed and milled in polymer infiltrated ceramic network (PICN, VITA Enamic), zirconia-reinforced lithium silicate (ZLS, VITA Suprinity) and high translucent yttrium oxide-reinforced tetragonal zirconia (YZHT, VITA YZ HT). Dental preparations were conditioned, restorations were treated according to the manufacturers' recommendations, and adhesively cemented. Then, 3 samples of each group were monotonically tested to determine the fatigue parameters. The mean of the monotonic test was respectively for PRGC, ZLS and YZHT 674.18N; 560.58N and 918.98N. The stepwise stress accelerated life test (SSALT) was performed until specimen fracture or until suspension of the test after 1.2 x 106 cycles. Regarding survival, using the Kaplan Meir method, PRGC presented results for the mean and median of 245.21 and 225, respectively; ZLS had an average of 175.76 and a median of 168 and YZHT with an average of 383.30 and a median of 366. Regarding the Weibull method, PRGC showed results of 5.43 and 264 for form and scale, respectively; ZLS had 36.14 for form and 380.67 for scale; and YZHT presented 4.95 for form and 417.38 for scale. The palatal veneers were also evaluated in computational models through finite element analysis. The highest voltage value being calculated for YZ HT, ZLS, CVRP respectively. It is possible to conclude that all tested materials have the possibility of being used for rehabilitation on the palatal surface of upper canines.