Water as Veneering Modeling Liquid Affects Microhardness of Glassy Matrix Veneering Ceramic.

PURPOSE/AIM: To evaluate the effect of different veneering liquids used for modeling on microhardness, fracture toughness and biaxial flexural strength of a glass-veneering ceramic. MATERIAL AND METHODS: The manufacturer recommended modeling liquid (ML), distilled water (DW), isopropyl alcohol (IA), 0.5% (P05), 1% (P1), and 2% (P2) polyethylene glycol solutions were mixed with feldspathic ceramic powder to form disc-shaped samples (n=20, 15 mm × 1.2 mm). After sintering, samples were mirror-polished and subjected to Vickers indentation (n=5) for measurement of microhardness and fracture toughness. The remaining 15 samples from each group were subjected to biaxial flexural strength. Data were subjected to one-way ANOVA and Weibull analysis. RESULTS: The microhardness was affected by veneering liquid (p=0.002): DW promoted higher microhardness values than ML and IA. Fracture toughness (p=0.301) and flexural strength (p=0.930) were not affected by the veneering liquid but Weibull parameters were affected. All groups presented surface pores under high magnification. CONCLUSION: Even though the use of DW led to higher values of surface microhardness than the ML, all obtained values are inside the range of enamel microhardness values reported in the literature. Such parameters may affect antagonist wear and should be reported in clinical trials.

Failure probability and stress distribution of milled porcelain-zirconia crowns with bioinspired/traditional design and graded interface.

OBJECTIVE: To evaluate the failure probability and stress distribution of traditional and bioinspired porcelain-zirconia milled crowns, with and without silica infiltration (graded zirconia). METHODS: Traditional crown design had a zirconia infrastructure veneered with porcelain; Bioinspired, had a porcelain infrastructure with translucent-zirconia veneer; Graded and Graded Bioinspired crowns had their zirconia layer infiltrated by silica (n = 25). The cameo surface of each crown (porcelain or zirconia) was glazed. The restoration layers were fused by a vitreous connector and the crowns were adhesively cemented to dies. The specimens were then mechanically cycled in a sliding machine using 100 N load at 4 Hz. The specimens were tested until 2 × 106 cycles, and every 0.5 × 106 cycles the crowns were evaluated under stereomicroscopy for the presence of failures. The stress distribution was inspected with Finite Element Analyses. RESULTS: The predominant failure modes for the Traditional and Graded crowns were delamination and cracking, respectively. The Weibull parameters beta and eta were, respectively: Traditional 1.30 and 2.3 × 106 cycles, and Graded 1.95 and 2.3 × 106 cycles. Thus, the Traditional and Graded crowns presented greater susceptibility to failure due to fatigue, while the Bioinspired and Graded Bioinspired crowns showed no fatigue effect using 100N load, showing beta = 1 and eta of approximately 17 × 106 cycles. Also, through finite element analyses, it was verified that the Bioinspired and Graded Bioinspired crowns presented the best stress distribution on both crowns and dental structures. SIGNIFICANCE: Bioinspired and Graded Bioinspired crowns had the lowest failure probability and better stress distribution and may be considered robust long lasting restorations.

Fatigue behavior of ultrafine tabletop ceramic restorations.

OBJECTIVE: The goal of this study was to investigate the fatigue life, failure modes, and stress distribution of partial ultrafine restorations for posterior teeth in different ceramics. METHODS: Sixty standard tabletop preparations in epoxy resin G10 received lithium-silicate-based zirconia-reinforced (ZLS) or hybrid ceramic (PIC) restorations in 0.5- or 1-mm thickness bonded with resin cement. The same cycling protocol was applied for all specimens, which consisted of 5000 cycles at 200N, followed by 450-N cycles until the specimens' fracture or the suspension of the test after 1.5×106 cycles. Axial load was carried out with a 4Hz frequency in Biocycle V2 equipment (Biopdi, São Carlos, SP), with samples immersed in water. The presence of cracks and/or fractures was checked every 2.5×105 cycles, and the survival analysis was performed with the number of cycles in which each specimen failed. All specimens were evaluated by stereomicroscopy and scanning electron microscopy (SEM). After data tabulation, Kaplan-Meier and Mantel-Cox (log-rank test) analyses were performed, followed by multiple pairwise comparison, all with a significance level of 5%, and Weibull analysis. Through three-dimensional finite element analysis, stress distribution and maximum principal stresses in the posterior occlusal veneers were evaluated by comparison of different types of substrate (G10, enamel/dentin, enamel), thicknesses, and ceramic materials. RESULTS: Zirconium-reinforced lithium silicate restorations with 0.5-mm thickness (ZLS.5) showed lower fatigue strength compared with that of 1.0-mm hybrid ceramic restorations (PIC1), and both were similar to other restorations (PIC.5 and ZLS1) (log-rank test, χ2=11.2; df=3; p=0.0107<0.05). ZLS groups presented random defects that culminated in fracture, whereas PIC groups presented defects that increased with mechanical fatigue after some cycling time. Stereomicroscope images show radial cracks due to the translucency of the material. There was no damage caused by the applicator. MPS (maximum principal stress) distributions were similar for the different substrate types, but the highest modulus of elasticity showed slightly lower stress concentration. SIGNIFICANCE: PIC is more likely to be used in thinner thickness than indicated by the manufacturer, with fatigue strength similar to that of thicker ZLS restorations.

Desempenho, frequência de diarreia, produção de fezes e custos de dietas com teores crescentes de farelo de abacaxi para leitões desmamados / Performance, diarrhea frequency, feces production and costs of diets with increasing levels of pineapple byproducts in weaned piglets

Esta pesquisa objetivou avaliar dietas com teores crescentes de farelo de abacaxi na alimentação de leitões desmamados. Foram utilizados 56 leitões, no intervalo de 21 a 63 dias de idade, que receberam dietas compostas principalmente por milho, farelo de soja e produtos lácteos, com adição de farelo de abacaxi em 0%, 3,4%, 6,8% e 10,2%. Foram avaliados o desempenho zootécnico; a incidência de diarreia; as excreções nas fezes, totais e por unidade de peso vivo ganho, de matérias seca (MS), mineral (MM) e orgânica (MO), nitrogênio (N) e fósforo (P); os custos relativos ao ganho de peso dos animais e os índices de eficiência econômica e de custo. As avaliações foram efetuadas dos 21 aos 35 dias; dos 21 aos 49 dias; e dos 21 aos 63 dias de idade dos leitões. Adotou-se delineamento em blocos ao acaso, de acordo com os pesos dos animais no início do experimento, com quatro tratamentos e sete repetições. Dos 21 aos 49 dias os animais submetidos às dietas com 3,4 e 6,8% de farelo de abacaxi consumiram mais ração (P<0.05) do que os alimentados com a dieta controle, e dos 21 aos 63 dias verificou-se maior ganho de peso (P<0.05) somente dos animais que receberam a dieta com 3,4% de farelo de abacaxi em relação aos leitões controle. Dos 21 aos 63 dias os animais que receberam as dietas com farelo de abacaxi apresentaram excreções de MS, MM, MO e N superiores (P<0.05) às dos animais controle. Contudo, ao se verificarem as excreções destes componentes nas fezes por unidade de peso vivo ganho neste mesmo período, foi constatado que não houve diferença (P>0.05) entre os leitões que receberam as dietas sem farelo de abacaxi e os que consumiram a dieta com 3,4% do produto. Portanto, a inclusão do farelo de abacaxi em dietas para leitões desmamados em 3,4% é viável, por não interferir negativamente nas excreções por unidade de peso vivo ganho e nos índices de custos das dietas e por proporcionar melhor ganho de peso aos leitões em relação àqueles que não consumiram farelo de abacaxi.(AU)

This research aimed to evaluate diets with growing levels of pineapple meal in weaned piglets feeding. Fifty-six piglets, from 21 to 63 days old, were fed diets composed mainly of corn, soybean meal, and dairy products, with the addition of pineapple byproduct in 0%, 3.4%, 6.8% and 10.2%. The parameters evaluated were: growth performance; diarrhea incidence; excretion in feces, total and per unit of weight gain, of dry (DM), mineral (MM) and organic (OM) matters, nitrogen (N) and phosphorous (P); diet costs related to weight gain, index of economic efficiency and of costs. The evaluations were performed from 21 to 35 days; from 21 to 49 days; and from 21 to 63 days of age. A complete randomized block design was adopted, according to the animal's weight in the beginning of the trial, with four treatments and seven repetitions. From day 21 to 49 the animals fed diets with 3.4 and 6.8% of pineapple meal consumed more feed (P<0.05) than those fed the control diet, and from day 21 to 63 only the animals that received the diet with 3.4% of pineapple presented a higher weight gain (P<0.05) than control piglets. From day 21 to 63 animals fed diets with pineapple meal presented higher (P<0.05) excretions of DM, MM, OM, and N than the control animals. However, checking the excretions of these components in the feces per unit of live weight gain in the same period, it was found that there was no difference (P>0.05) among the piglets fed diets without pineapple meal and those who consumed the diet with 3.4% of the product. Thus, the inclusion of pineapple meal in weaned piglet's diets at 3.4% is feasible, because it did not interfere negatively on excretions per unit of live weight gain and in diet cost indices, and provided better weight gain to the animals, as compared with pigs who did not consume pineapple meal.(AU)