OBJECTIVES: The objectives of this study was to determine the differences in failure load between cemented and fused machined veneers to zirconia while observing the effects of real time aging on failure load between cemented and fused machined veneers to zirconia. The study was to examine the differences in aging and fatigue resistance amongst a machined glass-ceramic veneer and a machined feldspathic porcelain veneer. MATERIALS AND METHODS: VITA In Ceram YZ zirconia blocks were used as a substructure framework for the three unit fixed partial denture. The veneering material was either milled IPS e.max CAD (glass-ceramic) or milled VITABLOCS Triluxe Forte (feldspathic porcelain). The types of linking material between the substructures and veneering material were either fusing or cementation. Observations were compared between aged and non-aged specimens divided into two main groups; (a) non-aged group (b) aged for three years at room temperature. Each group has two subgroups; fused and cemented which are further divided into static and cyclic fatigue at 20K, 60K and 80K. Specimens were subjected to load to failure test using universal test machine. 40% of failure load was calculated for the cyclic fatigue subgroups. In order to examine the difference in failure load between the static and fatigued specimens, the Tukey-Kramer HSD test was used to analyze the data. RESULTS AND CONCLUSIONS: The VITABLOCS Triluxe Forte (feldspathic porcelain) fused to YZ zirconia showed significantly lower failure load values compared to all the other groups (p˂0.05). The non-aged VITABLOCS Triluxe Forte cemented to YZ zirconia (static and cyclic) showed significantly higher load to failure than the aged cemented Triluxe fatigued groups (p˂0.05). There is no significant difference in failure load between IPS e.max CAD fused and IPS e.max CAD cemented to YZ zirconia framework (p˃0.05). The aged IPS e.max CAD fatigued (20K, 60K and 80K cycles) cemented to YZ zirconia showed lower significant difference in failure load among all the other IPS e.max groups. (p˂0.05).

SyfteSyftet med föreliggande studie är att undersöka om slipning av zirkonia med silikatkarbid, diamant, vattenkylning, höghastighetsturbin och låghastighetshandstycke påverkar böjhållfastheten hos zirkonia.Material och metodFemtio provkroppar av yttriumoxidstabiliserad tetragonal zirkonia framställdes med CAD/CAM. Provkropparna delades in i 5 grupper med 10 i varje; polerad med låghastighetshandstycke (P), vattenkylning med finkornig diamantfräs (HDW), höghastighetsturbinshandstycke utan vattenkylning med finkornig diamantfräs (HDD), låghastighetshandstycke med finkornig diamantfräs (LD) och låghastighetshandstycke med kiselkarbidfräs (LC). Efter slipningen polerades alla provkropparna med låghastighetshandstycke och polertrissa. Artificiell åldring genomfördes med cyklisk dynamisk förbelastning och termocykling. Provkropparna testades med ett biaxialt böjhållfasthetstest i en universaltestmaskin. Resultaten analyserades med hjälp av en One-way ANOVA, Tukey’s test. Signifikansnivån sattes till α = 0,05.ResultatResultatet visade ingen signifikant skillnad mellan de olika grupperna. MPa medelvärde för varje grupp och standardavvikelser; P 1061(±82), HDW 1023(±92), HDD 1002(±127), LD 812(±228) and LS 984(±83).SlutsatsInom begränsningarna för föreliggande studie kan slutsatsen dras att böjhållfastheten hos zirkonia inte signifikant påverkas efter användning av följande slipningsprocesser:Höghastighetstubin med fin diamant och vattenkylning eller med höghastighetsturbin med fin diamant och utan vattenkylning eller med låghastighetshandstycke med fin diamant eller kiselkarbidfräs när zirkoniaytan är polerad. / AimThe purpose of this study is to investigate whether grinding zirconia with silicon carbide, diamond, water cooling, high speed turbine and low speed handpiece affects the flexural strength of zirconia.Material and methodFifty specimens of yttrium oxide stabilized tetragonal zirconia were produced using CAD/CAM. The specimens were divided into 5 groups with 10 in each; polished with low speed handpiece (P), high speed turbine with water cooling using a fine diamond burr (HW), high speed turbine without cooling using a fine diamond burr (H), low speed handpiece with a fine diamond burr (LD) and low speed handpiece with silicon carbide burr (LC). After grinding all specimens were polished with a slow speed handpiece and a polishing wheel. Artificial aging was performed using cyclic dynamic loading and thermocycling. The specimens were then tested in a biaxial flexural strength test using a universal testing machine. The results were analysed using One-way ANOVA, Tukey’s test. Level of significance was set at α = 0.05.ResultsThe results showed no significant differences between the groups. MPa means for each group and SD; P 1061(±82), HDW 1023(±92), HDD 1002(±127), LD 812(±228) and LS 984(±83).ConclusionWithin the limitations of this study it can be concluded that flexural strength of zirconia is not significantly affected using the following grinding processes: High-speed turbine with fine diamond and water cooling or with fine diamond without water cooling, low-speed handpiece with fine diamond or with silicon carbide burr when the zirconia has been polished.

This in vitro study was conducted to evaluate the influence of surface treatments on the bond strength between an yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic and resin cement. For this purpose, 120 Y-TZP blocks (IPS e.max® ZirCAD in inLab®) were randomly distributed into 12 experimental groups (n = 10), according to six surface treatment strategies and two storage conditions (24 hours post cementation and after 60 days in water and 10,000 thermocicles): AS (as sintered, no treatment); TBS (tribochemical silica coating followed by silanization); AAP (particle abrasion with 50 μm aluminum oxide followed by application of Monobond®Plus); FS (fusion sputtering); SN (5 nm SiO2 nanofilm deposition and silanization) and FSSN (FS + SN). The Y-TZP blocks were embedded in acrylic resin and cylinders of resin cement (Ø=0.96 mm x 1 mm in height) (RelyX ARC) were built up on the ceramic surface. After the storage, the specimens were submitted to microshear test (μSBS) (1 mm/min) in a universal testing machine. After testing, the surfaces were analyzed with a stereomicroscope and scanning electron microscope (SEM) in order to categorize the failure modes. One additional specimen per surface treatment strategy was analyzed by X-ray diffraction, for phases content, and by SEM for micromorphology observation. Bond strength values were statistically analyzed by Kruskal-Wallis and Mann Whitney tests for surface treatments (p <0.001) and aging factor (p <0.05). In both storage conditions, TBS and AAP provided higher bond strength values, followed by FSSN, FS and SN groups. The aging negatively influenced the results, with one exception for the FS. An increase in the amount of monoclinic phase was observed in the abraded groups. Sandblasting of alumina particles followed by application of a primer with MPA is as effective as the tribochemical treatment combined with silane for pretreatment of the Y-TZP surface, with respect to the bond strength to the composite. / No presente trabalho objetivou-se avaliar, in vitro, o efeito de diferentes tratamentos de superfície na resistência de união de uma cerâmica à base de zircônia policristalina tetragonal estabilizada por ítria (Y-TZP) a um cimento resinoso. Para tanto, 120 blocos de Y-TZP (IPS e.max® ZirCAD for inLab®, Ivoclar-Vivadent, Schaan, Liechtenstein) foram distribuídos randomicamente em 12 grupos experimentais (n=10), conforme 6 estratégias de tratamento de superfície e 2 condições de envelhecimento (24 horas e após o envelhecimento em água e termociclagem): AS (sem tratamento); TBS (jateamento de partículas de alumina revestidas por sílica e silanização); AAP (abrasão com partículas de alumina seguida da aplicação de primer universal); FS (pulverização de micropartículas de zircônia na superfície livre da Y-TZP e após, fusão por sinterização); SN (deposição de nanofilme de sílica com 5 nm) e FSSN (FS seguido de SN). Os blocos de Y-TZP foram embutidos em resina acrílica e microcilindros de cimento resinoso (0,96 mm de diâmetro; 1 mm de altura) (RelyX ARC) foram confeccionados na superfície cerâmica. Após o armazenamento, os testes de microcisalhamento foram conduzidos a uma velocidade de 1 mm/min, em máquina de ensaios universal. Após o teste, as superfícies foram analisadas com estereomicroscópio e microscópio eletrônico de varredura (MEV) para caracterização das falhas. Em um espécime adicional, também foi conduzida análise de fases do material por difração de raios-X e caracterização da micromorfologia de superfície em MEV. Os valores de resistência de união foram submetidos aos testes estatísticos Kruskal-Wallis e Mann Whitney para os tratamentos testados (p<0.001) e para o fator envelhecimento (p<0.05). Em ambas as condições de envelhecimento, TBS e AAP proporcionaram os maiores valores de resistência adesiva, seguidos dos grupos FSSN, FS e SN. O envelhecimento influenciou negativamente os resultados, com única exceção para o FS. A difractometria revelou aumento de conteúdo monoclínico nos grupos jateados. FS não alterou a percentagem de fase monoclínica. O jateamento de partículas de alumina seguido da aplicação de um primer com MPA apresentou-se tão efetivo quanto o tratamento triboquímico aliado ao silano, para o pré-tratamento da superfície da Y-TZP, no que diz respeito à resistência de união ao compósito.