Comparative physical and mechanical properties of a 3D printed temporary crown and bridge restorative material

The objective was to compare physic-mechanical properties of different materials used for temporary restorations.Protemp 4/bisacrylic resin, Jet/acrylic resin, and Nexdent C&B/3D-printed resin samples (10mm diameter x 2mm thickness) were analyzed for surface roughness and color stability tests (baseline, after 5 thousand brushing cycles; and after artificial aging in water at 60oC for 24 hours) and Knoop microhardness. All data were checked for normality using Shapiro-Wilk test. Surface roughness and color stability were analyzed using two-way repeated measurements ANOVA, microhardness data was subjected to one-way ANOVA. All tests were followed by Tukey test and were performed with α=0.05.For roughness, material (p=.002), time points (p=.002) and interaction between both (p<.001) were significant. All groups presented similar roughness for measurements of baseline and after brushing. After artificial aging, 3D printed resin showed decreased roughness when compared with other resins, and with its baseline reading. Acrylic resin showed an increase in surface roughness (when compared with measurement after brushing cycles). Considering color stability, only the material (p=.039) and the time (p<0.001) were significant. All groups showed similar color variation before and after artificial aging. There was an increase in color alteration after artificial aging for all groups. Considering microhardness test (p<.001), the 3D printed resin showed the highest values and acrylic resin the lowest. Bysacylic resin was similar to both 3D printed and acrylic resins.The tested 3D printed resins present similar or better properties than other tested temporary materials while being integrated with the digital workflow

Influence of the conditioning technique of a lithium disilicate vitroceramic

Introduction: Lithium disilicate reinforced glass ceramics are materials that require good adhesion to ensure clinical success. Objective: To evaluate the bond strength of resin cements to lithium-disilicateenhanced vitroceramics using different cleaning techniques of recently conditioned ceramics. Material and methods: Twelve ceramic discs (IPS Empress II) were made and inserted into PVC pipes using acrylic resin. The ceramic surface was designed and submitted to a 10% hydrofluoric acid conditioning process for 20s. Then, the specimenswere divided into 3 groups (n = 16) according to the cleaning techniques of recently conditioned ceramics: 1) control - conventional technique (no cleaning after the conditioning process); 2) application of 37% phosphoric acid for 20s; 3) 90% ethyl alcohol bath in a ultrasound tub for 4 min. After cleaning, the silane agent was applied for 1 minute and silicon matrices (1 mm in diameter x 1 mm in height) were made for further application of the resin cement (Vitique, DMG), which was handled according to the manufacturer’s instructions. Four cylinders were prepared on each ceramic surface. The specimens were storedin distilled water for 48 hours and subjected to the micro-shear test in a universal testing machine. After the micro-shear test, a failure analysis of the specimens was performed. Data were submitted to ANOVA (analysis of variance for a criterion) with a significance level of 5%. Results: There was no significant difference between groups (p > 0.05). Conclusion: the cleaning technique of the recently conditioned ceramics does not interfere with the resin/cement bond strength valuesIntroduction: Lithium disilicate reinforced glass ceramics are materials that require good adhesion to ensure clinical success. Objective: To evaluate the bond strength of resin cements to lithium-disilicateenhanced vitroceramics using different cleaning techniques of recently conditioned ceramics. Material and methods: Twelve ceramic discs (IPS Empress II) were made and inserted into PVC pipes using acrylic resin. The ceramic surface was designed and submitted to a 10% hydrofluoric acid conditioning process for 20s. Then, the specimenswere divided into 3 groups (n = 16) according to the cleaning techniques of recently conditioned ceramics: 1) control - conventional technique (no cleaning after the conditioning process); 2) application of 37% phosphoric acid for 20s; 3) 90% ethyl alcohol bath in a ultrasound tub for 4 min. After cleaning, the silane agent was applied for 1 minute and silicon matrices (1 mm in diameter x 1 mm in height) were made for further application of the resin cement (Vitique, DMG), which was handled according to the manufacturer’s instructions. Four cylinders were prepared on each ceramic surface. The specimens were storedin distilled water for 48 hours and subjected to the micro-shear test in a universal testing machine. After the micro-shear test, a failure analysis of the specimens was performed. Data were submitted to ANOVA (analysis of variance for a criterion) with a significance level of 5%. Results: There was no significant difference between groups (p > 0.05). Conclusion: the cleaning technique of the recently conditioned ceramics does not interfere with the resin/cement bond strength value

Influence of the concentration and type of functionalization of TiO2 nanostructures on the properties of experimental resins

O objetivo deste trabalho in vitro foi avaliar a influência de diferentes concentrações de nanoestruturas de TiO2 funcionalizadas e não-funcionalizados nas propriedades de uma resina experimental. Nanotubos e nanopartículas de TiO2 foram sintetizadas e funcionalizadas utilizando o silano 3-(aminopropil) trietoxisilano (APTMS) e o 3-(trimetoxisilil)propil metacrilato (TSMPM). As nanoestruturas de TiO2 foram caracterizadas através de difratometria de raios X, EDS, potencial Zeta, MEV e MET. Foi preparada uma resina experimental contendo BisGMA/TEGDMA e foram divididos de acordo com a nanoestrutura de TiO2 (nanotubo e nanopartícula), concentração (0,3% e 0,9%) e funcionalização (APTMS e TMSPM). Noventa e um discos de resina foram confeccionados (n=7) e fotoativados (1000 mW/cm2). O Grau de conversão (GC) foi avaliado imediatamante e após 24 horas e a microdureza Knoop (KHN) foi avaliada após 7 dias e após imersão em etanol 100% para análise de densidade de ligações cruzadas. Os testes foram submetidos à análise estatística através de ANOVA a um critério com medidas repetidas e Tukey (=0,05). Para o grau de conversão, houve diferença significante entre as resinas (p < 0.001) e o tempo (p < 0.001). Para a KHN, houve diferenças estatísticas entre as resinas (p < 0.001), após imersão no álcool (p < 0.001) e houve interação entre as variáveis (p < 0.001). Os maiores valores de GC foram encontrados no período de 24 horas para os grupos com nanotubos de TiO2 na concentração de 0,3% funcionalizados com TMSPM. Resultados satisfatórios também foram encontrados para nanopartículas de TiO2 na concentração de 0,9%. Os mesmos resultados também foram observados para a dureza após imersão em etanol. Pode-se concluir que as nanoestruturas de TiO2 possuem diferentes características e podem interferir diretamente nas propriedades da resina avaliada.The aim of this in vitro study was to evaluate the influence of different concentrations of functionalized and non-functionalized TiO2 nanostructures on the properties of an experimental resin. TiO2 nanotubes and nanoparticles were synthesized and functionalized by 3- (aminopropyl)triethoxysilane (APTMS) and 3-(trimethoxysilyl)propyl methacrylate (TSMPM). TiO2 nanostructures were characterized by x-ray diffractometer, EDS, zeta potential, SEM, and TEM. Bis-GMA/TEGDMA resin mixtures were prepared and divided according to TiO2 nanostructure (nanotube and nanoparticle), concentration (0.3 and 0.9%), and functionalization (APTMS and TSMPM). Ninety-one resin discs were made (n = 7) and photoactivated (1000 mW/cm2). The degree of conversion (DC) was evaluated immediately and after 24 hours, and Knoop hardness (KHN) was evaluated after 7 days and after immersion in 100% ethanol for analysis of crosslink density. Data were analyzed with one-way repeated measures ANOVA and Tukey\'s HSD ( = 0.05). For DC, there was a significant difference between resins (p < 0.001) and times (p < 0.001). For KHN, significant differences were found between resins (p < 0.001) and between before and after immersion in alcohol (p < 0.001). The resin × hardness interaction was significant (p < 0.001). The highest values of DC were found at 24 hours for the groups with 0.3% TiO2 nanotubes functionalized with TSMPM. The same results were also observed for hardness after immersion in ethanol. We conclude that TiO2 nanostructures have different characteristics and can directly interfere with the properties of the resin

Dentin bond strength evaluation between a conventional and universal adhesive using etch-and-rinse strategy

Aim: The aim of this study was to compare the microtensile bond strength (μTBS) and the characteristics of the adhesive interface of Scotchbond Universal - SU – etch-and-rise mode (3M ESPE) and Adper Scotchbond Multi-Purpose - MP (3M ESPE) to dentin over time. Methods: Class I cavity preparations were performed in 60 human molars that were randomly divided according to the dentin bonding system (DBS) used (n=30): (1) Acid conditioning + SU and (2) Acid conditioning + MP. For bonding strength (BS) analysis, 30 teeth (n = 15) were sectioned into sticks and submitted to the microtensile test in a universal testing machine after 24 hours and 12 months. The adhesive interface of the others 30 teeth was analyzed in a confocal microscope after 24 hours and 12 months. The data of μTBS were analyzed by two-way repeated measures ANOVA and Tukey’s HSD (α = 0.05). Results: SU presented the lowest DBS compared to MP (p=0.000). Time did not influenced DBS for both adhesive systems (p=0.177). Confocal microscopy analysis showed no cracks between both adhesive systems tested. Conclusion: The results indicate that MP - μTBS showed a better performance compared to SU in total-etch mode