Search results for "strength"
showing 10 items of 2415 documents
Bond strength of lithium disilicate after cleaning methods of the remaining hydrofluoric acid
2020
Background Complex implant treatments have steadily increased within implant prosthodontics. Based on the lower implant mobility, implant impressions need high accuracy in the model transfer to receive a high passive fit within the final prosthodontic restoration. To analyze the accurate 3-dimensional (3D) inter-implant-positions, a reference point is indispensable. However, there is no reference in the patients mouth, so the aim of the present study was to develop a new method based on a custom-made-measuring-aid (CMA) to assess the inter implant dimensions (InID) in patients. Material and Methods Initially an implant master model (IMM/patient equivalent) was digitized by computed tomograp…
Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics
2012
Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of th…
Bond strength evaluation of the veneering-core ceramics bonds.
2009
The purpose of this study was to determine whether the bond of veneering porcelain to a ceramic core in bilayered ceramics was similar to that of the metal ceramic control of well known behaviour. Six groups of nine specimens each were fabricated, whose dimensions were 15 mm long and 8 mm in diameter at the core, and 2 mm long and 8 mm in diameter for the veneer. The groups were GR. 1 (control group): CrNi alloy/d.SIGN (Ivoclar), GR. 2: IPS e.maxPress/IPS e.maxCeram (Ivoclar), GR. 3: IPS e.maxZirCad/ IPS e.maxZirPress (Ivoclar), GR. 4: IPS e.maxZirCad/IPS e.maxCeram (Ivoclar), GR. 5: Lava Frame (3M ESPE)/ Lava Ceram (3M ESPE) and GR. 6: Lava Frame (3M ESPE)/IPS e.maxCeram (Ivoclar). A shear…
Microstructure and mechanical effects of spark plasma sintering in alumina monolithic ceramics
2013
The specific effects of spark plasma sintering (SPS) on the creep behavior, microstructure and mechanical properties of alumina monolithic ceramic were investigated. SPS introduces strains that concentrate at grain boundaries and inhibit crack growth, resulting in an improvement in the flexural strength and fracture toughness. However, creep blocks grain boundary movements and decreases the reliability of the material. These strains can be removed by a post-sintering thermal treatment, which plays an important role in the distribution of dislocations.
Effects of femtosecond laser and other surface treatments on the bond strength of metallic and ceramic orthodontic brackets to zirconia.
2017
Femtosecond laser has been proposed as a method for conditioning zirconia surfaces to boost bond strength. However, metallic or ceramic bracket bonding to femtosecond lasertreated zirconia surfaces has not been tested. This study compared the effects of four conditioning techniques, including femtosecond laser irradiation, on shear bond strength (SBS) of metallic and ceramic brackets to zirconia.Three hundred zirconia plates were divided into five groups: 1) control (C); 2) sandblasting (APA); 3) silica coating and silane (SC); 4) femtosecond laser (FS); 5) sandblasting followed by femtosecond laser (APA+SC). A thermal imaging camera measured temperature changes in the zirconia during irrad…
Mechanical performance of experimental acrylic resins modified by nanoparticles after chemical and mechanical degradation.
2020
Background Different materials have been incorporated into the polymethylmethacrylate matrix to improve its performance. The aim of this study was to evaluate the degree of conversion (DC), the flexural strength (FS), the elasticity modulus (EM), and the effect of exposure to food-simulating liquids prior to brushing simulation on the gloss loss (GL) of experimental acrylic resins modified by nanoparticles. Material and methods Three different types of nanoparticles; silicon oxide (SiO2), cerium oxide (CeO2) and titanium oxide (TiO2) were added to a poly (methylmethacrylate) matrix, in proportions of 0.5wt%, 1wt% and 3wt% each, forming nine experimental groups. The acrylic resin was also te…
Taopatch® combined with home-based training protocol to prevent sedentary lifestyle and biochemical changes in MS patients during COVID-19 pandemic
2021
In Multiple sclerosis (MS) it is important to preserve the residual physiological functions of subjects. The aim of the present study was to investigate the influence of nanotechnological device treatment combined with home-based training program (TP) on lactate level, hand grip strength and cervical mobility on MS patients. Seventeen MS patients were enrolled in the study and randomly assigned to an experimental group (EG) in which the Taopatch® nanotechnological device was applied or to a control group (CG). All the participants carried out a cervical range of motion (1) assessment and the hand grip test at baseline (T0) and after TP (T1), also investigating the lactate levels to figure o…
Secular trends in muscular fitness among Finnish adolescents.
2010
Aim: To investigate secular change over time in health-related muscular fitness and how leisure time physical activity (LTPA), sport club participation, and body mass index are associated with muscular fitness in adolescents. Methods: Two cross-sectional samples of Finnish 13—16-year-old adolescents were studied in 1976 (n = 643; 312 boys and 331 girls) and in 2001 (n = 579; 308 boys and 271 girls). Muscular fitness index was calculated as the sum of age- and sex-specific z-scores of four tests measuring muscular fitness and agility. Height and weight were also measured. Self-reported weekly frequency of LTPA of at least 30-min duration and regularity of participation in organised sport we…
Longitudinal associations of student–teacher relationships and behavioural and emotional strengths on academic achievement
2017
Positive student–teacher relationships are related to students’ academic achievement and behavioural and emotional adjustment. How a student’s behavioural and emotional strengths are associated with these relationships and how the relationships influence students’ academic performance remains unknown. We examined this framework using a cross-lagged panel model with a group of Finnish students and their parents from Grade 5 to Grade 7. The results revealed that the parents rated behavioural and emotional strengths are stable over a 1-year (r = .78) and 2-year (r = .71) period and that students’ perceptions of student–teacher relationships demonstrated greater change over time (r’s = .54, .35…
The Effect of Taper and Apical Diameter on the Cyclic Fatigue Resistance of Rotary Endodontic Files Using an Experimental Electronic Device
2021
The aim of this study was to analyze the effect of the taper and apical diameter of nickel&ndash