This work aimed to analyze the micro shear bond strength of ceramic and dental substrates to Multilink® Speed self-adhesive/curing resin cement (Ivoclar Vivadent, Schaan, Liechtenstein).
The groups ...were composed of (1) ceramic/cement interfaces: LD - Lithium Disilicate (IPS e.max CAD®); ZLS - Zirconia-reinforced lithium silicate (Celtra Duo®); Y-TZP MO – Medium Opacity Yttria-stabilized tetragonal zirconia polycrystal (IPS ZirCAD MO®); Y-TZP T - Translucency yttria-stabilized tetragonal polycrystal (IPS ZirCAD MT®), and by (2) cement/dental interfaces (enamel or dentin): E + E – selective phosphoric acid etching enamel; E - unetched enamel; Dentin - middle dentin. Ceramic blocks were sectioned into 2mm thick slices in a cutting machine with a diamond disc under cooling, followed by standardized polishing, crystallization or sintering, PVC inclusion, final polishing, and surface treatments according to each ceramic composition (n=20). Teeth slices (2mm thick) were obtained from human third molars, PVC included, followed by polishing. The cement cylinders (Ø = 1.4; height = 1.0) were bonded to substrates, following the manufacturer's instructions. The specimens were stored in deionized water at 37°C for 24h and subjected to the micro shear bond strength test. Data were submitted to statistical analysis using the Kruskal-Wallis and Dunn tests. Failure types were classified as adhesive, cohesive, and mixed, with a representative specimen of each failure submitted to a scanning electron microscope (SEM). Weibull statistical analysis was performed to obtain the following metrics: the probability of failure, Weibull modulus (m) (reliability), and characteristic strength (σ0).
The E + E group showed the highest median value, lower probability of failure, higher reliability, and higher characteristic strength among all the evaluated groups, with significant similarity to the ZLS and LD groups and a statistically significant difference to the other dental substrates. E and Dentin showed the lowest medians among all substrate types. The Glass-ceramics the ZLS showed high characteristic strength and the LD showed greater reliability. The adhesive failure mode was predominant among the failure types.
Glass-ceramics showed higher characteristic strength, lower probability of failure, and greater reliability, being similar to selectively etched enamel.
Hydroxyapatite (HA) from bovine bone structure has high importance among biomaterials due to its biocompatibility, bioactivity and its sustainable renewable source. However, pure dense HA bioceramics ...still present poor mechanical properties when used in a dense form to be applied as an implant or restoration material. Thus, this study aimed to characterize the thermal behavior of pure bovine HA powder as well as evaluate its behavior when subjected to two sintering methodologies.
Therefore, HA was extracted from bovine bones, turned into nanoparticles in a ball mill and subjected to uniaxial and isostatic pressing into discs, according to the ISO 6872 standard. Two sintering methodologies were used: 1) conventional curve (HA/Conv), in a single curve with a maximum temperature peak of 1300 °C and slow cooling to room temperature; and 2) 2-step curve (HA/2step) with a maximum peak of 950 °C with rapid cooling to 880°C and subsequent slow cooling to room temperature. The nanoparticulate powder was subjected to differential thermal analysis (DTA), dilatometry and x-ray diffractometry (XRD). The sintered samples of both groups were characterized by XRD, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) relative density and biaxial flexural strength.
The dilatometric curve shows the beginning of the sintering process at 1050 °C. In the DTA analysis it was possible to observe a gain in mass in about 650 °C with subsequent loss of part of the acquired mass until reaching a temperature of 1000 °C. The XRD analysis demonstrates the classic crystallographic peaks both before and after the sintering process by the two groups, showing no change in the crystalline characteristic. The FTIR spectrum demonstrated the classical bands of HA-related bonds. The HA/Conv group obtained statistically higher values of relative density (2.92g/cm3) and in flexural strength (109MPa) (p<0.05). The results of the HA/2step group (2.08g/cm3; 25.7MPa) are justified by the SEM images that demonstrate greater porosity and less cohesion between the ceramic grains.
It was possible to conclude that the HA bioceramics submitted to temperatures above 1000 °C, can reach a higher degree of sintering and densification, thus optimizing its mechanical properties.
The objective of this study was to evaluate the influence of adhesives with different 10-MDP concentrations on the shear bond strength of a resin cement to zirconia.
Six experimental adhesives were ...prepared with the following composition: camphorquinone, 1,2-diaminobenzene, butylhydroxytoluene, diphenyliodonium hexafluorophosphate, 2-hydroxyethyl methacrylate triethylene glycol dimethacrylate, ethoxylated bisphenol A glycol dimethacrylate, urethane dimethacrylate, bisphenol A diglycidyl methacrylate, and ethanol. The 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) monomer was added at 0wt%, 3wt%, 6wt%, 9wt%, 12wt%, or 15wt%. Three commercially available adhesives were evaluated: Single Bond Universal, Single Bond 2, and Signum Zirconia Bond. Resin cement cylinders made with RelyX Ultimate were bonded to yttria-stabilized tetragonal zirconia polycrystal with one of the evaluated adhesives and were subjected to the shear bond strength evaluation. Failure modes were analyzed with a stereoscopic loupe. Statistical analyses were performed with one-way analysis of variance and the Tukey's Honestly Significant Difference test (α=0.05). Pearson's was used to correlate the percentage of 10-MDP in the experimental adhesives and shear bond strength.
There were significant differences between adhesives (p<0.00001). The highest shear bond strength values were obtained with the Signum Zirconia Bond and Single Bond Universal. Single Bond 2 showed the lowest values. There were no differences between experimental adhesives. All groups showed adhesives failures. A nonlinear correlation was found between bond strength and percentage of 10-MDP in experimental adhesives (r=0.872).
The commercially available adhesives indicated for bonding to zirconia showed the highest bonding values.
The present in vivo randomized, triple-blinded, and split-mouth clinical study evaluated the effectiveness of a hybrid light (HL) source on the color change, stability, and tooth sensitivity in ...patients submitted to different in-office bleaching techniques. Twenty volunteers were divided into two groups and four subgroups. A split-mouth design was conducted to compare two in-office bleaching techniques (with and without light activation): 35% Lase Peroxide Sensy (LPS) + HL: 35% hydrogen peroxide (HP) + HL; 35% LPS: 35% HP; 25% LPS + HL: 25% HP + HL; and 35% Whiteness HP (WHP): 35% HP. For the groups activated with HL, the HP was applied on the enamel surface three consecutive times using a 3 × 2-minute protocol (three HL activations for two minutes each, with a 30-second interval for a total of seven minutes and 30 seconds) for each gel application, totaling 22 minutes and 30 seconds. For the other groups, HP was applied 3 × 15 minutes, totaling 45 minutes. A spectrophotometer was used to measure the color change (ΔE) before the treatment and 24 hours, one week, and one, 12, and 36 months after. A visual analog scale was used to evaluate the tooth sensitivity before the treatment, immediately following treatment, 24 hours, and one week after. Analysis of variance, Tukey's, Kruskall-Wallis, and Wilcoxon tests, all with α = 0.05 were performed. Statistical analysis did not reveal any significant differences (ΔE) between the in-office bleaching techniques with or without HL in the periods evaluated; the activation with HL required 50% less time to achieve such results. The groups without HL presented statistical differences for ΔE when comparing 24 hours with the other follow-up times (intergroup) and an increase in tooth sensitivity in the initial periods. All techniques and bleaching agents were effective on bleaching during a 36-month evaluation of color stability. The groups activated with HL presented lower sensitivity and required a lower activation time.
The aim of this clinical report is to present a possible alternative treatment, with 24-month follow-up, for restoring tooth loss due to extensive erosive tooth wear. A 21-year-old male patient, ...complaining of intense sensitivity in the maxillary posterior teeth, and presenting severe wear on maxillary premolar and molar teeth due to gastroesophageal reflux, sought care in the university clinics. The planned treatment was to refer for medical treatment and perform restorations with the high-viscosity glass ionomer cement Equia Forte (GC Corporation, Tokyo, Japan), aiming to restore the dental anatomy and to consequently decrease the pain symptomatology. A silicone guide, obtained from a diagnostic waxing, was used during the restorative approach considering the patient's occlusion. After all the clinical steps of the restorative technique, an occlusal adjustment of restorations was performed. During monthly recalls up to 24 months, the treatment was stable and in service. In addition, the patient reported no pain and improved chewing, leading to a better quality of life.
To evaluate the quality of primary and permanent dentin by Fourier transformed Raman spectroscopy (FT-Raman), and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS).
The middle ...dentin of crowns was reached by carbide bur abrading providing a uniform smear layer. Self-etching primers were applied in order to simulate the etching of self-etching adhesive systems. The groups were (n = 6): G1 (primary dentin smear layer); G2 (primary dentin etched by primer of Clearfil Protect Bond); G3 (primary dentin etched by Adper Prompt); G4 (permanent dentin smear layer); G5 (permanent dentin etched by primer of Clearfil Protect Bond); G6 (permanent dentin etched by Adper Prompt). SEM/EDS were made in order to obtain additional elemental data to complement FT-Raman. FT-Raman data were submitted to cluster analysis.
Overall, FT-Raman showed differences between primary and permanent dentin concerning organic content, but not for inorganic content. FT-Raman showed differences in the organic content between primary and permanent dentin after self-etching primer use. HEMA usage caused molecular changes in the organic content, while phosphoric acidic ester caused molecular changes in the inorganic content of primary and permanent dentin. The SEM/EDS identified C, O, P, and Ca, which could not replace ions to change mineral molecular arrangement. Both organic and mineral content arrangements were similar after self-etching primers action. The organic content of dentin was modified by both Clearfil PB primer and Adper Prompt for primary dentin but only by Clearfil PB for permanent dentin. The inorganic content of primary middle dentin was similar to the inorganic content of permanent middle dentin, even when Adper Prompt is used.
Observations on collaboration in agile software development Franca, J. B. S.; Dias, A. F. S.; Borges, M. R. S.
2015 IEEE 19th International Conference on Computer Supported Cooperative Work in Design (CSCWD),
05/2015
Conference Proceeding
Collaboration is an important concept for workgroups involved in agile development processes. However, enhancing collaboration within those groups is not an easy task. This research aims to create a ...Collaboration Observation Framework (COF) suitable for workgroups that practice agile software development fundamentals. To this end, observations were conducted in agile development workgroups to validate and identify criteria for the collaboration evaluation. In this paper, COF is presented, and its applicability is discussed in the representatives' workgroup view.
