Investigation of bonding properties of denture bases to silicone-based soft denture liner immersed in isobutyl methacrylate and 2-hydroxyethyl methacrylate

Hakan Akin,Faik Tugut,Burcu Mutaf,Umit Guney 대한치과보철학회 2014 The Journal of Advanced Prosthodontics Vol.6 No.2

PURPOSE. The purpose of this study was to investigate the bondingn properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS. Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and y mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minutes (Group 4) and resilient in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5mm/min. Data were evaluated by 1-way ANOVA and post hot Tukey-Kramer multiple comparisons tests (α=0.05). RESULTS. The highest mean value of force was observed in Group 3 sepcimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063) CONCLUSION. Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture based materials compared to the control group.

Investigation of bonding properties of denture bases to silicone-based soft denture liner immersed in isobutyl methacrylate and 2-hydroxyethyl methacrylate

Akin, Hakan,Tugut, Faik,Mutaf, Burcu,Guney, Umit The Korean Academy of Prosthodonitics 2014 The Journal of Advanced Prosthodontics Vol.6 No.2

PURPOSE. The purpose of this study was to investigate the bonding properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS. Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and 7 mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minute (Group 4), and resilient liner immersed in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5 mm/min. Data were evaluated by 1-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (${\alpha}$=0.05). RESULTS. The highest mean value of force was observed in Group 3 specimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063). CONCLUSION. Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture base materials compared to the control group.

New Eutectic High‑Entropy Alloys Based on Co–Cr–Fe–Mo–Ni–Al: Design, Characterization and Mechanical Properties

Hakan Gasan,Akin Ozcan 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

New eutectic high-entropy alloys based on novel (CoqCrvFewMoyNiz)100−xAlx alloy systems were designed using both thermodynamicand computational approaches. After considering 324 equilibrium diagrams, ten potential eutectic compositionswere determined to possess a eutectic point comprising FCC and B2 phases. (Co40Cr10Fe5Mo5Ni40)82,2Al17.8 was found tohave a fully eutectic structure through experimental analysis, which had a negligible error (0.23%) compared to that of thecomputational modeling. The XRD patterns showed that the alloy was composed of only FCC and B2 phases (with volumefractions of 73.4% and 26.6%, respectively) and did not contain σ phase, which was predicted by the computational modelto appear at low temperatures. Among all other alloys, the hypereutectic (18 at% Al) alloy exhibited the highest compressiveyield strength (729 MPa) and ultimate compressive strength (2844 MPa), and the hypoeutectic (16 at% Al) alloy had thehighest compressive ductility (~ 39%). For all fabricated alloys (hypoeutectic, eutectic, and hypereutectic), the compressivestrength and strain exceeded 2514 MPa and 27%, respectively.

Effects of Al on the Phase Volume Fractions and Wear Properties in the AlxCoCrFeMoNi High Entropy Alloy System

Hakan Gasan,Ersu Lökçü,Akin Ozcan,Osman Nuri Celik,Ibrahim Celikyurek,Mustafa Ulutan,Yavuz Kurtulus 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.3

A detailed investigation was carried out to study the effect of Al on the phase volume fractions and wear properties in theAlxCoCrFeMoNihigh entropy alloy (HEA) system. The analysis of phases was studied by X-ray diffraction for further Rietveldrefinement was performed to determine the volume fraction of phases. In order to accomplish experimental studies, thevolume fraction of phases has been analyzed by CALPHAD based simulations. The wear behavior of HEAs were studiedunder dry sliding conditions using a ball-on-disc geometry. The alloy system includes FCC, σ, B2 and BCC phases andexhibits a broad range of phase transformations with varying Al content. The wear behavior of HEAs, in the present work, iscorrelated with their volume fraction of phases and hardnesses. The minimum wear rate, 3.04 × 10−5 mm3/(Nm), is observedin A1.5CoCrFeMoNialloy containing relatively hard σ, B2 and BCC phases, which has a maximum hardness 829.8 HV.

Effect of repetitive firing on passive fit of metal substructure produced by the laser sintering in implant-supported fixed prosthesis

Altintas, Musa Aykut,Akin, Hakan The Korean Academy of Prosthodonitics 2020 The Journal of Advanced Prosthodontics Vol.12 No.3

PURPOSE. The aim of the present study was to investigate the passive fit of metal substructure after repetitive firing processes in implant-supposed prosthesis. MATERIALS AND METHODS. Five implants (4 mm diameter and 10 mm length) were placed into the resin-based mandibular model and 1-piece of screw-retained metal substructure was produced with the direct metal laser sintering (DMSL) method using Co-Cr compound (n = 10). The distance between the marked points on the multiunit supports and the marginal end of the substructure was measured using a scanning electron microscope (SEM) at each stage (metal, opaque, dentin, and glaze). 15 measurements were taken from each prosthesis, and 150 measurements from 10 samples were obtained. In total, 600 measurements were carried out at 4 stages. One-way ANOVA test was used for statistical evaluation of the data. RESULTS. When the obtained marginal range values were examined, differences between groups were found to be statistically significant (P<.001). The lowest values were found in the metal stage (172.4 ± 76.5 ㎛) and the highest values (238.03 ± 118.92 ㎛) were determined after glaze application. When the interval values for groups are compared with pairs, the differences between metal with dentin, metal with glaze, opaque with dentin, opaque with glaze, and dentin with glaze were found to be significant (P<.05), whereas the difference between opaque with metal was found to be insignificant (P=.992). CONCLUSION. Passive fit of 1-piece designed implant-retained fixed prosthesis that is supported by multiple implants is negatively affected by repetitive firing processes.

Gallstone Disease Does Not Predict Liver Histology in Nonalcoholic Fatty Liver Disease

( Yusuf Yilmaz ),( Talat Ayyildiz ),( Hakan Akin ),( Yasar Colak ),( Oguzhan Ozturk ),( Ebubekir Senates ),( Ilyas Tuncer ),( Enver Dolar ) 대한소화기학회 2014 Gut and Liver Vol.8 No.3

Background/Aims: We sought to examine whether the presence of gallstone disease (GD) in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD) is associated with liver fibrosis and histological nonalcoholic steatohepatitis (NASH) score. Methods: We included 441 Turkish patients with biopsy-proven NAFLD. GD was diagnosed in the presence of sonographic evidence of gallstones, echogenic material within the gallbladder with constant shadowing and little or no visualization of the gallbladder or absence of gallbladder at ultrasonography, coupled with a history of cholecystectomy. Results: Fifty-four patients (12.2%) had GD (GD+ subjects). Compared with the GD- subjects, GD+ patients were older, had a higher body mass index and were more likely to be female and have metabolic syndrome. However, GD+ patients did not have a higher risk of advanced fibrosis or definite NASH on histology. After adjustment for potential confounding variables, the prevalence of GD in NAFLD patients was not associated with significant fibrosis (≥2) (odds ratio [OR], 1.06; 95% confidence interval [CI], 0.53 to 2.21; p=0.68) or definite NASH (OR, 1.03; 95% CI, 0.495 to 2.12; p=0.84). Conclusions: The presence of GD is not independently associated with advanced fibrosis and definite NASH in adult Turkish patients with biopsy-proven NAFLD.

Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks

Ayse Gozde Turk,Mubin Ulusoy,Mert Yuce,Hakan Akin 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.6

PURPOSE. To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS. A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled (5-55°C, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS. The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION. Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks.

Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks

Turk, Ayse Gozde,Ulusoy, Mubin,Yuce, Mert,Akin, Hakan The Korean Academy of Prosthodonitics 2015 The Journal of Advanced Prosthodontics Vol.7 No.6

PURPOSE. To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS. A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled ($5-55^{\circ}C$, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS. The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION. Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks.