Gulsen Can

Effect of surface treatments of porcelain on the shear bond strength of applied dual-cured cement

The effect of different surface treatments of porcelain on the shear bond strength of the applied dual-cured cement was examined. Acid etching with hydrofluoric acid, roughening the porcelain surface by means of grinding with a diamond bur, and the use of silane coupling agent alone and with combinations of these surface treatments were used. Silane treatment resulted in a shear bond strength on roughened porcelain surfaces that was statistically significantly greater than all other treatment groups (p < 0.05). However the use of two mechanical bond systems together with a chemical bond did not improve the shear bond strength.

Retentive characteristics of different dental magnetic systems

It is necessary to recognize the retentive capabilities of magnetic systems to assess their clinical performance. This study determined the retentive characteristics of one open-field and two closed-field commercial dental magnetic systems. The effect of speed of separation and the space between the magnet and its keeper on the retention force were evaluated. The magnets and their respective keepers, embedded in acrylic resin blocks, were tested with fast and slow speeds of separation. The maximum retention values of the magnetic systems were tested with slow speed of separation. The fast speed of separation was designed to reflect mandibular movement. Various spaces were developed between the magnets and their respective keepers, and magnetic systems were tested only in slow speed of separation. The fast speed of separation dramatically lowered the retention force of each magnetic system. As the space increased between the magnet and keeper, the retention values diminished rapidly. While closed-field systems demonstrated higher retentive forces than the open-field system, the open-field system was less affected by the various spaces.

Coating of silicone-based impression materials in a glow-discharge system by acrylic acid plasma.

OBJECTIVES The main purpose of this study was to demonstrate an increase in the wettability of silicone-based impression materials after coating them with a hydrophilic film in a glow-discharge system. METHODS Two vinyl polysiloxane impression materials, Extrude (Kerr) and Accuflex (GC America Inc.) were used. Impression specimens were treated in a glow-discharge reactor at a radio frequency of 13.56 MHz at different discharge powers (5-20 W) and exposure times (5-60 min). Surface analysis of the specimens was done by FTIR. Surface contact angles were obtained by a captive-bubble method. These results were analyzed by ANOVA and Duncans Multiple Range test (p < 0.05). The total number of voids on the die stone casts was observed microscopically. Linear dimensional accuracy, detail reproducibility, and surface hardness of the die stone casts were also determined. A Student t-test was performed for statistical analysis of these parameters (p > 0.05). RESULTS FTIR spectra indicated that the number of hydroxyl groups on the surfaces increased (p > 0.05) because of the glow-discharge treatment. Contact angle measurements showed an increase (p < 0.05) in surface hydrophilicity. Total void formation in the stone casts decreased. There were no significant differences in the linear dimensional accuracy, detail reproducibility, and hardness, before and after glow-discharge treatment (p > 0.05). SIGNIFICANCE It was concluded that the surface wettability of the impression materials may be increased by plasma deposition, and therefore, the formation of voids was reduced in the stone casts.

Stability and Marginal Bone Level Changes of SLActive Titanium-Zirconium Implants Placed with Flapless Surgery: A Prospective Pilot Study

BACKGROUND Immediately-loaded, narrow-diameter implants can be a less invasive alternative for the implant-supported fixed rehabilitation of narrow, posterior crests. PURPOSE To determine the stability and marginal bone level (MBL) changes of narrow-diameter, titanium-zirconium (TiZr) implants placed with flapless surgery and loaded immediately in the posterior region. MATERIALS AND METHODS Thirty-eight TiZr implants (3.3 mm diameter, 10 mm length, Roxolid, Straumann AG) were placed in the posterior crests of 14 patients with computer-guided flapless surgery as a support of 3-unit posterior bridges. Eighteen implants were loaded immediately, and 20 implants were loaded conventionally. The implant stability quotients were determined at the 1, 2, 4, and 8. weeks of healing before conventional loading, and at the 3, 6, and 12. months after loading by resonance frequency analysis. The MBL changes were measured by digital radiography. RESULTS The surgical protocols were accomplished without any biological complications. There was no significant difference in the stability changes of TiZr implants between the loading groups (p > .05). The MBL changes were -0.18 ± 0.27 mm and -0.24 ± 0.27 mm at the 12. month of immediate and conventional loading, respectively, which was not statistically significant (p > .05). CONCLUSION The stability and MBL changes of TiZr implants supporting posterior 3-unit bridges were clinically acceptable at the first year of loading.

Effects of environment on the release of Ni, Cr, Fe, and Co from new and recast Ni-Cr alloy.

STATEMENT OF PROBLEM The addition of previously cast alloy to new alloy for economic reasons may increase the release of elements. PURPOSE The purpose of this study was to analyze the effects of the immersion period, immersion media, and addition of previously cast alloy to new alloy on the release of elements. MATERIAL AND METHOD Disk-shaped specimens were prepared from a Ni-Cr alloy (Ni: 61 wt%, Cr: 26 wt%, Mo: 11 wt%, Si: 1.5 wt%, Fe, Ce, Al, and Co <1 wt%) (Remanium CS; Dentaurum) with new alloy (group N) and 50% new/50% recast alloy (group R). After the immersion of the specimens in both NaCl (pH 4) and artificial saliva (pH 6.7) for 3, 7, 14, 30, and 60 days, the release of ions was determined by using atomic absorption spectrometry. Data were analyzed with a 3-way ANOVA (α=.001). RESULTS The release of Ni was significantly affected by the immersion period, of Ni and Cr by the alloy and media (P<.01), and of Fe by the alloy (P<.01). Ion release from the recast alloy in artificial saliva was 109.71 for Ni, 6.49 for Cr, 223.22 for Fe, and 29.90 μg/L for Co. The release of Co in NaCl was below the detection limit in both groups. CONCLUSION The release of Ni in NaCl and artificial saliva increased with the length of the immersion period in both groups. The release of Cr and Fe was higher in artificial saliva than in NaCl in group R, regardless of the immersion period. The release of Co in NaCl was below the detection limit in both groups.

Zinc Inhibits Collagenolysis by Cathepsin K and Matrix Metalloproteinases in Demineralized Dentin Matrix

The enzymatic degradation of dentin organic matrix occurs via both the action of matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs). Zinc can prevent collagen hydrolysis by MMPs. However, its effect on the activity of dentin-bound CCs is not known. The aim of this study was to investigate the effect of zinc on matrix-bound cathepsin K and MMP activity in dentin. Completely demineralized dentin beams were divided into test groups (n = 9) and incubated at 37°C in an incubation media (1 mL) containing ZnCl2 of 0.02 (physiological level, control), 0.2, 0.5, 1, 5, 10, 20, 30, or 40 mM. The dry mass changes of the beams were determined, and incubation media were analyzed for cathepsin K- and MMP-specific collagen degradation end products - CTX (C-terminal cross-linked telopeptide of type I collagen) and ICTP (cross-linked carboxy-terminal telopeptide of type I collagen) - at 1, 3, and 7 days of incubation. The mass loss of the beams decreased when the zinc level in the incubation media was ≥5 mM (p < 0.05). The release of liberated collagen degradation telopeptides decreased in accordance with the decrease in the mass loss rates of the beams. Cathepsin K-induced dentin collagen degradation can be strongly inhibited by zinc. Zinc levels of ≥5 mM can be considered as a reliable threshold for the stabilization of dentin matrices.

Yetişkin bireylerde yaş ve cinsiyet ile ilişkili diş kaybı ve parsiyel dişsizlik

Amac: Koruyucu onlemler ve restoratif tekniklerdeki gelismelere ragmen, dis kaybi gunumuzde hala onemli bir sorun olarak karsimiza cikmaktadir. Bir toplumdaki dissizlik oraninin belirlenmesi hastalara ozgu tedavi alternatiflerinin ortaya konulmasinda yeni bir bakis acisi saglayabilir. Bu bakimdan, calismamizda cinsiyet ve yas faktorlerinin dis kaybi ve dissizlik uzerine etkisini degerlendirmek amaclanmistir. Gerec ve Yontemler: Ankara Universitesi, Dishekimligi Fakultesi, Protetik Dis Tedavisi Anabilim Dali’ na 2015-2016 yillari arasinda dissizlik tedavisi icin basvuran hastalardan (188 kadin, 173 erkek hasta; yas araligi 28-79) 722 adet maksiller ve mandibular teshis modeli elde edilmistir. Tum modeler tam disli, Kennedy Sinif I-IV ve tam dissiz olmak uzere 6 grup altinda incelenmistir. Her bir model hastanin yas ve cinsiyetine gore siniflandirilmistir. Ki-kare testi ve log-lineer model analizi ile istatistiksel degerlendirmeler yapilmistir (p˂0,05). Ayrica odds oranlari da hesaplanmistir. Bulgular: Yas, dis kaybi ve dissizlik uzerinde etkili bir faktor olarak bulunurken (p 0,05). Cinsiyet esas alindiginda, 34, 36 ve 37 numarali dislerin kaybi bayanlarda daha yaygin gorulurken (p<0,05), 24 numarali dis kayip orani erkeklerde daha yuksek tespit edilmistir (p<0,05). Sonuc: Yas ile birlikte dis kaybi ve dissizlik onemli oranda artmasi ancak cinsiyet ile dis kaybi ve dissizlik arasinda onemli bir iliski bulunmamasi, agiz sagligini koruyucu onlemlerin ileri yaslardaki bireylerde arttirilmasi geregini ortaya koymustur.