Canan Akay

Resin cementation of zirconia ceramics with different bonding agents

The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations.

Influence of nano alumina coating on the flexural bond strength between zirconia and resin cement

PURPOSE The purpose of this in vitro study is to examine the effects of a nano-structured alumina coating on the adhesion between resin cements and zirconia ceramics using a four-point bending test. MATERIALS AND METHODS 100 pairs of zirconium bar specimens were prepared with dimensions of 25 mm × 2 mm × 5 mm and cementation surfaces of 5 mm × 2 mm. The samples were divided into 5 groups of 20 pairs each. The groups are as follows: Group I (C) – Control with no surface modification, Group II (APA) – airborne-particle-abrasion with 110 µm high-purity aluminum oxide (Al2O3) particles, Group III (ROC) – airborne-particle-abrasion with 110 µm silica modified aluminum oxide (Al2O3 + SiO2) particles, Group IV (TCS) – tribochemical silica coated with Al2O3 particles, and Group V (AlC) – nano alumina coating. The surface modifications were assessed on two samples selected from each group by atomic force microscopy and scanning electron microscopy. The samples were cemented with two different self-adhesive resin cements. The bending bond strength was evaluated by mechanical testing. RESULTS According to the ANOVA results, surface treatments, different cement types, and their interactions were statistically significant (P<.05). The highest flexural bond strengths were obtained in nanostructured alumina coated zirconia surfaces (50.4 MPa) and the lowest values were obtained in the control group (12.00 MPa), both of which were cemented using a self-adhesive resin cement. CONCLUSION The surface modifications tested in the current study affected the surface roughness and flexural bond strength of zirconia. The nano alumina coating method significantly increased the flexural bond strength of zirconia ceramics.

Effectiveness of disinfectants on the adherence of Candida albicans to denture base resins with different surface textures

The aim of the present study was to compare the effects of some disinfectants, including ethanol extract of propolis (EEP), on the adhesion of Candida albicans to denture base resins. Seventy-two acrylic resin samples were prepared, half of which was polished and the other half was roughened. C. albicans strain ATCC 10231 was incubated on Sabouraud dextrose agar (SDA) at 37°C for 48 h. The adhesion period was completed by keeping the cells in this suspension for 90 min at 37°C. Specimens were then immersed in the following solutions: 1%, 2%, and 5% sodium hypochlorite; 4% chlorhexidine gluconate; and 10% EEP. Quantification of the antifungal activity of the chemical solutions was performed using the colorimetric MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay test. One-way ANOVA and post-hoc Tukey tests were performed to evaluate the effectiveness of chemical agents. Polished and roughened surfaces were compared using independent sample t-test. The mean surface roughness value was 0.35 (±0.04) µm for the polished group and 1.2 (±0.2) µm for the roughened group. The contact angles of both surfaces showed statistically significant difference, and 10% EEP solution exhibited significantly less removal of adherent viable C. albicans cells in both groups. All forms of sodium hypochlorite solutions yielded higher efficiency than 4% chlorhexidine gluconate and EEP solutions (P < 0.05). (J Oral Sci 58, 431-437, 2016).

In vitro shear bond strength between fluorinated zirconia ceramic and resin cements

PURPOSE The purpose of this study was to evaluate the efficiency of a gas-phase fluorination method under different fluorination periods through using two resin cements. MATERIALS AND METHODS 84 zirconia specimens in dimensions of 5 mm × 5 mm × 2 mm were prepared and surface treated with 50 µm aluminum oxide particles or gas phase fluorination for 2 min, 5 min, or 10 min. One specimen in each group was surface analyzed under scanning electron microscope. The remaining specimens were bonded to composite cylinders in dimensions of 2 mm diameter and 3 mm high with Panavia SA Plus or Variolink N. Then, the specimens were stored in 37℃ distilled water for 24 hours and shear bond strength test was applied at a speed of 1 mm/min. RESULTS The highest shear bond strength values were observed in the samples fluorinated for 5 minutes and cemented with Panavia SA Plus. Variolink N did not elicit any statistical differences between surface treatments. Panavia SA Plus resin cement and Variolink N resin cements featured statistically significant difference in shear bond strength values only in the case of 5 minutes of fluorination treatment. CONCLUSION According to the results of this study, application of 5 minutes of fluorination with 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP) containing Panavia SA Plus resin cement increased the resin bond strength of zirconia. Fluorination of the zirconia surface using conventional resin cement, Variolink N, did not lead to an increase in bond strength.

Kolorimetrik MTT testi kullanarak geleneksel protez kaide materyali ile yumuşak astar materyalinin in vitro sitotoksik özelliklerinin değerlendirilmesi

Ozet Amac: Bu calismada protez yapiminda kullanilan geleneksel kaide materyali ile yumusak astar materyalinin fare fibroblast hucreleri uzerinde zamanla meydana gelen sitotoksik etkilerinin degerlendirilmesi amaclandi. Materyal ve Metod: Protez kaide materyali (rodeks) ve yumusak astar materyalinin (dentusil) disk sekilli test numuneleri ureticinin talimatlarina gore aseptik sartlar altinda hazirlandi.. Ornekler, agiz ortamini taklit etmek icin 5.000 termal donguye tabi tutuldu. Yaslanma prosedurlerini takiben, materyallerin sitotoksik etkisi, 24 saat, 48 saat ve 72 saatlik hucre inkubasyon doneminden sonra L929 fare fibroblast hucreleri kullanilarak [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] testi ile degerlendirildi. Her grup icin hucre canliligi degerleri hesaplandi. Verilerin istatistiksel analizi, iki yonlu tekrarlanan bir olcum yontemi kullanilarak gerceklestirildi. (P <0.001) Bulgular: 24 saat ve 48 saat inkubasyon periyodunda yumusak astar materyali, 72 saat inkubasyon periyodunda ise kaide materyali daha fazla hucre canliligi gostermistir. Istatistiksel olarak iki materyal arasinda anlamli fark bulunmustur. Inkubasyon periyotlari arasinda ise 24 saat inkube edilen grup 48 saat ve 72 saatden istatistiksel olarak farklidir. 72 saat ve 48 saat arasinda anlamli fark bulunamamistir. Sonuc: Kaide materyallerinin altina kullanmis oldugumuz yumusak astar materyali kaide materyaline gore daha biyouyumludur.

In Vitro Cytotoxicity of Maxillofacial Silicone Elastomers: Effect of Nano-particles

PURPOSE Silicone elastomers are generally used for maxillofacial extraoral prostheses. The purpose of this in vitro study was to evaluate the cytotoxicity of different kinds of nanoparticles added to two types of maxillofacial elastomers. MATERIALS AND METHODS A-2000 and A-2006 silicone elastomers were used. The silicone specimens were divided into eight groups according to the presence of additional nanoparticles (n = 18). The following represents the groups in the study: Group A: A-2000 silicone (control group); Group B: A-2006 silicone (control group); Group C: A-2000 silicone and the addition of titanium dioxide (TiO2 ); Group D: A-2006 silicone and the addition of TiO2 ; Group E: A-2000 silicone and the addition of fumed silica; Group F: A-2006 silicone and the addition of fumed silica; Group G: A-2000 silicone and the addition of silaned silica; Group H: A-2006 silicone and the addition of silaned silica. A paired sample t-test was used to analyze the cytotoxicity of each group after 24, 48, and 72 hours. RESULTS Based on the results of the 24-hour analysis, the biocompatibility values of the (A-2006) fumed silica group were higher than those of the control groups. There was no statistically significant difference in A-2006 and A-2000 groups. The cytotoxicity values of the control groups and TiO2 (A-2000 silicone) elastomer groups increased at all test times; however, the cytotoxicity values of the TiO2 (A-2006), fumed silica (A-2006), silaned silica (A-2006), fumed silica (A-2000), and silaned silica (A-2000) groups increased significantly only from 24 to 48 hours. CONCLUSION Nanoparticles of TiO2 , fumed silica, and silaned silica added to a commercial silicone-based elastomer used for fabrication of maxillofacial prostheses are nontoxic.

Cytotoxicity of long-term denture base materials

Introduction: The aim of this study was to evaluate the cytotoxic effect of various denture base materials following four different aging periods. Methods: In total, 48 disc-shaped specimens per each group were prepared: Group I: acrylic resin polymerized in cool water and heated up to 100°C over 45 min and boiled for 15 min; Group II: acrylic resin polymerized under pressure in 40°C–45°C water bath for 10 min; Group III: autopolymerized hard relining resin Cold Liner Rebase; Group IV: autopolymerized hard relining resin Truliner; Group V: soft relining resin DentuSil. Then the specimens were stored in water for 24 h or 15 days, or thermocycled 2500 times or 10,000 times. Cytotoxicity was evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L929 cells after 72-h cell incubation. Cell viability percentages were counted and statistical analyses were performed. The results were also evaluated according to ISO standard 10993-5. Results: All materials showed similar cell viability percentages following 24-h water storage and 2500 and 10,000 thermal cycles. Following 15-day water storage, a statistically significant difference was observed between the materials. Comparisons of the aging periods for each material showed statistically significant differences. Groups III and IV showed moderately cytotoxic effect following 15-day water storage. The remaining groups showed slightly cytotoxic or non-cytotoxic effect. Discussion: Polymerizing acrylic resins under pressure can be an alternative to conventional polymerizing to ensure a faster denture repair while providing similar cell viability values. Heat-cured acrylic resins provide higher cell viability than hard chairside lining materials in a 15-day period.

Coloration of provisional restoration materials: a comparison of the effects of mouth rinses and green tea

Purpose The present study aimed to evaluate the color stability of provisional restorative materials stored in different mouth rinses and green tea extract for 14 days. Materials and methods Forty cylinders of fixed provisional restoration material of 15-mm diameter and 2-mm thickness were prepared. The samples were separated into four storage solutions (three different mouth rinses and green tea) (n=10). The values of L*, a*, and b* were determined before and after storage in the solutions using a spectrophotometer, and the ΔE* value was calculated. The effect of mouth rinses and green tea extract on the color change of provisional restoration materials was determined with one-way analyses of variance. The Tamhane multiple comparison analysis was used to determine the differences between the groups (p<0.05). Results The color stability of the provisional restoration materials varies depending on the solution. Listerine mouth rinse showed more color change than Sensodyne or Colgate did. Minimal color change was found in the green tea solution. Conclusion The effect of mouth rinses on the color stability of fixed temporary restorative materials is remarkable. As green tea shows less color change, it can be suggested as an alternative to mouth rinses.

Effects of Hot Chemical Etching and 10-Metacryloxydecyl Dihydrogen Phosphate (MDP) Monomer on the Bond Strength of Zirconia Ceramics to Resin-Based Cements.

PURPOSE The purpose of this in vitro study was to evaluate the hot chemical etching method on the shear bond strength between zirconia and two resin cements. MATERIALS AND METHODS Sixty zirconia specimens (13 × 7.5 × 2.5 mm3 ) were prepared and treated as follows: (1) airborne-particle abrasion with 50 μm Al2 O3 particles; (2) hot chemical etching for 10 minutes; (3) hot chemical etching for 30 minutes. Sixty composite cylinders of 3 mm diameter and height were prepared and bonded to zirconia specimens, which were divided into subgroups A and B. Group A: cemented with conventional resin cement (Variolink II); group B: cemented with 10-metacryloxydecyl dihydrogen phosphate (MDP) monomer containing resin cement (Panavia SA) after the application of surface treatments. Next, the specimens were stored in 37ºC distilled water for 24 hours. Following water storage, shear bond strength test was performed at a 1 mm/min crosshead speed in a universal testing machine. The statistical analyses were performed with one-way ANOVA and post hoc Tukey tests. p < 0.05 was considered statistically significant. RESULTS The results from all of the tested groups exhibited lower shear bond strength values than group II-B and higher shear bond strength values than group I-A (p < 0.05). CONCLUSION The use of the hot chemical etching method for 10 minutes increased the shear bond strength of zirconia ceramics to both conventional and resin cements and seems to be an effective method. The MDP monomer-containing resin cement, Panavia SA, improved the resin bonding of zirconia ceramics when combined with airborne-particle abrasion.

THE COLORATION OF PROVISIONAL RESTORATION MATERIALS: COMPARISON OF THE EFFECTS OF MOUTHWASHES AND GREEN TEA

Purpose: The present study aims to evaluate the colour stability of provisional restorative materials stored in different mouth rinses and green tea extract for 14 days. Materials and methods: 40 cylinders of 15 mm in diameter and 2 mm thick fixed provisional restoration material were prepared. The samples were separated into 4 groups according to the storage solutions. (3 different mouth rinses and green tea) (n=10) The values of L *, a *, b * were determined before and after storage in the solutions using spectrophotometer, and the ΔE * value was calculated. The effect of the mouth rinses and the provisional restoration materials of the green tea extract on colour change was determined by one way ANOVA. The Tamhane multiple comparison analysis was used to determine the differences between the groups (p<0,05) Result: The colour stability of provisional restoration materials varies depending on the solution used. Listerine mouth rinses showed more colour change than did sensodyne and colgate. The minimal colour change was found in the green tea solution. Conclusion: The effect of mouth rinses on colour stability of fixed temporary restorative materials is remarkable. As green tea shows less colour change, it can be suggested as an alternative to mouth rinses.