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Öğe Antibacterial effect of dental cements evaluated using agar diffusion test(TAYLOR & FRANCIS LTD, 2015) Dundar, Ayse; Karacam, Nejla; Yavuz, Tevfik; Ozturk, Nilgun; Pinarkara, YaseminPurpose: Secondary caries can occur around the restoration, fixed prosthesis, and orthodontic band margins because of cariogenic bacteria. Long-lasting antibacterial effectiveness of dental cements used contemporarily can reduce this phenomenon. The purpose of this study was to examine the antibacterial activities of nine dental cements (BisCem((R)), Super-Bond C&B, Rely X-TM, Panavia(TM) F 2.0, Variolink((R)) II, Unitek(TM) Multi Cure, Multilink((R)) Automix, Clearfil(TM) Esthetic Cement, Transbond(TM) LR) using agar diffusion test. Materials and methods: The test materials were inserted into the wells of Muller Hinton agar plates inoculated with Streptococcus mutans and Streptococcus salivarious. The diameters of the inhibition zones produced around the materials were measured after 24h of incubation. Two-Way ANOVA, the Kruskal-Wallis, and the Mann-Whitney U tests at a significance level of pResults: Unitek Multi Cure cement exhibited a significant difference from the control group against both S. mutans and S. salivarious (p<0.05). While the zone of inhibition of Unitek Multi Cure cement was shorter (8.50 +/- 1.77) than the control group (12.63 +/- 1.30), Unitek Multi Cure had antibacterial effect against S. mutans and S. salivarious (p<0.05). S. mutans displayed a significantly lower resistance to Unitek Multi Cure, BisCem, and Superbond C&B than S. salivarious (p<0.05). Conclusion: Conventional glass ionomer cement, Unitek Multi Cure, exhibited greatest in vitro antibacterial activity against both S. mutans and S. salivarious. Formation of dental caries had been suppressed by the fluoride-releasing GICs.Öğe Comparison of the Effects of Surface Treatments on Roughness of Two Ceramic Systems(MARY ANN LIEBERT, INC, 2012) Dilber, Erhan; Yavuz, Tevfik; Kara, Haluk Baris; Ozturk, A. NilgunObjective: The aim of this study was to evaluate the effects of different surface treatments on the surface roughness of lithium disilicate-based core (IPS Empress 2, shade 210, Ivoclar Vivadent, Schaan, Liechtenstein) and feldspathic ceramics (Vita VM9, VITA Zahnfabrik H. Rauter GmbH & Co. KG, Bad Sackingen, Germany). Background data: Er:YAG laser irradiation is expected to be an alternative surface treatment, thus enhances surface roughness of procelains and produces morphological changes. Methods: Fifty lithium disilicate-based core ceramic discs and 50 feldspathic ceramic discs were prepared (diameter, 10 mm; thickness, 1 mm) according to the manufacturers' instructions. All-ceramic discs were polished to standardize, and surface roughness of the discs was evaluated before treatment and serving as controls. Both of two ceramic groups were divided into five groups (n = 10), and the following treatments were applied: (1) sandblasting with aluminum oxide (Al2O3; Group SB); (2) Al2O3 + Er:YAG laser (Group SB-L); (3) Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10W; manually, contact handpiece [R 14]) (Group L); (4) 5% hydrofluoric acid etching (Group HF); and (5) Er: YAG laser + 5% hydrofluoric acid (Group HF-L). Surface roughness was evaluated by profilometry, and specimens were then examined with atomic force microscopy. Results: Data were analyzed by Wilcoxon signed rank, Mann-Whitney U, and Kruskal-Wallis tests (alpha = 0.05). The Wilcoxon signed rank test results indicated that surface roughness after sandblasting was significantly different from the surface roughness after laser irradiation and acid etching (p < 0.001). Mann-Whitney U and Kruskal-Wallis test results indicated that groups SB and SB-L had significantly higher mean roughness values (p < 0.05) than those in the other groups. Conclusions: Groups SB and SB-L had rougher surfaces than the groups subjected to the other surface treatment methods. There was no significant difference in surface roughness between the HF acid etching, Er:YAG laser irradiation, and HF and Er:YAG (p < 0.05).Öğe Effect of different surface shapes formed by femtosecond laser on zirconia-resin cement shear bond strength(TAYLOR & FRANCIS LTD, 2015) Akpınar, Yusuf Ziya; Yavuz, Tevfik; Aslan, Muhammed Ali; Kepceoğlu, Abdullah; Kılıç, Hamdi ŞükürObjective: The purpose of this study was to evaluate the effect of different surface shapes formed by femtosecond (FS) laser on zirconia (Y-TZP)-resin cement shear bond strength (SBS). Background data: All ceramic restoration is used as an alternative to metal-ceramic restorations, due to its better aesthetics, strength, and toughness properties. However, bond strength of restoration to tooth and other materials is effective to long term success of the restoration, and to achieve it surface treatment is required on ceramic surface. Materials and methods: Forty square-shaped zirconia samples were prepared and assigned to four groups of 10. The details of the groups are as follows: Group A, square-shaped recessed surface; Group B, square-shaped projection surface; Group C, circular-shaped recessed surface; Group D, circular-shaped projection surface. The SBSs values were performed with a universal testing machine at a crosshead speed of 1mm/min. The data were analyzed statistically using analysis of variance (ANOVA) and Tukey HSD multiple comparisons tests. Results: The one-way ANOVA results on SBSs of the zirconia material bonded with resin cement revealed significant differences among the groups (p<0.05). The Tukey HSD test results revealed that Group B and D had significantly higher SBS values than other groups (p<0.05), but there were no significant differences between each other (p>0.05). Additionally, Group A and C had significantly lower values than other groups (p<0.05). Conclusions: Different surface shapes formed by FS laser provided a significant increase in SBSs. The SBS values of projection surfaces of circular and square-shapes are greater than that of recessed surfaces of circular and square-shapes.Öğe Effect of Different Surface Treatments on Porcelain-Resin Bond Strength(WILEY, 2017) Yavuz, Tevfik; Ozyilmaz, Ozgun Yusuf; Dilber, Erhan; Tobi, Elif Sumeyye; Kilic, Hamdi SukurPurpose:The aim of this study was to evaluate the effects of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. Materials and Methods: total of 192 disk-shaped cores were prepared using two all-ceramic systems, of which 168 were submitted to SBS tests, and 24 were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The ceramics used were IPS Empress e.max (EX) lithium glass-ceramic and Vita In-Ceram Zirconia glass-infiltrated zirconia (ICZ). The specimens were randomly divided into seven groups (n = 12) on the basis of the surface treatment used: control; SB-sandblasting with 50 mu m Al2O3 particles; CJ-chairside silica coating with 30 mu m SiO2 particles and silanization (Clearfil Porcelain Bond Activator); HF-etching in 5% hydrofluoric acid and silanization; ER-etching with an Er:YAG laser (10 W); ND-Nd:YAG laser etching (0.8 W); and FS-etching with a femtosecond laser (860 mW). A luting cement (Clearfil Esthetic) was photopolymerized on each treated ceramic disk. After subjecting the specimens to thermocycling (1000 cycles, 5 degrees C to 55 degrees C), SBS tests were performed using a universal testing machine. The data were analyzed with two-way ANOVA and Tukey's tests using a significance limit of 5%. Results: ong the EX ceramics, the CJ (29.10 MPa) and HF (26.07 MPa) specimens had statistically higher SBS values. For the ICZ ceramics, the highest value (28.08 MPa) was obtained for the CJ specimens. Conclusions: lanization after coating with silica improves the bond strengths of both EX and ICZ specimens, while HF etching is favorable only for the EX specimens.Öğe Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement(SPRINGER LONDON LTD, 2015) Akpınar, Yusuf Ziya; Kepceoğlu, Abdullah; Yavuz, Tevfik; Aslan, Muhammed A.; Demirtağ, Zülfikar; Kılıç, Hamdi S.; Üşümez, AslıhanYttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90A degrees, 75A degrees, 60A degrees, 45A degrees). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1 mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45A degrees angle which resulted in significantly higher SBS (18.2 A +/- 1.43 MPa) than other groups (at 90A degrees angulation (10.79 A +/- 1.8 MPa), at 75A degrees (13.48 A +/- 1.2 MPa) and at 60A degrees (15.85 A +/- 0.81 MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.Öğe Effect of Femtosecond Laser Treatment on the Shear Bond Strength of a Metal Bracket to Prepared Porcelain Surface(MARY ANN LIEBERT, INC, 2015) Akpınar, Yusuf Ziya; Irgın, Celal; Yavuz, Tevfik; Aslan, Muhammed Ali; Kılıç, Hamdi Şükür; Üşümez, AslıhanObjective: The aim of this study was to investigate the effects of femtosecond laser treatment (Group FS) on the shear bond strength (SBS) of a metal bracket to prepared porcelain surface, and to compare it with other surface treatment techniques [50 mu m Al2O3 sandblasting (Group SB), 9.6% hydrofluoric acid gel (Group HF), and neodymium-doped yttrium aluminium garnet (Nd:YAG laser) (Group NY)]. Background data: Because of the increasing number of adult patients in current orthodontic practice, achieving sufficient bond strength of composite resin to porcelain restorations without bond failure during the treatment is a challenge for orthodontists. Methods: In total, 80 glazed feldspathic porcelain samples were prepared and randomly assigned to four groups of 20. Treated surfaces were treated with a silane agent. Brackets were bonded to porcelain samples. The specimens were stored in distilled water for 24 h and then thermocycled for 500 cycles between 5 degrees and 55 degrees C. The SBS of the brackets was tested with a universal testing machine at a crosshead speed of 1 mm/min, until bonding failure occurred. The data were analyzed statistically using analysis of variance (ANOVA) and Tamhane multiple comparisons tests. The results of ANOVA indicated that the SBS values varied according to the surface treatment method (p<0.001). Results: Results of the Tamhane post-hoc tests indicated that the bond strength in Group NY (5.11 +/- 1.53) was significantly lower than the other groups (p<0.05). There were no statistically significant differences among Groups SB (9.07 +/- 3.76), HF (9.09 +/- 3.51), and FS (11.58 +/- 4.16) (p=0.28). Conclusions: The results of this study showed that FS treatment produced high SBS of the processes assessed; therefore, it appears to be an effective method for bonding orthodontic metal brackets to prepared porcelain surfaces.Öğe Effect of Nd:YAG Laser Bleaching and Antioxidizing Agents on the Shear Bond Strength of Brackets(MARY ANN LIEBERT, INC, 2013) Akin, Mehmet; Ozyilmaz, Ozgun Yusuf; Yavuz, Tevfik; Aykent, Filiz; Basciftci, Faruk AyhanObjective:The aims of this study were to evaluate the effect of hydrogen peroxide bleaching agents, both nonactivated and activated by a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, and of antioxidant treatment on the shear bond strength (SBS) of orthodontic brackets. Background data:Nd:YAG laser activation is expected to accelerate the bleaching therapy without decrease shear bond strength. Materials and methods: Ninety extracted maxillary central incisors were divided into two experimental groups and a control group. Group I was the control group, Group II was bleached with 35% hydrogen peroxide and had no photoactivation, and Group III was bleached with 35% hydrogen peroxide with activation by a Nd:YAG laser (4.0 W, 60 Hz frequency, 1mm distance, 20 sec). Each group was divided into two subgroups:Subgroup A was immersed in artificial saliva for 2 weeks, and then bonded using the total etch system, whereas subgroup B was treated with an antioxidant agent (10% sodium ascorbate) and then bonded using the same system. The samples were stored in water for 24 h at 37 degrees C, and thermocycled. The SBS in megapascals (MPa) was determined by a shear test with 1mm/min crosshead speed, and failure types were classified with modified adhesive remnant index scores. The data were analyzed with two way analyses of variance, Tukey, and chi(2) tests at the alpha = 0.05 level. Results:In both Groups II and III, the SBSs of brackets bonded after bleaching (Group II 15.16, Group III 17.50 MPa) were significantly lower than those of brackets in the bonded unbleached group (Group I 22.13MPa); however, sodium ascorbate treatment significantly increased the SBSs of brackets in the bleached groups (Group II 21.52, Group III 22.43MPa), but had an insignificant effect on the SBS of the control group (Group I 23.66MPa). Conclusions: Hydrogen peroxide bleaching agents reduce the SBSs both with and without Nd:YAG laser activation; however, treatment of the bleached enamel surface with 10% sodium ascorbate prior to bonding negates the effect.Öğe The effect of silane applied to glass ceramics on surface structure and bonding strength at different temperatures(KOREAN ACAD PROSTHODONTICS, 2016) Yavuz, Tevfik; Eraslan, OguzPURPOSE. To evaluate the effect of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS. 288 specimens (lithium-disilicate, leucite-reinforced, and glass infiltrated zirconia) were first divided into two groups according to the resin cement used, and were later divided into four groups according to the given surface treatments: G1 (hydrofluoric acid (HF)+silane), G2 (silane alone-no heat-treatment), G3 (silane alone-then dried with 60 degrees C heat-treatment), and G4 (silane alone then dried with 100 degrees C heat-treatment). Two different adhesive luting systems were applied onto the ceramic discs in all groups. SBS (in MPa) was calculated from the failure load per bonded area (in N/mm(2)). Subsequently, one specimen from each group was prepared for SEM evaluation of the separated-resin ceramic interface. RESULTS. SBS values of G1 were significantly higher than those of the other groups in the lithium disilicate ceramic and leucite reinforced ceramic, and the SBS values of G4 and G1 were significantly higher than those of G2 and G3 in glass infiltrated zirconia. The three-way ANOVA revealed that the SBS values were significantly affected by the type of resin cement (P<.001). FIN ceramics had the highest rate of cohesive failure on the ceramic surfaces than other ceramic groups. AFM images showed that the surface treatment groups exhibited similar topographies, except the group treated with HF. CONCLUSION. The heat treatment was not sufficient to achieve high SBS values as compared with HF acid etching. The surface topography of ceramics was affected by surface treatments.Öğe Effects of Different Demineralization-Inhibiting Methods on the Shear Bond Strength of Glass-Ceramics(WILEY, 2015) Dilber, Erhan; Akin, Mehmet; Yavuz, Tevfik; Erdem, AliPurposeThis in vitro study was undertaken to evaluate the effects of different demineralization-inhibiting methods on the shear bond strength (SBS) of glass-ceramics. Materials and MethodsNinety extracted intact human mandibular lateral insicors were randomly divided into six equal groups. Group C was left untreated, while enamel subsurface demineralization was induced in the other groups. In group D, porcelain discs (3 mm in diameter) were cemented to demineralized enamel by using total-etch photopolymerizing luting composite resin without pretreatment. Demineralized specimens in groups F, CA, M, and I were pretreated with fluoride gel, CPP-ACP paste, microabrasion, and resin infiltration, respectively, and then porcelain discs were cemented. SBS (MPa) was calculated from the failure load (N) per bonded area (mm(2)). Fracture types were examined by optical microscopy (40x magnification). Data were analyzed with ANOVA, Tukey's test, and G-test. ResultsANOVA revealed significant intergroup differences (p < 0.01). No significant differences in SBS (MPa) were found between groups C (19.48 2.0) and I (20.02 +/- 1.6). Lower SBS values were recorded in groups D (7.93 +/- 0.8), F (12.51 +/- 1.5), CA (17.08 +/- 1.3), and M (14.84 +/- 1.4). Mixed and cohesive failures were the most prevalent in groups M and I, respectively. ConclusionResin infiltration enhanced the SBS of porcelain discs bonded to demineralized enamel when compared with the other demineralization-inhibiting methods. Clinical Relevance: Resin infiltration could be useful to enhance adhesion of glass-ceramics to teeth with white spot lesions.Öğe Effects of different surface treatments on shear bond strength in two different ceramic systems(SPRINGER LONDON LTD, 2013) Yavuz, Tevfik; Dilber, Erhan; Kara, Haluk Baris; Tuncdemir, Ali Riza; Ozturk, A. NilgunThe purpose of this study was to evaluate the influence of different surface treatments (sandblasting, acid etching, and laser irradiation) on the shear bond strength of lithium disilicate-based core (IPS Empress 2) and feldspathic ceramics (VITA VM 9). One hundred ceramic discs were divided into two groups of 50 discs each for two ceramic systems: IPS Empress 2 (group I) and VITA VM 9 (group II). Each of the two groups was further divided into five surface treatment groups (ten each) as follows: group SB, sandblasting with alumina particles (50 mu m); group HF, 5 % hydrofluoric acid etching; group L, Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10 W; manually, noncontact R14 handpiece); group SB-L, sandblasting + Er:YAG laser; and group HF-L, 5 % hydrofluoric acid + Er:YAG laser. Luting cement (Panavia 2.0) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, a shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference tests (alpha = 0.05). The two-way ANOVA indicated that the shear bond strength was significantly affected by the surface treatment methods (p < 0.05), but there was no significant interaction between the ceramic systems. Group SB-L had the highest mean values for each ceramic system. Sandblasting, followed by Er:YAG laser irradiation, enhanced the bond strength, indicating its potential use as an alternative method. The atomic force microscopic evaluation revealed that group SB had the most distinct sharp peaks among the groups.Öğe An evaluation of the apical seal in oval-shaped root canals prepared with either self- adjusting files or protaper files(2014) Yiğit, Dilek Helvacıoğlu; Oruçoğlu, Hasan; Yavuz, Tevfik; Yavuz, Cavit Işık; Yılmaz, Ayça; Kaba, Yusuf Nuri; Özden, SametObjectives: This study aimed to evaluate the apical seal obtained with lateral compaction of gutta-percha in oval-shaped root canals prepared with either self-adjusting files or ProTaper Universal rotary files. Materials and Methods: Twelve pairs of extracted mandibular premolars with oval-shaped root canals were randomly divided into two groups. The first group was biomechanically prepared with ProTaper Universal files, while the self-adjusting file system was used in the second group. The roots were better filled using cold lateral compaction of gutta-percha. Apical microleakage was measured with the computerized fluid filtration method. The results were analyzed statistically using the Mann-Whitney U test. Results: All of the roots in both groups showed leakage. Group 1 demonstrated significantly less microleakage (p<0.05). Conclusions: Instrumentation of oval-shaped canals using a self-adjusting file system with cold lateral compaction of gutta-percha demonstrated significantly greater apical microleakage when compared to ProTaper Universal. The apical leakage with different filling techniques, combined with self-adjusting files, should be evaluated in further studies.Öğe Farklı ısılarda uygulanan silanın cam seramiklerin yüzey yapısına ve bağlanma dayanımına etkisi(Selçuk Üniversitesi Sağlık Bilimleri Enstitüsü, 2013) Yavuz, Tevfik; Eraslan, OğuzBu çalışmanın amacı farklı yüzey işlemlerinin (asit+silan, oda sıcaklığında uygulanan silan, 60°C' de uygulanan silan ve 100 °C' de uygulanan silan) farklı seramiklerin yüzey yapısı üzerinde yaptığı değişiklikleri ve bağlantısına olan etkisini tespit etmektir. Çalışmamızda, 3 farklı seramik sisteminden 96 adet seramik bağlanma dayanımı testi için ve 8 adet seramik AFM görüntüsü için olmak üzere toplam 312 adet cam seramik örneği kullanıldı. Makaslama bağlanma testi için, şeffaf akrilik kalıba yerleştirilen seramik örnekleri; ilk önce kullanılan rezin simanlara göre 2 gruba ve daha sonra uygulanan yüzey işlemlerine göre 4 gruba ayrıldı: Grup 1 (hidroflorik asit+silan), Grup 2 (oda sıcaklığında yalnız silan uygulaması), Grup 3 (Silan+60 °C'lik ısı uygulaması), Grup 4 (Silan+100 °C'lik ısı uygulaması). Yüzey işlemleri sonrası bütün gruplardaki cam seramik diskler üzerine uyumlu bir kalıp sayesinde Variolink Veneer N ve Clearfil Esthetic ışıkla sertleşen rezin siman manuple edildi. Daha sonra termal siklus uygulaması (10 000 devir, 5-55°C) gerçekleştirilen örnekler makaslama testine maruz bırakıldı ve kırık tipleri (adeziv, koheziv, karma) incelendi. Son aşamada ise yüzey işlemleri uygulanan cam seramik örneklerinin SEM ve AFM görüntüleri incelendi. Makaslama bağlanma dayanım değerleri normal dağılıma uygunluk gösterdiğinden çok yönlü varyans analizi yapılmıştır. Çok yönlü varyans analiz sonucu istatistiksel olarak önemli derecede farklılık gösteren gruplar arasındaki farkın kaynağını tespit etmek için ?Tukey HSD testi? yapıldı. (p=0,05). Farklı ısılarda uygulanan silan ajanının, farklı seramikler üzerinde bağlanma dayanımı değerlerinde önemli fark bulunmuştur (p<0.05). Grup 1'in seramik-rezin bağlanma dayanımı değerleri IPS Empress e.max ve Finesse All-Seramik örnekleri için diğer gruplardan istatiksel olarak anlamlı derecede yüksek çıkmıştır; Vita In-ceram Zirkonya örnekleri için ise seramik-rezin bağlanma dayanımı değerleri Grup 4 ve Grup 1'de, Grup 2 ve Grup 3'den istatiksel olarak önemli oranda yüksek bulunmuştur (p<0.05). IPS Empress e.max ve Finesse All-Seramik örnekleri için Grup 3 ve Grup 4 arasında istatiksel olarak bir fark bulunmazken (p>0.05), Grup 2'den önemli derecede yüksek, Grup 1'den önemli derecede düşük bulunmuştur (p<0.05). AFM görüntülerinde, farklı yüzey işlemleri uygulanan 3 farklı cam seramik örneklerin yüzey topografisinde değişimler olduğu gözlenmektedir. Isı işlemi, yüzey topografisinde önemli bir fiziksel değişikliğe neden olmamıştır.Öğe Porcelain laminate veneer conditioning for orthodontic bonding: SEM-EDX analysis(SPRINGER LONDON LTD, 2015) Aksakallı, Sertaç; İleri, Zehra; Yavuz, Tevfik; Malkoç, Meral Arslan; Öztürk, NilgünThe purpose of this in vitro study was to evaluate and compare the effects of different surface treatments and laser irradiation on the bond strength of brackets bonded to porcelain laminate veneer. Porcelain laminate veneer specimens were embedded in the centers of acrylic resin blocks. Thirty-nine teeth were used for shear bond strength testing and the remaining three (one tooth for each group) were used for evaluation of the debonded bracket interface. Specimens were randomly divided into three groups, each containing 13 specimens. The details of the groups are as follows: Group SB, sandblasting with alumina particles (50 mu m); Group HFA, 9.6 % hydrofluoric acid etching; Group ER, erbium-doped yttrium-aluminum-garnet (Er: YAG) irradiation (from 1 mm distance, 2 W, 10 Hz for 10 s). After conditioning, the upper central brackets were bonded to the porcelain surfaces. Porcelain laminate veneers were examined under stereomicroscope for adhesive remnant index and surface damage after debonding. The highest shear bond strength values were obtained with Group HFA (10.8 +/- 3.8 MPa) and Group ER (9.3 +/- 1.5 MPa), whereas Group SB revealed the lowest values. Scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis revealed that the silicon level in the porcelain decreased after debonding in all groups. The sandblasting method did not demonstrate any ideal bond strength values; however, the 9.6 % hydrofluoric acid etching and Er: YAG laser did. There were no significant differences among all groups in terms of laminate surface damages. The Er: YAG laser therefore can be selected for ideal bond strength and minimal damage to porcelain laminates.Öğe Push-out bonding strengths of four different dowel systems luted with two different adhesive systems(TAYLOR & FRANCIS LTD, 2014) Orucoglu, Hasan; Yavuz, Tevfik; Demir, Necla; Ozturk, Nilgun; Ozturk, BoraThis in vitro study investigates the bonding capacity of resin cements to dowels, using the push-out bonding strength of four different dowel systems, namely, stainless steel dowels (SSD), resin-supported polyethylene fiber dowels (RSPFD), zirconia dowels (ZD), and superpost glass fiber dowels (GFD), luted in root canals, using two different resin cements, namely, Multilink Automix Cement and Clearfil Esthetic Cement. Ninety-six maxillary central incisor teeth were sectioned below the cementoenamel junction, and the roots were treated endodontically. Then the roots were placed into four groups, based on the dowel systems used. The roots were further placed into two subgroups, based on the cement type used as subgroup A and subgroup B. Push-out bonding tests were performed on the bonded specimens, which were cut into 1mm thick sections. A two-way ANOVA test and Tukey's HSD tests were performed. The push-out bonding strength values for SSD, ZD, and RSPFD were not significantly different (p>0.05). The means for GFD were significantly higher than the means for ZD (p<0.05) when Multilink Automix Cement was used. However, when Clearfil Esthetic Cement was used, the means for RSPFD were significantly higher (p<0.001) than the means for the other systems. When Clearfil Esthetic Cement was used, the RSPF dowel system provided significantly higher bonding strength values than the other systems.Öğe Temperature rises during tooth bleaching with different light-curing units(TAYLOR & FRANCIS LTD, 2015) Ozyilmaz, Ozgun Yusuf; Yavuz, Tevfik; Sari, Tugrul; Aykent, Filiz; Ozturk, Atiye NilgunThe aim of this study was to evaluate the influence of three different light-curing units on the temperature rise induced in the pulpal cavity, when bleached with 35% hydrogen peroxide (HP). Forty extracted maxillary central incisors were randomly divided into four groups according to photoactivation procedure (n=10). Whiteness HP (WHP) bleaching agent which contains 35% HP bleach was placed on the facial tooth surface and no photoactivation device was used (control); an blue light-emitting diode (LED, 40s), a diode laser (4W, Continous mode, 20s), and Nd:YAG laser (4W, 60Hz frequency, 20s). Temperature rise in the pulpal chamber was measured with a J-type thermocouple wire that was connected to a data logger before and immediately after each 20-40s application. One tooth of each group was selected for scanning electron microscope analysis. Data were analyzed using one-way ANOVA followed by the Games Howell post hoc test at a preset alpha of 0.05. One-way ANOVA revealed that there was a significant difference among the light-curing units (p<0.05) and between control group and light-curing units (p<0.05). The Nd:YAG induced significantly, which resulted in higher temperature increase than other light-curing units (10.7 degrees C). The LED unit produced the lowest temperature changes (3.2 degrees C) among the light-curing units. The presence of the bleaching gel did not cause a temperature increase in control group (0 degrees C). The results suggested that using light-curing units caused temperature changes in the intrapulpal cavity during tooth bleaching. The use of LED will be more safer for pulpal health when assisted with WHP bleaching gel.
