Person: KARA, ÖZLEM
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Publication Metadata only Custom Cast Post Treatment on an Implant Platform in 2 Patients(2015-08-01) DİLBER, Erhan; BAYTAROĞLU, Ebru Nur; Kara, Haluk Baris; Kara, Ozlem; KARA, ÖZLEMPublication Open Access In vitro study of fracture strength of provisional crown materials(2015-02-01) Karaokutan, Isil; Sayin, Gulsum; Kara, Ozlem; KARA, ÖZLEMPURPOSE. The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. MATERIALS AND METHODS. A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at 37°C for 24 hours, and then they were thermocycled (TC, 5000×, 5-55°C) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (α=.05). RESULTS. Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). CONCLUSION. Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CADCAM technique offers more advantages than the direct technique. [J Adv Prosthodont 2015;7:27-31]Publication Metadata only Effect of Various Lasers on the Bond Strength of Two Zirconia Ceramics(2015-02-01) Kara, Ozlem; Kara, Haluk Baris; Tobi, Elif Sumeyye; Ozturk, Atiye Nilgun; Kilic, Hamdi Sukur; KARA, ÖZLEMObjective: The purpose of this study was to compare and evaluate the effects of various laser systems on surface roughness and shear bond strengths of zirconia ceramics. Material and methods: Seventy-two ceramic discs (10 mmx2 mm) obtained from two sintered zirconia ceramics (Zirkonzahn, Zirkonzahn Prettau((R))) were divided into two groups (n=36) according to the computer-aided design (CAD)-computer-aided manufacturing (CAM) technique and then further divided into three groups (n=12). Each group was treated with one of the following: (1) femtosecond (FS), (2) Nd:YAG (NY), and (3) Er:YAG (EY) lasers. After laser irradiation, a scanning electron micrograph (SEM) was taken at 500x magnification for qualitative examination. Following surface roughness measurement by profilometry, resin cement (Rely X U200) was bonded to the ceramic specimens using Teflon tubes (3 mm height, 4 mm diameter). Specimens were stored in distilled water at 37 degrees C for 24 h and then thermal cycled for 5000 cycles. A shear bond strength (MPa) test was performed using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed by two way analysis of variance (ANOVA) and Tukey honest significant difference (HSD) tests for pairwise comparisons among groups (p=0.05). Results: MPa and roughness were significantly affected by laser type (p0.05). In the SEM, the surfaces of the FS group were rougher than those of the NY and EY groups. NY and EY surfaces were nearly smooth. Conclusions: FS laser is an effective surface treatment for roughening surfaces of zirconia ceramics. Furthermore, it reveals the highest MPa.Publication Open Access Mechanical properties of zirconia after different surface treatments and repeated firings(2014-12-01) Subasi, Meryem Gulce; Demir, Necla; Kara, Ozlem; Ozturk, A. Nilgun; Ozel, Faruk; KARA, ÖZLEMThis study investigated the influence of surface conditioning procedures and repeated firings on monoclinic content and strength of zirconia before cementation. MATERIALS AND METHODS. Sintered barshaped zirconia specimens were subjected to no surface treatment (control), air abrasion, or grinding (n=21). Their roughness was evaluated using a profilometer, and microscope analysis was performed on one specimen of each group. Then, 2 or 10 repeated firings (n=10) were executed, the monoclinic content of specimens was analyzed by X-ray diffraction, and a three-point flexural strength test was performed. Surface roughness values were compared using one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests, the monoclinic content values were tested using Kruskal-Wallis and Mann-Whitney U tests, and the flexural strength values were tested using two-way ANOVA and Tukey HSD tests (P=.05). Spearman’s correlation test was performed to define relationships among measured parameters. RESULTS. Surface-treated specimens were rougher than untreated specimens and had a higher monoclinic content (P<.005), and the relationship between roughness and monoclinic content was significant (P<.000). Neither surface treatment nor firing significantly affected the flexural strength, but Weibull analysis showed that for the air-abraded samples the characteristic strength was significantly lower after the 10th firing than after the 2nd firing. CONCLUSION. After firing, a negligible amount of monoclinic content remained on the zirconia surfaces, and rougher surfaces had higher monoclinic contents than untreated surfaces. Multiple firings could be performed if necessary, but the fracture probability could increase after multiple firings for rougher surfacesPublication Metadata only The effect of surface treatments on the bonding strength of ceramic inlays to dentin(2017-01-01) Kara, Ozlem; Ozturk, Atiye Nilgun; KARA, ÖZLEMAim: To compare and evaluate the effects of different surface treatments on surface roughness and the microtensile bonding strengths of four different ceramics to dentin. Methods: 160 human molar teeth were used. The teeth were divided into four groups (n=40). FC (Finesse), LC (IPS Empress Esthetics), LDC (IPS Empress e-Max) and MZC (Zirkonzahn Prettau) ceramic restorations were prepared. The specimens were divided into eight groups: (1) control, (2) air abrasion (AA), (3) HF acid etching (HF), (4) experimental hot etching (EHE), (5) Nd:YAG laser irradiation, (6) Nd:YAG laser+air abrasion, (7) Nd:YAG laser+HF acid, and (8) Nd:YAG laser+experimental hot etching. The surface roughness of the ceramics was determined with atomic force microscopy. After the cementation process, the specimens were thermal cycled and subjected to a microtensile bond strength (MBS) test. Two-way ANOVA and a Tukey-s test were used to analyse the surface roughness and MBS values of variance (p=0.05). Results: HF acid etching showed the highest surface roughness in FC (p<0.05). HF increased MBS in LC specimens where AA and HF increased MBS in LCD specimens. For the MZC specimens, AA and Nd:YAG+AA was effective in increasing the MBS (p<0.05). Conclusion: Different surface treatments must be applied to different ceramics to improve the mechanical retention and MBS.Publication Metadata only The effect of different in-office bleaching techniques and etching procedures on bond strength of orthodontic brackets(2017-01-01) YAZICI, AYŞE RÜYA; GÖRÜCÜ, JALE; ÜŞÜMEZ, Aslihan; Kara, Ozlem; KARA, ÖZLEMThe aim of this study was to compare the effects of different in-office bleaching techniques and acid/laser etching on bond strength of orthodontic brackets. Ninety-six extracted human premolar teeth were used in the study. The teeth were randomly divided into four groups according to different in-office bleaching techniques (n=24); Group I: Diode laser-assisted bleaching, Group II: Er:YAG laser-assisted bleaching, Group III: In-office bleaching with LED, Group IV: Unbleached (control). After the samples were kept in artificial saliva for 2 weeks, each group were randomly divided into 2 subgroups according to etching methods; a-acid etching; b-laser etching. For laser etching Er,Cr:YSGG laser was used at 1.5W, 15Hz with 140s pulse duration for 20s. For acid etching, 37% phosphoric acid was used for 30s. The shear bond strength testing was performed using Instron Testing Machine with a crosshead speed of 1mm/min. Adhesive Remnant Index (ARI) scores were also measured. Data was analyzed using two-way ANOVA, Bonferroni, Kruskal Wallis and Mann Whitney U tests (p0.05). There were statistically significant differences between acid and laser etching within each group (p0.05), acid etching caused statistically higher ARI scores than laser etching groups (p<0.05). In conclusion in-office bleaching either with LED or laser before bracket bonding did not affect bond strength. Prior to bracket bonding, acid etching of enamel caused higher shear bond strength values than laser etching.Publication Open Access Effects of various denture cleansers on surface roughness of hard permanent reline resins(2015-04-01) Cakan, Umut; Kara, Ozlem; Kara, Haluk Baris; KARA, ÖZLEMThe aim of this study was to investigate the influence of denture cleansers on surface roughness (Ha, mu m) of two hard permanent reline resins and a conventional acrylic denture base resin. Fifty specimens of each material, measuring 10 mmx2 mm were randomly divided into 1 control and 4 experimental subgroups (n=10). Surface roughness values were measured using profilometer before and after immersion in distilled water and in 4 different denture cleansers for 8 h for 140 days. The Kruskal Wallis and Wilcoxon Signed Ranks tests were used for comparison among groups with a significance level of alpha=0.05. Immersion in denture cleansers significantly increased the surface roughness of reline resins and the difference among the cleansers was statistically significant (p=0.059). Denture cleansers can cause significant surface roughness alterations on hard permanent reline resins and denture base resin where their effect may differ according to the selected resin material.