Person: KARA, ÖZLEM
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Publication EFFECT OF DİFFERENT LASERS ON BOND STRENGTH OF MONOLİTHİC ZİRCONİA CERAMİCS(2018-09-30) KARA, ÖZLEM; KARA, ÖZLEMPublication The metameric effect of monolithic zirconias with varying yttrium ratios(2024-01-01) Güven M. E.; KARA Ö.; GÜVEN, MEHMET EJDER; KARA, ÖZLEMPURPOSE. To evaluate the metameric disparities among monolithic zirconia materials with differing yttrium compositions across various lighting conditions. MATERIALS AND METHODS. Thirty-six square-shaped zirconia samples measuring 10 X 10 X 0.5 mm were prepared from monolithic zirconia materials with three different yttrium contents. A 0.2 mm thick layer of polymerized dual-polymerizable self-adhesive resin cement was created using a silicone mold with the same dimensions as the prepared zirconia specimens. To evaluate metamerism, color measurements were conducted using a spectrophotometer device on a neutral gray background in a color measurement cabinet that offers four different illumination environments. All samples underwent aging by subjecting them to 10000 thermal cycles using a thermal cycle tester. Following thermal aging, color measurements were taken once more, and the data were recorded using the CIE L*, a*, b* color system. Two-way ANOVA and Post-hoc Bonferroni tests were employed to analyze the data. RESULTS. It was observed that there was no statistical difference among the color measurements made in different illumination environments of the monolithic zirconia ceramics used to evaluate metamerism P(>. 05). This observation remained consistent both before and after thermal aging. After thermal aging, the color of monolithic zirconia materials exhibited a tendency towards red and yellow hues, accompanied by a decrease in brightness levels. CONCLUSION. It can be stated that different illumination conditions did not affect the metamerism of monolithic zirconia materials, but there was a color change in monolithic zirconia materials after a thermal aging period equivalent to one year. [J Adv Prosthodont 2024;16:48-56]Publication 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 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 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.Publication Craniofacial Implant-Retained Auricular Prosthesis: A Case Report(2013-08-01T00:00:00Z) DİLBER, Erhan; Koc, Ozlem; Ozturk, Atiye Nilgun; Karamese, Mehtap; KARA, ÖZLEMImplants provide patients with a safe and reliable method for anchoring auricular prostheses that enable restoration of their normal appearance and offer improved quality of life. In this case report, an auricular prosthesis was fabricated for a patient who had lost his right external ear in a traffic accident. Extraoral implants and bar-and-clip retention for the proper connection of the auricular prosthesis to the implant were used.Publication 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 Evaluation of various denture cleansers on color stability and surface topography of polyetherketoneketone, polyamide, and polymethylmethacrylate(2020-08-01T00:00:00Z) ÖZYILMAZ, ÖZGÜN YUSUF; AKIN, CEYDA; KARA, ÖZLEM; ÖZYILMAZ, ÖZGÜN YUSUF; KARA, ÖZLEMThe aim of this study was to evaluate the effect of sodium perborate effervescent tablets and citric acid solution on the color stability and surface topography of a new generation of high-performance polymer polyetherketoneketone (PEKK), thermoinjection-molded polyamide, and polymethylmethacrylate (PMMA). Fifty disc-shaped specimens were fabricated (10 mm x 2 mm) from PEKK (P group), polyamide (D group), and PMMA (M group). These groups were divided into five subgroups (n= 10) according to the storage media. The test groups were immersed in the following solutions: distilled water (Control), Corega, Protefix, Perlodent, and Curaprox. The color stability values (Delta E) were measured using a spectrophotometer before and after immersion in distilled water and four different denture cleansers for 8 hr/day for 140 days. Topography alterations after treatments were assessed with scanning electron microscopy (SEM). Data were analyzed by one-way analysis of variance (ANOVA) followed by Tukey-s Honest Significant Difference test. Thep < .05 was considered significant. All denture cleansers increased the Delta Evalues relative to the baseline values in the M, D, and P groups (p < .05). The Perlodent denture cleanser demonstrated the highest Delta Evalue in all groups, which was unacceptable. Curaprox denture cleanser showed the lowest Delta Evalue in the M and D groups (p < .05). Curaprox in all groups showed a increment Evalue less than 3.7. For patients who have PEKK- and polyamide-based prosthesis, the use of citric acid-based cleansers may be more recommended than sodium perborate-containing cleansers because of its clinically acceptable color changes on polymers in terms of color stability.Publication Protetik tedavilerde lazerlerin kullanımı(2015-04-01) AKPINAR, YUSUF ZİYA; TAK, ÖNJEN; KARA, ÖZLEM; ÜŞÜMEZ, ASLIHAN; KARA, ÖZLEMPublication Atomic force microscopy investigation of lithium disilicate glass ceramic after various surface treatments(2014-07-01T00:00:00Z) Kara, H. B.; Kara, O.; Sayin, G.; Cakan, U.; Ozturk, A. N.; KARA, ÖZLEMThe aim of this study is to evaluate the influence of various surface treatments on the surface roughness of a lithium disilicate glass ceramic. A total of 25 discs of lithium disilicate glass ceramic were prepared. Specimens were divided into five groups: (1) no treatment, (2) air abrasion, (3) acid etching, (4) Nd:YAG laser irradiation and (5) Er:YAG laser irradiation. Digital images from the surfaces were obtained by means of an atomic force microscope in tapping mode. Surface roughness was measured in 10x10 mu m boxes. Surface roughness data were analysed by one way analysis of variance. The air abrasion group (550 +/- 212 nm) had a significantly higher mean surface roughness value than the other groups. The acid etching group (392 +/- 157 nm) had a significantly higher mean roughness value than the control group (228 +/- 105 nm). Surface roughness of lithium disilicate glass ceramic was not increased by any of the laser irradiation treatments.