Person: KARA, ÖZLEM
Now showing 1 - 10 of 33
- PublicationMetadata onlyThe effect of different distance of curing light and ceramic materials on microhardness of the resin(2018-01-01) ATAY, AYŞE; Gürdal, IŞIL; TAŞIN, SİMGE; KARA, ÖZLEM; ÜŞÜMEZ, ASLIHAN; ATAY, AYŞE; GÜRDAL, IŞIL; KARA, ÖZLEM
- PublicationOpen AccessMechanical 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 surfaces
- PublicationOpen AccessEffects 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.
- PublicationMetadata onlyAtomic 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.
- PublicationMetadata onlyLasers in Dentistry: Case Series(2018-10-28) KARA, ÖZLEM; KARA, ÖZLEM
- PublicationMetadata onlyEffect of different surface treatments on roughness of IPS Empress 2 ceramic(2012-03-01T00:00:00Z) Kara, Haluk Baris; Dilber, Erhan; Koc, Ozlem; Ozturk, A. Nilgun; Bulbul, Mehmet; KARA, ÖZLEMThe aim of this study was to evaluate the influence of different surface treatments (air abrasion, acid etching, laser irradiation) on the surface roughness of a lithium-disilicate-based core ceramic. A total of 40 discs of lithium disilicate-based core ceramic (IPS Empress 2; Ivoclar Vivadent, Schaan, Liechtenstein) were prepared (10 mm in diameter and 1 mm in thickness) according to the manufacturer-s instructions. Specimens were divided into four groups (n = 10), and the following treatments were applied: air abrasion with alumina particles (50 mu m), acid etching with 5% hydrofluoric acid, Nd:YAG laser irradiation (1 mm distance, 100 mJ, 20 Hz, 2 W) and Er:YAG laser irradiation (1 mm distance, 500 mJ, 20 Hz, 10 W). Following determination of surface roughness (R-a) by profilometry, specimens were examined with atomic force microscopy. The data were analysed by one-way analysis of variance (ANOVA) and Tukey HSD test (alpha = 0.05). One-way ANOVA indicated that surface roughness following air abrasion was significantly different from the surface roughness following laser irradiation and acid etching (P 0.05). Air abrasion increased surface roughness of lithium disilicate-based core ceramic surfaces more effectively than acid-etching and laser irradiation.
- PublicationOpen AccessIn 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]
- PublicationMetadata onlyEffect of Thermal and Mechanical Cycling on Dentin Bond Strength(2015-09-03T00:00:00Z) İnan İnegöl, Pelin; Kara, Barış; Sarı, Tuğrul; Özyılmaz, Özgün Yusuf; Kara, Özlem; Üşümez, Aslıhan; ÖZYILMAZ, ÖZGÜN YUSUF; KARA, ÖZLEM
- PublicationMetadata onlyEdentulous Full Arch Fixed Implant Rehabilitation using Hybrid Prostheses: Case Report(2017-05-04T00:00:00Z) Kara, Özlem; Özyılmaz, Özgün Yusuf; Kara, Barış; Delilbaşı, Barış Çağrı; KARA, ÖZLEM; ÖZYILMAZ, ÖZGÜN YUSUF
- PublicationMetadata onlySeramik restorasyonların mikrosızıntısı üzerine yüksek yoğunluklu LED işık kaynağı mesafesinin değerlendirilmesi(2016-04-01) KARA, ÖZLEM; ATAY, AYŞE; GÜVEN, MEHMET ESAD; ISMATUALLEV, Artur; ÜŞÜMEZ, ASLIHAN; KARA, ÖZLEM; ATAY, AYŞE