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Öğe Bonding Strength of Ceromer with Direct Laser Sintered, Ni-Cr-Based, and ZrO2 Metal Infrastructures After Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments-A Comparative In Vitro Study(MARY ANN LIEBERT, INC, 2016) Gorler, Oguzhan; Ozdemir, Ali KemalObjective: Laser modalities instead of conventional surface treatment techniques have been suggested to obtain an adequate micromechanical bonding between dental super-and infrastructures. The present study was undertaken to assess the effect of surface treatment with Ho: YAG, Er: YAG, and Nd:YAG laser modalities on the shear bond strength (SBS) of ceromer to different types of metal infrastructures in in vitro settings. Methods: The study specimens consisted of 40 direct laser sintered (DLS), 40 Ni-Cr-based, and 40 zirconium oxide (ZrO2) infrastructures. In each infrastructure group, the specimens were divided randomly into five treatment modalities (n = 8): no treatment (controls), sandblasting, Er: YAG, Nd: YAG, and Ho: YAG lasers. The DLS, Ni-Cr-based, and ZrO2 infrastructures were prepared in the final dimensions of 7 mm in diameter and 3 mm in thickness in line with the ISO 11405 standard. Ceromer as superstructure was applied to all the infrastructures after their surface treatments according to the selected treatment modality. SBS test was performed to test the effectiveness of surface treatments. A stereomicroscope was used to determine the changes in the surface morphology of specimens. Results: Among the laser modalities and sandblasting, Ho: YAG laser caused the most important increase in the DLS and Ni-Cr-based infrastructures but sandblasting caused the most important increase in the ZrO2 infrastructure. In all the infrastructures, Nd: YAG laser has the least effectiveness, and Er: YAG laser makes an intermediate success. The stereomicroscopy images presented that the applications of laser surface treatments altered the surface in all the infrastructures. Conclusions: Overall, in current experimental settings, Ho: YAG, Nd: YAG, and Er: YAG lasers, in order of strength, are effective in improving the bonding of ceromer to all the infrastructures. Ho: YAG laser is more effective in the DLS and Ni-Cr-based infrastructures, but sandblasting is more effective in the ZrO2 infrastructure. The studied laser modalities need to be subjected for further studies to determine their appropriate settings and the specifications to be used in prosthodontics.Öğe Effect of corrosive environments and thermocycling on the attractive force of four types of dental magnetic attachments(ELSEVIER TAIWAN, 2013) Akin, Hakan; Ozdemir, Ali KemalBackground/purpose: One of the problems that has limited magnets' wide acceptance by clinicians is their low corrosion resistance. The purpose of this study was to determine the effect of corrosive environments and thermocycling on the attractive force of different types of new generation magnetic attachments. Materials and methods: We measured the attractive forces of 60 magnetic attachment systems (Hyper slim, Hicorex slim, Dyna, and Steco) with a universal test machine. We then immersed 40 of the magnetic attachment systems in two media, namely, 1% lactic acid solution (pH 2.3), and 0.9% NaCl solution (pH 7.3). The remaining magnetic attachments were put through 10,000 thermal cycles (5 degrees C/55 degrees C). We measured the attractive forces of the magnetic attachment systems again after immersion and thermocycling to compare data. The data were statistically evaluated with one-way analysis of variance, paired samples t-test, and post hoc Tukey-Kramer multiple comparison tests (alpha = 0.05). Results: We found significant differences between the mean values before and after immersion in corrosive environments (P < 0.05). In contrast to the Dyna and Steco systems (P < 0.001), the differences between the attractive forces before and after thermocycling were not statistically significant for the Hicorex slim and Hyper slim systems (P > 0.05). Conclusion: Magnetic attachments showed lower attractive force after immersion in corrosive environments compared to their initial retentive force. In addition, closed-field systems were not affected by the thermocycling procedures and were more resistant than open-field systems to thermal variations characteristic of the oral cavity. Copyright (c) 2012, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.Öğe Effects of boron on the mechanical properties of polymethylmethacrylate denture base material(Istanbul Univ Press, Istanbul Univ Rectorate, 2021) Ozdemir, Ali Kemal; Dogan, Derya Ozdemir; Tugut, Faik; Demir, Hakan; Akin, HakanPurpose The objective of this study was to determine whether the addition of different types of boron (Borax, Boric Acid and Colemanite) to polymethyl methacrylate denture base resin would improve flexural and impact strengths, and surface hardness of polymethyl methacrylate. Materials and Methods Borax, Boric acid, Colemanite were added to heat polymerized polymethyl methacrylate specimens were prepared for flexural strength (65x10x2.5 mm), impact strength (50x6x4 mm), and hardness (20x6x4 mm) tests according to the manufacturers' instructions (n=10). To determine flexural strength of the specimens, they were loaded until failure on a universal testing machine using a three point bending test. Specimens were subjected to the Charpy impact test machine. Hardness of the specimens was measured with an analog shoremeter Shore D. The data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (alpha=0.05). Results The highest mean flexural strength value was seen in 3% Borax group and followed by 1% Colemanite group. In addition, the highest mean impact strength value was recorded in 1% Colemanite group, and differences between 1% Colemanite group and control group were found to be statistically significant (p=0,001). Furthermore, there was significant difference in hardness between control group and all other groups (p<0.001). Conclusion The addition of 1% Colemanite to polymethyl methacrylate improved the mechanical properties of PMMA.Öğe The Effects of Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments to Acrylic Resin Denture Bases on the Tensile Bond Strength of Silicone-Based Resilient Liners(MARY ANN LIEBERT, INC, 2015) Gorler, Oguzhan; Dogan, Derya Ozdemir; Ulgey, Melih; Goze, Aysegul; Hubbezoglu, Ihsan; Zan, Recai; Ozdemir, Ali KemalObjective: The present study was to assess the effect of surface treatments of Er:YAG, Nd:YAG, and Ho:YAG lasers on the tensile bond strength of a silicone-based resilient liner to an acrylic denture in an in vitro setting. Methods: Experimental dumbbell-shaped specimens (75mm) were produced by combining two acrylate pieces fabricated from heat-polymerized acrylic resin (36mm) with 3mm of Molloplast((R))-B filling between them. The specimens (n=200) were randomly divided in half for thermocycling, and each 100 specimen set was randomized into five groups (n=20) with different surface treatments: control (no surface treatment), sandblasting, Er:YAG laser, Nd:YAG laser, and Ho:YAG laser. A tensile bond strength test was performed. The effect of the laser surface treatments was examined with scanning electron microscopy. Results: Only the Er:YAG laser increased the tensile bond strength compared with the other treatments. The other laser groups showed lower bond strengths. The Ho:YAG laser resulted in considerably reduced tensile bond strength. The scanning electron microscopy images showed that applying laser surface treatments modified the surface of the denture base resin. Conclusions: There was not an overall improvement with the use of the studied laser modalities in the adhesion quality of resilient denture liner to acrylic resin, although Er:YAG laser showed a potential to improve their adhesion. These laser modalities need to be subjected to further studies to determine optimal setup for use in prosthodontics.Öğe Histopathological evaluation of the effects of fiber reinforced acrylic resins on living tissues(INFORMA HEALTHCARE, 2013) Ozdemir, Ali Kemal; Polat, Nilufer Tulin; Turgut, Mehmet; Dogan, Derya Ozdemir; Goze, FahrettinObjective. The aim of this study was the histopathological evaluation of the effects of the fiber reinforced acrylic resins on living tissues. Materials and methods. The study was performed on 21 rabbits. Three groups, each including seven subjects, were formed. There was no applied plate in the control group. For the second group, heat-polymerized acrylic resin plates were inserted. For the third group, heat-polymerized acrylic resin plates containing proportionally 5% chopped silanated E type glass fiber were inserted. Plates were fixed to the palatine bone of the rabbits with titanium screws. Before the implementation of the plates and 1 month after the plates were applied, soft tissue samples were taken from the buccal mucosa of the rabbits. Also, tissue samples were taken from the control group. All samples were evaluated histopathologically. Results. In the control group, only a focal atrophy was observed. In the acrylic group, large decomposition containing erythrocytes under the parahyperkeratotic region and micro-vesicle like spongiotic tissue reactions were observed. In the fiber reinforced acrylic group, widespread focal atrophy, bulgy look of the epithelium cells similar to apoptosis, over-distension and sub-corneal decomposition had been observed. In terms of atrophy and hyperkeratosis there were no statistically significant differences among groups. However, in respect to sub-corneal decomposition, there was a statistically significant difference in the fiber reinforced group (p < 0.01). Conclusions. The statistically significant difference in the sub-corneal decomposition of the fiber reinforced group had made us think that fiber edges had a traumatic effect on the reaction.Öğe Investigation of flexural strength and cytotoxicity of acrylic resin copolymers by using different polymerization methods(KOREAN ACAD PROSTHODONTICS, 2015) Sahin, Onur; Ozdemir, Ali Kemal; Turgut, Mehmet; Boztug, Ali; Sumer, ZeynepPURPOSE. The aim of this study was to appraise the some mechanical properties of polymethyl methacrylate based denture base resin polymerized by copolymerization mechanism, and to investigate the cytotoxic effect of these copolymer resins. MATERIALS AND METHODS. 2-hydroxyethyl methacrylate (HEMA) and isobutyl methacrylate (IBMA) were added to monomers of conventional heat polymerized and injection-molded poly methyl methacrylate (PMMA) resin contents of 2%, 3%, and 5% by volume and polymerization was carried out. Three-point bending test was performed to detect flexural strength and the elasticity modulus of the resins. To determine the statistical differences between the study groups, the Kruskall-Wallis test was performed. Then pairwise comparisons were performed between significant groups by Mann-Whitney U test. Agar-overlay test was performed to determine cytotoxic effect of copolymer resins. Chemical analysis was determined by FTIR spectrum. RESULTS. Synthesis of the copolymer was approved by FTIR spectroscopy. Within the conventional heat-polymerized group maximum transverse strength had been seen in the HEMA 2% concentration; however, when the concentration ratio increased, the strength decreased. In the injection-molded group, maximum transverse strength had been seen in the IBMA 2% concentration; also as the concentration ratio increased, the strength decreased. Only IBMA showed no cytotoxic effect at low concentrations when both two polymerization methods applied while HEMA showed cytotoxic effect in the injection-molded resins. CONCLUSION. Within the limitations of this study, it may be concluded that IBMA and HEMA may be used in low concentration and at high temperature to obtain non-cytotoxic and durable copolymer structure.Öğe A longitudinal study on lung disease in dental technicians: What has changed after seven years?(VERSITA, 2013) Dogan, Derya Ozdemir; Berk, Serdar; Gumus, Cesur; Ozdemir, Ali Kemal; Akkurt, IbrahimThe aim of this 7-year follow-up study was to determine respiratory changes in dental technicians. In our region, in the year 2005, 36 dental technicians were evaluated with a cross-sectional study on respiratory occupational diseases, and in 2012 we evaluated them again. Inclusion of information on respiratory symptoms and demographic features questionnaires was applied. Pulmonary function tests (PFT) were performed. Chest X-rays (CXR) were evaluated according to the ILO-2000 classification. For the comparisons of the technicians' findings in 2005 and 2012, data analyses were performed with the Wilcoxon test in addition to descriptive statistical procedures. In 2012, 19 out of the 36 technicians continued to work in the same place, so we were able to evaluate their findings. The prevalence of respiratory symptoms in dental technician was as follows: dyspnea 7 (37%), cough 6 (32%), and phlegm 5 (26%). According to ILO classifications in 2005, among the 36 technicians, 5 (13.8%) had pneumoconiosis. At the end of 7 years, there were 9 pneumoconiosis cases among the 19 remaining technicians (47%). Thus, there was a statistically significant progression on the profusion of the radiologic findings (p < 0.005). Also there was a significant worsening on spirometric findings (p < 0.05). In dental technicians, a determination of both radiologic and functional progressions at the end of 7 years demonstrate that the primary and secondary preventive measures are necessary for these workplaces. Workplaces must be regularly controlled for worker health and hygiene.Öğe Multidisciplinary Approach for Esthetic, Functional, and Quality-of-Life Outcome in Soft Palate Cleft Patient(ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS, 2012) Akin, Hakan; Coskun, Mehmet Emre; Akin, Emine Gulsah; Ozdemir, Ali KemalThe fabrication of a Suersen obturator prosthesis with titanium framework is described in the case of a 43-year-old man with congenital absence of the soft palate. The patient revealed an open soft palate, bilateral cleft lip and palate, Angle Class III dental malocclusion, and anterior and posterior crossbite. He was treated with a multidisciplinary approach. A Dolder bar was fabricated between the maxillary canines, and telescopic crowns were prepared for maxillary premolars. Angle Class III tooth relation was readjusted to tooth-tooth relation; closure of the nasopharynx and oropharynx was performed by Suersen method, which improves speech.Öğe Shear Bond Strength of Resin Cement to Zirconia Ceramic After Aluminum Oxide Sandblasting and Various Laser Treatments(MARY ANN LIEBERT, INC, 2011) Akin, Hakan; Ozkurt, Zeynep; Kirmali, Omer; Kazazoglu, Ender; Ozdemir, Ali KemalObjective:The aim of this study was to evaluate the effect of different surface treatments; sandblasting, Er:YAG, Nd:YAG, or CO2 laser irradiation on the shear bond strength (SBS) of zirconia ceramic to dentin. Background data:Zirconia is not properly luted with resin cements. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to resin cements. There is no study that compared the effect of different laser types (Er:YAG, Nd:YAG, CO2) with sandblasting on SBS between zirconia and dentin. Methods:One hundred and twenty human maxillary third molar teeth were sectioned 3mm below the occlusal surfaces, embedded in a metal ring with autopolymerizing acrylic resin, and stored in distilled water at 37(0)C. One hundred and twenty disc-shaped zirconia specimens were fabricated (6mm in diameter and 4mm in thickness), and randomly assigned to six groups (n = 20):Group 1, untreated (control); Group 2, sandblasted; Group 3, Er:YAG laser irradiated; Group 4, Nd:YAG laser irradiated with contact; Group 5, Nd:YAG laser irradiated with non-contact; Group 6, CO2 laser irradiated. They were cemented onto the dentin with dual-cured resin cement (Variolink (R)). After they were stored in distilled water at 37(0)C for 24 h, the SBS test was performed at a crosshead speed of 1mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Results:Results of this study did not show statistically significant differences between Groups 1 and 2, or among Groups 3, 4 and 5. The lowest SBS was recorded in Group 6 (CO2 laser), and the highest SBS was recorded in Group 4 (Nd:YAG laser with contact), followed by Group 3 (Er:YAG laser). The adhesive failure mode was predominantly observed in Groups 2, 3, 5, and 6. Group 1 showed 45% mixed failure and Group 4 showed 50% mixed failure. Conclusions:This study shows that Er:YAG and Nd:YAG laser treatment increased the bond strength of zirconia compared to sandbasting and CO2 laser treatment.Öğe Shear Bond Strength of Veneering Ceramic to Zirconia Core After Different Surface Treatments(MARY ANN LIEBERT, INC, 2013) Kirmali, Omer; Akin, Hakan; Ozdemir, Ali KemalObjective: The aim of this study was to evaluate the effect of different surface treatments: sandblasting, liners, and different laser irradiations on shear bond strength (SBS) of pre-sintered zirconia to veneer ceramic. Background data: The SBS between veneering porcelain and zirconium oxide (ZrO2) substructure was weak. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to veneering porcelain. There is no study that evaluated the bond strength between veneering porcelain and the different surface treatments on pre-sintered ZrO2 substructure. Methods: Two hundred specimens with 7mm diameter and 3mm height pre-sintered zirconia blocks were fabricated. Specimens were randomly divided into 10 groups (n = 20) according to surface treatments applied. Group C, untreated (Control); Group E, erbium: yttrium-aluminum-garnet (Er:YAG) laser irradiated; Group N, neodymium: yttrium-aluminum-garnet (Nd:YAG) laser irradiated; Group SB, sandblasted; Group L, liner applied; Group NL, Nd:YAG laser irradiated + liner applied; Group EL, Er:YAG laser irradiated + liner applied; Group SN, sandblasted + Nd:YAG laser irradiated; Group SE, sandblasted + Er:YAG laser irradiated; and Group SL, sandblasted + liner applied. The disks were then veneered with veneering porcelain. Before the experiment, specimens were steeped in 37 degrees C distilled water for 24 h. All specimens were thermocycled for 5000 cycles between 5 degrees C and 55 degrees C with a 30 sec dwell time. Shear bond strength test was performed at acrosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Results: Surface treatments significantly changing the topography of the yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic according to scanning electron microscopic (SEM) images. The highest mean bond strength value was obtained in Group SE, and the lowest bond strength value was observed in NL group. Bond strength values of the other groups were similar to each other. Conclusions: This study shows that sandblasting + Er:YAG, sandblasting, Er:YAG + liner, sandblasting + Nd:YAG, and Er:YAG laser treatment on pre-sintered ZrO2 substructure increased the bond strength to veneering porcelain, compared with other surface treatments. After different surface treatments, there was no difference in surface roughness of pre-sintered zirconia to compare after sintering; sintering enhanced the bond strength within the limitations of present study.
