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Öğe Adhesion between glass fiber posts and resin cement: evaluation of bond strength after various pre-treatments(INFORMA HEALTHCARE, 2014) Sipahi, Cumhur; Piskin, Bulent; Akin, Gulsah E.; Bektas, Ozden Ozel; Akin, HakanPurpose. To evaluate surface roughness and bond strength of glass fiber posts to a resin cement after various surface treatments. Materials and methods. Sixty individually formed glass fiber posts with a diameter of 1.5 mm and a length of 20 mm were used for this study. They were randomly assigned to six groups of pre-treatment (n = 10/group): Group C, untreated (control); Group SB, sandblasted; Group SC, silica coated; Group HF, hydrofluoric acid-etched; Group N, Nd: YAG laser irradiated; Group E, Er: YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. The posts were then bonded to resin cement and tensile bond strengths were determined in a universal testing machine. For statistical analysis, two-way ANOVA and post-hoc comparison tests (alpha = 0.05) were performed. Results. The highest bond strength value was observed in group HF, followed by group SC. There was a statistically significant difference in bond strength between group C and groups HF, SC and E (p < 0.001, p = 0.002 and p = 0.041, respectively). Posts of group SB and group N showed the highest surface roughness. Conclusions. The findings of the present study reveal that hydrofluoric acid-etching, silica coating and Er: YAG laser irradiation provided a significant increase in bond strength between glass fiber posts and resin cement.Öğe Bond Strengths of One-Step Self-Etch Adhesives to Laser-Irradiated and Bur-Cut Dentin After Water Storage and Thermocycling(MARY ANN LIEBERT, INC, 2012) Akin, Gulsah E.; Herguner-Siso, Seyda; Ozcan, Mutlu; Ozel-Bektas, Ozden; Akin, HakanObjective: The objectives of this study were to evaluate the microtensile bond strength (mu TBS) of one-step self-etch adhesive systems to Er:YAG laser-irradiated and bur-cut dentin after water storage and thermocycling. Background data: The Er:YAG laser is a promising alternative method for cavity preparation; however, no study has compared the effect of laser irradiation and aging procedures on the adhesion of one-step self-etch adhesives to dentin. Methods: Seventy-two third molars were selected and randomly divided according to cavity preparation method (Er:YAG laser and bur-cut). One-step self-etch adhesive systems (Clearfil S-3 Bond, AdheSE One and Adper Easy One) were used to bond the composite to dentin. Following the adhesive procedure, the specimens were subdivided according to aging conditions (24 h in water control [C], 6 months of water storage [WS] and 10.000 thermocycles [TC]). The mu TBS was determined in a universal testing machine. Three-way ANOVA, independent samples t test, and post-hoc comparisons test (alpha = 0.05) were performed on all data. Results: There was no statistical difference in mu TBS between Er:YAG laser-irradiated and bur-cut dentin (p > 0.05). Similarly, no significant difference was found in mu TBS between C, WS, and TC specimens (p > 0.05). Moreover, Clearfil S-3 Bond presented the highest mu TBS to dentin in both laser-irradiated and bur-cut cavity preparation methods. Conclusions: Neither bur-cut nor Er:YAG laser-irradiated dentin was affected by the aging methods used to simulate degradation of the adhesive interface. Er: YAG laser treatment may be used as an alternative cavity preparation method.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 Effect of Different Chemical Disinfectants on Color Stability of Acrylic Denture Teeth(WILEY, 2014) Piskin, Bulent; Sipahi, Cumhur; Akin, HakanPurpose: The purpose of this study was to evaluate the effects of chemical disinfectants on the color stability of acrylic denture teeth (ADT) via spectrophotometric analysis. Materials and Methods: A total of 120 central ADT specimens were randomly assigned to eight experimental groups and immersed in the following solutions (n=15). Tapwater/control group (CON), neutral soap (NTS), 2% sodium hypochlorite (SHC1), 5.25% sodium hypochlorite (SHC2), sodium perborate (SPB), povidone-iodine (PVI), chlorhexidine gluconate (CHG), and glutaraldehyde (GTA). Color measurements of teeth were performed by spectrophotometry after 10, 30, 48, 72, 144, and 960 immersion cycles in each tested solution. Color differences (Delta E*) were then evaluated using the Commission Internationale D'Eclairage (CIE) L* a* b* color system. Furthermore, Kruskal-Wallis, Mann-Whitney U, and Friedman comparison tests (alpha=0.05) were performed on all data. Results: There were significant differences in Delta E* values (p < 0.05) among the eight experimental groups. In addition, the highest Delta E* values were obtained in group SHC2, followed, respectively, by the SHC1, CHG, SPB, PVI, NTS, and CON groups. Conclusion: All the chemical disinfectants used in the study affected the color values of ADTs. Furthermore, Delta E* values increased along with the number of immersion cycles and total immersion time.Öğe Effect of different impression materials on the marginal fit of frameworks: An in-vitro study(Cumhuriyet University Faculty of Dentistry, 2016) Türk, Ayşe Gözde; Ulusoy, Mubin; YÜce, Mert; Akin, HakanObjectives: The objective of this study was to compare the accuracy of three different impression materials with evaluating the marginal fits of metal frameworks using replica technique. Materials and Methods: A phantom premolar tooth was prepared with a 1 mm circumferential chamfer preparation. Four impression materials: two vinyl polysiloxane (VPS) (Affinis Precious, (Group A); Elite HD, (Group E)), one polyether (Impregum Penta Soft, (Group P)) and one vinyl siloxanether (Identium, (Group I)) were used for producing stone casts of this master model. Twelve measurements per replica were carried out using a light microscope X40 magnification by Leica software, to assess the vertical marginal gap (VMG). Data were analyzed using the analysis of variance followed by Tukey's test (p=0.05). Results: Specimens of the Group A and Group I showed significantly lower VMG values than those of Group E and Group P (p<0.001). Differences were not significant between Group A and Group I, and Group E and Group P either (p>0.05). Conclusions: All impression materials were clinically acceptable. As well as composition of the impression materials, size of filler particles and fluid mechanics of flow into very small spaces can be effective on accuracy of the materials. © 2016. All Rights Reserved.Öğe Effect of Different Temporary Crown Materials and Surface Roughening Methods on the Shear Bond Strengths of Orthodontic Brackets(MARY ANN LIEBERT, INC, 2015) Goymen, Merve; Topcuoglu, Tolga; Topcuoglu, Sedef; Akin, HakanObjective: The aim of this study was to evaluate the effect of different temporary crown materials (TCMs) and surface roughening methods on the shear bond strength (SBS) of orthodontic brackets. Background data: TCMs are widely used during orthodontic treatment in teeth in need of prosthetic treatment, to prevent damage to the final restoration. However, there is no consensus considering the best method for roughening of the surface of TCMs. Methods: Five different TCMs [Dentalon Plus-(D), Basworth Trim II-(B), Voco Structure Premium-(V), 3M ESPE Protempt 4-(P), and Revotek LC-(R)] were used in this study. Different surface roughening methods (37% phosphoric acid, sandblasting, and Er:YAG laser) were employed in three subgroups (n=20). The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group. Results: The highest mean SBS value was observed in group V, followed by groups D and P, regardless of the surface treatment. The lowest SBS values were observed in group B. The laser-irradiated groups had higher SBS values than the sandblasted and acid-etched groups. Furthermore, a significant difference in SBS values was observed between the laser-irradiated group V and all other groups (p<0.005). Conclusions: The effects of the chemical nature of TCMs on the SBS values appeared to be clinically negligible, whereas the type of surface treatments had a significant influence on bond strengths. Er:YAG laser irradiation caused a significant increase in bond strength between the TCMs and orthodontic brackets.Öğe Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks(KOREAN ACAD PROSTHODONTICS, 2015) Turk, Ayse Gozde; Ulusoy, Mubin; Yuce, Mert; Akin, HakanPURPOSE. To determine whether the fracture strengths and failure types differed between metal and zirconia: frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS. A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled (5-55 degrees C, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS. The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION. Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks.Öğe Effect of Er:YAG laser application on the shear bond strength and microleakage between resin cements and Y-TZP ceramics(SPRINGER LONDON LTD, 2012) Akin, Hakan; Tugut, Faik; Akin, Gulsah Emine; Guney, Umit; Mutaf, BurcuThe objective of this study was to investigate the effect of Er:YAG laser irradiation on shear bond strength and microleakage between resin cements and yttrium-stabilized tetragonal zirconia (Y-TZP) ceramics. Eighty disc specimens of Y-TZP ceramics (6 mm x 4 mm) were prepared. The specimens were divided into two groups according to surface treatment (control and Er:YAG laser-treated). The control and lased specimens were separated into two groups for shear bond strength test (n = 20), and microleakage evaluation (n = 10). Specimens were subjected to shear bond strength test by a universal testing machine with a crosshead speed of 1 mm/min. Specimens for microleakage evaluation were then sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and evaluated under a stereomicroscope. The data were analyzed with one-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (alpha = 0.05) for shear bond strengths and a two related-samples tests (alpha = 0.05) for microleakage scores. Higher bond strength values were found in the laser-treated groups compared to the control groups. Microleakage scores among the groups showed that the laser-treated specimens had lower microleakage scores than those of control specimens in the adhesive-ceramic interface. Roughening surface of Y-TZP ceramic by Er:YAG laser increased the shear bond strengths of ceramic to dentin and reduced the microleakage scores.Öğe Effect of irrigation solution tempature on the osseointegration of dental implants(Cumhuriyet University Faculty of Dentistry, 2020) Yilmaz, Doğukan; Furuncuoğlu, Halit; Varol, Osman; Akin, HakanObjectives: Thermal trauma during implant surgery limits the proper healing process. The aim of the study wasto investigate the effect of different irrigation temperatures during implant surgery on the osseointegration of dental implants. Materials and Methods: Eight adult male New Zealand white rabbits were used in this study. Total of 32 implants were inserted in each tibia of each rabbit's rear legs. Rabbits were randomly divided according to different irrigation procedures applied (37°C, 24°C, 10°C, and 1°C). Resonance frequency analysis (RFA) was performed following to implant surgery, 1th week, 2nd week, 3rd week, and 1th month. In addition, removal torque values (RTVs) were measured from sacrificed tibias at the end of 30 days. Results: No significant difference in implant stability quotient (ISQ) was detected between groups from the first measurement to 5th measurement. However, there was a statistically significant difference in RTVs between 1°C and 37°C, and 1°C and 10°C (p=0.024 and p=0.013, respectively). Conclusions: Different irrigation temperatures during implant surgery were not effective on the primary and secondary stability values of dental implants in rabbit models. © 2020, Cumhuriyet University Faculty of Dentistry.Öğe Effect of repetitive firing on passive fit of metal substructure produced by the laser sintering in implant-supported fixed prosthesis(Korean Acad Prosthodontics, 2020) Altintas, Musa Aykut; Akin, HakanPURPOSE. The aim of the present study was to investigate the passive fit of metal substructure after repetitive firing processes in implant-supposed prosthesis. MATERIALS AND METHODS. Five implants (4 mm diameter and 10 mm length) were placed into the resin-based mandibular model and 1-piece of screw-retained metal substructure was produced with the direct metal laser sintering (DMSL) method using Co-Cr compound (n = 10). The distance between the marked points on the multiunit supports and the marginal end of the substructure was measured using a scanning electron microscope (SEM) at each stage (metal, opaque, dentin, and glaze). 15 measurements were taken from each prosthesis, and 150 measurements from 10 samples were obtained. In total, 600 measurements were carried out at 4 stages. One-way ANOVA test was used for statistical evaluation of the data. RESULTS. When the obtained marginal range values were examined, differences between groups were found to be statistically significant (P<.001). The lowest values were found in the metal stage (172.4 +/- 76.5 mu m) and the highest values (238.03 +/- 118.92 mu m) were determined after glaze application. When the interval values for groups are compared with pairs, the differences between metal with dentin, metal with glaze, opaque with dentin, opaque with glaze, and dentin with glaze were found to be significant (P<.05), whereas the difference between opaque with metal was found to be insignificant (P=.992). CONCLUSION. Passive fit of 1-piece designed implant-retained fixed prosthesis that is supported by multiple implants is negatively affected by repetitive firing processes.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 Effects of complete dentures on respiratory performance: spirometric evaluation(WILEY-BLACKWELL, 2014) Piskin, Bulent; Sipahi, Cumhur; Karakoc, Omer; Atay, Arzu; Ciftci, Faruk; Tasci, Canturk; Akin, Hakan; Arisan, Volkan; Sevketbeyoglu, Haldun; Turker, TurkerObjectivesThere is a lack of data regarding whether edentulous subjects should remove dentures during spirometric measurements or not. The purpose of this study is to determine influences of complete dentures on spirometric parameters in edentulous subjects. Materials and methodsA total of 46 complete denture wearers were included in this study. Respiratory functions of the subjects were evaluated by spirometric tests that were performed in four different oral conditions: without dentures (WOD), with dentures, lower denture only and upper denture only. Forced vital capacity (FVC), peak expiratory flow, forced expiratory volume in 1s and forced expiratory flow between 25% and 75% were evaluated. The data were analyzed with Friedman, Wilcoxon and paired-samples t tests (=0.05). ResultsSignificant differences were found between spirometric parameters in different oral conditions (p<0.05). In all spirometric parameters, the most important significant differences were found between conditions WOD, FVC and with lower dentures (FVC), and WOD (forced expiratory volume in 1s) and with upper dentures (forced expiratory volume in 1s) (p<0.001). ConclusionIt was observed that complete dentures may unfavourably affect spirometric values of edentulous subjects. However, current findings need to be confirmed with advanced respiratory function tests.Öğe Effects of Different Surface Treatments on the Bond Strength of Acrylic Denture Teeth to Polymethylmethacrylate Denture Base Material(MARY ANN LIEBERT, INC, 2014) Akin, Hakan; Kirmali, Omer; Tugut, Faik; Coskun, Mehmet EmreObjective: The purpose of this study was to investigate the effects of various surface pretreatments in the ridge lap area of acrylic resin denture teeth on the shear bond strength to heat-polymerized polymethylmethacrylate (PMMA) denture base resin. Background data: Tooth debonding of the denture is a major problem for patients with removable prostheses. Methods: A total of 84 central incisor denture teeth were used in this study. Seven test groups with 12 specimens for each group were prepared as follows: untreated (control, group C), ground, with a tungsten carbide bur (group H), airborne-particle abrasion (group AA), primed with methyl methacrylate (group M), treated with izobutyl methacrylate (group iBMA), Eclipse Bonding Agent applied (group E), and Er:YAG laser irradiated (group L). Test specimens were produced according to the manufacturers' instructions and mounted to a universal testing machine for shear testing with a crosshead speed of 1 mm/min. Data were evaluated by one way variance analysis (ANOVA) and Tukey's test (alpha = 0.05). Results: Similar bond strength values were found between groups L and M, and these were the highest shear bond strengths among the groups. The lowest one was observed in group E. All surface treatments, except group E, exhibited significant difference when compared with group C (p < 0.05). Conclusions: Lasing of the ridge lap area to enhance the bond strength of acrylic resin denture teeth to PMMA denture base resin might be an alternative to wetting with MMA monomer. To overcome tooth debonding, surface treatment of the ridge lap area should be performed as part of denture fabrication.Öğe Effects of Sandblasting and Laser Irradiation on Shear Bond Strength of Low-fusing Porcelain to Titanium(QUINTESSENCE PUBLISHING CO INC, 2013) Akin, Hakan; Tugut, Faik; Topcuoglu, Sedef; Kirmali, OmerPurpose: To investigate the bond strength of low-fusing porcelain to commercially pure titanium (Ti) that was laser irradiated with different levels of energy and sandblasted. Materials and Methods: A total of 30 titanium rods (10 mm in length and 12 mm in diameter) were prepared. The rods were divided into three groups (n = 10) according to surface treatments: SB: sandblasted; L1: Nd: YAG laser irradiated at 100 mJ, 10 Hz, and 1 W; L2: Nd: YAG laser irradiated at 200 mJ, 10 Hz, and 2 W. After surface treatment, low-fusing porcelain was applied onto the titanium specimens according to the manufacturer's instructions, and these specimens were stored in distilled water at 37 C for 24 h. The shear bond strength test was performed at a crosshead speed of 1 mm/min. In addition, Kruskal-Wallis and Mann-Whitney U-tests were used to compare the bond strength results (alpha = 0.05). SEM and EDS analysis were also performed for one specimen of each group after the shear bond strength test to evaluate the nature of the fracture surface. Results: Group L2 produced the highest shear bond strength among the groups. There was a statistically significant difference in shear bond strength between groups L1 and L2 (p < 0.001). Nevertheless, no significant difference was found between groups SB and L1. EDS analysis revealed that laser treatment reduced presence of oxygen on the surface of Ti. In contrast to the sandblasted specimens, laser-irradiated specimens showed predominantly adhesive failure. Conclusion: Laser treatment may be an alternative method to sandblasting for enhancing the bond strength of low-fusing porcelain to commercially pure titanium.Öğe Evaluation of a self-adhering flowable composite in terms of micro-shear bond strength and microleakage(TAYLOR & FRANCIS LTD, 2013) Bektas, Ozden Ozel; Eren, Digdem; Akin, Emine Gulsah; Akin, HakanPurpose. The objective of this study was to evaluate dentin bond strength and microleakage of a self-adhering flowable resin with or without adhesive resin. Materials and methods. Dentin pieces were randomly assigned to three groups (n = 10): Group OR (Optibond+Revolution Formula 2 Flow); Group VF (Vertise Flow); and Group OVF (Optibond+Vertise Flow). Then specimens were stressed in shear at a cross-head speed of 1 mm/min until the bond failed. Moreover, microleakage was determined by restoring Class V cavities. A statistical analyses was carried out using Mann-Whitney U and Kruskal-Wallis tests (p < 0.05). Results. Group OVF specimens produced the highest mean shear bond strength. In addition, the results showed that the marginal seal in group VF was similar to that in group OR. Conclusion. Self-adhering flowable composite resin combined with adhesive resin provided stronger dentin bond strength and a better marginal seal than when it was used individually. VF is a useful material with an acceptable bond strength and marginal seal.Öğe Evaluation of surface roughness and bond strength of quartz fiber posts after various pre-treatments(INFORMA HEALTHCARE, 2014) Akin, Gulsah E.; Akin, Hakan; Sipahi, Cumhur; Piskin, Bulent; Kirmali, OmerPurpose. Debonding at the post-adhesive interface is a major problem for quartz fiber posts. The objective of this study was to evaluate surface roughness and bond strength of quartz fiber posts after various surface treatments. Materials and methods. Sixty-six quartz fiber posts were randomly divided into six experimental groups (n = 11) including group C, untreated (control); group SB, sandblasted; group SC, silica coated; group HF, hydrofluoric acid-etched; group N, Nd:YAG laser irradiated; group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. They were then bonded to resin cement and tensile bond strength was determined in a universal testing machine. Furthermore, two-way ANOVA and post hoc comparison tests (alpha = 0.05) were performed on all data. Results. The highest mean force value was observed in group SB and followed by group E. Tukey's HSD test showed that there was no statistical difference between group SB and group E (p = 0.673). The highest mean roughness value was observed in group SB and a significant difference was found between group SB and all other groups (p < 0.001). This study reveals that sandblasting and Er:YAG laser irradiation provided a significant increase in bond strength between quartz fiber posts and resin cement. Conclusions. Sandblasting or Er:YAG laser-irradiation of the surface of the quartz fiber post before cementation is recommended for increasing retention.Öğe EVALUATION OF THE ATTRACTIVE FORCE OF DIFFERENT TYPES OF NEW-GENERATION MAGNETIC ATTACHMENT SYSTEMS(MOSBY-ELSEVIER, 2011) Akin, Hakan; Coskun, M. Emre; Akin, E. Gulsah; Ozdemir, A. KemalStatement of problem. Rare earth magnets have been used in prosthodontics, but their tendency for corrosion in the oral cavity and insufficient attractive forces limit long-term clinical application. Purpose. The purpose of this study was to evaluate the attractive force of different types of new-generation magnetic attachment systems. Material and methods. The attractive force of the neodymium-iron-boron (Nd-Fe-B) and samarium-cobalt (Sm-Co) magnetic attachment systems, including closed-field (Hilop and Hicorex) and open-field (Dyna and Steco) systems, was measured in a universal testing machine (n=5). The data were statistically evaluated with 1-way ANOVA and post hoc Tukey-Kramer multiple comparison test (alpha=.05). Results. The closed-field systems exhibited greater (P <.001) attractive force than the open-field systems. Moreover, there was a statistically significant difference in attractive force between Nd-Fe-B and Sm-Co magnets (P<.001). The strongest attractive force was found with the Hilop system (9.2 N), and the lowest force was found with the Steco system (2.3 N). Conclusions. The new generation of Nd-Fe-B closed-field magnets, along with improved technology, provides sufficient denture retention for clinical application. (J Prosthet Dent 2011;105:203-207)Öğe Evaluation of the effects of age, gender, education and income levels on the tooth loss and prosthetic treatment(Cumhuriyet University Faculty of Dentistry, 2011) Akin, Hakan; Tuğut, Faik; Güney, Umit; Akar, Turker; Özdemir, Ali KemalObjectives: The purpose of this study was to investigate the effects of age, gender, education and income levels of the patients on their teeth losses and prosthodontic needs. Materials and Methods: This study was performed on 615 patients who were referred to the Department of Prosthodontics, Faculty of Dentistry, Cumhuriyet University. Age, gender, education and income levels and teeth losses of the patients were recorded. Furthermore, prosthodontic treatments, removable partially denture designs and the colors of the dentures were noted. The data were analyzed with Chi- Square test (A=0,05). Results: The most incidence of tooth loss was seen in the molar region. Moreover, there was a significant difference between education and income levels and prosthodontic needs (p=0,001). On the other hand, no significant difference was found between gender and edentolousness (p=0,381), and edentulousness and income level (p=0,334). However, there was a significant difference between education level and edentulousness (p=0,005). In addition, full palatal plaque (in the upper jaw) and lingual bar (in the lower jaw) were the most used removable partially denture designs. It was found that the most preferred color in both removable and fixed dentures was A2. Conclusions: Improving knowledge level of the patient about oral health should be required. Thus, this enables decreasing tooth loss and high ratio of the removable prosthodontic need.Öğe Evaluation of the surface roughness of zirconia ceramics after different surface treatments(TAYLOR & FRANCIS LTD, 2014) Kirmali, Omer; Akin, Hakan; Kapdan, AlperObjective. This study aimed to investigate the effects of different mechanical surface treatments of pre-sintered zirconium oxide (ZrO2) in an attempt to improve its bonding potential. Materials and methods. One hundred and twenty IPS e-max ZirCAD (Ivoclar Vivadent) pre-sintered zirconia blocks (7 mm diameter, 3 mm height) received six different surface treatments (n = 20): Group C was untreated (control); Group E was Er: YAG laser irradiated; Group N was Nd: YAG laser irradiated; Group SB was sandblasted, Group SN was sandblasted and Nd:YAG laser irradiated; and Group SE was sandblasted and Er: YAG laser irradiated. After the surface treatments, the average surface roughness (Ra, mu m) of each specimen was determined with a profilometer, then all the specimens were sintered. The surface roughness values were analysed through one-way ANOVA and Tukey's test. Changes in the morphological characteristics of ZrO2 were examined through scanning electron microscopy (SEM). Results. Sintered sandblasted, Er:YAG laser treatment, sandblasted + Er: YAG laser and sandblasted + Nd:YAG laser irradiation resulted in a rougher surface than the other treatments. Conclusion. Nd:YAG laser irradiation alone was not effective in altering the zirconia surface morphology.Öğe In Vitro Comparison of the Cytotoxicity and Water Sorption of Two Different Denture Base Systems(WILEY-BLACKWELL, 2015) Akin, Hakan; Tugut, Faik; Polat, Zubeyde AkinPurposeDenture base resins have the potential to cause cytotoxicity in vivo, and the mechanical properties of resins are affected by water sorption. There is a correlation between residual monomer and water sorption. Thus, the purpose of this study was to evaluate water sorption and cytotoxicity of light-activated urethane dimethacrylate (UDMA) denture base resin compared to a conventional heat-activated polymethyl methacrylate (PMMA) resin. Materials and MethodsTwo denture base resins, heat-activated PMMA (Meliodent) and light-activated UDMA (Eclipse), were used in this study. Cytotoxicity (5 x 1 mm(2)) and water sorption (1 x 1 mm(2)) specimens were made following the manufacturers' instructions (n = 10). Cytotoxicity tests of denture base resins were performed according to ISO10993-5:1999, and water sorption was evaluated according to ISO 1567:1997. ANOVA tests were employed for evaluating data ( = 0.05). ResultsThere was no cytotoxic effect in either the PMMA or UDMA group. In addition, contrary to short-term water storage, a significantly lower water sorption value was shown for UDMA resins compared to PMMA resins in both 3- and 6-month storage periods (p = 0.043 and p = 0.002, respectively). ConclusionThe tested denture base materials adhered to the ISO standards for both cytotoxicity and water sorption. The cytotoxicity of the light-activated UDMA resin tested was statistically similar to that of the heat-activated PMMA resin; however, the UDMA resin exhibited decreased water sorption in long-term water storage.
