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Öğe Composite-veneering of polyether-ether-ketone (PEEK): evaluating the effects of different surface modification methods on surface roughness, wettability, and bond strength(Springer London Ltd, 2023) Turkkal, Fatos; Culhaoglu, Ahmet Kursad; Sahin, VolkanThis study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 x 7 x 2 mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.Öğe The effect of repetitive firings on the color of an alumina ceramic system with varying ceramic shade and thickness(Wiley, 2019) Sahin, Volkan; Aydin, Hilal Gulgezen; Akyel, Alim; Uludag, Bulent C.Objective The color of all-ceramic restorations is one of the main criteria to achieve esthetical success. Many factors such as ceramic thickness, condensation techniques, firing temperature, and numbers can affect the final color of restoration. The purpose of this study was to investigate the color changes in alumina-based ceramic system according to ceramic shade and thickness during the multiple firings. Materials and Methods Sixty disc-shaped specimens with two different veneering porcelain shades (A1 or A3), and with three different ceramic thicknesses (0.5, 1, or 1.5 mm), were fabricated from an alumina-based ceramic system. Multiple firings (3, 5, 7, or 9 firings) were performed, and color changes (Delta E-00) were determined using a spectrophotometer. Repeated-measures ANOVA were used to analyze the data. The Duncan test was used for multiple comparisons (alpha = .05). Results The L*a*b* values of the specimens were affected by the number of firings (3, 5, 7, or 9), veneering ceramic shades (A1 or A3) and veneering ceramic thicknesses (0.5, 1, or 1.5 mm). Significant interactions were present between the number of firings, veneering ceramic shade, and veneering ceramic thickness for L* (p < .001), a* (p < .001), and b* (p < .001) values. Conclusions No statistically significant color change was observed between 3rd and 9th firings. Clinical Significance Veneering ceramic shade, veneering ceramic thickness, and number of firings should be carefully considered to obtain an acceptable color match of the definitive restorations.Öğe Effect of storage time on mechanical properties of extended-pour irreversible hydrocolloid impression materials(MOSBY-ELSEVIER, 2020) Sahin, Volkan; Jodati, Hossein; Evis, ZaferStatement of problem. Recent commercial extended-pour irreversible hydrocolloid impression materials (EPIHIMs) claim to maintain dimensional stability up to 120 hours. However, data regarding their mechanical properties and performance after 120 hours of storage are lacking. Purpose. The purpose of this in vitro study was to test the elastic recovery, strain in compression, and tear strength properties of 5 commercially available EPIHIMs, immediately after preparation and after 120 hours of storage under specific storage conditions. Material and methods. A total of 150 specimens were prepared in accordance with the ISO 21563:2013 standard from 5 commercially available EPIHIMs (Blueprint Xcreme, Kromopan, Alginmax, Hydrogum 5, and Alginelle). The specimens were subjected to elastic recovery, strain in compression, and tear strength tests immediately after specimen preparation (n=5) and after 120 hours of storage inside clear plastic zipper bags held at 23 degrees C (n=5). Data were analyzed with a multivariate analysis of variance (MANOVA) test for brand and duration parameters. Normality of data was analyzed with the Shapiro-Wilk test. The Duncan test or Games-Howell test was used for multiple comparisons (alpha=.05). Results. Elastic recovery and strain in compression values of the EPIHIMs tested were affected by brand and duration parameters (P<.001). Tear strength values of the EPIHIMs tested were affected by brand (P<.001); however, they were not affected by duration (P>.05). Data distribution was normal except for Alginmax in terms of the elastic recovery values and Blueprint Xcreme in terms of the strain in compression values (P<.05). Significant interactions were present between brand and duration for the strain in compression and tear strength values of the EPIHIMs tested (P<.05). Statistically significant difference was not found among mean elastic recovery values of the tested EPIHIM brands (P<.001). Moreover, a statistically significant increase was present in elastic recovery values of the tested EPIHIMs after 120 hours of storage (P<.001). Statistically significant difference was not found among mean strain in compression values of the tested EPIHIM brands tested immediately after preparation (P>.05). However, 120 hours of storage led both to a statistically significant decrease in mean strain in compression values of the tested EPIHIMs (P<.001) except for Alginelle (P>.05) and a statistically significant difference among mean strain in compression values of the tested EPIHIM brands (P<.001). Storage time did not influence mean tear strength values of the EPIHIMs tested (P>.05). However, statistically significant differences were present among mean tear strength values of the tested EPIHIM brands tested immediately after preparation (P<.001) and after 120 hours of storage (P<.001). Conclusions. Despite variations in elastic recovery, strain in compression, and tear strength properties of the EPIHIMs tested, all the materials fulfilled the requirements to comply with the ISO 21563:2013 standard even after 120 hours of storage.Öğe Effect of Various Treatment Modalities on Surface Characteristics and Shear Bond Strengths of Polyetheretherketone-Based Core Materials(WILEY, 2020) Culhaoglu, Ahmet Kursat; Ozkir, Serhat Emre; Sahin, Volkan; Yilmaz, Burak; Kilicarslan, Mehmet AliPurpose To investigate the effect of different surface treatments on the surface roughness (Ra), wettability, and shear bond strength of polyetheretherketone (PEEK) to composite resin. Materials and Methods One hundred ninety eight PEEK specimens were divided into six groups (n = 33). Specimen surfaces were treated with the following surface treatment modalities: silicoating (CoJet), acetone treatment, acid etching (H2SO4), airborne particle abrasion (Al2O3), laser irradiation (Yb:PL laser), and the nontreated surface serving as the control. Surface roughness was measured with an profilometer (n = 11) and a goniometer was used to measure the surface wettability through contact angle (theta)(n = 11). PEEK surfaces were veneered with a composite resin (n = 11). The specimens were then thermocycled for 10,000 cycles at 5 to 55 degrees C. Shear bond strengths between the PEEK and composite resin were measured with an universal test machine. One-way ANOVA was used to analyze the data. Tukey's post-hoc test was used to determine significant differences between groups (alpha = 0.05). Results Surface roughness and wettability of PEEK surfaces along with shear bond strength of PEEK to composite resin were influenced by the surface treatments. (p < 0.01) Highest mean Ra values were obtained for PEEK surfaces treated by laser irradiation (2.85 +/- 0.2 mu m) followed by airborne particle abrasion (2.26 +/- 0.33 mu m), whereas other surface treatment modalities provided similar Ra values, with the acid-etched PEEK surfaces having the lowest mean Ra values (0.35 +/- 0.14 mu m). Silicoating provided the most wettable PEEK surfaces (48.04 +/- 6.28o), followed by either acetone treatment (70.19 +/- 4.49o) or acid treatment (76.07 +/- 6.61o). Decreased wettability was observed for airborne particle abraded (84.83 +/- 4.56o) and laser-treated PEEK surfaces (103.06 +/- 4.88o). The highest mean shear bond strength values were observed for acid-etched PEEK surfaces (15.82 +/- 4.23 MPa) followed by laser irradiated (11.46 +/- 1.97 MPa), airborne particle abraded (10.81 +/- 3.06 MPa), and silicoated PEEK surfaces (8.07 +/- 2.54 MPa). Acetone-treated (5.98 +/- 1.54 MPa) and untreated PEEK surfaces (5.09 +/- 2.14 MPa) provided the lowest mean shear bond strengths. Conclusions The highest mean shear bond strengths were observed for acid-etched PEEK surfaces, followed by laser-irradiated, airborne particle abraded, and silicoated PEEK surfaces providing similar mean shear bond strengths. Since shear bond strengths higher than 10 MPa are considered acceptable, acid etching, laser irradiation, and airborne particle abrasion of PEEK surfaces may be considered viable surface treatment modalities for the PEEK material tested.Öğe Effects of Implant Angulations and Attachment Configurations on the Retentive Forces of Locator Attachment-Retained Overdentures(Quintessence Publishing Co Inc, 2014) Uludag, Bulent; Polat, Serdar; Sahin, Volkan; Comut, Ali AlperPurpose: The aim of this study was to evaluate the effects of different implant angulations and attachment configurations on the retentive forces of locator attachment-retained overdentures over a simulated time period of 6 months. Materials and Methods: Two acrylic resin models (models 1 and 2) were fabricated to represent an edentulous mandible. In model 1, the midline implant (in the central region) was vertical and the other two implants (in the canine regions) were 20 degrees divergent from the midline, reaching a total divergence of 40 degrees. In model 2, all three implants were vertically oriented, perpendicular to the occlusal plane and parallel to each other. Three-point vertical pull-out forces were employed in a universal testing machine at a constant crosshead speed of 50 mm/min after overdenture construction and a simulation of 6 months of repeated insertions/removals of the overdenture. Locator attachments with different male combinations and bar and clip attachments were tested in model 1. Clear locator attachments and bar and clip attachments were tested in model 2 and served as controls. Results: The initial retentive forces of all attachments in both models ranged from 26.58 to 62.05 N, whereas the initial retentive forces of the attachments for only model 1 ranged from 49.58 to 62.05 N. The highest retention value was recorded for clear green locator attachments and the lowest for hader bar yellow clip attachments. Locator attachments showed higher retention values than hader bar yellow clip attachments. Conclusion: All attachment systems demonstrated a decrease in retention over time. Locator attachments provided better retention than hader bar yellow clip attachments. The highest retention values were obtained when green male locators were used in combination with male attachments.Öğe Effects of the doping concentration of boron on physicochemical, mechanical, and biological properties of hydroxyapatite(Elsevier Sci Ltd, 2022) Jodati, Hossein; Tezcaner, Aysen; Alshemary, Ammar Z.; Sahin, Volkan; Evis, ZaferIon doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa-0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, <= 260 mu g/l and 770 mu g/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release & LE;260 mu g/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.Öğe The first step of patient-specific design calvarial implant: A quantitative analysis of fresh parietal bones(Springer, 2018) Govsa, Figen; Celik, Servet; Turhan, Tuncer; Sahin, Volkan; Celik, Meral; Sahin, Korhan; Kazak, ZuhalBackgroundAccurate knowledge of the fracture of cranial bone can provide insight into the prevention of skull fracture injuries and help aid the design of energy-absorbing head protection systems and safety helmets. When cranial bone needs to be removed or is lost, subsequent reconstruction of the defect is necessary to protect the underlying brain, or correct esthetic deformities, or both. Ideal reconstruction of defected bone is possible utilizing a biocompatible implant with a bone-like design individualized for the specific patient. The purpose of this study is to investigate the anatomical and mechanical characteristics of fresh frozen human parietal bones and determine compliance of polylactic acid-based personalized three-dimensional implants in terms of mechanical properties in order to replace such defective bones.MethodsParietal bone specimens were extracted from 19 fresh frozen cadavers. Morphological parameters of individual bone specimens were measured using Image J software. Three-point bend tests were performed to extract Young's modulus and tensile strength of the specimens from the measured force and displacement data by modeling the bone specimens as curved linear elastic beams. Also, three-point bend tests were performed to polylactic acid-based three-dimensional replicas mimicking geometry of the bone specimens in order to determine whether the material's Young's modulus and tensile strength properties comply with parietal bones.ResultsEntire fresh parietal specimens were observed to be comprised of a three-layered structure: external layers consisting of compact, high-density cortical bone and the central layer consisting of low-density, irregularly porous bone structure. Mean thickness of three-layered structure was 6.251.46mm. Mean Young's modulus and tensile strength of the specimens were 1.401.34GPa and 44.56 +/- 21.94MPa, respectively where no statistically significant differences among genders were detected (p>0.05). Mean Young's modulus and tensile strength of the polylactic acid-based three-dimensional implants mimicking geometry of the bone specimens were 1.8 +/- 0.7GPa and 72.8 +/- 2.5MPa, respectively.ConclusionsPolylactic acid-based three-dimensional implants can be considered as acceptable candidates for temporary replacement of parietal defects in terms of mechanical properties.Level of Evidence: Not ratable.Öğe Microleakage of Inlay Ceramic Systems Luted with Self-adhesive Resin Cements(Quintessence Publishing Co Inc, 2014) Uludag, Bulent; Yucedag, Elif; Sahin, VolkanPurpose: To evaluate the microleakage of Cerec 3, IPS e. max Press, and Turkom-Cera inlays cemented with three self-adhesive resin cements. Materials and Methods: Ninety standardized class III MOD cavities were prepared in intact human mandibular third molars. Ceramic inlays were fabricated according to the manufacturer's instructions and were cemented using three self-adhesive resin cements (RelyX Unicem, Smartcem 2, and SpeedCEM). The specimens were stored in distilled water at 37 degrees C for 24 h and subjected to 1000 thermocycles in water between 5 degrees C and 55 degrees C with a dwell time of 30 s. Subsequently, the specimens were subjected to 100,000 cycles of mechanical loading of 50 N at 1.6 Hz in 37 degrees C water. The specimens were immersed in 0.5% basic fuchsine for 24 h and were sectioned using a low-speed diamond blade. The percentage of dye leakage at the tooth/restoration interface was measured and compared by Kruskal-Wallis tests with Bonferonni correction and Mann-Whitney U-tests at a significance level of p < 0.05. Results: Microleakage at the RelyX Unicem interface was lower than that with Smartcem 2 and SpeedCEM resin cements (p < 0.05). Microleakage of the Turkom-Cera system was higher than Cerec 3 and IPS e. max Press ceramic inlays (p < 0.05). Conclusions: Regardless of the ceramic system and self-adhesive resin cement used, dentin margins were associated with higher microleakage than enamel margins.Öğe Replacement of a Lost Removable Partial Dental Prosthesis Using Ball-Attachment Analogs: A Clinical Report(Wiley-Blackwell, 2011) Uludag, Bulent; Sahin, Volkan; Polat, SerdarAttachment-retained removable partial dental prostheses (RPDPs) may be lost. Although in such situations, the RPDP should be remade, no method has yet been described for replacing lost attachment-retained RPDPs. This report describes a method for fabrication of a replacement for a lost maxillary RPDP using ball-attachment analogs.Öğe Symphyseal Bone Cylinders Tapping With the Dental Implant Into Insufficiency Bone Situated Esthetic Area at One-Stage Surgery: A Case Report and the Description of the New Technique(Allen Press Inc, 2011) Tekin, Umut; Kocyigit, Doruk I.; Sahin, VolkanPeriodontal defects and trauma at the anterior maxillary region can cause a severe alveolar ridge deficiency resulting in an unesthetic view. Ideal implant positioning can be compromised by inadequate alveolar bone in terms of height and width. Reconstruction of osseous defects with autogenous bone allows ideal implant positioning and creates a more natural soft and hard tissue profile, which influences esthetic crown anatomy at the anterior maxillary region. In this case report, an alveolar ridge defect due to periodontally compromised tooth extraction was filled with autogenous bone cylinder and dental implant at one-stage surgery. In the presented case, a new technique was described which included bone reconstruction of the defects at the anterior maxillary region and simultaneous placement of the dental implant.
