Topdağı, Başak; Oktay, Fatih; Akar, Türker

Objectives: This in vitro study aimed to evaluate the feasibility and accuracy of digitally aligning zirconia customized abutment library files onto incomplete abutment scan datasets. Superimposition was compared to the conventional “Close holes” reconstruction function in computer-aided design (CAD) software. Materials and Methods: A single-implant dental model was used, and a custom zirconia abutment was scanned to generate a digital library file. Complete scans of the abutment and adjacent teeth served as the control group (C). Two experimental datasets were produced by selectively deleting marginal regions (NC2) and both marginal and proximal surfaces (NC3) from the complete scan. Defective scans were processed either by digital superimposition with the abutment library file (S group) or by applying the “Close holes” function in CAD software to reconstruct missing areas (CH group). All datasets were analyzed in Geomagic Control X (3D Systems, USA) to assess trueness using root mean square (RMS) error and point-based deviation analysis. Statistical evaluation was performed using one-way ANOVA and Tukey HSD post hoc tests Results: Superimposition significantly improved trueness compared with unprocessed scans. RMS values decreased from 39.11 ± 0.98 μm in the IOS (intraoral scanner) group to 35.41–37.59 μm across the C, NC2, NC3, and S groups datasets (p = 0.032). The CH group showed significantly higher deviations than all superimposition groups (p < 0.001). Point-based analysis confirmed lower deviations after superimposition (p = 0.008). No significant differences were found among the superimposed groups. Conclusions: Digital superimposition of zirconia abutment library data onto incomplete scans enhances trueness and geometric reliability. This method is superior to conventional reconstruction tools for restoring incomplete implant impressions.

Celik, Elif; Celik, Fatih; Unver, Edhem; Karavas, Erdal; Diyarbakır, Samih

Objectives: In this study, the dimensions of the soft palate, the position of the hyoid bone in relation to the mandibular plane and C3 vertebrae, and the width of the upper airway were measured on lateral cephalograms of patients with obstructive sleep apnea syndrome of different severities diagnosed by polysomnography. This study aimed to investigate the association between increased apnea severity and anatomical formations relevant to dental practice. Materials and Methods: Our study was designed as a retrospective data analysis of 182 patients, 78 females and 104 males. In our study, patients were divided into four groups: patients with simple snoring with an Apnea-Hipopnea index (AHI) value below 5, patients with mild OSAS with an AHI value of 5–15, patients with moderate OSAS with an AHI value of 15–30 and patients with severe OSAS with an AHI value above 30. Measurements obtained from lateral cephalograms were compared between these groups. Results: Statistically significant narrowing was observed in all other groups compared to the control group in oropharyngeal width values in upper airway measurements (P<0.05). The distance between the hyoid and mandibular plane was significantly lower in the control group than in the severe OSAS group (P=0.001). A statistically significant elongation of the soft palate was also observed in patients with OSAS compared to the control group (P<0.05). Conclusions: Our findings support that the position of the hyoid bone is important in the diagnosis of OSAS. Furthermore, a significant correlation was found between soft palate length and OSAS. These results suggest that surgical techniques such as maxillary advancement or mandibular advancement, or both, to increase airway width may be effective in the treatment of OSAS. Copyright This work is licensed under Creative Commons Attribution 4.0 International License

Özkanoğlu, Seda; Akin, Emine Gülşah Göktolga

Objectives: The aim of this study is to evaluate and compare the bond strength and micro-leakage of three different universal adhesive systems applied in self-etch mode to dentin. Materials and Methods: To evaluate bond strength, the mid-coronal dentin surfaces of forty-five human molar teeth were exposed and randomly assigned into three groups according to the following adhesive application: Single Bond Universal (3M ESPE), Optibond XTR (Kerr), and Tokuyama Universal (Tokuyama Dental) (n=15). The shear bond strength test was performed after composite build-up. Then, the fractured surfaces were evaluated using a scanning electron microscope (SEM). To evaluate micro-leakage, facial class V cavities were prepared to forty-five human premolars and randomly assigned into identical three experimental groups described above (n=15). After composite resin restoration of cavities, the specimens were thermo-cycled for 500 cycles and then immersed in basic fuchsine, sectioned, and examined under a stereo-microscope. Data were evaluated using one-way ANOVA, Tukey’s, Chi-square and Mann Whitney U tests. Results: Among the adhesives, the highest bond strength was achieved in Optibond XTR, while Tokuyama Universal showed the lowest bond strength values (p<0.05). In micro-leakage results, no significant difference was reported in occlusal margins among groups. In gingival margins, Optibond XTR showed less leakage compared to Tokuyama and Single Bond Universal (p<0.05). Conclusions: The study findings indicated that two-step universal adhesive system is more successful than one-step universal adhesive systems in bonding to dentin. Considering that bonding plays a major role in the longevity of the restoration, it can be said that the use of two-step universal adhesive systems in dentin can give more successful results.

Coskun, M. Emre; Akar, Turker; Bozkurt çirak, Burcu

Objective: The aim of this study was to compare the effect of anodization and air-particle abrasion surface treatments on shear bond strength between Ni-Cr and ceramics. Material and Methods: 30 cylindrical Ni-Cr specimens (7 × 10 mm) were divided into three groups according to the surface treatments [control group (no-treatment), air-particle abrasion group (110 μm Al2O3 at 75 psi from 20 cm for 30 seconds), and anodization group]. One sample from each group was evaluated by using SEM. Ceramics with a dimension (5 × 3 mm) built-up on specimens and shear bond strength tests were performed by using universal testing machine with a 1 mm/min crosshead speed. Stereomicroscope was used to evaluate the failure mode of specimens. One-way ANOVA with post-hoc Tukey's test was used to analyze the differences in shear bond strength values. Results: The shear bond strength of air-particle abrasion (21.35∓4.64) was higher than anodization group (20.92∓4.85) however, no statistically significant difference was detected (p=0.893). Both groups showed higher bond strength than control group (8.02∓1.47) (p < .05). Conclusion: The evaluation of the surface treatment methods showed that the anodization process can be used in order to increase the metal-ceramic bond strength. © 2018 Cumhuriyet University Faculty of Dentistry.; Amaç: Bu çalişmanin amaci, anodizasyon ve kumlama yüzey işlemlerinin Ni-Cr ve seramik arasindaki makaslama bağlanti dayanimi üzerine etkilerini karşilaştirmaktir. Gereç ve Yöntem: 30 adet silindir şeklinde Ni-Cr örnek (7 × 10 mm) uygulanan yüzey işlemlerine göre üç gruba ayrildi [kontrol group (hiç işlem görmedi), kumlama grubu (110 μm Al2O3, 75 psi basinçla, 20 cm uzakliktan, 30 saniye süresince) ve anodizasyon grubu]. Her gruptan birer örnek alinarak SEM analizleri gerçekleştirildi. Hazirlanan örneklerin üzerine 5 × 3 mm boyutlarinda seramikler pişirildi ve makaslama bağlanti dayanim testleri universal test cihazinda kafa hizi 1mm/dk olacak şekilde gerçekleştirildi. örneklerin kopma şekillerinin tespitinde stereomikroskop kullanildi. Makaslama bağlanti dayanim değerlerinin analizinde One-way ANOVA ve post-hoc Tukey's testleri kullanildi. Bulgular: Kumlama grubunun makaslama bağlanti dayanimi (21,35∓4,64) anodizasyon grubuna (20,92∓4,85) göre yüksek olarak bulunmasina rağmen her iki grup arasindaki farklilik istatistiksel olarak önemli bulunmamiştir (p = 0.893). Her iki grupta kontrol grubuna göre (8,02∓1,47) yüksek bağlanti dayanimina sahip olduğu tespit edilmiştir (p < 0,05). Sonuç: Yüzey uygulama metotlarinin değerlendirilmesi sonucunda anodizasyon uygulamasinin metal-seramik bağlantisinin artirilmasi için kullanilabilecek bir yöntem olduğunu tespit edilmiştir.