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    Biomechanical evaluation of three full-arch immediate loading protocols in the mandible via finite element analysis: All-on-4, Trefoil, and Five-implant design
    (Bmc, 2025) Baki, Nagehan; Yildirim Avcu, Guler; Tuzlali, Mesut
    Background Immediate-loading full-arch concepts such as All-on-4, Trefoil, and Five-Implant protocols are widely used for mandibular rehabilitation, yet their comparative biomechanical behavior remains insufficiently defined. This study aimed to biomechanically compare three immediate loading full-arch rehabilitation protocols-Trefoil, All-on-4, and 5-Implant designs-in the edentulous mandible using three-dimensional (3D) finite element analysis (FEA), focusing on stress distribution, strain accumulation, and deformation patterns under functional loading. Materials and Methods A digital edentulous mandible model was constructed, incorporating cortical and cancellous bone layers, and standardized prosthetic designs for each configuration. Three implant-supported protocols were simulated: Trefoil (three axial implants with a prefabricated bar), All-on-4 (two axial anterior and two posterior tilted implants), and a Five-Implant design (midline, canine, and second premolar implants). The implant-bone interface, simulating immediate loading without full osseointegration, was assigned a coefficient of 0.30. Axial and 45 degrees oblique loads of 100 N were applied to the first molar. Von Mises stress, principal stresses, equivalent strain, and total deformation were analyzed. Results The Five-Implant model exhibited the most favorable biomechanical outcomes, demonstrating the lowest stress and strain values across prosthesis, implant components, and cortical bone. The Trefoil system showed the highest prosthetic stress (156.48 MPa axial; 119.32 MPa oblique) and abutment screw deformation, attributed to its reduced implant support and increased cantilever length. All-on-4 generated elevated cortical bone strain under oblique loading (4180 mu epsilon), surpassing the pathological overload threshold (>4000 mu epsilon), whereas, the Five-Implant model maintained cortical strain within the physiological remodeling range. Conclusion Implant number and distribution significantly affect biomechanical behavior in immediate full-arch rehabilitation. The Five-Implant design offers biomechanical superiority in stress mitigation and bone-strain control, while Trefoil and All-on-4 configurations present design-dependent biomechanical challenges. Treatment planning considering anatomical limitations and functional loading conditions is essential to optimize clinical outcomes.
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    Evaluating the performance of AI chatbots in responding to dental implant FAQs: A comparative study
    (Bmc, 2025) Tuzlali, Mesut; Baki, Nagehan; Aral, Kubra; Aral, Cuneyt Asim; Bahce, Erkan
    Background This study aims to evaluate and compare the performance of five publicly accessible large-language-model (LLM) based chatbots-ChatGPT-o1, Deepseek-R1, Google-Gemini-Advanced, Claude-3.5-Sonnet, and Perplexity-Pro-in providing responses to frequently asked questions (FAQs) about dental implant treatment. The primary goal was to assess the accuracy, completeness, clarity, relevance, and consistency of chatbot-generated answers. Methods A total of 45 FAQs commonly encountered in clinical practice and online patient forums regarding dental implants were selected and categorized into nine thematic domains. Each question was submitted to the chatbots individually using a standardized protocol. Responses were independently assessed by a panel of four dental experts and one layperson using a 5-point Likert-scale. Python with Google-Colab was used for statistical analysis. Results ChatGPT-o1 achieved the highest overall performance, particularly in relevance (M = 4.99), consistency (M = 4.97), and accuracy (M = 4.96). Deepseek-R1 followed closely, with strong scores in completeness and relevance. Claude-3.5-Sonnet ranked moderately, while Gemini-Advanced and Perplexity-Pro showed lower performance in completeness and clarity. Significant differences were observed among chatbots across all criteria (p < 0.001). Inter-rater reliability was high (alpha = 0.87), confirming consistency among evaluators. Conclusions AI-driven chatbots demonstrated strong potential in delivering accurate and patient-friendly information about dental implant treatment. However, performance varied considerably across platforms, with ChatGPT-o1 and Deepseek-R1 showing the highest reliability. These findings highlight the emerging role of AI chatbots as supplementary tools in dental education and patient communication, while also underscoring the need for continued validation and ethical oversight in clinical applications.
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    Mechanical analysis of 3D printed dental restorations manufactured using different resins and validation with FEM analysis
    (Bmc, 2025) Gul, Buse Cebi; Demirci, Fatih; Baki, Nagehan; Bahce, Erkan; Ozcan, Mutlu
    Purpose The aim of this study was to compare the wear and fracture resistance of single crowns produced from newly developed 3D printer resins used to produce permanent crowns and currently used composite CAD/CAM discs, after being thermomechanically aged in a chewing simulator. Materials and methods A total of 112 stainless steel die models simulating mandibular left first molars were produced, 8 for each group. Single crowns were produced from 3 different discs (Grandio Voco [GR], breCAM HIPC [HC], and Shofu HC [SF]) by CAD/CAM milling method and manufactured from from 4 different permanent composite resins (Nexdent C&B MFH [ND], Permanent Bridge Saremco [PB], VarseoSmile Crownplus [VSC], and & Scedil;enertek P-Crown [PC]) using the 3D printing method. Stereomicroscopy, scanning electron microscope (SEM) and Finite Element Method (FEM) analysis was performed. Data were analyzed using ANOVA, paired-t tests and Tukey's HSD test (alpha = 0.05). Results As a result of thermomechanical aging, significant difference was found between the groups in wear and fracture resistance (P < .05). The highest wear resistance was found in the VSC group, and the lowest wear resistance in the PC group. As a result of the compression test, the highest fracture resistance was noted in the GR group and the lowest in the PC group. FEM analysis performed to validate fracture experiments showed an 87% similarity to the in-vitro data. Conclusions The crowns in all groups produced by CAD/CAM milling and 3D printing provided acceptable in vitro wear and fracture resistance for clinical application. The wear and fracture resistance of resin-based materials should be supported by clinical studies.
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    Stress distribution and prosthesis deformation analysis of different bar materials considering weight in trefoil implant system under various loading conditions: a finite element study
    (Taylor & Francis Ltd, 2025) Tuzlali, Mesut; Baki, Nagehan
    This study evaluated seven bar materials-Titanium (Ti), Cobalt-Chromium (Co-Cr), Zirconia (Zr), Polyetheretherketone (PEEK), Carbon-Fiber-Reinforced PEEK (CFR-PEEK), 3D-printed resin (3D-Pr), and Polymethyl methacrylate (PMMA)-in the Trefoil implant system using three-dimensional finite element analysis under vertical and oblique loads. Stress distribution and prosthesis deformation were analyzed, and a Performance Index combining mass and deformation was calculated. Bar material mainly influenced deformation: metallic bars (Ti, Co-Cr, Zr) showed minimal, while non-metallic (3D-Pr, PMMA) showed higher deformation. Titanium had the best performance, followed by zirconia and CFR-PEEK. Selecting optimal bar materials enhances biomechanical efficiency in Trefoil prostheses.
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    Weibull-Based Reliability of Full-Arch Zirconia Prostheses in a Mandibular All-on-4 Model: Monolithic Versus Titanium-Bar-Supported Designs
    (Mdpi, 2026) Tuzlali, Mesut; Baki, Nagehan; Avcu, Guler Yildirim; Bahce, Erkan
    Full-arch zirconia prostheses for mandibular All-on-4 rehabilitations are provided as screw-retained monolithic zirconia (Zr-Mono) or as a zirconia suprastructure luted to a CAD/CAM titanium bar (Zr-TiBar). Because zirconia is a brittle and flaw-sensitive ceramic, design assessment should incorporate stress-field-weighted fracture risk. This in silico study compared zirconia tensile stress, deformation, and Weibull-based reliability between Zr-Mono and Zr-TiBar designs in a standardized edentulous mandibular All-on-4 model (posterior implants tilted 30 degrees) using linear static finite element analysis. Accordingly, 300 N posterior unilateral loads were applied at the first molar (axial; 45 degrees oblique). Outcomes were maximum principal tensile stress in zirconia (S1max), total prosthesis deformation, and Weibull-predicted fracture probability (Pf) derived from the tensile S1 field. Under axial loading, S1max was essentially identical between designs (similar to 277 MPa). Under oblique loading, S1max was modestly lower for Zr-TiBar (similar to 227 MPa) than for Zr-Mono (similar to 234 MPa), and deformation was slightly lower for Zr-TiBar (<0.07 mm in all cases). Pf remained very low for both designs (10(-6)-10(-7) range) and differed only slightly between them. Under the modeled single 300 N posterior load case, the titanium-bar support reduced deformation and modestly reduced oblique-load peak tensile stress but did not materially reduce the predicted zirconia Pf compared with monolithic zirconia.