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18 →- ArticleYayıncıda açık erişim2026Biomechanical Behavior of Endodontically Treated Abutment Teeth with Periapical Lesions: A 3D Finite Element Analysis
Klrmall, Ömer; Zeynalll, Ayten; Akar, Türker; Celik, Huseyin Kursat
Objectives The stress distribution of teeth with periapical lesions, which are used as abutments in fixed prostheses, and its effect on the success of the restoration are not well known. This study investigates stress distribution in abutment teeth with periapical lesions and surrounding tissues under occlusal load using finite element analysis. Materials and Methods Three models were constructed: (1) a healthy mandibular premolar, (2) a premolar with a periapical lesion restored using a fiber post and single crown, and (3) a similar premolar used as an abutment for a three-unit bridge. A static load of 300 N was applied at a 45-degree angle to the tooth's long axis, targeting the lingual slope of the buccal cusp. Stress and deformation were analyzed across all structural components, including dental tissues and the surrounding trabecular bone. Results The results demonstrated that, in model 2, stress propagation extended more prominently along the root surface and progressed apically, resulting in a higher stress concentration in the periapical lesion region (0.061 MPa) when compared with model 3 (0.054 MPa). Furthermore, the greatest deformation was also observed in model 2. Across all models, peak stress was consistently localized in the cervicobuccal collar region of the tooth. Conclusion These findings underline the importance of prosthesis design in reducing the stress concentration in abutment teeth with periapical lesions and demonstrate the biomechanical advantage of splinted restorations over single crowns in cases with periapical lesions.
RDL Kalıcı Kaydıİncele - ArticleYayıncıda açık erişim2026Finite Element Analysis of Dentoalveolar Stress in Combat Sports Using Hybrid and Conventional Mouthguards
Kalafat, Çağla Nur; Yeşil, Zeynep
Aim: This study aimed to contribute to the development of modern mouthguards by evaluating the stresses generated by hook and uppercut punches applied during combat sports on dentoalveolar structures and mouthguards, the protective effectiveness of different mouthguard designs, and the resulting deformations using three-dimensional finite element analysis. Materials and Methods: Three-dimensional solid models of the maxilla, mandible, teeth, alveolar bone, and mouthguards were constructed using an anatomical head model with Class I occlusion and complete permanent dentition. A conventional mouthguard with a uniform thickness of 4 mm made of ethylene vinyl acetate and a hybrid mouthguard consisting of a 3 mm polycarbonate occlusal surface with EVA axial walls were modeled. Hook and uppercut punch loads were simulated at an impact velocity of 12 m/s with an effective mass parameter of 5 kg. Von Mises equivalent stresses and displacement values occurring in the jaws, teeth, alveolar structures, and mouthguards were analyzed using three-dimensional finite element analysis. Results: During hook and uppercut punch application, the highest von Mises stress values in the mandible were observed in the model without a mouthguard (200 and 520 MPa, respectively), while the lowest values were detected in the model with a hybrid mouthguard (170 and 260 MPa). Similarly, mandibular teeth exhibited the highest stress values in the model without a mouthguard (1100 and 1600 MPa) and the lowest values in the hybrid mouthguard model (300 and 500 MPa). Stress transmission to the maxilla and maxillary teeth was minimal in all models. For both punch types, the hybrid mouthguard demonstrated higher stress values than the conventional mouthguard. In models using mouthguards, maximum displacement occurred later after impact, and deformation was distributed over a wider surface area rather than being localized. Conclusion: Hybrid mouthguards demonstrated superior biomechanical performance compared with conventional mouthguards by reducing stress transmission to dentoalveolar structures. The combination of a rigid occlusal component and flexible axial walls enabled more effective energy distribution, particularly under high-energy vertical loading. These findings suggest that hybrid mouthguards represent an effective option for preventing dentoalveolar trauma in combat sports.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Comparison of Biomechanical Effects of All-on-Four Implant Prostheses with Different Types and Weights: A Three-Dimensional Finite Element Analysis
Gömleksiz, Oğuzhan; Altintas, Subutay Han
Objective: The aim of this study is to comparatively evaluate the stress values created by all-on-four prostheses of different types and weights on the implant, infrastructure, and peri-implant bone tissue under occlusal forces using the three-dimensional (3D) finite element analysis (FEA) method. Methods: A completely edentulous lower jaw model was designed in a computer environment using the FEA method, and implants were placed according to the all-on-four technique. Five different infrastructure materials were simulated in the 3D models, including chromium-cobalt (Cr-Co), titanium, zirconia, fiber, and polyetheretherketone (PEEK). The superstructure material of the prostheses was designed as monolithic zirconia crown and composite resin gingiva, which would be the same in all models. The weights of the created all-on-four prosthesis models were calculated. A rigid food material was used for a 100 newton (N) force application. Maximum principal (Pmax) and minimum principal (Pmin) stress values for cortical bone and Von mises stress values for the implant and infrastructure were calculated. Results: The weight of prostheses with different types of infrastructures affected the stress distribution in the implant, infrastructure, and peri-implant bone tissue. Lower stress values were observed in the implants and peri-implant bone tissues in Cr-Co, titanium, and zirconia infrastructures compared to fiber and PEEK. When the stresses occurring within the infrastructure materials were evaluated, lower stresses were obtained in fiber and PEEK infrastructures. Conclusion: Following the results of the biomechanical comparison made with 3D FEA, it can be said that long-term success can be achieved in the implant and the bone tissue around the implant as the elasticity modulus of the infrastructure material increases and the use of Cr-Co, titanium, and zirconia materials as infrastructures can be more advantageous. The weight of the modeled all-on-four prostheses did not reach harmful stress values in the bones around the implant together with the occlusal forces.
RDL Kalıcı Kaydıİncele - ArticleYayıncıda açık erişim2025Digital Alignment Accuracy of Zirconia Abutments Using Library Data on Incompletely Captured Implant Impressions: An In Vitro Study; [Eksik Dijital İmplant Ölçülerinde Zirkonya Abutmentlerin Kütüphane Verisi ile Dijital Eşleştirme Doğruluğu: İn Vitro Çalışma]
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.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Effect of cavity depth on degree of conversion and microhardness of low-shrinkage resin composites
Gömleksiz, Seda; Gömleksiz, Oğuzhan
Background: The study aimed to investigate the effect of different cavity depths on the degree of conversion (DC) and surface microhardness (MH) of low-shrinkage resin composites. Methods: Three low-shrinkage resin composites (Clearfil Majestry Posterior/CMP, Beautifil II LS/BL, Charisma Diamond/CD) and one conventional nanohybrid resin composite (Filtek Z550/FZ) as control were evaluated. For each composite material, a total of 12 disc-shaped samples were prepared using plastic molds with two different depths (2 mm and 4 mm) (n = 6). The same sample preparation protocol was applied for the DC and MH tests, and a total of 96 samples were prepared, 48 for each test. Resin composites filled into molds with the incremental technique were cured with LED light unit only from the top surface. DC was determined by Fourier transform infrared (FTIR) spectroscopy; MH was determined using the Vickers hardness tester. Data were statistically analyzed using Robust and two-way variance analyses (p < 0.05). Results: For all resin composites, there was no significantly difference in DC and MH between the 2 mm and 4 mm cavity depths. BL showed the highest DC values at both cavity depths, while CD showed the lowest (p < 0.001). At both cavity depths, the highest MH values on bottom-top surfaces were obtained in CMP, while the lowest were in BL. The top surface MH values were higher in all resin composites than the bottom surfaces. Conclusions: Increasing cavity depth may not negatively affect the DC and MH of low-shrinkage resin composites. Moreover, resin composite material formulations may have a higher potential effect on these parameters. Clinical trial number: Not applicable.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024The Effect of Various Surface Treatments and Materials on the Bond Strength in the Repair of Glass Hybrid Restorative Material
Gömleksiz, Seda; Gömleksiz, Oğuzhan
Objective: The purpose of this in vitro study is to evaluate the effect of various surface treatments (STs) and restorative materials on the shear bond strength (SBS) of glass hybrid (GH) restorative materials. Methods: Sixty-three GH restorative material samples (Equia Forte Fil, GC) were prepared (6 × 2 mm) and randomly divided into 3 groups according to the subsequent ST (n = 21): phosphoric acid etching (PA), aluminum oxide sandblasting (AO), and diamond bur roughening (DB). After that, 3 subgroups were created from the samples in each group based on the restoration material applied: Ionofil Molar AC (IM; Voco), Fuji II LC (FLC; GC), and Charisma Smart (CS; Kulzer). The bonded specimens were subjected to the SBS test. In addition, the samples were evaluated with a scanning electron microscopy. The results were statistically examined using twoway analysis of variance with post hoc test (P = .05). Results: The CS groups were higher in SBS compared to the other groups, whereas the IM groups had low bond strength (P < .05). The FLC, CS, DB, and PA groups showed the highest SBS (P < .05). The lowest SBS values were observed in the PA group in IM (P < .05). Conclusion: The GH restorative materials were successfully repaired with composite resin using diamond bur roughening or phosphoric acid etching.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Applied and computational investigation of plasticizing effects of dibutyl maleate on polymethyl methacrylate acrylic resin material
Tuğut, Faik; Bolayır, Giray; Gülnahar, Evrem; Kaya, Savaş; Boztuğ, Ali; Maslov, Mikhail M.
In this study, the amount of change in the glass transition temperature (Tg) of PMMA was analyzed by DSC by adding different ratios of dibutyl maleate (DBM) plasticizer to polymethyl methacrylate (PMMA), which is used as the main ingredient of prosthetics in dentistry. For this, liquid DBM was added to powdered PMMA at a rate of 2, 5, 8 and 15 % by mass, and polymerization was carried out at 100 °C. Mechanical tests such as impact resistance, transverse resistance and maximum flexion tests were applied to these prepared mixtures. It was observed that there was a significant parallelism between the Tg values calculated from the DSC curves and the mechanical tests. The Tg value of PMMA was reduced by approximately half with the addition of DBM plasticizer. Additionally, the chemical interaction between PMMA and DBM was analyzed in the light of the Density Functional Theory (DFT) calculations. The binding energy for the mentioned interaction was determined as 1.591 eV. After both species interacted with each other, the glass transition temperature of the formed complex system was theoretically also predicted through the quantitative structure-property relationship (QSPR) model. For theoretical prediction of Tg, the molecular traceless quadrupole moment Θ and the molecular average hexadecapole moment Φ, are used. The change determined as experimental in glass transition temperature as a result of the interaction between PMMA and DBM was supported with theoretical calculations. Experimental and theoretical data are in good agreement.
RDL Kalıcı Kaydıİncele - ArticleYayıncıda açık erişim2023Investigation of the Effectiveness of Titanium Dioxide Nanotube Coating on Titanium–Resin Cement Bond Strength
Coskun, Mehmet Emre; Akar, Türker
Objective: The aim of this in vitro study was to investigate the effect of the titanium dioxide formed by anodization process on the titanium–resin cement microshear bond strength. Methods: Forty titanium cylinders (9 × 11 mm) were randomly divided into 4 groups according to the surface treatment methods: Control group, no treatment; airborne-particle abrasion group, 120 μm Al2O3; primer group, 120 μm Al2O3 + metal primer; and tita- nium dioxide group, titanium dioxide nanotube (n-TiO2) formed by anodization process. Scanning electron microscope analysis was performed to determine the surface alterations of the specimens. Then, dual-polymerizing resin cement was applied on the speci- mens by using Tygon tubes, and microshear bond strength tests were performed by using a universal testing machine. The obtained data were analyzed by using 1-way analysis of variance and the Tukey post hoc test (α = 0.05). Results: Each surface treatment application increased the titanium–resin cement bond strength (P< .05). The highest bond strength value was obtained by titanium dioxide nanotube application, and the difference between groups was statistically significant (con- trol group: 4.91 ± 1.10; airborne-particle abrasion group: 5.66 ± 1.90; primer group: 6.700 ± 2.05; and titanium dioxide group: 9.44 ± 1.20) (P < .05). All groups showed an adhesive failure mode. Conclusion: The formation of titanium dioxide nanotube on titanium by anodization process increased the microshear bond strength significantly higher than that of the airborne-particle abrasion group or the metal primer group.
RDL Kalıcı Kaydıİncele - ArticleYayıncıda açık erişim2023Articaine versus lidocaine inferior alveolar nerve block in posterior mandible implant surgeries: a randomized controlled trial
Gülnahar, Yakup; Alpan, Aysan Lektemur; Gülnahar, Evrem
Background: The aim of this study is to compare the effects of %4 articaine and %2 lidocaine on inferior alveolar nerve block (IANB) for implant surgery in the posterior mandible. Material and Methods: The patients who have inserted implants in the posterior mandible were divided into 2 groups for IANB: lidocaine and articaine. VAS = visual analog scale, pain during surgery and injection, lip numbness time, mandibular canal-implant apex distance, age, gender, bone density, implant number, release incision, adjacent teeth, and duration of surgery were analyzed using t-test, Mann-Whitney U test, Spearman's coefficient, and, Pearson's chi-squared test. This trial followed the recommendations of the Consort Statement for reporting randomized controlled trials. Results: 577 patients were included and 1185 dental implants were analyzed. There was no significant difference between the two groups in terms of injection and surgery VAS values (p>0.05). The lip numbness time of lido-caine was 3.06±3.22min while articaine was found to be 2.96±3.09min (p>0.05). Mandibular canal-implant apex distance was found to be 2.28±0.75mm in the articaine and 2.45±0.86mm in the lidocaine group (p<0.05). Release incision was made more in the articaine group (51/252) than in the lidocaine group (40/325) (p<0.05). Conclusions: There was no difference between the %4 articaine and %2 lidocaine in terms of pain perception in posterior mandible implant applications. Both anesthetics provided adequate anesthesia for implant application.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2023Effect of Dentin and Zirconia Surface Treatments with Laser Irradiation Versus Sandblasting on the Bonding Ability of Zirconia
Akar, Türker; Ä°çen, Gülşah
Objective: This study aimed to investigate the effects of laser irradiation applied to zirconia and tooth surfaces on shear bond strength (SBS) compared with acid etching and sandblasting. Background: The effect of laser irradiation on the bond strength between zirconia and adhesives is a controversial issue for dentin surface treatments. In addition, the effects of different combinations of surface treatments to increase adhesion on both the zirconia and dentin surfaces remain unclear. Materials and methods: A total of 90 tooth samples were assigned into groups according to various pretreatments: control group was left untreated, acid etching, and Erbium, Chromium:Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser irradiation group (15 Hz, 2 W). In addition, the zirconia specimens were separated into three groups (n = 10) according to the different surface treatments performed: sandblasting (120 μm Al2O3), Er,Cr:YSGG laser (15 Hz, 2 W), and as untreated surface. The zirconia samples were cemented to the dentin surface using dual-cure resin cement and subjected to an SBS test at a speed of 0.5 mm/min under a universal testing machine until fractures occurred in the bonding surface. Results: The highest SBS values were observed in Group tooth acid (TA)-zirconia Er,Cr:YSGG laser (ZL), followed by Group tooth Er,Cr:YSGG laser (TL)-zirconia sandblasting (ZS) and Group TA-zirconia control (ZC). The lowest SBS values were found in Group TA-ZS. Significant intergroup difference was noted between Group TA-ZL, Group tooth control (TC)-ZC, Group TL-ZS, and Group TC-ZC. However, no significant difference was noted between Group TA-ZL, Group TL-ZS, and Group TA-ZC. Conclusions: Acid etching and laser treatments applied to the dentin and zirconia surfaces were found to be effective techniques for improving the zirconia-dentin bond, respectively. Clinical Trial Registration number: 33216249-604.01.02-E.24308.
RDL Kalıcı Kaydıİncele
Tam Kayıt
| Alan | Değer | Dil |
|---|---|---|
| dc.date.accessioned | 2026-10-20T15:26:09.110459203Z | |
| dc.date.available | 2026-10-20T15:26:09.110459203Z | |
| dc.identifier.uri | https://rdlopen.rawdatalibrary.net/r/ebyu/22889 | |
| dc.rights | info:eu-repo/semantics/openAccess | |
| dc.title | Protetik Diş Tedavisi Anabilim Dalı | tr |
| dc.title | Department of Prosthodontics | en |
| dspace.entity.type | OrgUnit | |
| organization.identifier.code | dis-protetik | |
| organization.unitType | department | |
| rdl.unit.alias | prosthod |