Objectives: the aim of this study was to examine the stress distribution of enamel, dentin, and restorative materials in sound first molar teeth with restored cavities with conventional resin composites and bulk–fill composites, as well as to determine their fracture lifetimes by using the three-dimensional finite element stress analysis method. Materials and Methods: an extracted sound number 26 tooth was scanned with a dental tomography device and recorded. Images were obtained as dicom files, and these files were transferred to the Mimics 12.00 program. In this program, different masks were created for each tooth tissue, and the density thresholds were adjusted manually to create a three-dimensional image of the tooth, and these were converted to a STL file. The obtained STL files were transferred to the Geomagic Design X program, and some necessary adjustments, such as smoothing, were made, and STP files were created. Cavity preparation and adhesive material layers were created by transferring STP files to the Solidworks program. Finally, a FE model was created in the ABAQUS program, and stress distributions were analyzed. Results: when the bulk–fill composite and conventional resin composite materials were used in the restoration of the cavity, the structures that were exposed to the most stress as a result of occlusal forces on the tooth were enamel, dentin, restorative material, and adhesive material. When the bulk–fill composite material was used in restoration, while the restorative material had the longest fracture life as a result of stresses, the enamel tissue had the shortest fracture life. When the conventional resin composite material was used as the restorative material, it had the longest fracture life, followed by dentin and enamel. Conclusion: when the bulk–fill composite material was used instead of the conventional resin composite material in the cavity, the stress values on enamel, dentin, and adhesive material increased as a result of occlusal forces, while the amount of stress on the restorative material decreased. In the fracture analysis, when the bulk–fill composite material was used instead of the conventional resin composite material, a decrease in the number of cycles required for the fracture of enamel, dentin, and restorative materials was observed as a result of the forces generated in the oral cavity.

The aim of this study was to investigate the types and thicknesses of adhesive materials used in restorative treatment in dentistry in class I occlusal and class II disto‐occlusal cavities and to examine the effects of stress distribution on enamel, dentin, restoration material, and adhesive material using the finite element stress analysis method. A 3‐dimensional geometry of the tooth was obtained by scanning the extracted 26 numbered upper molar tooth with dental tomography. The 3D geometry obtained by using the Geomagic Design X 2020.0 software was divided into surfaces, and necessary arrangements were made. With the Solidworks 2013 software, 2 different cavity modeling, class I occlusal and class II disto‐occlusal, with a cavity angle of 95 degrees on the 3D model, as well as 10, 30, and 50 micrometers thick, four types of adhesive materials and the modeling of the bulk‐fill composite material on it were made. With finite element stress analysis, the stress distribution was analyzed using the Abaqus software. The materials used in the study are included in the simulation as isotropic linear elastic. Periodontal ligament and jawbone were not included in the analysis. A total of 600 N pressure was applied on the models. In our study, it was observed that the amount of stress on the tooth structures changed when the thickness, elastic modulus, and Poisson ratios of the adhesive material were changed. In addition, when all models are examined, it is seen that when the thickness is increased, more stress is placed on the adhesive material compared to the restoration, while when 50‐micrometer‐thick adhesive material is used, more stress is placed on the restoration compared to the adhesive material.

Background: This study aimed to compare the stress distribution and fracture resistance of dental tissues and restorative materials with varying adhesive layer thicknesses and different restorative materials. Methods: A caries-free mandibular first molar (tooth #36) was scanned using CBCT. The scanned files were processed in Mimics 12 software for segmentation of enamel, dentin, and pulp tissues and then exported to STP format. Cavity preparations (DO, MO, MOD, and O) were designed in SolidWorks 2023. Bulk-fill composite, conventional composite, and hybrid composite were used for restorations with adhesive layers of 10, 15, and 20 μm thick. Stress distribution and fracture resistance were analyzed using 3D finite element analysis. Results: The highest stress values in enamel, dentin, and adhesive material were observed in models restored with bulk-fill composite, while the highest stress values within the restoration were found in models restored with hybrid composite. As the adhesive layer thickness decreased, stress accumulation within the restorative material increased. Enamel fractures occurred first in models with bulk-fill composite. Among restorative materials, fractures initiated first in models restored with hybrid composite, while the latest fracture onset was observed in models with bulk-fill composite. Conclusions: Restorative materials with low Young’s modulus cause excessive stress accumulation in enamel and dentin, leading to early fracture of these tissues. In contrast, materials with a high Young’s modulus transfer more stress to the restoration, causing premature fracture of the restorative material.

Background: The aim of this study was to compare the stress distributions and fracture life of dental tissues and restorative materials restored using different thicknesses of adhesive materials and different restorative materials. Methos : A tooth number 36 without caries and loss of material was scanned using a CBCT device. The files obtained were transferred to Mimics software. Using this software, enamel tissue, dentin tissue and pulp regions were extracted separately in STL format. STL files were transferred to Geomagic Design X software for surface correction and saved in STP format. The obtained STP files were transferred to the Solidworks programme and 4 different (DO, MO, MOD, O) cavity preparations were made on the models. Each of these cavities was restored with bulk-fill composite, conventional composite and hybrid composite in the computerised environment. A layer of adhesive material with a thickness of 10, 15 and 20 micrometres was applied under all materials and stress distributions and fracture lifetimes were analysed by 3D finite element stress analysis method. Results: When we evaluated the models with different thicknesses of adhesive material, the stress values on enamel, dentin and adhesive material were highest in the models with bulk-fill composite, while the stress values on the restoration were highest in the models with hybrid composite. As the thickness of the adhesive material decreased, the stress values accumulated on the material increased. In addition, the models in which the enamel tissue started to fracture the earliest were the models restored with bulk-fill composite. The models in which the restorative materials started to fracture the earliest were the models restored with hybrid composites, while the models in which the restorative materials started to fracture the latest were the models restored with bulk-fill composites. Conclusion: When materials with low young's modulus are used for restorative purposes, they cause too much stress accumulation on enamel and dentin tissues. Accordingly, these tissues start to fracture early. When materials with large Young's modulus are used, too much stress is applied to the restoration and the restoration fractures prematurely.

Aim: The aim of this study was to examine the stress distribution on the tooth structure, restorative materials, and periodontal tissues prepared in a computer environment as a result of the forces acting on the mandibular premolar tooth surface, using the finite element stress analysis method. Methodology: The extracted mandibular premolar tooth was scanned with a dental tomography device and recorded. Images were obtained as digital imaging and communications in medicine (DICOM) files, which were transferred to the Mimics 12.00 program. This program was used to create a 3D image of the tooth, which was converted into a Standard Tessellation Language (STL) file. The resulting STL files were transferred to the Geomagic Design X program, some necessary adjustments, such as smoothing, were made, and Standard for the Exchange of Product Model Data (STP) files were created. The STP files were transferred to the SolidWorks program and Class I cavity preparation, restorative material layers, adhesive material layers, and periodontal tissues were created. Finally, the finite element (FE) model was created in the ABAQUS program, and the stress distributions were analyzed. Results: In the model restored with bulk-fill, compared to the model restored with amalgam, the amount of stress on dentin was found to be higher, while the amount of stress on cortical bone, trabecular bone, periodontal ligament, and enamel was found to be lower. In both models restored with bulk-fill composite and amalgam, the structure exposed to the most stress was the enamel layer, while the structure exposed to the least stress was the periodontal ligament. The amount of stress on the amalgam material was found to be higher than the amount of stress on the bulk-fill composite material. Conclusion: Amalgam and bulk-fill composite materials are frequently used today in posterior teeth with large cavities. As a result of our study, bulk-fill composite material caused less stress distribution than amalgam in all tissues except dentin tissue. How to cite this article: Karaköy H, Gönder HY, Mohammadi R, Harmankaya A, Tunçdemir MT, Yüksel İB, Göktolga EG. Examination of stress distribution on Class I cavity restored using amalgam and bulk-fill composite: A 3D finite element stress analysis. Int Dent Res. 2024;14(S1):98-105. https://doi.org/10.5577/indentres.570

Bu olgu üst santral ve lateral dişlerde bulunan eski restorasyon kenarlarında oluşan sekonder çürüklerin ve kanin dişte oluşan çürüğün direkt kompozit rezin ile tek seansta estetik restorasyonlarının yapılmasını içermektedir. 35 yaşındaki erkek hasta üst ön bölgedeki dişlerinde yer alan estetik bozukluk şikayeti ile kliniğimize başvurdu. Başlangıçta gün ışığında dişlerde kullanılması uygun olan kompozit rezinin rengi seçildi. Eski restorasyonlar ve çürükler dişler üzerinden uzaklaştırıldıktan sonra mine kenarları bizote edilerek lastik örtü ile izole edildi. Ardından santral ve lateral dişlerde Estelite Sigma Quick A3 ve Estelite Sigma Quick A3.5 , kanin dişte ise Ceram.x SphereTEC One marka kompozit rezin kullanılarak restore edildi. Hem estetik hem fonksiyonel olarak hastanın beklentilerini karşılayan bir restorasyon ile tedavi tamamlanmış ve hastanın şikayetleri giderilmiştir.