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BACKGROUND: In the treatment of oral implant repair, different occlusal contact methods affect the internal structure of the implant and the stress distribution in the bone tissue. Whether the stress distribution is balanced or not determines the long-term life of the implant and the stability of the surrounding bone level. OBJECTIVE: To explore the effects of different occlusal contact modes on the internal stress distribution of restoration, implant, abutment, retention screw, bone tissue, binder and restoration in three kinds of occlusal relationship of maxillary central incisor implant. METHODS: The cone beam CT image data of one volunteer undergoing implant restoration of the maxillary central incisor were extracted from the database. Mimics 19.0 software was utilized to build the maxillary model, and the maxillary model was imported into Solidworks 2017 software to build the maxillary central incisor crown restoration model. Using ANSYS Workbench 17.0 software, three occlusal contact modes of end-to-end occlusion, normal occlusion, and deep overbite occlusion were loaded by simulating the distal middle edge of the crown, the midpoint of the implant diameter and the midpoint of the joint crown. The stress distribution of each structure and bone tissue in the implant restoration was analyzed under the influence of three kinds of occlusal relationship and three loading modes. RESULTS AND CONCLUSION: (1) In the end-to-end occlusion group, when the contact mode changed from the distal margin to the midpoint of the implant diameter and the midpoint of the crown, the stress of the internal structure, bone tissue and binder of the implant decreased accordingly. (2) In the normal group, when the contact mode changed from the distal margin to the midpoint of the implant diameter and the midpoint of the joint crown, the stress of the internal structure, bone tissue and binder of the implant decreased accordingly. (3) In the deep overbite group, when the contact mode changed from the distal margin to the midpoint of the implant diameter and the midpoint of the crown, the stress of the internal structure and bone tissue of the implant increased accordingly, while the stress of the binder gradually increased. (4) The results show that different occlusal contact modes and occlusal relationship affect the distribution of stress in each structure, bone tissue and binder of implant restoration. This conclusion may provide a reference basis for the adjustment of occlusal contact of implant restoration. [ABSTRACT FROM AUTHOR]

BACKGROUND: In oral implant repair, soft tissue level implants are different from bone level implants, which adopt non-embedded surgical methods. A good neck design can promote bone bonding or reduce marginal bone absorption and facilitate the formation of stable soft tissue sealing. Therefore, the neck structure design of implants is one of the key factors for the success of implant repair. OBJECTIVE: To simulate and analyze the stress distribution of implant components and implant-bone interface during the restoration of mandibular molars with four different smooth collar implants using three-dimensional modeling and finite element analysis software. METHODS: The cone-beam CT image data of a patient undergoing mandibular first molar implantation were selected, and the mandible model was established by Mimics 21.0 software. The mandible model was imported into Solidworks 2018 software. Smooth neck implant models were constructed as follows: the standard conventional cervical implant (2.8 mm in height, 4.8 mm in diameter), standard wide cervical implant (2.8 mm in height, 6.5 mm in diameter), aesthetic conventional neck implant (1.8 mm in height, 4.8 mm in diameter), and aesthetic wide neck implant (1.8 mm in height, 6.5 mm in diameter). The four models were repaired with pure titanium base table and zirconia full-crown screw fixation. The von-Mises stress distribution of implant components and the implant-bone interface in four groups of different smooth collar implants were compared and analyzed under vertical and oblique loadings. RESULTS AND CONCLUSION: (1) Whether it was vertical loading or oblique loading, the peak values of von-Mises stress were located in the neck region of the implant, and the peak values of von-Mises stress at the implant-bone interface were located in the cortical bone region of the neck region of the implant. (2) When using the same smooth collar implant, compared with the vertical loading group, the peak values of Von-Mises stress were greater in the four different smooth collar implants in the oblique loading group. (3) Under vertical or oblique loading, the maximum von-Mises stress of the standard implant group was greater than that of the standard implant group, and the maximum von-Mises stress of the aesthetic implant group was lower than that of the aesthetic implant group. (4) The maximum von-Mises stress on the implant-bone interface in the wide-neck standard implant group was lower than that in the other smooth cervical implant groups, regardless of vertical or oblique loading. (5) The results showed that the stress distribution of implant components and implant-bone interface was different with different smooth collar implants. [ABSTRACT FROM AUTHOR]

BACKGROUND: In oral implant restoration, patients with single missing maxillary anterior teeth often have alveolar bone absorption and defect due to different reasons. To avoid the risk of bone grafting, inclined implants are often used to avoid the alveolar bone absorption area. The angle abutment is used to restore the normal overcovering relationship of patients. The size and distribution of the influence of different abutment materials on the occlusal force transfer of the implant and the surrounding bone were studied. OBJECTIVE: To compare the influence of time on the peak value of bone stress around the implant with three abutment materials under simulated dynamic loading under three implantation conditions. METHODS: Cone beam CT data of a healthy adult undergoing implant restoration of maxillary central incisor were selected. Minics software was used to cut the jaw bone. Solidworks 2018 was used to establish the implant, jaw bone, and angle abutment (angle 0°, 15°, and 25°). Base stations materials included pure titanium, zirconium dioxide, and alumina), central screw, and zirconium dioxide full porcelain crown model. Assembly was complete, for embedded in the original maxillary fang root cutting direction 0° angle, then simulated palate to tilt 15° and 25°, no implanted implant thread exposure. According to different implant angles, they were divided into 0°, 15°, and 25° groups. Dynamic loading was performed for 0.2 seconds, to obtain the time-dependent relationship between the peak value of equivalent stress of bone around the implant prosthesis of each material abutment. RESULTS AND CONCLUSION: (1) All abutment implant restorations had the same peak distribution of surrounding bone stress when they were subjected to occlusal force, all of which were located in the bone cortex of the implant neck. The fastest time period for the increase of bone stress around abutment implant restorations of each material was within 0.025-0.05 seconds. The range of high stress value of cortical bone in the 15° group was larger than that in the 0° group. The initial stress value of cortical bone of implant in the 25° group was significantly higher than that of the other two groups. The residual stress value of cortical bone was higher after loading. After titanium abutment implantation, the bone stress around the prosthesis had the largest increase, and the range of high stress value was relatively concentrated. (2) In the 15° group, the peak value of bone stress around the implanted prosthesis on the abutment of the three materials was located in the neck of the implant. The increase in bone stress around the titanium abutment implanted prosthesis was relatively large but not obvious, and the distribution range of high stress was relatively consistent. Compared with the other two groups, the high stress value of the 25° group was more concentrated; the initial stress value was higher and the range of change was greater, among which the bone stress around the implanted prosthesis on the dialumina abutment increased the most within 0-0.1 seconds. At 0.2 seconds, the peak value of bone equivalent stress of zirconia abutment decreased to 0, and high residual stress remained in the bone around the implants of the other two abutments. (3) It is concluded that based on the analysis of the distribution of different influences of the implant angle and abutment material on the bone interface, the bone stress of the implants using zirconia abutment was relatively stable at all time points in the three groups. [ABSTRACT FROM AUTHOR]

BACKGROUND: Less is reported on the influence of cortical bone thickness on displacement and equivalent stress. OBJECTIVE: To analyze the influence of cortical bone thickness on the maximum displacement and equivalent stress at the implant-bone interface through a three-dimensional finite element method, thereby providing some suggestions for oral implantation. METHODS: In this experiment, we selected the cone-shaped CT image data of a patient who was scheduled for mandibular first molar implant restoration. First, we established a mandibular model in Mimics13 software, and then imported it into Solid works 2022 software. According to the related product information, we drew the cone-shaped implant (4.1 mm×10 mm) and the upper prosthesis model. Cortical bone models were obtained according to different cortical bone thicknesses (2.5, 2.0, 1.5, 1.0 mm) and named D1, D2, D3, and D4, respectively. All the models were imported into ANSYS Workbench 2021 software and crosscombined. Finally, we applied vertical and oblique loads to the four groups of models, and analyzed the stress of the models in each group. RESULTS AND CONCLUSION: The peak equivalent stress is lowest in the cancellous bone and highest in the upper prosthesis, that is, at the abutment-implant junction. The peak stress increases with the decrease of cortical bone thickness. The peak stress of the abutment increases with the decrease of cortical bone thickness, and a similar explanation can also be applied to the other implant restoration components. The peak stress in bone tissue and implants increases with the increase of cortical bone thickness. In models D1, D2, D3, the peak stress in implants is higher than that in bone tissue, but the results are reversed in D4. [ABSTRACT FROM AUTHOR]