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Objective To investigate the biomechanical behavior of porous scaffold with different materials (Ti, Ta, PEEK, HA) for repairing rabbit femur defects under immediate loading by three-dimensional finite element analysis (FEA), so as to explore the best porous scaffold material from the perspective of biomechanics. Methods The CBCT combined with software such as Mimics, SolidWorks, Geomagic Studio, ANSYS were used to establish an immediate loading model for the repair of rabbit femur defects with porous scaffolds at different stages of bone healing. The stress and strain distributions on the scaffolds and the surrounding tissues were calculated. Results The maximum equivalent stress of porous scaffold decreased along with the bone healing. In the granulation tissue and fibrous tissue model, the ratio of the maximum equivalent stress to the yield strength of porous scaffold was: HA＞Ta＞PEEK＞Ti. The maximum equivalent stress of the HA porous scaffold was greater than its yield strength. The number of suitable strain elements in tissues around the porous scaffolds was: PEEK＞Ta＞Ti＞HA. The number of potential fracture strain elements in tissues around the porous scaffolds was: HA＞Ta＞PEEK＞Ti. Conclusions The HA porous scaffold could not bear the immediate load and guide bone healing well under immediate loading. The elastic modulus of PEEK porous scaffold was similar to that of bone tissues, which could preferably guide bone healing. PEEK was an ideal porous scaffold material under immediate loading. The research findings provide
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Objective@#To preliminarily evaluate the clinical effect of the three-dimensional (3D) printing individualized titanium mesh combined with guided bone regeneration technology for repairing alveolar bone defects.@*Methods@#Six patients with alveolar bone defects (4 males and 2 females, aged 18-27 years, mean 23.3 years) were selected from the Department of Oral Implantology, Stomatological Hospital of Chongqing Medical University from January to June 2018. The patients′ cone-beam CT (CBCT) data was imported into the digital design software, and the individualized titanium meshes were designed based on the ideal bone mass around the implant, alveolar bone morphology and soft tissue condition. Then, the ".stl" files were output and the meshes were fabricated by 3D printing technology. The individualized titanium meshes combined with the mixture of autogenous bone and bone substitute materials were used to augmentation during operation. All patients were reviewed at 1, 3 and 6 months after surgery to observe the complications and evaluate the effect of bone augmentation. After taking out the titanium mesh, the CBCT was compared with the preoperative CBCT. The increased bone height and bone width were measured and the bone incremental volume was calculated.@*Results@#Titanium mesh exposure occurred in 2 patients with no obvious infection, and no early removal. In 6 patients, the bone width increased by 1.75-7.54 mm (mean 3.58 mm), the bone height increased by 0.91-11.80 mm (mean 3.37 mm), and bone incremental volume increased by 247-676 mm3 (mean 503 mm3). All of the cases showed sufficiently grafted volume for implant placement.@*Conclusions@#The individualized 3D printing titanium meshes combined with guided bone regeneration could repair alveolar bone defects with excellent clinical effect, but a better design needed to be explored in the future to solve or delay the exposure of titanium mesh.
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<p><b>OBJECTIVE</b>This study was conducted to determine the three-dimensional structure, course, and adjacent structure of the mandibular incisive canal (MIC) to ensure safety of dental implantation by cone beam CT (CBCT).</p><p><b>METHODS</b>The CBCT images of the bilateral mandibles of 80 patients were retrospectively studied. The diameters of the mandibular incisive canal and the location in the adjacent structure were determined, including the distances between the MIC and the buccal and lingual plates of the alveolar bone, the inferior border of the mandible and the tooth apex, and the horizontal plane of the mental foramen.</p><p><b>RESULTS</b>Approximately 78.75% (63 cases) of the CBCT scans showed the presence of the MIC with a mean diameter of 1.21 mm +/- 0.29 mm. The distances from the canal to the inferior border of the mandible and to the tooth apex were 7.82 mm +/- 1.86 mm and 7.24 mm +/- 2.82 mm, respectively. The distances between the canal and the buccal plate as well as between the canal and the lingual plate of the alveolar bone were 3.80 mm +/- 1.37 mm and 4.45 mm +/- 1.34 mm, respectively. The distance from the canal to the horizontal plane of the mental foramen was 5.62 mm +/- 2.21 mm.</p><p><b>CONCLUSION</b>CBCT could clearly show the three-dimensional structure, course, and adjacent structure of the MIC. Therefore, this technique could provide guidance for dental implantation in clinical applications.</p>