OBJECTIVEThis 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).

METHODSThe 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.

RESULTSApproximately 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.

CONCLUSIONCBCT 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.

Bone and Bones ; Cone-Beam Computed Tomography ; Dental Implants ; Humans ; Mandible ; anatomy & histology ; Maxilla ; Retrospective Studies ; Tongue

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.

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

ObjectiveTo observe the effect of Huangqi Baihe granules on the hypoxia-inducible factor 1α （HIF-1α）/nuclear factor-κB （NF-κB）/NOD-like receptor hot protein domain related protein 3 （NLRP3） signaling pathway in a rat model of high altitude hypoxia. MethodSixty male SPF SD rats were randomly divided into blank group， model group， dexamethasone group （5 mg·kg^-1）， and high， middle， and low-dose groups of Huangqi Baihe granules （4.1， 2.05， 1.025 g·kg^-1）. Among them， each Chinese medicine group was administrated orally for continuously 14 d， once a day， and the dexamethasone group was injected intraperitoneally for continuously 3 d as the positive control group. On the 15^th d， the model group， dexamethasone group， and high， middle， and low dose groups of Huangqi Baihe granules were exposed to the simulated high altitude， low pressure， and low oxygen environment in the animal low-pressure simulation cabin， and the exposure lasted for 3 d. Blood was collected from the abdominal aorta and serum was separated， and the brain tissue was taken after being killed. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in brain tissue. Enzyme-linked immunosorbent assay （ELISA） was used to detect the content of tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and interleukin-1β （IL-1β） in rat serum. Western blot was used to detect HIF-1α， NLRP3， phosphorylated nuclear factor-κB （p-NF-κB）， NF-κB， desquamation D （GSDMD）， and cysteine aspartate-specitis protein-1（Caspase-1） in rats of each group. The mRNA expression levels of HIF-1α， NLRP3， NF-κB p65， GSDMD， and Caspase-1 were detected by real-time quantitative polymerase chain reaction （Real-time PCR）. ResultThe results of HE staining showed that as compared with the normal group， the pathological sections of brain tissues in the model group showed that pyramidal cells were loosely arranged and distributed in disorder， with different sizes. Compared with the model group， the pathological changes in pyramidal cells in the dexamethasone group and high and middle-dose groups of Huangqi Baihe granules were reduced. The results of ELISA showed that as compared with the normal group， the content of TNF-α， IL-6， and IL-1β in the serum of rats in the model group was significantly higher （P<0.01）. Compared with the model group， the content of TNF-α， IL-6， and IL-1β in the serum of rats in the dexamethasone group and high and middle-dose groups of Huangqi Baihe granules decreased significantly （P<0.05， P<0.01）. The results of Western blot showed that as compared with the normal group， the relative protein expression levels of HIF-1α， NLRP3， p-NF-κB p65， GSDMD， and Caspase-1 in the brain tissue of the model group were significantly higher （P<0.01）. As compared with the model group， the relative expressions of HIF-1α， NLRP3， p-NF-κB p65， GSDMD， and Caspase-1 in the brain tissue of rats in the dexamethasone group and the high-dose group of Huangqi Baihe granules were significantly decreased （P<0.05， P<0.01）. The relative protein expression levels of HIF-1α， NLRP3， p-NF-κB p65， and Caspase-1 in the brain tissue of rats in the middle-dose group of Huangqi Baihe granules decreased significantly （P<0.01）， and the relative protein expression of HIF-1α in the brain tissue of rats in the low-dose group of Huangqi Baihe granules was reduced （P<0.05）. The Real-time PCR analysis showed that as compared with the normal group， the mRNA expression levels of HIF-1α， NLRP3， NF-κB p65， GSDMD， and Caspase-1 in the brain tissue of the model group were significantly increased （P<0.01）. As compared with the model group， the mRNA expression levels of HIF-1α， NLRP3， NF-κB p65， GSDMD， and Caspase-1 in the brain tissue of rats in the dexamethasone group were significantly decreased （P<0.01）. The mRNA expression levels of HIF-1α， NF-κB p65， GSDMD， and Caspase-1 in the brain tissue of rats in the high-dose group of Huangqi Baihe granules decreased significantly （P<0.01）. The mRNA expression levels of HIF-1α， NLRP3， and Caspase-1in the brain tissue of rats in the middle-dose group of Huangqi granules decreased （P<0.05， P<0.01）. ConclusionThe protective effect of Huangqi Baihe granules on acute brain injury in low-pressure hypoxic rats may be related to the HIF-1α/NF-κB/NLRP3 signaling pathway.