BACKGROUND:The output of computed tomography (CT) is Digital Imaging and Communications in Medicine (DICOM), whereas the input of three-dimensional (3D) printing is an object Standard Template Library model represented by a triangular mesh. The process of data handing and forrmat conversion are keys to the combination of these two techniques. OBJECTIVE:To explore how to convert CT data into a stereoscopic 3D model efficiently. METHODS:The DICOM in Medicine format data of the patients with femoral fractures were edited and produced by Mimics. We made a 3D model by adjusting the parameters of the 3D printer slicing software, and discussed the significance of 3D model in medical field, especially orthopedics. RESULTS AND CONCLUSION:Mimics software is the bridge to connect two-dimensional CT scan images and 3D images, to create a 3D model by editing the data of DICOM which comes from the CT scanner, with a 3D printing technology. The 3D Model can help doctors for routine clinical diagnosis and treatment, to improve the communication between doctors and patients and the quality of clinical medical teaching. 3D printing also makes medicine more personalized, remote, minimally invasive, and promote the development of medicine to the direction of digital medicine.

Objective To investigate the feasibility and safety*with the low dose fentanyl for valve replacement fast track cardiac anesthesia. Methods 40 cases with cardiac valve replacement were divided into two groups,group Ⅰ :20 cases with fast track anesthesia,group Ⅱ :20 cases with large dose fentanyl anesthesia. The blood presure, HR, SpO2, CVP,Temperature, airway pressure were observed at different time points. The postoperative extubation time,ICU stay,hospital stay,postoperative pulmonary complications were recorded. Results The fentanyl(μg/kg) of group Ⅰ (23. 25 ± 1.32) was less than that of group Ⅱ ( 35.75 ± 6. 84) ( P < 0. 05 ); Extubation time (hours), ICU stay ( hours),length of stay (days) were ( 7.92 ± 3. 16), (25. 12 ± 7.50), ( 28.50 ± 8. 94 ) in group Ⅰ , and that were (13.70±5.63) ,(37.53 ±13. 19) ,(38.00 ± 12. 90) in group Ⅱ. The group Ⅰ were shorter than the group Ⅱ ,P<0. 05; There were four cases of lung infection in group Ⅱ, no one in group Ⅰ ( P < 0. 05 ); There were significant differences between the two groups. There were no significant differences in the remaining observations. Conclusion The low dose fentanyl anesthesia for fast track anesthesia in heart valve replacement surgery was reliable and safe;It could help to reduce postoperative extubation time, ICU stay time and hospital stay time and reduce postoperative pulmonary complications and hospital costs.

BACKGROUND:Polyhydroxybutyrate-co-volerate (PHBV) is a noticeable tissue engineering material of polyhydroxyalkanoates family. It has the properties of low immune rejection response and good biocompatibility, and its degradation products are non-toxic.
OBJECTIVE:To investigate the biocompatibility of PHBV membrane material and human bone marrow mesenchymal stem cel s in vitro.
METHODS:Human bone marrow mesenchymal stem cel s at passage 3 were seeded upon PHBV membrane as experimental group and upon conventional culture plates as control group. Then we calculated the adherent cel number of two groups at 1, 2 and 4 hours and got the cel adherent rate. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay was used at days 2, 4, 6, 8 to observe the cel proliferation of two groups. Fluorimetric method with the fluorescent dye Hoechst 33258 was used to detect the DNA content of cel s at days 3, 6, 9 and 12 in both groups. After cel s were seeded upon PHBV membrane for 5 days, the cel growth upon the material was examined under a scanning electron microscope.
RESULTS AND CONCLUSION:When the cel s were cultured for 1 hour, the adherent rate in the experimental group was lower than that in the control group;but there were no significant differences between two groups at the other two periods. No difference was found in the cel proliferation and the DNA content between the two groups. Human bone marrow mesenchymal stem cel s seeded upon PHBV membrane for 5 days grew wel with spindle morphology and the intercel ular connections were tight and more extracel ular matrices were observed by scanning electron microscopy. Taken together, PHBV membrane material shows a good biocompatibility with human bone marrow mesenchymal stem cel s.

BACKGROUND:In the treatment of tibial plateau fractures, because of the variety of fracture, the complexity of anatomical changes, X-ray films or three-dimensional CT scan limited by two-dimensional plane, increases the difficulty in preoperative plan and surgical treatment. The application of three-dimensional (3D) printing technology has attracted attention in the department of orthopedics. OBJECTIVE:To explore the auxiliary role of 3D printing technique in preoperative plan and treatment for tibial plateau fractures. METHODS:Thirty patients with tibial plateau comminuted fractures were enroled in this study and divided into two groups: experimental and control groups, with 15 patients in each group. In the experimental group, patients underwent 3D CT scan, which was stored in DICOM format, and processed by Mimics software. Data were converted into STL format, entered 3D printer, and a 1:1 entity size of the fracture model was made, in accordance with repair plan of 3D fracture model. Operation time and intraoperative blood loss were compared between the two groups. At 12 months after treatment, their outcomes were assessed using Rasmussen evaluation criteria. RESULTS AND CONCLUSION: The 3D printing fracture models of 1:1 ratio identified fracture type and made a repair program before surgery in the experimental group. Operation time and intraoperative blood loss were significantly less in the experimental group than in the control group (P < 0.05). After surgery, patients were folowed up for 12 to 18 months. The healing time was 3-5 months, averagely 4.3 months. At 12 months after treatment, the Rasmussen evaluation criteria results showed that the excelent and good rate was significantly higher in the experimental group than in the control group (P < 0.05). These results suggest that the fracture model of 3D can help to make the operation plan. The treatment of tibial plateau fractures is more precise, personalized and visual.

With the development of implant technology and materials, the aesthetic of implant prosthesis has been paid more and more attention. Implant prosthesis should be coordinated with patients’ characteristics, the existing aesthetic indices have no unified standard. Based on current research and clinical experiences, this review narrated the esthetic indices of implant crowns and peri-implant soft tissue and influencing factors of dental implant in the aesthetic area.

BACKGROUND:Titanium and titanium aloy are used mostly in artificial joints, fracture fixation, and oral transplantation, while there are complex cases of insufficient bone mass in these areas. The deepened research of stem cels offers a solution for bone injury to promote new bone formation. The biocompatibility of titanium and stem cels and optimization of titanium surface modification have aroused people's attention. OBJECTIVE:To investigate whether the biocompatibility of titanium and human adipose-derived mesenchymal stem cels can be improved by type I colagen modification of titanium sheets. METHODS:The experiment was divided into two groups. Modification group: titanium sheet was modified with type I colagen; control group: titanium sheet was not modified with type I colagen. Human adipose-derived mesenchymal stem cels at passage 6 were implanted into titanium sheet in two groups. Then we calculated the number of adherent cels in two groups at 1, 2 and 4 hours after implantation, and compared the celladhesion rate. MTT assay was used to observe the proliferation of cels on titanium sheet at 2, 4, 6 and 8 days after implantation. DNA and protein content of cels were detected at 3, 6, 9 days after implantation. The growth of human adipose-derived mesenchymal stem cels seeded upon the titanium sheets was observed under scanning electron microscope at 6 days. RESULTS AND CONCLUSION:When the cels were cultured for 1 hour and 2 hours, the number of adherent cels in the modification group was higher than in the control group (P < 0.05). The absorbance of cels in two groups was increased as the culture time, as detected by MTT assay. The modification group had a significantly higher absorbance value than the control group at 4, 6, 8 days (P < 0.05). DNA and protein contents of the cels in the modification group were higher than that in control group at 6 and 9 days (P < 0.05). At 6 days, the number of adherent cels and secretion of adherent stromal cellmatrix in the modification group were significantly better than that in control group, observed by scanning electron microscopy. Type I colagen modified titanium sheets have good surface activity and biocompatibility, and can promote the proliferation of human adipose-derived mesenchymal stem cels.

BACKGROUND:As a noticeable tissue engineering material of polyhy droxyalka noates family, poly (3-hydroxybutyrate-co-4-hydroxybutyrate)(P3HB4HB) exhibitsgood biocompatibility, adhesion and mechanicalproperties, presenting aextensive application future in tissue-engineered research.
OBJECTIVE:To investigate the biocompat ibilityin vitroand ectopic osteogenic differentiationin vivoof P3HB4HB and human bone marrow mesenchymal stem cels.
METHODS:Passage 5human bone marrow mesenchymal stem cels transplanted ontothe three-dimensional P3HB4HB scaffoldwereincubated with osteogenic induction medium (test group)or with no osteogenic induction(control group), respectively. After 5-day incubation, thecelgrowth was assessed by acridine orange staining and scanning electron microscopy; after14-day incubation, both kinds of cel-scaffold composites were subcutaneously implanted into the nude mice. At 16 weeks after implantation, the cel-scaffold composites were removed to observeectopic osteogenic differentiationin vivousing hematoxylin-eosin staining, von Kossa staining and colagen type I immunohistochemical staining.
RESULTS AND CONCLUSION:Acridine orange staining showed that cels adhered wel on the surface of the scaffold;under thescanning electron microscope, induced celsgrew wel on the P3HB4HB scaffold and produced abundant extracelular matrixes. In addition, at 16 weeks after implantation, there were osteoidtissues in the test group, positive for von Kossa staining as wel as colagen type I immunohistochemical staining;furthermore, hematoxylin-eosin staining showednumerous osteoblasts and bone lacunas. In contrast, no bone tissues appeared in the control group. To conclude, P3HB4HB is a suitable material for bone tissue engineering.

BACKGROUND:Autologous tissue-engineered bone marrow mesenchymal stem cel s (BMSCs) transplantation is one of the most common methods of treating early osteonecrosis of femoral head, but now there is stil no any special-purpose grafter available in the market. Such surgical transplantation is a laborious, time-consuming and tedious process, which goes against its clinical promotion. OBJECTIVE:To develop a supporting, efficient, special-purpose grafter, to solve the difficulty in stem cel s transplantation during core decompression of femoral head. METHODS:CAD software was used to perform solid modeling for this special-purpose grafter and print them by three-dimensional (3D) fast printing technology. The performance of this special-purpose grafter was tested by femoral head core decompression combined with BMSCs transplantation. It was compared with traditional surgical instrument in terms of duration of operation, intraoperative blood loss, visual analogue scale (VAS) of stem cel/biological fiber col agen complex omission amount and doctor’s satisfaction score. RESULTS AND CONCLUSION:(1) A kind of special-purpose grafter was developed by 3D printing technology rapidly. (2) Compared with the control group, duration of operation, intraoperative blood loss, VAS scores and doctor’s satisfaction scores were significantly improved in the trial group (P<0.05). (3) CAD software combined with 3D printing technology is a highly efficient means for front-line clinicians to perform independent development. The research and development of this special-purpose grafter provides a perfect solution to the laborious, time-consuming and tedious process of cel/biological col agen fiber transplantation.

BACKGROUND:Bone tissue remodeling is closely related to stress loading.Currently,there are few studies or guidelines on the relationship between bone and occlusal adjustment of implant prostheses and there is also a lack of scientific evidence. OBJECTIVE:To investigate the effects of different implant occlusal gaps on stress distribution,stress peak and displacement at the implant-bone interface under Ⅰ-Ⅳ bone conditions by a finite element method. METHODS:After scanning the equal-scale tooth model with an optical scanner,equal-scale models of the upper right first molar Straumann 4.8×8 mm BL RC implant and its related components was constructed using Solidworks 2022.Then,using Mimics,Geomagic,and Solidworks software,the maxillary and mandibular bone models of class Ⅰ-Ⅳ bones were established based on the bone classification proposed by ZARB and LEKHOLM in the literature,and the NORTON and TRISI bone density classification method.The models were assembled with the occlusal gaps of 0,20,40,60,80,and 100 μm for the restorations,and an additional set of homogeneous models without density ratio settings was constructed for comparison.After the above models were imported into Hypermesh for meshing,the material assignment,boundary constraints and parameter setting were performed for the finite element analysis.Finally,250 N was used as the loading force to simulate the maxillary and mandibular stress conditions.Stress distribution,peak stress and displacement of the implant-bone interface in each group of models were analyzed and compared. RESULTS AND CONCLUSION:Under the same loading conditions,the stresses in the implant restorations were evenly distributed with the occlusal contact points.When the occlusal gap reached 80 and 100 μm,stress interruptions occurred in the implant crowns under class Ⅰ bone and class Ⅱ,Ⅲ and Ⅳ bones,respectively.The displacement of the implant-bone interface was mainly concentrated in the cortical bone region around the implant and transmitted down the long axis of the implant to the cancellous bone region at the bottom.With the changes of class Ⅰ-Ⅳ jaw bones,the displacement and Von Mises stress in the cortical bone region increased in all groups,and were greater than those in the cancellous bone region.The Von Mises stress in the cancellous bone region was similar to that in the cortical bone region except that it showed a downward trend from class Ⅱ bone.However,when the occlusal gap increased,the stress and displacement peak values in the cortical bone and the cancellous bone showed a decreasing trend.The stress of the implant-bone interface was between 20 MPa and 60 MPa when the occlusal gap was 0-40 μm for class Ⅱ-Ⅳ bones and 60 μm for class Ⅳ bone,and the stress of the other groups was less than 20 MPa.The Von Mises stress was mainly concentrated in the neck of the implant,and the peak value of von Mises stress in class Ⅱ-Ⅳ bones with the occlusal gap of 20 μm was higher than that(144.10 MPa)in class Ⅰ bone with the occlusal gap of 0 μm.In the homogeneous model with different elastic moduli,the distribution of stress and displacement was more uniform than that in the heterogeneous model and the occlusal space should increase with the decrease of jaw bone density in clinical practice.To conclude,from the perspective of biomechanics,the alveolar bone should be taken into account in the occlusal adjustment of implant denture.An occlusal gap of 20-40 μm between a single dental implant and a natural tooth in the opposite jaw is a relatively suitable solution for occlusal adjustment under different bone conditions.However,due to the particularity of finite element analysis method,it needs to be further studied in combination with clinical practice.