Evaluation of a custom-designed human-robot collaboration control system for dental implant robot.

BACKGROUND: The purpose of this study is to develop a methodology to better control a human-robot collaboration for robotic dental implant placement. We have designed a human-robot collaborative implant system (HRCDIS) which is based on a zero-force hand-guiding concept and a operational task management workflow that can achieve highly accurate and stable osteotomy drilling based on a surgeon's decision and robotic arm movements during implant surgery. METHOD: The HRCDIS brings forth the robot arm positions, exact drilling location, direction and performs automatic drilling. The HRCDIS can also avoid complex programing in the robot. The purpose of the study is to evaluate the accuracy of drilling resulting from our developed operational task management method (OTMM). The OTMM can enable the robot to switch, pause, and resume drilling tasks. The force required for hand-guiding in a zero-force control mode of the robot was detected by a 6D force sensor. We compared our force data to those provided by the manufacturer's manual. The study was conducted on a phantom head with a 3D-printed jaw bone to verify the validity of our HRCDIS. We appraised the discrepancies between free-hand drillings and the HRCDIS controlled drillings at apical centre and head centre of the implant and implant angulation to the baseline data from a virtual surgical planning model. RESULTS: The average required force used by hand-guiding to operate the robot with HRCDIS was near 7 Newton which is much less than the manufacturer's specification (30 Newton). The results from our study showed that the average error at implant head was 1.04 ± 0.37 mm, 1.56 ± 0.52 mm at the implant apex, and deviation of implant angle was 3.74 ± 0.67°. CONCLUSIONS: The results from this study validate the merit of the human-robot collaboration control by the HRCDIS. Based on the improved navigation system using HRCDIS, a robotic implant placement can provide seamless drilling with ease, efficiency and accuracy.

Accuracy of dental implant surgery with robotic position feedback and registration algorithm: An in-vitro study.

BACKGROUND: The purpose of this study was to develop and validate a positioning method with hand-guiding and contact position feedback of robot based on a human-robot collaborative dental implant system (HRCDIS) for robotic guided dental implant surgery. METHODS: An HRCDIS was developed based on a light-weight cooperative robot arm, UR5. A three-dimensional (3D) virtual partially edentulous mandibular bone was reconstructed using the cone bone computed tomography images. After designing the preoperative virtual implant planning using the computer software, a fixation guide worn on teeth for linking and fixing positioning marker was fabricated by 3D printing. The fixation guide with the positioning marker and a resin model mimicking the oral tissues were assembled on a head phantom. The planned implant positions were derived by the coordinate information of the positioning marker. The drilling process using the HRCDIS was conducted after mimicking the experimental set-up and planning the drilling trajectory. Deviations between actual and planned implant positions were measured and analyzed. RESULTS: The head phantom experiments results showed that the error value of the central deviation at hex (refers to the center of the platform level of the implant) was 0.79 ± 0.17 mm, central deviation at the apex was 1.26 ± 0.27 mm, horizontal deviation at the hex was 0.61 ± 0.19 mm, horizontal deviation at the apex was 0.91 ± 0.55 mm, vertical deviation at the hex was 0.38 ± 0.17 mm, vertical deviation at the apex was 0.37 ± 0.20 mm, and angular deviation was 3.77 ± 1.57°. CONCLUSIONS: The results from this study preliminarily validate the feasibility of the accurate navigation method of the HRCDIS.

Digital design of scaffold for mandibular defect repair based on tissue engineering.

Mandibular defect occurs more frequently in recent years, and clinical repair operations via bone transplantation are difficult to be further improved due to some intrinsic flaws. Tissue engineering, which is a hot research field of biomedical engineering, provides a new direction for mandibular defect repair. As the basis and key part of tissue engineering, scaffolds have been widely and deeply studied in regards to the basic theory, as well as the principle of biomaterial, structure, design, and fabrication method. However, little research is targeted at tissue regeneration for clinic repair operations. Since mandibular bone has a special structure, rather than uniform and regular structure in existing studies, a methodology based on tissue engineering is proposed for mandibular defect repair in this paper. Key steps regarding scaffold digital design, such as external shape design and internal microstructure design directly based on triangular meshes are discussed in detail. By analyzing the theoretical model and the measured data from the test parts fabricated by rapid prototyping, the feasibility and effectiveness of the proposed methodology are properly verified. More works about mechanical and biological improvements need to be done to promote its clinical application in future.

[Nitric oxide regulates c-fos expression in osteoblastic cells induced by wall-shear].

OBJECTIVE: To observe regulation of nitric oxide on c-fos expression in osteoblastic cells in response to changes in wall-shear stress in vitro. METHODS: Isolated and purified osteoblastic cells from the calvaria of newborn SD rats were cultured and passaged. The third generation cells, pre-treated with 10% FBS DMEM, 0.3 mmol/L L-NMMA DMEM and 0.1 mmol/L SNP DMEM separately, were subjected to wall-shear stress of 1.2 Pa. Gene expression of the c-fos and NOS activity were studied before (0 min) and 10 min, 15 min, 30 min, 60 min after treated with wall-shear stress. RESULT: The expression of c-fos mRNA was increased transiently after application of 1.2 Pa wall-shear stress in osteoblastic cells and peaked at 15 min. The expression of c-fos mRNA was decreased after pre-application with L-NMMA and increased after use of SNP. CONCLUSION: Changes in the osteoblastic cells mechanical environment may cause a dramatic induction of NO and c-fos expression.

[Apoptosis induces by exogenous nitric oxide in Tca8113 cells].

OBJECTIVE: To observe the apoptosis induced by exogenous NO in Tca8113 cells and to investigate the possible mechanism. METHODS: SNP as NO donor was used to treat the tongue squamous cell carcinoma Tca8113 cells. Cytotoxic and apoptotic effects of NO on Tca8113 cells were examined by using MTT assay, acridine orange (AO) staining, Wright-Giemsa staining, agarose gel electrophoresis and flow cytometry. Western blot was performed for investigating the apoptotic mechanism. RESULTS: NO had a remarkable proliferation inhibiting effect on Tca8113 cells. After being exposed to exogenous NO, Tca8113 cells showed series of apoptotic morphological changes such as cell shrinkage, nuclear condensation; and also showed DNA fragmentation, G2/M phase arrest as well as upregulation of the tumor suppressor P53 protein. CONCLUSION: Exogenous NO has a proliferation inhibition and apoptosis induction effect on Tca8113 cells in a concentration and time-dependent manner, P53 protein may be involved in the apoptosis induced by NO.

[Activating protein-1 members in response to changes of wall-shear stress in osteoblastic cells].

OBJECTIVE: To observe activating protein-1 (AP- 1) members in response to changes of wall-shear stress in osteoblastic cells in vitro. METHODS: Isolated and purified osteoblastic cells from the calvaria of newborn SD rats were cultured and subcultured. The third generation cells were subjected to wall-shear stress of 0.8 Pa, 1.2 Pa, 1.4 Pa and 1.6 Pa separately. Gene expression of the seven AP-1 members were studied before (0 h) and 10 min, 15 min, 30 min, 60 min after treated with wall-shear stress. RESULTS: The expression of FosB, c-Fos, c-Jun, JunD and JunB mRNA increased transiently after application of 1.2 Pa wall-shear stress in osteoblastic cells compared to 0.8 Pa , 1.4 Pa and 1.6 Pa stress, and peaked at 15 min. CONCLUSION: Mechanical environment changes in osteoblastic cells induced a dramatic induction of most of the AP-1 members.

Nitric oxide induces oral squamous cell carcinoma cells apoptosis with p53 accumulation.

Nitric oxide has been reported to have cytotoxic effects in several tumor cells. The objective of this study was to investigate the effects of exogenous nitric oxide on apopotosis in oral squamous cell carcinoma cells and to reveal its possible mechanism. Tca8113 cells were cultured with various concentrations of nitric oxide that were released from sodium nitroprusside (SNP). Nitrite/nitrate levels in the culture supernatant were determined using a commercial available nitric oxide kit. Cellular proliferation was determined by MTT assay. Apoptosis was detected by flow cytometry. Expression of inducible nitric oxide synthase (iNOS) was determined by immunocytochemistry. p53 expression was assessed by Western blot. SNP can release nitric oxide into the culture medium in a dose-dependent manner. Nitric oxide remarkably inhibits proliferation in a dose and time-dependent manners and lead to apoptosis of the Tca8113 cell. The p53 expression was elevated accompanying by the increased apoptotic cells. No difference of iNOS was found whether or not the cells were treated with SNP. Exogenous nitric oxide had an inhibitory effect on Tca8113 cells proliferation in a dose and time-dependent manners and possibly via p53 dependent apoptosis pathway. Exogenous nitric oxide had no significant effect on cellular iNOS protein.