Endoscopic transnasal transmaxillary approach to the upper parapharyngeal space and the skull base.

PURPOSE: Treatment of tumors arising in the upper parapharyngeal space (PPS) or the floor of the middle cranial fossa is challenging. This study aims to present anatomical landmarks for a combined endoscopic transnasal and anterior transmaxillary approach to the upper PPS and the floor of the middle cranial fossa and to further evaluate their clinical application. METHODS: Dissection of the upper PPS using a combined endoscopic endonasal transpterygoid and anterior transmaxillary approach was performed in six cadaveric heads. Surgical landmarks associated with the approach were defined. The defined approach was applied in patients with tumors involving the upper PPS. RESULTS: The medial pterygoid muscle, tensor veli palatini muscle and levator veli palatini muscle were key landmarks of the approach into the upper PPS. The lateral pterygoid plate, foramen ovale and mandibular nerve were important anatomical landmarks for exposing the parapharyngeal segment of the internal carotid artery through a combined endoscopic transnasal and anterior transmaxillary approach. The combined approach provided a better view of the upper PPS and middle skull base, allowing for effective bimanual techniques and bleeding control. Application of the anterior transmaxillary approach also provided a better view of the inferior limits of the upper PPS and facilitated control of the internal carotid artery. CONCLUSIONS: Improving the knowledge of the endoscopic anatomy of the upper PPS allowed us to achieve an optimal approach to tumors arising in the upper PPS. The combined endoscopic transnasal and anterior transmaxillary approach is a minimally invasive alternative approach to the upper PPS.

Endoscopic transvestibular anatomy of the infratemporal fossa and upper parapharyngeal spaces for clinical surgery: a cadaver study.

AIMS: To investigate the anatomy of the infratemporal fossa (ITF) and to discuss the practicality of endoscopic transvestibular surgery for an ITF tumor. METHODS: Five fresh cadaveric specimens (10 sides) with vascular silicone injection were prepared for endoscopic anatomy. A transvestibular vertical incision was made along the ramus of the mandible, and pivotal nerves, arteries, and muscles were exposed to sculpt the anatomic landmarks of the ITF. RESULTS: The endoscopic transvestibular approach exposed the detailed structure of the ITF. The buccinator muscle and the adjoining superior pharyngeal constrictor muscle shaped the paramedian border of the ITF, while the medial pterygoid muscle (MPM) and the lateral pterygoid muscle formed the lateral border. The ITF was delimited by the skull base in the upper margin, and it was proximal to the parapharyngeal space in the inferior part. The inferior alveolar nerve was the first reference point, and the maxillary artery and the lateral pterygoid muscle were also the landmarks of the ITF. The lingual nerve, the eustachian tube (ET), and the middle meningeal artery were also located in the posterior part of the ITF. CONCLUSION: The endoscopic transvestibular approach provides a feasible and facile corridor to the ITF. With accurate hemostasis, this approach may provide another option for accessing the ITF for removal of tumors.

Endoscopic endonasal approach for trigeminal schwannomas: our experience of 39 patients in 10 years.

BACKGROUND: The anatomical locations involved in trigeminal schwannomas (TSs) are quite complex. The endoscopic endonasal approach provides a minimal damage access corridor to both anterior and middle skull base for surgery. Given the nerve function recovery and postoperative neurological deterioration varied in different reports, the author demonstrates his surgery tips and the functional outcomes under endoscopic surgery in one single institution. METHODS: A retrospective review of patients with TSs was undertaken to assess the outcome of endoscopic surgery from 2006 to 2016. Clinical features, imaging findings, preoperative/postoperative neurological deficits, surgical approaches and followed up data were collected. RESULTS: Thirty-nine patients with TSs were included in this study. Surgical approaches include endoscopic medial maxillectomy approach (n = 8), endoscopic endonasal-assisted sublabial transmaxillary approach (n = 27) and endoscopic endonasal-assisted sublabial transmaxillary combined with septectomy (n = 4). Gross total resection and sub-total resection were achieved in 27 and 10 patients, respectively. The most common chief complaint was facial numbness, accounting for 41%, with a resolved rate of 62.5% after treatment. Fifteen patients developed new neurologic symptoms, including facial numbness/pain (n = 9 and 2, respectively), dry eye (n = 3) and mastication weakness (n = 1). Eight of these patients had partial improvement except for patients with dry eye. CONCLUSION: Endoscopic endonasal approach represents a safe and effective surgical procedure for TSs in pterygopalatine fossa, infratemporal fossa and even Meckel cave. Tumor resection can be achieved by endoscope with few neurologic deficits and complications.

A biomechanical study to evaluate the effect of PMMA augmentation and restoration of the strength of cervical vertebral screws inserted in an osteoporotic vertebral body.

STUDY DESIGN: An experimental study. OBJECTIVE: To compare the peak pull-out force (PPF) of vertebral screws fixed in osteoporotic vertebrae versus polymethylmethacrylate (PMMA) used for augmentation or restoration, before and after fatigue. SUMMARY OF BACKGROUND DATA: Failure of screw fixation in anterior cervical interbody fusion remains a significant clinical problem. However, little is known of the biomechanical characteristics of cervical vertebral screws before and after restoration or augmentation, especially after fatigue. METHODS: Fifty fresh cervical vertebrae, of which 40 were randomly selected, from 12 adult cadavers were used. The vertebrae were divided into healthy controls, osteoporotic controls, a PMMA restoration group, and a PMMA augmentation group. In each of the control groups, 2 pilot holes on each side of 20 vertebral bodies were implanted with vertebral screws (4 mm in diameter). Each side randomly received either acute PPF or PPF beyond fatigue that was ensured using cyclic loading (2 Hz; 20,000 times). In the PMMA groups, pilot holes were drilled parallel to the sagittal plane and injected with 0.6-1.0 mL PMMA before the vertebral screw was inserted. Each side of each vertebral body randomly received either PPF or PPF beyond fatigue that was ensured using cyclic loading (2 Hz; 20,000 times). A Bose3510-AT fatigue testing machine measured the PPF of vertebral screws with or without PMMA for all specimens before and after fatigue. RESULTS: In all groups, the prefatigue PPF was significantly higher than the postfatigue PPF. Compared with the prefatigue PPF, postfatigue PPF was reduced by 37.40%, 43.10%, 32.08%, and 31.85% in the healthy controls, osteoporotic controls, PMMA restoration, and PMMA augmentation groups, respectively. The acute and postfatigue PPFs of the healthy controls were significantly higher from that of the osteoporotic controls. The acute and postfatigue PPFs of both control groups were significantly lower from that of both PMMA groups. There was no difference in acute and postfatigue PPFs between the PMMA restoration and augmentation groups. CONCLUSIONS: The results indicated that both PMMA augmentation and PMMA restoration could significantly increase cervical screw pull-out strength and antifatigue capability. The results provide a biomechanical justification for spine surgeons to use PMMA for augmentation or restoration in cases of surgeries with poor bone quality or osteoporotic vertebral bodies.

Porphyromonas gingivalis bacteremia increases the permeability of the blood-brain barrier via the Mfsd2a/Caveolin-1 mediated transcytosis pathway.

Bacteremia induced by periodontal infection is an important factor for periodontitis to threaten general health. P. gingivalis DNA/virulence factors have been found in the brain tissues from patients with Alzheimer's disease (AD). The blood-brain barrier (BBB) is essential for keeping toxic substances from entering brain tissues. However, the effect of P. gingivalis bacteremia on BBB permeability and its underlying mechanism remains unclear. In the present study, rats were injected by tail vein with P. gingivalis three times a week for eight weeks to induce bacteremia. An in vitro BBB model infected with P. gingivalis was also established. We found that the infiltration of Evans blue dye and Albumin protein deposition in the rat brain tissues were increased in the rat brain tissues with P. gingivalis bacteremia and P. gingivalis could pass through the in vitro BBB model. Caveolae were detected after P. gingivalis infection in BMECs both in vivo and in vitro. Caveolin-1 (Cav-1) expression was enhanced after P. gingivalis infection. Downregulation of Cav-1 rescued P. gingivalis-enhanced BMECs permeability. We further found P. gingivalis-gingipain could be colocalized with Cav-1 and the strong hydrogen bonding between Cav-1 and arg-specific-gingipain (RgpA) were detected. Moreover, P. gingivalis significantly inhibited the major facilitator superfamily domain containing 2a (Mfsd2a) expression. Mfsd2a overexpression reversed P. gingivalis-increased BMECs permeability and Cav-1 expression. These results revealed that Mfsd2a/Cav-1 mediated transcytosis is a key pathway governing BBB BMECs permeability induced by P. gingivalis, which may contribute to P. gingivalis/virulence factors entrance and the subsequent neurological impairments.

Biomechanical study of the atlantoaxial joint after artificial atlanto-odontoid joint arthroplasty.

OBJECTIVE: To investigate the stability and three-dimensional movements of the atlantoaxial joint after artificial atlanto-odontoid joint (AAOJ) arthroplasty by comparing with a conventional method. METHODS: After anterior decompression, 24 human cadaveric spinal specimens of C0-C3 were randomly divided into two groups: Group A receiving artificial AAOJ arthroplasty; Group B experiencing anterior transarticular screw (ATAS) fixation. Two groups underwent flexibility test in intact and instrumented states. Rotational angle of the C0-C3 segments was measured to study the immediate stability and function of anterior decompression with AAOJ arthroplasty compared with the intact state and ATAS fixation. RESULTS: Compared with the intact state, anterior decompression with AAOJ arthroplasty resulted in a significant decrease in the range of motion (ROM) and neutral zone (NZ) during flexion, extension and lateral bending (P less than 0.05); however, with regard to axial rotation, there was no significant difference in ROM and NZ (P larger than 0.05). Compared with anterior decompression with ATAS fixation, anterior decompression with AAOJ arthroplasty during flexion, extension and lateral bending, significant difference was found in ROM and NZ (P larger than 0.05); however, as for axial rotation, there was a significant increase in ROM and NZ (P less than 0.05). CONCLUSION: The self-designed AAOJ has an excellent biomechanical performance, which can restore excellent instant stability and preserve the movement of the atlantoaxial joint.

Transinfratemporal Fossa Transposition of the Temporalis Muscle Flap for Skull Base Reconstruction after Endoscopic Expanded Nasopharyngectomy: Anatomical Study and Clinical Application.

Objective Temporalis muscle flap (TMF) is widely used in traditional skull base surgery, but its application in endoscopic skull base surgery remains rarely reported. We aimed to investigate the surgical anatomy and clinical application of TMF for reconstruction of skull base defects after expanded endoscopic nasopharyngectomy. Methods Nine fresh cadaver heads (18 sides) were used for endoscopic dissection at the University of Pittsburgh School of Medicine in the United States. TMF was harvested using a traditional open approach and then transposed into the maxillary sinus and nasal cavity through the infratemporal fossa using an endoscopic transnasal transmaxillary approach. TMF length was then measured. Moreover, TMF was used for the reconstruction of skull base defects of six patients with recurrent nasopharyngeal carcinoma after expanded endoscopic nasopharyngectomy. Results The length of TMF harvested from the temporal line to the tip of the coronoid process of the mandible was 11.8 ± 0.9 cm. The widest part of the flap was 9.0 ± 0.4 cm. When TMF was dislocated from the coronoid process of the mandible, approximately another 2 cm of reach could be obtained. When the superficial layer of the temporalis muscle was split from the deep layer, the pedicle length could be extended 1.9 ± 0.2 cm. TMF could cover skull base defects in the anterior skull base, sellar, and clivus regions. Conclusion TMF can be used to reconstruct skull base defects after endoscopic expanded nasopharyngectomy and can effectively prevent the occurrence of serious complications in patients with recurrent nasopharyngeal carcinoma.

A New Steel Defect Detection Algorithm Based on Deep Learning.

In recent years, more and more scholars devoted themselves to the research of the target detection algorithm due to the continuous development of deep learning. Among them, the detection and recognition of small and complex targets are still a problem to be solved. The authors of this article have understood the shortcomings of the deep learning detection algorithm in detecting small and complex defect targets and would like to share a new improved target detection algorithm in steel surface defect detection. The steel surface defects will affect the quality of steel seriously. We find that most of the current detection algorithms for NEU-DET dataset detection accuracy are low, so we choose to verify a steel surface defect detection algorithm based on machine vision on this dataset for the problem of defect detection in steel production. A series of improvement measures are carried out in the traditional Faster R-CNN algorithm, such as reconstructing the network structure of Faster R-CNN. Based on the small features of the target, we train the network with multiscale fusion. For the complex features of the target, we replace part of the conventional convolution network with a deformable convolution network. The experimental results show that the deep learning network model trained by the proposed method has good detection performance, and the mean average precision is 0.752, which is 0.128 higher than the original algorithm. Among them, the average precision of crazing, inclusion, patches, pitted surface, rolled in scale and scratches is 0.501, 0.791, 0.792, 0.874, 0.649, and 0.905, respectively. The detection method is able to identify small target defects on the steel surface effectively, which can provide a reference for the automatic detection of steel defects.

PEGylated Indium Nanoparticles: A Metallic Contrast Agent for Multiwavelength Photoacoustic Imaging and Second Near-Infrared Photothermal Therapy.

Indium, a low melting point metal, is well-known for constructing eutectic gallium-indium liquid metal. However, unlike liquid metal nanoparticles, the biomedical applications of metallic indium nanoparticles (In NPs) remain in their infancy. Herein, an ultrasound-assisted liquid-reduction synthesis strategy was developed to prepare PEGylated In NPs, which were then used as a high-performance contrast agent for enhancing multiwavelength photoacoustic imaging and second near-infrared (NIR-II) photothermal therapy of the 4T1 breast tumor. The obtained In NPs depicted remarkable optical absorption from the first near-infrared (NIR-I) to NIR-II region and a high photothermal conversion efficiency of 41.3% at 1064 nm, higher than the majority of conventional NIR-II photothermal agents. Upon injection into the tumor, the photoacoustic intensities of the tumor section post-injection were obviously increased by 2.59-, 2.62-, and 4.27-fold of those of pre-injection by using excitation wavelengths of 750, 808, and 970 nm, respectively, depicting an excellent multiwavelength contrast capability of photoacoustic imaging. In addition, efficient ablation of the 4T1 tumor was achieved through the photothermal performance of PEGylated In NPs under NIR-II laser irradiation. Importantly, as the widely used element in the clinic, In NPs were highly biocompatible in vitro and in vivo. Therefore, this work pioneered the biomedical applications of PEGylated In NPs for cancer diagnosis and treatment.

Exosomes Derived from Stem Cells from the Apical Papilla Promote Dentine-Pulp Complex Regeneration by Inducing Specific Dentinogenesis.

Regenerative endodontic procedures (REPs) are a new option for the treatment of dental pulp or periapical diseases in permanent teeth with open apices. Histologically, the new tissues formed in the root canal after REPs are mainly cementum- or bone-like mineralised tissues, but not the real dentine-pulp complex. Therefore, how to promote dentine-pulp complex regeneration and improve the clinical effects of REPs has become a prominent research topic. Stem cells from apical papilla (SCAP) are derived from the dental papilla that can differentiate into primary odontoblasts and dental pulp cells that produce root dentine and dental pulp. Exosomes are the key regulator for the paracrine activity of stem cells and can influence the function of recipient cells. In this study, SCAP-derived exosomes (SCAP-Exo) were introduced into the root fragment containing bone marrow mesenchymal stem cells (BMMSCs) and transplanted subcutaneously into immunodeficient mice. We observed that dental pulp-like tissues were present and the newly formed dentine was deposited onto the existing dentine in the root canal. Afterwards, the effects of SCAP-Exo on the dentinogenesis of BMMSCs were elucidated in vitro. We found that the gene and protein expression of dentine sialophosphoprotein and mineralised nodule formation in BMMSCs treated with SCAP-Exo were significantly increased. In summary, SCAP-Exo were endocytosed by BMMSCs and obviously improved their specific dentinogenesis. The use of exosomes derived from dental stem cells could comprise a potential therapeutic approach for dentine-pulp complex regeneration in REPs.

[Percutaneous vertebroplasty with EH composite material: an experiment study].

OBJECTIVE: To investigate the appropriate ratio of liquid/powder and use of radiopaque agent in EH composite material for percutaneous vertebroplasty (PVP). METHODS: (1) EH composite material was divided into 6 groups. The material without contrast with the liquid/powder ratios 8:9, 8:8, and 8:7 was classifieds as groups I, II, and III; and the EH composite material with the liquid/powder ratios 8:9, 8:8, and 8:7 and with the addition of 20% barium sulfate by weight was classified as the groups IV, V, and VI. The curing temperature was measured. The bone cement of different groups was made into cylinders to be X-rayed to observe the opacity. Universal tester was used to examine the strength and stiffness. (2) The vertebrae (T8 approximately L5) were isolated from the cadaver of an elder female patient with osteoporosis. Universal tester was used to examine the strength and stiffness of the vertebral bodies (VBs). Osteoporotic vertebral compression fracture (OVCF) model was made. PVP procedure was mimicked by puncturing through the bilateral pedicle of vertebral arch into the anterior 1/3 of the vertebral bodies and the EH composite materials of the groups II and V were injected into the VBs Then the temperatures of the geometric center (CT) and spinal canal posterior wall (PT) of the VBs were measured in a water bath with the temperature of 37 degrees C. Twenty-four hours later the vertebrae underwent X-ray examination to observe the opacity and underwent examination of strength and stiffness with universal tester. RESULTS: (1) The sticking periods (?) of the groups IV, V, and VI were significantly longer than those of the corresponding groups I, II, and III respectively by about 60 s, and the highest temperature of the groups IV, V, and VI were significantly lower than those of the corresponding groups I, II, and III respectively. Addition1 of barium sulfate increased the opacity of the bone cement, but did nor significantly influence the strength of the bone cement. The properties of the group V was the best. (2) The bone cement was easy to be injected into the VBs. The peak PT was not beyond 50 degrees C. After the injection of the bone cement of the groups II, the strength and stiffness of the VB were (1501.6 +/- 5.0) N/mm and (285.6 +/-) N/mm, both significantly higher than those before the injection [(547.5 +/- 3.1) N/mm and (104.1 +/- 1.3) N/mm]; and after the injection of the bone cement of the groups V, the strength and stiffness of the VB were (1355.0 +/- 4.5) N/mm and (257.7 +/- 1.9), both significantly higher than those before the injection [(543.8 +/- 2.7) N/mm and (103.4 +/- 1.1) N/mm]. The opacity of the VBs injected with the bone cement of the group V was better than those injected with the bone cement of the group II. CONCLUSION: The EH (8/8) with 20% barium sulfate is a proper and effective filling material for the treatment of OVCF.

Biomechanical analysis of differential pull-out strengths of bone screws using cervical anterior transpedicular technique in normal and osteoporotic cervical cadaveric spines.

STUDY DESIGN: Biomechanical in vitro study. OBJECTIVE: To determine whether the peak pull-out force (PPF) of cervical anterior transpedicular screw (ATPS) fixed in osteoporotic vertebrae positively influence screw stability or not before and after fatigue. SUMMARY OF BACKGROUND DATA: Multilevel cervical spine procedures with osteoporosis can challenge the stability of current screw-and-plate systems. A second surgical posterior approach is coupled with potential risks of increased morbidity and complications. Hence, anterior cervical instrumentation that increases primary construct stability, while avoiding the need for posterior augmentation, would be valuable. METHODS: Sixty formalin-fixed vertebrae at different levels were randomly selected. The vertebrae were divided into healthy controls (groups A1, A2), osteoporotic controls (B1, B2), healthy ATPS groups (C1, C2), osteoporotic ATPS groups (D1, D2), and osteoporotic restoration controls (E1, E2). The procedure of ATPS insertion was simulated with 2 pilot holes being drilled on each side of 20 vertebral bodies that were implanted with either vertebral screw or polymethylmethacrylate. Each side randomly received either instant PPF or PPF beyond fatigue (2.5 Hz; 20,000 times). RESULTS: The prefatigue PPFs were significantly higher than the postfatigue PPFs in all groups (group A: 366.06 ± 58.78 vs. 248.93 ± 57.21 N; group B: 275.58 ± 23.18 vs. 142.79 ± 44.78 N; group C: 635.99 ± 185.28 vs. 542.57 ± 136.58 N; group D: 519.22 ± 122.12 vs. 393.16 ± 192.07 N, and group E: 431.78 ± 75.77 vs. 325.74 ± 95.10 N). The postfatigue PPFs were reduced by 32.00% (group A), 48.19% (group B), 14.69% (group C), 24.28% (group D), and 24.72% (group E). The acute and postfatigue PPFs of both control groups were significantly lower than that of ATPS groups (P < 0.05). The cyclic osteoporosis ATPS group achieved the same PPF compared with the vertebral restoration screw group. CONCLUSION: The findings of this study suggest that instant PPF and fatigue resistance capability of an ATPS fixation were significantly better than other control groups, especially in the osteoporotic vertebrae.

[Reconstruction of the mandibular model using a three-dimensional laser scanner].

OBJECTIVE: To construct a three-dimensional (3D) mandibular model using a 3D laser scanner, and explore a new method for reconstructing the finite element geometry model. METHODS: A mandible specimen was scanned with the 3D laser scanner to form the point clouds of the mandibular surface, which were subsequently aligned for reconstruction of the mandibular model. RESULT: A 3D model of the mandible surface was reconstructed, which could be used for finite element simulation. CONCLUSION: The 3D laser scanning system can be used to reconstruct the 3D model with irregular geometry for finite element simulation.

[Mechanical strength and in vivo degradation of human hair keratin-polylactic acid composite rods].

OBJECTIVE: To test the mechanical strength and observe the in vivo degradation of self-made human hair keratin-polylactic acid (HHK-PLA) composite rods designed for use in internal fixation. METHODS: Twenty such HHK-PLA composite rods were tested for shear strength, bending strength and bending modulus using the material testing system MTS-858 Mini Bionix. A total of 36 samples of HHK-PLA composite rods designed for internal fixation of bone fracture were randomly implanted in dorsal subcutaneous tissue of 18 SD rats, and weight losses of these rods were measured 1, 2, 4, 8, 12, 16, 20, 24 and 28 weeks after the implantation to evaluate the in vivo degradation of the material. RESULTS: The initial shear strength of HHK-PLA rod was 241 MPa, bending strength 358 MPa, and bending modulus 13 GPa. The test demonstrated a slower rate of degradation in SD rats in earlier period following implantation than in later period. CONCLUSION: HHK-PLA composite rods have good initial mechanical strength and tolerable degradation in vivo, and may be used potentially for internal fixation of the weigh-bearing bones of the limbs.

Construction and accuracy assessment of patient-specific biocompatible drill template for cervical anterior transpedicular screw (ATPS) insertion: an in vitro study.

BACKGROUND: With the properties of three-column fixation and anterior-approach-only procedure, anterior transpedicular screw (ATPS) is ideal for severe multilevel traumatic cervical instabilities. However, the accurate insertion of ATPS remains challenging. Here we constructed a patient-specific biocompatible drill template and evaluated its accuracy in assisting ATPS insertion. METHODS: After ethical approval, 24 formalin-preserved cervical vertebrae (C2-C7) were CT scanned. 3D reconstruction models of cervical vertebra were obtained with 2-mm-diameter virtual pin tracts at the central pedicles. The 3D models were used for rapid prototyping (RP) printing. A 2-mm-diameter Kirschner wire was then inserted into the pin tract of the RP model before polymethylmethacrylate was used to construct the patient-specific biocompatible drill template. After removal of the anterior soft tissue, a 2-mm-diameter Kirschner wire was inserted into the cervical pedicle with the assistance of drill template. Cadaveric cervical spines with pin tracts were subsequently scanned using the same CT scanner. A 3D reconstruction was performed of the scanned spines to get 3D models of the vertebrae containing the actual pin tracts. The deviations were calculated between 3D models with virtual and actual pin tracts at the middle point of the cervical pedicle. 3D models of 3.5 mm-diameter screws were used in simulated insertion to grade the screw positions. FINDINGS: The patient-specific biocompatible drill template was constructed to assist ATPS insertion successfully. There were no significant differences between medial/lateral deviations (P = 0.797) or between superior/inferior deviations (P = 0.741). The absolute deviation values were 0.82±0.75 mm and 1.10±0.96 mm in axial and sagittal planes, respectively. In the simulated insertion, the screws in non-critical position were 44/48 (91.7%). CONCLUSIONS: The patient-specific drill template is biocompatible, easy-to-apply and accurate in assisting ATPS insertion. Its clinical applications should be further researched.

Dual-factor triggered fluorogenic nanoprobe for ultrahigh contrast and subdiffraction fluorescence imaging.

Ultrahigh contrast fluorescence molecular imaging has long been pursued over the past few decades from basic sciences to clinics. Although new classes of near-infrared (NIR) molecular probes are emerging, the requirement of fluorophores with high quantum yield, high signal to noise (S/N) ratio, and being activatable to microenvironment changes can hardly be fulfilled. In this study, a new NIR dye embedded fluorogenic nanoprobe (fg-nanoprobe) was developed for ultrahigh contrast in vitro and in vivo imaging with negligible background interference. The achieved S/N ratio was found to be attributed to the synergistic effects of the cellular compartmental triggered fluorogenicity and pH tunable fluorescence on/off character. In addition, this constructed fluorogenic nanoprobe could be coupled with image processing method for super-resolution subdiffraction imaging. The developed fg-nanoprobe integrated photophysical merits of the synthesized NIR fluorophore and advantages of engineered nanoparticle for enhanced fluorescence molecular imaging. This probe may open another avenue for ultrahigh contrast fluorescence molecular imaging in the future.

Cable-strengthened C2 pedicle screw fixation in the treatment of congenital C2-3 fusion, atlas occipitalization, and atlantoaxial dislocation.

BACKGROUND: Atlas occipitalization and congenital C2-3 fusion often result in atlantoaxial dislocation (AAD) and superior odontoid migration that requires occipitocervical fixation. The widely used technique is posterior occiput-C2 fixation with pedicle screws. However, congenital C2-3 fusion cases tend to have thinner C2 pedicles that are inadequate for normal-sized pedicle screw fixation. With the presence of AAD, the strength of the fixation is further compromised as the C2 pedicle screws (C2PS) sustain considerable cephalic shearing force during the reduction procedure. Therefore, a novel technique has been developed to augment the C2 pedicle screw fixation with a strengthening cable. OBJECTIVE: To introduce and assess this new technique. METHODS: Seventy-six patients who underwent this procedure were reviewed. The position of the instrument and resultant fusion were examined retrospectively. In the biomechanical test, 6 fresh specimens were subjected to 2 types of fixation in the order of Oc-C2 screw-plate fixation followed by additional use of strengthening cable. Under 3 loading modes (extension-flexion, lateral bending, and axial rotation), the relative movement between the occiput and C2 was measured and compared in the form of range of motion. RESULTS: The average follow-up time was 26 months. Solid fusion was achieved in 75 patients (98.7%) as assessed radiologically. The only patient who experienced hardware failure eventually obtained solid fusion between the occiput and C2 after revision. Biomechanically, there was significant difference between the occiput and C2 fixation and cable-strengthened fixation in range of motion for all modes. CONCLUSION: This technique is a promising option for the treatment of AAD with congenital C2-3 fusion and occipitalization. Biomechanically, this technique can reduce the occipital-axial motion significantly compared with occiput-C2 fixation.

[Six degree-of-freedom acquisition and analysis of jaw opening and closing with motion capture system].

OBJECTIVE: To explore the six degrees of freedom of jaw opening and closing movement with motion capture and analysis system to establish a quantitative method for studying mandibular movement and a digital basis for virtual reality study of mandibular movement. METHODS: In a male adult with normal dentition without temporomandibular joint disorders, 3 fluorescent markers were pasted in the upper dentition and 4 in the lower dentition. Six cameras of the motion capture system were arranged in a semi-circular fashion. The subject sat in front of the camera at an 80-cm distance with the Frankfort plane kept parallel to the horizontal plane. The degree-of-freedom (3 linear displacement and 3 angular displacement) of jaw opening and closing movement was obtained by collecting the marker motion. RESULTS: Six degrees of freedom of jaw opening and closing were obtained using the motion capture system. The maximum linear displacements of X, Y and Z axes were 5.888 089 cm, 0.782 269 cm, and 0.138 931 cm, and the minimum linear displacements were -3.649 83 cm, -35.961 2 cm, -5.818 63 cm, respectively. The maximum angular displacements of X, Y and Z axes were 0.760 088°, 2.803 753°, and 0.786 493°, with the minimum angular displacements of -2.526 18°, -0.625 94°, and -25.429 8°, respectively. Variations of linear displacements during jaw opening and closing occurred mainly in the Y axis, and those of angular displacement occurred mainly in the Z axis. CONCLUSION: The six degree-of-freedom of mandibular movement can be accurately obtained with the motion capture system to allow quantitative examination of the mandibular movement.

[Application of three-dimensional laser scanning-based maxillofacial soft tissue reconstruction in orthodontic treatment].

OBJECTIVE: To establish a convenient and rapid method for constructing a digital model of the maxillofacial soft tissue based on three-dimensional laser surface scanning to allow direct and accurate observation of the soft tissue changes in the course of orthodontic treatment. METHODS: The point cloud data of three-dimensional laser scanning of the maxillofacial region were acquired from a healthy woman with Angle Class I occlusion, who maintained a horizontal Frankfort plane during scanning with the scanner placed at a distance of 80 cm. The scanning was repeated twice after wearing the dental cast for an Angle Class I occlusion. The three-dimensional digital model of the maxillofacial soft tissue was constructed based on the point cloud using GeoMagic10.0 software. RESULTS: The high-resolution three-dimensional model of the maxillofacial soft tissue reconstructed allowed accurate observation of the distinct facial anatomical landmarks and represented directly the soft tissue changes in the process of orthodontic treatment by merging the models. Using the analytic tool provided by the software, this model also allowed direct quantitative measurement of the nasolabial angle and the distances from the esthetic plane to the upper lip, labral inferior, and mentolabial sulcus, which were 111.86°, -3.57 mm, -2.54 mm, and 3.95 mm before orthodontic treatment as compared to 114.31°, -2.73 mm, -1.06 mm, and 3.46 mm during treatment, and 116.53°, -0.15 mm, 0.64 mm, and 3.11 mm after the treatment, respectively. CONCLUSION: Three-dimensional laser surface scanning enables accurate and rapid construction of the digital model of the facial soft tissues, which may provide valuable assistance in orthodontic treatment.

[Biomechanical study on effect of polymethylmethacrylate augmentation on cervical stability after anterior cervical interbody fusion].

OBJECTIVE: To evaluate the effect of polymethylmethacrylate (PMMA) augmentation on cervical stability after anterior cervical interbody fusion (ACIF) before and after fatigue. METHODS: Twelve porcine cervical spines (C3-7) were subjected to testing angular displacement parameters, including the range of motion (ROM), neutral zone (NZ), and elastic zone (EZ), in nondestructive flexion and extension, right/left lateral bending, and left/right rotation on Motion Analysis motion capture system and MTS-858 servo-hydraulic testing machine. Intact cervical spines served as control group (group A); one-level discectomy and fusion was performed with anterior plate fixation based on group A as group B; flexion and extension, left/right lateral bending (5 000 cycles) fatigue testing based on group B as group C; the augmentation screw channel was used based on group C as group D; and flexion and extension, left/right lateral bending fatigue testing were performed based on group D as group E. RESULTS: The ROM, NZ, and EZ in group A were significantly different from those in other groups (P < 0.05) at flexion/extension, left/right bending, and left/right rotation. The ROM, NZ, and EZ in group B were significantly smaller than those in group C (P < 0.05) in flexion/extension, left/right bending, and left/right rotation, but there was no significant difference when compared with group D (P > 0.05). The ROM and NZ in flexion/extension and the EZ in flexion in group B were significant smaller than those in group E (P < 0.05), but there was no significant difference in the other indexes (P > 0.05). The ROM, NZ, and EZ in group C in flexion and extension, left/right lateral bending, and left/right rotation were significantly higher than those in groups D and E (P < 0.05). The ROM and NZ in flexion and extension and left/right lateral bending, and the ROM in left/right rotation, and the EZ in flexion and extension, right bending, and left/right rotation in group D were significantly smaller than those in group E (P < 0.05), but there was no significant difference in the other indexes (P > 0.05). CONCLUSION: PMMA augmentation can significantly increase the instant cervical stability and provide a biomechanics basis in cervical anterior plate fixation.