Identifying an optimal approach for the placement of pterygoid implants: A 3D finite element analysis.

STATEMENT OF PROBLEM: A consensus on the optimal approach to the placement of pterygoid implants is lacking. PURPOSE: The purpose of this finite element analysis study was to determine the optimal approach to the placement of pterygoid implants by comparing biomechanical behavior. MATERIAL AND METHODS: An edentulous and moderately atrophic maxilla with the anatomic structure of the pterygomaxillary region was constructed. Complete arch restorations with 4 standard anterior implants and pterygoid implants in 3 approaches were simulated: L70, long pterygoid implants (4.1×18 mm) inclined at 70 degrees relative to the Frankfort horizontal plane with anchorage in the pterygoid process; L45, long pterygoid implants (4.1×20 mm) inclined at 45 degrees with anchorage in the pterygoid process; and S45, shorter pterygoid implants (4.1×13 mm) inclined 45 degrees without apical anchorage. The L70, L45, and S45 groups were classified as D or S depending on the bone quality: D3 (dense trabecular bone) or D4 (sparse trabecular bone). A total of 6 finite element models were built. The bone failure theory, based on the von Mises theory, was used to judge yielding of the trabecular bone. The von Mises stress (σVM) distribution was measured in the cortical bone, the trabecular bone, and on the implant surface. Deformation (DF) distribution was obtained for the entire bone (DFB) and bone surrounding the pterygoid implant (DFP). RESULTS: L70 showed a lower maximum σVM value (maxσVM), more uniform σVM distribution in the cortical bone, trabecular bone, and on the implant surface and a lower maximum DFp value (maxDFp), especially in the D4 bone. The biomechanical behaviors were similar in L45 and S45 with no stress distribution in the pterygoid process. In the D4 bone, L70, L45, and S45 exceeded the limited stress of the bone failure theory by 50%, 130%, and 130%, while all values were under the limit in D3 bone. CONCLUSIONS: The approach of pterygoid implants inclined at 70 degrees relative to the Frankfort plane with anchorage in the pterygoid process was optimal, providing improved biomechanical behavior. Clinically, in the case of D4 bone, the inclined angulation of pterygoid implants should be 70 degrees to minimize the risk of failure.

3D-printed temporomandibular joint-mandible combined prosthesis: A prospective study.

OBJECTIVES: The study aimed to introduce and evaluate a new customized temporomandibular joint-mandible combined prosthesis with 3D printing fabrication. MATERIALS AND METHODS: This was a prospective study including patients with temporomandibular joint-mandible combined lesions. A 3D-printed customized temporomandibular joint-mandible combined prosthesis was implanted to repair the joint and jaw defect. Clinical follow-up and radiographic examinations were taken to assess the clinical efficacy. The assessment indices were compared by the Wilcoxon signed rank test. RESULTS: Eight patients were treated with the combined prosthesis and included in this study. All prostheses were accurately positioned and fixed without wound infection, prosthesis exposure, displacement, loosening, or fracture. All cases had no mass recurrence at the last follow-up point. Pain, diet, mandibular function, lateral mandibular movement to the diseased side, and maximal interincisal opening showed significant improvements at every follow-up point and went to a stable condition at 6 months after the operation. But the lateral movement to the non-operated side was still limited following surgery. CONCLUSION: The 3D-printed combined prosthesis may be an alternative to other well-established reconstructions for temporomandibular joint and mandible defects.

Improved Muscle Regeneration into a Joint Prosthesis with Mechano-Growth Factor Loaded within Mesoporous Silica Combined with Carbon Nanotubes on a Porous Titanium Alloy.

Total joint replacement (TJR) is widely applied as a promising treatment for the reconstruction of serious joint diseases but is usually characterized by critical loss of skeletal muscle attachment to metal joint prostheses, resulting in fibrous scar tissue formation and subsequent motor dysfunction. Tissue engineering technology may provide a potential strategy for skeletal muscle regeneration into metal joint prostheses. Here, a porous titanium (Ti) alloy scaffold coated with carbon nanotubes (CNTs) and mesoporous silica nanoparticles (MSNs) through electrophoretic deposition (EPD) was designed as a mechano-growth factor (MGF) carrier. This two-layered coating exhibits a nanostructured topology, excellent MGF loading, and prolonged release performance via covalent bonding to improve myoblast adhesion, proliferation and myogenic differentiation in porous Ti alloy scaffolds without cytotoxicity. The Akt/mTOR signaling pathway plays a key role in this process. Furthermore, in vivo studies show that the scaffold promotes the growth of muscle, rather than fibrotic tissue, into the porous Ti alloy structure and improves muscle-derived mechanical properties, the migration of satellite cells, and possibly immunomodulation. In summary, this nanomaterial-coated scaffold provides a practical biomaterial platform to regenerate periprosthetic muscle tissue and restore comparable motor function to that of the natural joint.

Evaluation of internal fixation techniques for extracapsular fracture: A finite element analysis and comparison.

BACKGROUND AND OBJECTIVES: This study explored the optimal plates and screws fixation for extracapsular fracture by finite element analysis, and provided a biomechanical basis for clinical treatment. METHODS: Four extracapsular fixation models were built and evaluated: A. One single straight four-hole plate with two bi-cortical screws on both sides and two mono-cortical screws in the middle; B. One single straight four-hole plate with four bi-cortical screws; C. Two straight four-hole plates, each with two bi-cortical screws on both sides and two mono-cortical screws in the middle; D. One L-shape four-hole plate in the back and one straight four-hole plate in the front, each with two bi-cortical screws on both sides and two mono-cortical screws in the middle. Displacements of fractured bone blocks and stress of plates, screws, cortical and cancellous bone and the deformation of plates were analyzed by finite element analysis to investigate their stability in clinical using. RESULTS: Groups A and B showed larger displacements of the fractured bone block, greater deformation of plates and higher risk of the plate breakage during masticatory motion. Groups C and D exhibited the minimum displacements of the fractured bone block, the stress distribution within the safe range and less deformation of the plates. In addition, double plates fixation and bi-cortical screws exceeded single plate fixation and mono-cortical screws in stability, respectively, while an L-shape plate exhibited no significant differences in the stress dispersion and the displacement reduction. CONCLUSIONS: Double plates fixation of the extracapsular condylar fracture was a safe and stable way and bi-cortical screws should be selected as far as possible.

DCB combined with provisional DES implantation in the treatment of De Novo Medina 0,1,0 or 0,0,1 left main coronary bifurcation lesions: A proof-of-concept study.

OBJECTIVE: To investigate the safety and efficacy of a percutaneous revascularization strategy that is based on the use of drug-coated balloon for the treatment of patients with acute coronary syndrome and de novo Medina type 0,1,0 or 0,0,1 left main stem bifurcation lesions. METHODS: In this multicenter, prospective, proof-of-concept study, patients fulfilling the above criteria were enrolled and received treatment with drug-coated balloon combined with provisional drug-eluting stent implantation in the proximal major branches of the left main stem. Patients who declined this revascularization approach were treated with drug-eluting stent implantation 1-2 mm distally to the left anterior descending or left circumflex artery ostium followed by drug-coated balloon therapy for the ostial disease. The primary endpoint of the study was the calculation of percent diameter stenosis on quantitative coronary angiography post-procedure as well as event rate at 8 months follow-up. RESULTS: A total of 30 patients were enrolled in the study; their mean age was 60.3 ± 7.8 years, while 22 (73.3%) were male. Twenty-two patients were treated only with drugcoated balloon and provisional drug-eluting stent implantation and 8 had drug-eluting stent implantation followed by drug-coated balloon therapy of the ostium of the left main stem major branch. All the procedures were successful with no immediate complications. The percent diameter stenosis of lesion decreased significantly post-procedure from 87.5% (80.0-90.0) to 20% (17.5-30.0), P <.001. During the follow-up period, no major adverse cardiac events were reported. CONCLUSIONS: This proof-of-concept study indicates that ostial drug-coated balloon therapy of the left main stem major branches is safe and effective. Larger clinical data and longer follow-up are needed before advocating its regular use in clinical practice.

Evaluation of internal fixation techniques for condylar head fractures: A finite element analysis and comparison.

OBJECTIVES: This study evaluated optimum stability of different screw techniques for condylar head fractures (CHF) (P close to an M fracture with the lateral pole preserved according to AO classification 2014) by finite element analysis (FEA) and provided a biomechanical basis for clinical treatment. STUDY DESIGN: Four CHF fixation models were evaluated: (A) single bicortical screw, (B) 2 bicortical screws, (C) 1 bicortical screw and 1 monocortical screw (used as a positional screw) inserted via a 2-hole titanium plate, and (D) 2 bicortical screws inserted via a titanium plate. Stresses were calculated (FEA) to measure mechanical properties. RESULTS: The displacement for A and C was larger than for B and D. The maximum stress on the screws for A and C exceeded their breaking limit but was safe for B and D. The stress on the titanium plate for C and D was safe. The stress on bone for A and C was larger than for B and D. CONCLUSIONS: The 2 bicortical screw fixation reduced the stress on implanted materials and surrounding bone tissue. Titanium plates further alleviated the lever action. Two bicortical screw fixation was more reliable for CHF, and early postoperative loading and functional training can be expected.

Multi-Scenario Analysis of Habitat Quality in the Yellow River Delta by Coupling FLUS with InVEST Model.

The past decades were witnessing unprecedented habitat degradation across the globe. It thus is of great significance to investigate the impacts of land use change on habitat quality in the context of rapid urbanization, particularly in developing countries. However, rare studies were conducted to predict the spatiotemporal distribution of habitat quality under multiple future land use scenarios. In this paper, we established a framework by coupling the future land use simulation (FLUS) model with the Intergrated Valuation of Environmental Services and Tradeoffs (InVEST) model. We then analyzed the habitat quality change in Dongying City in 2030 under four scenarios: business as usual (BAU), fast cultivated land expansion scenario (FCLE), ecological security scenario (ES) and sustainable development scenario (SD). We found that the land use change in Dongying City, driven by urbanization and agricultural reclamation, was mainly characterized by the transfer of cultivated land, construction land and unused land; the area of unused land was significantly reduced. While the habitat quality in Dongying City showed a degradative trend from 2009 to 2017, it will be improved from 2017 to 2030 under four scenarios. The high-quality habitat will be mainly distributed in the Yellow River Estuary and coastal areas, and the areas with low-quality habitat will be concentrated in the central and southern regions. Multi-scenario analysis shows that the SD will have the highest habitat quality, while the BAU scenario will have the lowest. It is interesting that the ES scenario fails to have the highest capacity to protect habitat quality, which may be related to the excessive saline alkali land. Appropriate reclamation of the unused land is conducive to cultivated land protection and food security, but also improving the habitat quality and giving play to the versatility and multidimensional value of the agricultural landscape. This shows that the SD of comprehensive coordination of urban development, agricultural development and ecological protection is an effective way to maintain the habitat quality and biodiversity.

Expression profile of circular RNA s in TMJ osteoarthritis synovial tissues and potential functions of hsa_circ_0000448 with specific back-spliced junction.

OBJECTIVE: As essential players in the occurrence and development of osteoarthritis, circular RNAs (circRNAs) have gradually received attention in recent years. However, their roles in temporomandibular joint osteoarthritis (TMJOA) featured with pain, restricted mouth opening and joint movement dysfunction, remains elusive. METHODS: The expression profile of circRNAs in TMJ synovial tissues was analyzed by RNA-Seq. The differentially expressed circRNAs in the TMJOA were identified. The potential biological functions of these circRNAs were evaluated. RESULTS: The expression profile of circRNAs in TMJ synovial tissues was stable and abundant, and most of which were newly discovered. A total of 58 differentially expressed circRNAs were identified in TMJOA, and four of which were identified by in vitro experiments. Among them, the up-regulated hsa_circ_0000448 with specific back-splice junction was involved in the TNF-α signaling pathway through CeRNA mechanism by targeting related microRNAs. Additionally, it was also predicted to bind several RNA binding proteins (RBPs), but almost had no protein-coding ability. CONCLUSION: circRNAs in TMJ synovial tissue participate in the progression of TMJOA and may become a potential therapeutic target. The highly up-regulated has_circ_0000448 probably promotes TNF-α secretion of synovium through CeRNA mechanism in TMJOA.