Expanded Polytetrafluoroethylene Membrane Research Articles

Moisture barriers used in firefighters' protective clothing: Effect of accelerated thermal aging on their mechanical and barrier performance

AbstractMoisture barriers are an essential component in firefighters' protective clothing as they allow water vapor to exit and prevent liquids from entering into the garment. However, they may be sensitive to thermal aging. This study investigates the effect of accelerated thermal aging at temperatures between 95 and 240°C on three different moisture barriers used in firefighters' protective clothing. Variations in their tear force, water vapor transmission rate (WVTR), and apparent contact angle were observed after thermal aging. These variations were influenced by factors such as the base fabric structure, fiber content, adhesive characteristics, and presence of an additional flame‐resistant polyurethane coating on top of the expanded polytetrafluoroethylene membrane. Adhesive degradation and delamination were observed in one moisture barrier, whilst different extents of base fabric degradation occurred in all three of them, leading to tear force reduction. Depending on the moisture barrier and aging temperature, the membranes experienced crack formation or pore closure, which affected the WVTR. The water‐repellent finish on the fabric side degraded in two moisture barriers but was not affected in the other. These findings highlight the importance of considering the constitutive materials and the structure of moisture barriers to understand their aging behavior and improve firefighters' safety.

Determination of terpene levels after the use of essential oil diffusers in vehicles and studio apartments using passive sampling

The exposure levels of selected terpenes (limonene, α- and β-pinenes, and γ-terpinene) emitted by essential oil diffusers in vehicles and studio apartments were assessed using a passive sampling method. A previously developed passive sampler composed of an expanded polytetrafluoroethylene membrane and adsorbent (ePTFE PS) was enlarged and made wearable. Before field deployment, the sampling performance of the modified ePTFE PS for selected terpenes was compared with that of active sampling in a lab-scale 5 m3 test chamber under constant exposure conditions, supporting that passive sampling provides reasonable estimates of the time-weighted exposure concentration. Fifty volunteers were recruited and asked to wear the ePTFE PS while using an essential oil diffuser inside their own vehicle while commuting and in their studio apartment while sleeping. Terpene levels without an essential oil diffuser were very low in vehicles and 47, 3.6, 1.6, and 0.62 μg m−3 for average concentrations of limonene, α- and β-pinenes, and γ-terpinene in studio apartments, respectively, close to those reported in previous studies. The indoor concentrations of all selected terpenes in vehicles and studio apartments were elevated by the use of essential oil diffusers, especially in vehicles. The average concentration of limonene in vehicles after the use of essential oil diffusers was 11 μg m−3, which was greater than that before use by a factor of 30. Therefore, cautious usage of essential oil diffusers indoors where the volume is limited, such as a vehicle, is needed to reduce exposure to terpenes.

Boosting gaseous oxygen transport in a Zn-air battery for high-rate charging by a bubble diode-inspired air electrode

Fruitful efforts are made in designing effective zinc electrodes and electrocatalysts for rechargeable Zn-air batteries, while furious gaseous oxygen evolution on the air electrode during charging is rarely spotlighted. Herein, a “bubble-diode” concept from fluid dynamics is introduced to address the bubble issues. As a proof of concept, an expanded polytetrafluoroethylene membrane is selected as the substrate to construct the air electrode. In-situ observation and numerical simulation reveal that bubbles selectively penetrate from a less aerophilic side to a more aerophilic side in the designed electrode, but are blocked in conventional ones. Further, this electrode enables a Zn-air battery to exhibit an extremely high charging limiting current density of 94 mA cm−2 at the cut-off voltage of 2.2 V and long-lasting stability for over 600 cycles at 10 mA cm−2. This work opens up a path to bubble removal from the electrode structure, favoring practical applications of gas-involving electrochemical technology.

Expanded Polytetrafluoroethylene Membranes for Vascular Stent Coating: Manufacturing, Biomedical and Surgical Applications, Innovations and Case Reports

Coated stents are defined as innovative stents surrounded by a thin polymer membrane based on polytetrafluoroethylene (PTFE)useful in the treatment of numerous vascular pathologies. Endovascular methodology involves the use of such devices to restore blood flow in small-, medium- and large-calibre arteries, both centrally and peripherally. These membranes cross the stent struts and act as a physical barrier to block the growth of intimal tissue in the lumen, preventing so-called intimal hyperplasia and late stent thrombosis. PTFE for vascular applications is known as expanded polytetrafluoroethylene (e-PTFE) and it can be rolled up to form a thin multilayer membrane expandable by 4 to 5 times its original diameter. This membrane plays an important role in initiating the restenotic process because wrapped graft stent could be used as the treatment option for trauma devices during emergency situations and to treat a number of pathological vascular disease. In this review, we will investigate the multidisciplinary techniques used for the production of e-PTFE membranes, the advantages and disadvantages of their use, the innovations and the results in biomedical and surgery field when used to cover graft stents.

Reconstruction of vertical alveolar ridge deficiencies utilizing a high-density polytetrafluoroethylene membrane /clinical impact of flap dehiscence on treatment outcomes: case series/

ObjectivesThe aim of this study was to evaluate the effects of membrane exposure during vertical ridge augmentation (VRA) utilizing guided bone regeneration with a dense polytetrafluoroethylene (d-PTFE) membrane and a tent-pole space maintaining approach by registering radiographic volumetric, linear and morphological changes.MethodsIn 8 cases alveolar ridge defects were accessed utilizing a split-thickness flap design. Following flap elevation VRA was performed with tent-pole space maintaining approach utilizing the combination of a non-reinforced d-PTFE membrane and a composite graft (1:1 ratio of autogenous bone chips and bovine derived xenografts). Three-dimensional radiographic evaluation of hard tissue changes was carried out with the sequence of cone-beam computed tomography (CBCT) image segmentation, spatial registration and 3D subtraction analysis.ResultsClass I or class II membrane exposure was observed in four cases. Average hard tissue gain was found to be 0.70 cm3 ± 0.31 cm3 and 0.82 cm3 ± 0.40 cm3 with and without membrane exposure resulting in a 17% difference. Vertical hard tissue gain averaged 4.06 mm ± 0.56 mm and 3.55 mm ± 0.43 mm in case of submerged and open healing, respectively. Difference in this regard was 14% between the two groups. Horizontal ridge width at 9-month follow-up was 5.89 mm ± 0.51 mm and 5.61 mm ± 1.21 mm with and without a membrane exposure respectively, resulting in a 5% difference.ConclusionsWith the help of the currently reported 3D radiographic evaluation method, it can be concluded that exposure of the new-generation d-PTFE membrane had less negative impact on clinical results compared to literature data reporting on expanded polytetrafluoroethylene membranes.

Dopamine-Induced Surface Zwitterionization of Expanded Poly(tetrafluoroethylene) for Constructing Thermostable Bioinert Materials.

Although energy-demanding, the surface modification of polytetrafluoroethylene (PTFE) for biomedical applications is mandatory to mitigate irreversible biofouling that occurs whenever PTFE comes into contact with biological fluids. Here, we propose to take advantage of the adhesive properties of dopamine (DA) and of the antifouling ability of various zwitterionic monomers (sulfobetaine methacrylate (SBMA), sulfobetaine methacrylamide (SBAA), sulfobetaine acrylamide (SBAA'), and 4-vinylpyridine propylsulfobetaine (4VPPS)) and form antifouling coatings by copolymerization on the surface of expanded PTFE membranes. This simple, low-energy, and one-step coating procedure arises in significant biofouling mitigation. All zwitterionic coatings led to important reduction of biofouling by red blood cell conentrate (88-94%), platelet conentrate (70-90%), whole blood (40-66%), or bacteria (83-96%). Also, it is shown that the interactions of polydopamine with ePTFE are stable even at high temperatures. However, the zwitterionic monomers are differently affected. While the performance of SBMA coatings decreased (as SBMA is prone to hydrolysis), those of SBAA, SBAA', and 4VPPS coatings were generally maintained. All in all, this study illustrates that efficient and stable antifouling zwitterionic coatings can be generated onto PTFE membranes for biomedical applications, without the use of conventional high-energy-demanding surface modification processes.

Complicações na técnica de regeneração óssea guiada associada à membrana de PTFE-d: relato de caso

ABSTRACT Guided bone regeneration aims to gain vertical and horizontal bone volume in atrophic ridges, using different regenerative techniques associated with biomaterials, with occasional post-surgical complications. The objective of the case report was to describe the successive approaches to minimize and eliminate the complications presented in the postoperative period of a patient submitted to the guided bone regeneration technique. In the first surgery, the dense expanded polytetrafluoroethylene membrane (d-PTFE), supported by the tent technique and autogenous platelet graft, was used to perform the guided bone regeneration technique. After three months, the membrane was exposed, with the membrane and the retaining screws removed in the seventh month, with the installation of three Internal Hexagon implants in the areas of teeth 13, 14 and 15. The exposed threads were covered with hydroxyapatites resorbable and covered with d-PTFE membrane. A four-month postoperative panoramic radiograph suggested implant osseointegration. The guided bone regeneration technique associated with the d-PTFE membrane enabled bone neoformation, enabling the installation of osseointegrated implants in an aesthetic and functional position. The exposure of the edges of the membrane allowed the penetration of fluids and contamination, suggesting the worsening of the signs of infection and purulent secretion. On the contrary, the exposure of central areas did not cause inflammatory and infectious signs.

Clinical, Radiographic, and Histomorphometric Evaluation of a Vertical Ridge Augmentation Procedure Using a Titanium-Reinforced Microporous Expanded Polytetrafluoroethylene Membrane: A Prospective Case Series with 1-Year Follow-Up.

Vertical ridge augmentation for long-term implant stability is difficult in severely resorbed areas. We examined the clinical, radiological, and histological outcomes of guided-bone regeneration using novel titanium-reinforced microporous expanded polytetrafluoroethylene (MP-ePTFE) membranes. Eighteen patients who underwent implant placement using a staged approach were enrolled (period: 2018–2019). Vertical ridge augmentation was performed in areas with vertical bone defects ≥4 mm. Twenty-six implant fixtures were placed in 14 patients. At implant placement six fixtures had relatively low stability. On cone-beam computed tomography, the average vertical changes were 4.2 ± 1.9 (buccal), 5.9 ± 2.7 (central), and 4.4 ± 2.8 mm (lingual) at six months after vertical ridge augmentation. Histomorphometric analyses revealed that the average proportions of new bone, residual bone substitute material, and soft tissue were 34.91 ± 11.61%, 7.16 ± 2.74%, and 57.93 ± 11.09%, respectively. Stable marginal bone levels were observed at 1-year post-loading. The residual bone graft material area was significantly lower in the exposed group (p = 0.003). There was no significant difference in the vertical height change in the buccal side between immediately after the augmentation procedure and the implant placement reentry time (p = 0.371). However, all implants functioned well regardless of the exposure during the observation period. Thus, vertical ridge augmentation around implants using titanium-reinforced MP-ePTFE membranes can be successful.

Comparison of different pulmonary valve reconstruction techniques during transannular repair of tetralogy of fallot.

Transannular patch, which results in pulmonary insufficiency (PI), is usually required during repair of tetralogy of fallot (TOF). In this study, we compared three types of pulmonary valve reconstruction techniques during transannular repair of TOF. Between February 2014 and January 2018, 50 patients with TOF underwent primary repair with transannular patch. These patients were divided into three groups. In Group 1, (n = 15), a single gluteraldehyde-treated autologous pericardial patch (standard method) was reconstructed as monocusp. In Group 2, (n = 16) Nunn's bileaflet pulmonary valve reconstruction technique was used with pericardial patch. In Group 3, (n = 19), Nunn's bileaflet technique was performed with expanded polytetrafluoroethylene membrane. The outcomes of the patients and early and midterm competency of the pulmonary valves were analyzed. These techniques were significantly effective in early postoperative period. Freedom from moderate to severe PI were 73.3%; 100% and 89.4%, respectively. Mortality, duration of intensive care unit and hospital stay were similar between the groups. The mean follow-up period was 17.5 ± 13.0 (3-57) months. Freedom from moderate to severe PI decreased to 40%; 81.2% and 73.7%, respectively at the end of the follow-up period. Presence of moderate to severe PI was significantly higher in Group 1 (p = .018 between Groups 1 and 2, p = .048 between Groups 1 and 3). All three pulmonary valve reconstruction techniques provided competent pulmonary valves. Nunn's bileaflet technique had better outcome at midterm. It has a potential to delay right ventricular dysfunction at long-term.

Unicuspid aortic valve repair with bicuspidization in the paediatric population.

Aortic stenosis or regurgitation that requires operations in children often results from unicuspid valve morphology. In all paediatric patients with this anomaly, we have performed unicuspid valve repair by bicuspidization, creating a new commissure via adding patch material. This study reviewed our experience with this procedure. All patients with a unicuspid aortic valve who underwent bicuspidization at ≤18 years of age between 2003 and 2018 were evaluated. Autologous pericardium had initially been used for cusp augmentation. Since 2014, decellularized xenogeneic tissue or expanded polytetrafluoroethylene membrane has been applied. There were 60 consecutive patients. The median operative age was 13 (1-18) years. Thirty patients had prior surgical or catheter valvuloplasties. Aortic regurgitation, aortic stenosis and their combination were present in 22, 11 and 27 patients, respectively. Autologous pericardium decellularized tissue and expanded polytetrafluoroethylene were used in 45, 11 and 4 patients, respectively, without intraoperative conversion to valve replacement. The overall survival was 96% at 10 years with 2 late deaths. Twenty patients underwent aortic valve reoperation due to patch degeneration (n = 11), suture dehiscence of the patch (n = 3), subaortic stenosis (n = 3) or other reasons (n = 3). Freedom from aortic valve reoperation was 73% and 50% at 5 and 10 years, respectively. Fifteen patients (25%) required valve replacement with pulmonary autograft (n = 14) or prosthesis (n = 1) 5.2 (0.2-13) years after bicuspidization at the age of 19 (10-32) years. Bicuspidization is a safe and reproducible alternative to valve replacement with acceptable freedom from reoperation. It can serve as a bridge to valve replacement providing superior outcomes in adults.

Can Redo Sternotomy Become as Easy as First-Time Sternal Opening?

Injury to vital vascular and cardiac structures is a redoubtable complication associated with redo sternotomy. This may be one reason why the pericardium should be closed whenever possible at least over the great vessels and the cranial part of the heart in every patient. This is of particular importance in those patients in whom a redo surgery may be expected (congenital surgery, valvular reconstruction and/or implantation of tissue valves, implantation of left ventricular device as bridging therapy). In many patients, however, a complete closure of the pericardium is not possible because of the intraoperative swelling of the heart or just because the necessary filling of the heart at the end of the procedure precludes a tension-free pericardial closure. In these cases, implantation of a pericardial or artificial membrane as pericardial replacement may be a wise decision. Independently of the presence of a membrane or not, computed tomography or magnetic resonance imaging is of great value before reopening the sternum to estimate the proximity of the posterior surface of the sternum to the most important cardiovascular structures (right ventricle, ascending aorta, innominate vein) or previous implants (pulmonary conduit or homograft, and saphenous vein grafts or internal thoracic artery in case of previous coronary artery bypass grafting). Previous subcutaneous implantation of different pericardial replacement patches in a porcine model has shown the following results: CorMatrix (CorMatrix Cardiovascular, Inc, Sunnyvale, CA) showed gradual and consistent patch resorption and subsiding inflammatory and fibrosis process. Full scaffold degradation and replacement by mild fibrosis and subcutaneous tissue were seen by 1 year. Xenopericardial patches remained intact, and the initially severe inflammatory and fibrotic reactions reduced gradually to moderate fibrosis and chronic inflammation. Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) showed foreign body reaction.1Mosala Nezhad Z. Poncelet A. Fervaille C. Gianello P. Comparing the host reaction to CorMatrix and different patch materials implanted subcutaneously in growing pigs.Thorac Cardiovasc Surg. 2019; 67: 44-49Crossref PubMed Scopus (6) Google Scholar The GoreTex polytetrafluoroethylene membrane has most probably been the most frequently implanted pericardial substitute so far. Its protective effects in case of redo sternotomy are recognized, but the adhesions with the epicardial surfaces may be strong. Among more recent alternatives, CorMatrix has been described as an interesting recellularized scaffold but the results among different studies were somewhat conflicting,2Bustamante-Munguira J. Serrano R. Figuerola-Tekerina A. et al.Is CorMatrix really a recellularization scaffold as a pericardial substitute in cardiac surgery?.J Cardiovasc Surg (Torino). 2018; 59: 142-143PubMed Google Scholar whereas bovine pericardium subjected to a novel anticalcification tissue-engineering process (CardioCel, LeMaitre Vascular, Inc, Burlington, MA) seems promising: A neointimal layer of varying thickness developed on the visceral surface of 5 CardioCel explants with endothelialization of the longest duration explant.3Prabhu S. Armes J.E. Bell D. et al.Histologic evaluation of explanted tisue-engineered bovine pericardium (CardioCel).Semin Thorac Cardiovasc Surg. 2017; 29: 356-363Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar In this issue of The Annals of Thoracic Surgery, Hu and coauthors4Hu C. Tang F. Wu Q. et al.Novel trilaminar polymeric anti-adhesion membrane prevents postoperative pericardial adhesion.Ann Thorac Surg. 2021; 111: 184-190Abstract Full Text Full Text PDF Scopus (8) Google Scholar from Beijing have to be congratulated for another important step—that is, a novel trilaminar membrane that was compared (mainly adhesive effects) to the well-known expanded polytetrafluoroethylene membrane in an animal study. The goal of this new membrane is to minimize post-sternotomy adhesions (through the resorbable components) while maintaining a permanent physical barrier (through the middle layer). All layers contain a novel polymer made of polyvinyl alcohol and carboxymethylcellulose. Because the generation of adhesions and granulation tissue are most active 5 to 7 days after implantation and adhesions become stable approximately from day 14 post implantation, the new material resorbs rapidly after implantation during initial surgery. This might be of particular interest if, for any reason, a reexploration becomes necessary during the early follow-up period. Looking at the microscopic specimen in animals, every cardiac surgeon may be eager to have this new pericardial replacement membrane in their fingers as soon as available on the market. Novel Trilaminar Polymeric Antiadhesion Membrane Prevents Postoperative Pericardial AdhesionThe Annals of Thoracic SurgeryVol. 111Issue 1PreviewPostoperative pericardial adhesion formation is a prominent cause of morbidity and death in cardiovascular surgery, but there is still no ideal prevention method, especially in redo cases. This study investigated a novel antiadhesion trilaminar polymeric film compared with the Gore PRECLUDE Pericardial Membrane (W. L. Gore & Associates, Flagstaff, AZ) and a negative control. Full-Text PDF

Perforating the GORE® CARDIOFORM septal occluder and atrial septal defect occluder to gain access to the left atrium.

Perforate the expanded polytetrafluoroethylene membrane of the GORE® CARDIOFORM Septal Occluder (GSO) and GORE® CARDIOFORM ASD Occluder (GCA) after implantation. Percutaneous transseptal access to the left atrium is necessary for many structural and electrophysiological procedures. The potential need to access the left atrium may influence decision-making for patent foramen ovale or atrial septal defect closure. Sixteen canines underwent implantation of equal number GSO or GCA devices. A transseptal crossing procedure was performed through the device 85 (±1) days postoccluder implantation. The crossing procedure was performed utilizing commercially available equipment: radiofrequency/SureFlex sheath and standard needle/Mullin's sheath. Progressive dilation of the perforation was performed to allow passage of a 12 French Mullin's sheath into the left atrium. Left atrial access was achieved in all cases. Postmortem analysis demonstrated passage through both occluder discs in all radiofrequency/SureFlex sheath cases (4 GSO, 4 GCA) and half of the standard needle/Mullin's sheath cases (3 GSO, 1 GCA). The remaining standard needle/Mullin's sheath cases demonstrated perforation through the right atrial disc but passage around the septal aspect of the left atrial disc, thus not perforating the left atrial disc. No acute embolic complications from the procedure were observed. Left atrial access may be achieved through the GSO or GCA devices after implantation and endothelialization. The combination of a radiofrequency needle and steerable sheath provides benefit over a standard needle and Mullin's sheath in accomplishing passage through both occluder discs.

Monitoring Atmospheric, Soil, and Dissolved CO2 Using a Low-Cost, Arduino Monitoring Platform (CO2-LAMP): Theory, Fabrication, and Operation

Variability of CO2 concentrations within the Earth system occurs over a wide range of time and spatial scales. Resolving this variability and its drivers in terrestrial and aquatic environments ultimately requires high-resolution spatial and temporal monitoring; however, relatively high-cost gas analyzers and data loggers can present barriers in terms of cost and functionality. To overcome these barriers, we developed a low-cost Arduino monitoring platform (CO2-LAMP) for recording CO2 variability in electronically harsh conditions: humid air, soil, and aquatic environments. A relatively inexpensive CO2 gas analyzer was waterproofed using a semi-permeable, expanded polytetrafluoroethylene membrane. Using first principles, we derived a formulation of the theoretical operation and measurement of PCO2(aq) by infrared gas analyzers submerged in aquatic environments. This analysis revealed that an IRGA should be able to measure PCO2(aq) independent of corrections for hydrostatic pressure. CO2-LAMP theoretical operation and measurement were also verified by accompanying laboratory assessment measuring PCO2(aq) at multiple water depths. The monitoring platform was also deployed at two sites within the Springfield Plateau province in northwest Arkansas, USA: Blowing Springs Cave and the Savoy Experimental Watershed. At Blowing Springs Cave, the CO2-LAMP operated alongside a relatively greater-cost CO2 monitoring platform. Over the monitoring period, measured values between the two systems covaried linearly (r2 = 0.97 and 0.99 for cave air and cave stream dissolved CO2, respectively). At the Savoy Experimental Watershed, measured soil CO2 variability capturing sub-daily variation was consistent with previously documented studies in humid, temperate soils. Daily median values varied linearly with soil moisture content (r2 = 0.84). Overall, the CO2-LAMP captured sub-daily variability of CO2 in humid air, soil, and aquatic environments that, while out of the scope of the study, highlight both cyclical and complex CO2 behavior. At present, long-term assessment of platform design is ongoing. Considering cost-savings, CO2-LAMP presents a working base design for continuous, accurate, low-power, and low-cost CO2 monitoring for remote locations.

Enhanced performance of an expanded polytetrafluoroethylene-based triboelectric nanogenerator for energy harvesting

Triboelectric nanogenerators (TENGs) are a well-known energy supply technology. Their output performance is highly important given their intended use in real-world applications. Expanded polytetrafluoroethylene (ePTFE) membranes, which are lightweight, fibrillated, microporous membranes formed by the expansion and stretching of PTFE, possess excellent flexibility and elasticity, unlike the traditional PTFE films that they are made from. Therefore, ePTFE membranes have tremendous potential to be a triboelectric material for energy harvesting. As the most important parameter in ePTFE processing, the uniaxial expansion ratio determines the final morphology of the ePTFE and, thus, the output performance of TENGs. Hence, it requires systematic study. Here, folded-paper TENGs consisting of ePTFE membranes with different expansion ratios and nylon fabrics as two paired tribolayers (i.e., ePTFE/Nylon-TENGs) were fabricated. A systematic study concerning the effect of the expansion ratio on the output performance of the ePTFE/Nylon-TENGs was carried out. The output performance of the ePTFE/Nylon TENGs with expansion ratios ranging from 0 to 400% were measured and compared. The results showed that the output electrical signals of the ePTFE/Nylon-TENGs first increased with the expansion ratio and then decreased steadily, with an optimum performance at an expansion ratio of 100%. In addition, the output performance of the TENGs with solid PTFE was approximately the same as that of the ePTFE/Nylon-TENGs with an expansion ratio of 300%. The ePTFE/Nylon-TENGs had excellent and stable performances and yielded a maximum power density of 1.01 mW/cm2, with an effective area of 1 cm2 and a load resistance of 1 MΩ. This work suggests that ePTFE is an effective material for improving the output performance of ePTFE-based TENGs.

Ridge Augmentation with Autogenous Bone Graft and Expanded Polytetrafluoroethylene Membrane using Tenting Screw: A Randomized Controlled Clinical Trial

The study aims to compare non-tenting screw and tenting with a reinforced expanded polytetrafluoroethylene (ePTFE) membrane in horizontal ridge augmentation using an autogenous bone graft. A randomized controlled clinical trial was conducted between 150 patients needing dental implants. The participants were randomly divided into three study groups; group 1: ridge augmentation using non-resorbable ePTFE membrane only, group2: ridge augmentation using an ePTFE and tenting screw with bone graft Bio-Oss mixed with autogenous bone particles and group 3 (control): ridge augmentation with a bone block. The initial measurement was done at the bone crest at the exact implant site and 10 mm apical to the bone crest. Repeat measurements were recorded after 6 months of healing. Statistical analysis was performed by paired sample t-test and two-way analysis of variance (ANOVA). Statistical significance was considered at p <0.05. There was a significant gain in the bone in all the three groups postsurgery. Group 3 recorded higher reading at the crest and apical sites when compared to groups 1 and 2 at 6 months (late measurements). The difference in the percentage gain was statistically significant after adjusting for age as well as the initial measurement. The highest gain was seen in group 3 followed by groups 2 and 1. The membrane with tenting screw group and block bone groups had a significantly higher increase in measurement when compared to the membrane only group. Tenting screw with Bio-Oss can be used in patients with autogenous bone at the donor site. Tenting screws in combination with membranes can be used to overcome the limitations posed by the use of membranes alone. It is also a useful method for a patient not consenting for block graft for any medical reason.

Bone grafting and osseointegration in the area of maxillary tooth agenesis. Case report

ABSTRACTThe high dental implant success rate is directly linked to the presence of adequate bone volume, which enables and maintains the osseointegration of dental implants. This study aimed to report a clinical case of a female with agenesis of the right maxillary lateral incisor (#12), due to cleft lip and palate.Because the bone and mucosal defects of the area, the treatment planning comprised guided bone regeneration with the association of autogenous bone, platelet rich plasm (PRP), and expanded polytetrafluoroethylene membrane (e-PTFE,Gore-Tex), performed in 2005. After nine months, a new evaluation was carried out and revealed that the area was still not suitable for implant placement. Thus, an allogenous bone graft was planned. Elapsed another nine months, the implant was placed. After six months, the implant was reopened and a metal-ceramic crown was installed. The 5-year following-up appointment showed the presence of fistula with purulent secretion at the buccal cortical plate. We attempted to control the fistula with antibiotics and follow-up clinically and radiographically. The examinations suggested a communication with the right nasal cavity, which decreased until nowadays. The osseointegrated dental implant was in function, without symptomatology. The autogenous bone graft is still more effective than allogenous bone graft. Further studies are necessary to achieve better evaluations. KeywordsBone graft; Dental implant; Osseointegration.

Safety and Efficacy of a Membrane-Tube-Type Glaucoma Shunt Device: An Animal Trial

ABSTRACTPurpose: To evaluate the safety and efficacy of a membrane-tube-type glaucoma shunt device (MT-device), which was developed to control intraocular pressure (IOP) with a lower chance of complications than conventional glaucoma surgery, in a rabbit model.Materials and Methods: The MT-device consists of an expanded polytetrafluoroethylene membrane (thickness 0.2 mm, area 2.5 × 2.5 mm2) and a tube (internal diameter 76 µm, external diameter 175.5 µm, length 7 mm) attached to the membrane. The device was implanted into the left eyes of nine New Zealand white rabbits. The tube was placed in the anterior chamber through paracentesis, and the membrane was fixated on the scleral surface; this induces aqueous drainage from the anterior chamber to the subconjunctival space. IOP, filtering bleb morphology, depth and inflammation of the anterior chamber, and possible complications were evaluated periodically for 8 weeks after surgery. Histological sections were analyzed at 2 and 8 weeks after the surgery.Results: Mean IOP decreased from a preoperative value of 8.7 ± 1.2–4.7 ± 0.6 mmHg at postoperative 8 weeks (p < 0.05). The filtering bleb was maintained during the study period. There were no major postoperative complications. Histologic assessment revealed that 2 weeks after the surgery, fibrous encapsulation, inflammatory cells, and fibroblasts were observed around the MT-device; however, 8 weeks after the surgery, minimal inflammation was observed.Conclusions: The MT-device showed good biocompatibility and effective IOP reduction with a low risk of complications in a rabbit model.

Novel membrane-tube type glaucoma shunt device for glaucoma surgery.

The background of this study is to introduce the surgical technique and outcomes of a novel membrane-tube (MT) type glaucoma shunt device (MicroMT), which was developed to achieve safer and more predictable intraocular pressure (IOP) control compared with conventional trabeculectomy. This is a retrospective, non-comparative, interventional case series study. The MicroMT was implanted in 43 glaucomatous eyes with insufficient IOP control despite medical treatment. The MicroMT consists of an expanded polytetrafluoroethylene membrane and a silicone tube with an intraluminal stent, which allows aqueous drainage from the anterior chamber to the lamellar scleral flap. The intraluminal stent prevents excessive aqueous drainage and allows additional IOP reduction through retraction or removal of the stent. The main outcome measures of this study are IOP changes and complications. The mean (SD) IOP decreased from a preoperative value of 22.5 (6.9) mmHg to 11.1 (3.6) mmHg 3 years after the operation (50.7% reduction from baseline; P < 0.01). Intraluminal stent removal 4 weeks after the operation induced an additional 40.2% IOP reduction (P < 0.01). When success was defined as an IOP between 6 and 21 mmHg, and an IOP reduction of ≥20% from baseline, the success rate was 89.5% at 3 years after the operation. No postoperative ocular hypotony (IOP <6 mmHg) or tube-related complications occurred. MicroMT implantation is a novel therapy that may reduce IOP safely and effectively, with no apparent risk of postoperative ocular hypotony. Glaucoma surgery using this device may be a good alternative to conventional glaucoma surgery.

Osseointegrated implants in vertical ridge augmentation with a nonresorbable membrane: a retrospective study of 75 implants with 1 to 6 years of follow-up.

The aim of this study was to retrospectively evaluate 75 implants inserted in vertically augmented bone at the time of or prior to implant placement after 1 to 6 years of prosthetic loading. The study included 21 patients (29 surgical sites). The vertical procedure was performed combining a titanium-reinforced expanded polytetrafluoroethylene membrane with autograft (7 sites), allograft (5 sites), or auto-xenograft (17 sites). Healing was uneventful in 24 surgical sites. Three sites showed premature exposure, and two sites presented an abscess. Two implants were lost, for a cumulative survival rate of 93.6%. Mean bone remodeling at 1, 2, 3, 4, 5, and 6 years was 0.34, 0.72, 1.04, 0.84, 0.56, and 0.61 mm, respectively. The implant success rate was higher with a simultaneous approach (82.5%) compared with a staged approach (66.8%). Implants surrounded by keratinized mucosa revealed a higher success rate (82.1%) than those without it (58.4%).

Pregnancy outcomes after myomectomy with polytetrafluoroethylene placement.

Background and Objectives:The aim of this study was to report preliminary data on pregnancy outcomes after myomectomy with placement of an expanded polytetrafluoroethylene adhesion barrier membrane.Methods:In this retrospective case series, 68 women who underwent myomectomy with expanded polytetrafluoroethylene membrane placement between January 1, 2003, and December 31, 2009, were identified. Of these women, 15 subsequently had documented pregnancies and were included in the final dataset.Results:Eighteen pregnancies were documented among 15 women. There were no reported cases of preterm labor, preterm premature rupture of membranes, or uterine rupture.Conclusion:In this case series, there were no documented cases of preterm labor, preterm premature rupture of membranes, or uterine rupture after myomectomy with expanded polytetrafluoroethylene membrane placement.