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Santis E.D.,São Paulo State University | Botticelli D.,ARDEC | Pantani F.,São Paulo State University | Pereira F.P.,São Paulo State University | And 2 more authors.
Clinical Oral Implants Research | Year: 2011

Aim: To compare the influence of autologous or deproteinized bovine bone mineral as grafting material on healing of buccal dehiscence defects at implants installed immediately into the maxillary second incisor extraction socket in dogs. Material and methods: In the maxillary second incisor sockets of 12 Labrador dogs, implants were installed immediately following tooth extraction. A standardized buccal defect was created and autologous bone particles or deproteinized bovine bone mineral were used to fill the defects. A collagen membrane was placed to cover the graft material, and the flaps were sutured to fully submerge the experimental areas. Six animals were sacrificed after 2 months, and six after 4 months of healing. Ground sections were obtained for histological evaluation. Results: After 2 months of healing, all implants were osseointegrated. All buccal dehiscence defects were completely filled after 2 months irrespective of the augmentation material (autologous bone or Bio-Oss ®) applied. Bone-to-implant contact (BIC) on the denuded implant surfaces was within a normal range of 30-40%. However, the newly formed tissue at 2 months was partially resorbed (>50% of the area measurements) after 4 months. Conclusions: Applying either autologous bone or deproteinized bovine bone mineral to dehiscences at implants installed immediately into extraction sockets resulted in high degree of regeneration of the defects with satisfactory BIC on the denuded implant surface. © 2011 John Wiley & Sons A/S.

Caneva M.,São Paulo State University | Botticelli D.,ARDEC | Salata L.A.,University of Sao Paulo | Scombatti Souza S.L.,University of Sao Paulo | And 2 more authors.
Clinical Oral Implants Research | Year: 2010

Aim: To evaluate the influence of resorbable membranes on hard tissue alterations and osseointegration at implants placed into extraction sockets in a dog model. Material and methods: In the mandibular premolar region, implants were installed immediately into the extraction sockets of six Labrador dogs. Collagen-resorbable membranes were placed at the test sites, while the control sites were left uncovered. Implants were intended to heal in a submerged mode. After 4 months of healing, the animals were sacrificed, and ground sections were obtained for histomorphometric evaluation. Results: After 4 months of healing, a control implant was not integrated (n=5). Both at the test and at the control sites, bone resorption occurred. While the most coronal bone-to-implant contact was similar between the test and the control sites, the alveolar bone crest outline was maintained to a higher degree at the buccal aspect of the test sites (loss: 1.7 mm) compared with the control sites (loss: 2.2 mm). Conclusions: The use of collagen-resorbable membranes at implants immediately placed into extraction sockets contributed to a partial (23%) preservation of the buccal outline of the alveolar process. © 2010 John Wiley & Sons A/S.

Favero G.,University of Habana | Lang N.P.,University of Hong Kong | De Santis E.,ARDEC | Gonzalez B.G.,University of Habana | And 3 more authors.
Clinical Oral Implants Research | Year: 2013

Aim: To evaluate the influence of deproteinized bovine bone mineral (DBBM), in conjunction with a collagen membrane, on bone resorption at implants installed in a lingual position immediately into extraction sockets with horizontal residual buccal defects >2.0 mm. Material & methods: The pulp tissue of the mesial roots of 1M1 was removed in six Labrador dogs, and the root canals were filled with gutta-percha and cement. Flaps were elevated. The molars were hemi-sectioned and the distal roots removed. Implants were installed in a lingual position and with the shoulder flush with the buccal bony crest. After installation, defects of about 2.5 and 2.7 mm in width resulted at the buccal aspects of the test and control sites, respectively. Only in the left site (test), deproteinized bovine bone mineral (DBBM) particles were placed into the defect concomitantly with the placement of a collagen membrane. On the control sites, no biomaterials were applied. A non-submerged healing was allowed. Results: After 3 months of healing, one control implant was not integrated and was excluded from the analysis, together with the contralateral test implant. All remaining implants were integrated into mature bone. The buccal alveolar bony crest was resorbed more at the test compared with the control sites, 2.2 ± 0.9 mm and 1.5 ± 1.3 mm, respectively. The vertical resorption of the lingual plate was 1.6 ± 1.5 mm and 1.5 ± 1.1 mm at the test and control sites, respectively. Only small residual DBBM particles were found at the test sites (1.4%). Conclusion: The use of DBBM particles to fill buccal defects of ≥2.5 mm at implants installed immediately into alveolar extraction sockets did not preserve the buccal bony wall. © 2012 John Wiley & Sons A/S.

Favero G.,University of Habana | Lang N.P.,University of Hong Kong | Caneva M.,ARDEC | Botticelli D.,University of Habana | And 2 more authors.
Clinical Oral Implants Research | Year: 2015

Objective: To compare with pristine sites bone resorption and soft tissue adaptation at implants placed immediately into extraction sockets (IPIES) in conjunction with deproteinized bovine bone mineral (DBBM) particles and a collagen membrane. Material and methods: The mesial root of the third premolar in the left side of the mandible was endodontically treated (Test). Flaps were elevated, the tooth hemi-sectioned, and the distal root removed to allow the immediate installation of an implant into the extraction socket in a lingual position. DBBM particles were placed into the defect and on the outer contour of the buccal bony ridge, concomitantly with the placement of a collagen membrane. A non-submerged healing was allowed. The premolar on the right side of the mandible was left in situ (control). Ground sections from the center of the implant as well as from the center of the distal root of the third premolar of the opposite side of the mandible were obtained. The histological image from the implant site was superimposed to that of the contralateral pristine distal alveolus, and dimensional variation evaluated for the hard tissue and the alveolar ridge. Results: After 3 months of healing, both histological and photographic evaluation revealed a reduction of hard and soft tissue dimensions. Conclusion: The contour augmentation performed with DBBM particles and a collagen membrane at the buccal aspects of implants placed IPIES was not able to maintain the tissue volume. © 2013 John Wiley & Sons A/S.

News Article | September 18, 2016

The ET-MP is the first lethal hand grenade developed for the US Army in 40 years(Credit: US Army) The US military is getting its first new hand grenade in 40 years as engineers at the US Army Armament Research, Development, and Engineering Center (ARDEC) at Picatinny Arsenal, New Jersey, work on a safer multi-purpose design. Called the Enhanced Tactical Multi-Purpose (ET-MP) hand grenade, it will allow soldiers to choose between concussive or fragmentation blasts with the flip of a lever. Though many people think of grenades as little green pineapples with pins sticking out of them, there are actually many different types for many different jobs. There are incendiary grenades for destroying equipment, gas grenades for crowd control, smoke grenades, stun grenades, anti-tank grenades, and even illumination grenades to cast a bit of light on the subject. Concussion grenades are listed as "offensive" because they kill by means of blast. They have a small danger radius, so soldiers can use them while advancing in the open without fear of being caught in the blast wave. Fragmentation grenades, on the other hand, are "defensive." In addition to a high-explosive charge, the fragmentation grenade has a sleeve filled with ball bearings or is wrapped in wire or a metal casing that shatters into lethal bits on detonation. These typically have a danger radius of 15 m (49 ft), so soldiers have to be behind cover when using them. According to the Army, the US inventory of lethal grenades has consisted solely of the M67 fragmentation grenade and its variants since 1975. In that year, the MK3A2 concussion grenade was withdrawn from service – ironically, because of an asbestos hazard. The ET-MP is aimed at replacing both fragmentation and concussion grenades with a safer, more flexible design. At the flip of a lever, the ET-MP changes from one mode to the other, reducing the need for troops to carry multiple grenades, yet having the one to suit the current situation. ARDEC says that the ET-MP is the result of five years development based on requests and feedback from troops wanting an improved grenade, as well as input from Infantry School representatives. Aside from its dual mode, it's also the first US ambidextrous grenade. Previous hand grenades were designed for right handers, which made it difficult for southpaws to use without special instruction. "We received direct input from the Army and Marine Corps early on, which was critical in ensuring the new arming and fuzing design was user friendly," says Matthew Hall, Grenades Tech Base Development Lead. "With these upgrades in the ET-MP, not only is the fuze timing completely electronic, but the detonation train is also out-of-line. Detonation time can now be narrowed down into milliseconds, and until armed, the hand grenade will not be able to detonate."

News Article | September 23, 2016

Engineers at the U.S. Army Armament Research, Development and Engineering Center (ARDEC) are designing a next-generation hand grenade, which will have two deadly modes and could offer more flexibility to U.S. soldiers. The U.S. military uses two types of grenades: fragmentation and concussion models. A fragmentation grenade explodes and it releases shrapnel and ball bearing that hits enemy combatants. Fragmentation grenades have a radius of about 49 feet. A concussion grenade results in a powerful blast that can incapacitate or kill. However, these grenades have a smaller radius, which means soldiers have to use them in close proximity. The hand grenade being developed by ARDEC is known as Enhanced Tactical Multi-Purpose, or ET-MP. This new device can combine the fragmentation and concussion models in one single grenade. Soldiers in war zones will be able to switch between modes from fragmentation to concussion or vice versa by flipping a lever in the grenade. Currently, soldiers in the U.S. army carry one M67 fragmentation grenade. In 1975, the military took the MK3A2 concussion grenade out of service because of asbestos hazard. ARDEC is also implementing some design changes to the ET-MP. Current fragmentation grenades require different arming procedures for right-handed and left-handed users. However, the next-gen ET-MP is ambidextrous and arming procedure is same for left-hand or right-hand users. The ET-MP will be fully electronic, which will result in greater precision and reliability of the grenade. "With these upgrades in the ET-MP, not only is the fuze timing completely electronic, but the detonation train is also out-of-line," says Matthew Hall, a development lead on the project. "Detonation time can now be narrowed down into milliseconds." Hall added that the new ET-MP grenade will not explode until it is armed by a soldier. Reports suggest that existing grenades have hardly seen any design changes in the last four decades. The need for a fresh hand grenade was made in 2010 while funding for the research of a new grenade got approved a few years later in 2013. Since then, engineers have worked together with Marines and soldiers on duty to understand the needs of a new grenade. Engineers have determined the requirement of a new grenade and the idea of ET-MP was born. By 2020, ARDEC is estimated to move the ET-MP to the following development stage at the Project Manager Close Combat Systems located at Picatinny Arsenal. The U.S. military will have to wait another few years before the ET-MP can be used in combat. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

Ucer T.C.,Oaklands Hospital | Botticelli D.,ARDEC | Stavropoulos A.,Malmö University | Mattheos N.,University of Hong Kong
European Journal of Dental Education | Year: 2014

Introduction: Previous surveys have shown that newly graduated dentists, in most European countries, do not obtain adequate theoretical knowledge and, especially, clinical skills in implant dentistry (ID) through their undergraduate education and must therefore acquire knowledge and develop competencies through further postgraduate study. Moreover, clinicians, in general, need to continue to maintain the currency of their competence by undertaking ongoing continuing professional development (CPD). This seems particularly important in ID as techniques, and materials develop rapidly due to advances in biomedical technology. Despite recent developments, CPD in ID remains poorly organised with little standardisation or harmonisation across Europe. The objective of this survey was to explore the current status and trends within CPD education in ID in Europe. Materials and methods: Stakeholders and opinion leaders associated with ID education were invited by email to fill an online questionnaire (closing date: 30th April 2013). Two hundred and forty-seven questionnaires were distributed, and two separate reminders were sent to participants in 38 European countries. The survey contained 14 multiple-choice questions, and the data were collected using SurveyMonkey© software, exported in SPSS (Inc, Chicago, IL, USA) format and analysed using descriptive statistics. Results: Two hundred respondents working in 24 countries replied to the survey (response rate of 81% of invitees and 63% of countries surveyed). The results demonstrated a wide divergence in the content and structure of CPD in ID in Europe. Conclusions: Dentists need CPD to develop their skills and to maintain their competence in ID. There is an urgent need for structured and accredited CPD, which should be readily available to all dentists practising ID. It should have pre-determined learning objectives, delivered by accredited CPD providers and educators, and have assessable outcome measures to ensure the best possible impact on clinical practice and patient safety. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Rossi F.,University of Bologna | Lang N.P.,University of Hong Kong | De Santis E.,ARDEC | Morelli F.,University of Habana | And 3 more authors.
Clinical Oral Implants Research | Year: 2014

Objective: To study the early sequential stages of osseointegration at implants installed in alveolar bony. Materials and methods: In 12 Labrador dogs, all mandibular premolars and first molars were extracted bilaterally. After 3 months of healing, full-thickness flaps were elevated in the edentulous region of the right side of the mandible. Implants were installed, and the flaps were sutured to allow a fully submerged healing. The timing of the installations in the left side of the mandible and of sacrifices were performed with a schedule that various observation periods to sacrifice from 5, 10, 20, and 30 days were available so that n = 6 was obtained per each healing period. Ground sections were prepared and analyzed. Results: Newly formed bone in contact with the implant surface was found after 10 days of healing and the percentage increased up to 50% after 1 month of healing. A higher percentage was found in the trabecular compared with the cortical bony compartment. Old bone decreased by about 50% during healing, being still present after 1 month (16%). The proportions of bone debris and bone particles were at 27% after 5 days and decreased during healing to 6% after 1 month. Conclusion: Osseointegration (new bone-to-implant contact) developed at various rates for cortical and trabecular compartments, respectively. In the trabecular region, mesenchymal cells were identified, subsequently developing into new bone in contact with the implant surface. In the cortical compartment, however, resorptive processes were observed throughout all periods of healing. The proportion of newly formed bone percentage was lower compared with that of the trabecular area. Old bone was still present after 1 month of healing in both compartments. Bone debris and small bone particles appeared to be involved in initial bone formation. © 2013 John Wiley & Sons A/S.

Wiegand D.A.,ARDEC | Redingius B.,ARDEC | Ellis K.,Atomic Weapons Establishment | Leppard C.,Atomic Weapons Establishment
International Journal of Solids and Structures | Year: 2011

The mechanical properties of a polymer composite plastic bonded explosive, EDC37, have been investigated as a function of hydrostatic confining pressure between 0.1 and 138 MPa. The results indicate different failure processes in two pressure ranges, a low pressure range between about 0.1 and 7 MPa and a higher pressure range between about 7 and 138 MPa. In the low pressure range slow crack processes are important in failure while in the higher pressure range plastic flow dominates. The pressure dependence of the compressive strength in the low pressure range is attributed to coulomb friction between surfaces of closed shear cracks and from the observed linear increase of the strength with pressure and the angle of the fracture plane a friction coefficient is obtained. Friction coefficients can also be obtained from the ratio of the compressive to tensile strength and directly from the above angle. The friction coefficients obtained from these separate observations are in agreement and this is taken as strong evidence for the importance of this friction in determining strength and mechanical failure. These results clearly establish experimentally the role of friction in determining strength with or without applied pressure. An empirical relationship between strength, pressure and strain rate is also obtained for this pressure range and the failure strength of EDC37 is more sensitive to pressure than strain rate. © 2011 Elsevier Ltd. All rights reserved.

Macri M.F.,ARDEC | Littlefield A.G.,ARDEC
International SAMPE Technical Conference | Year: 2016

Fielded and future military systems are increasingly incorporating composite materials into their design. Many of these systems subject the composites to physical trauma or environmental conditions that can cause micro damage leading to variations of the mechanical properties on the global scale and global sized fracture. Though several multiscale methods have been developed to account for the micro effects, little has been done to efficiently incorporate them into a finite element model, limiting their effectiveness. To contend with this issue, an algorithm has been developed to detect elements within a critical region and apply a partition of unity multiscale approach to capture the micro phenomena. Thus, in critical regions of the model, a multiscale approach can be implemented to accurately capture the material response, and throughout the rest of the model the efficient homogenization method will be employed. The elements surrounding the critical region are adapted to act as a transition from the multiscale region to the homogenization region.

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