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Sample records for condyle friction syndrome

  1. Patellar tendon-lateral femoral condyle friction syndrome: MR imaging in 42 patients

    International Nuclear Information System (INIS)

    Chung, C.B.; Skaf, A.; Campos, J.; Stump, X.; Resnick, D.; Roger, B.

    2001-01-01

    Objective: To demonstrate the MR imaging findings that occur between the posterior inferolateral patellar tendon and the lateral femoral condyle in patients with chronic anterior and or lateral knee pain. Patients and design: A retrospective review of the MR images in 42 patients who presented with chronic anterior or lateral knee pain was performed by two musculoskeletal radiologists. In 15 patients, post-contrast images were available. Results: Sagittal and axial imaging planes best demonstrated the patellar tendon and its relationship with the lateral femoral condyle. In 40 patients, there was obliteration of the fat planes and abnormal signal intensity in the lateral soft tissues of the inferior patellofemoral joint. Enhancement after administration of gadolinium was noted in all cases in which contrast was administered. Eighteen patients showed cystic changes in the soft tissues adjacent to the lateral femoral condyle in addition to fat plane obliteration. In two patients, only cystic changes were noted in the lateral soft tissues. Abnormal patellar alignment was noted in 37 patients. Patellar tendon pathology was seen in nine patients. Conclusion: In evaluating anterior knee symptoms, MR imaging allows identification of changes that may be related to patellar tendon-lateral femoral condyle friction syndrome and that should be distinguished from other causes of anterior or lateral knee pain. (orig.)

  2. Patellar tendon-lateral femoral condyle friction syndrome: MR imaging in 42 patients

    Energy Technology Data Exchange (ETDEWEB)

    Chung, C.B.; Skaf, A.; Campos, J.; Stump, X.; Resnick, D. [Dept. of Radiology, University of California, San Diego (United States); Roger, B. [Service de Radiologie Polyvalente, Groupe Hospitalier Pitie-Salpetriere, Paris (France)

    2001-12-01

    Objective: To demonstrate the MR imaging findings that occur between the posterior inferolateral patellar tendon and the lateral femoral condyle in patients with chronic anterior and or lateral knee pain. Patients and design: A retrospective review of the MR images in 42 patients who presented with chronic anterior or lateral knee pain was performed by two musculoskeletal radiologists. In 15 patients, post-contrast images were available. Results: Sagittal and axial imaging planes best demonstrated the patellar tendon and its relationship with the lateral femoral condyle. In 40 patients, there was obliteration of the fat planes and abnormal signal intensity in the lateral soft tissues of the inferior patellofemoral joint. Enhancement after administration of gadolinium was noted in all cases in which contrast was administered. Eighteen patients showed cystic changes in the soft tissues adjacent to the lateral femoral condyle in addition to fat plane obliteration. In two patients, only cystic changes were noted in the lateral soft tissues. Abnormal patellar alignment was noted in 37 patients. Patellar tendon pathology was seen in nine patients. Conclusion: In evaluating anterior knee symptoms, MR imaging allows identification of changes that may be related to patellar tendon-lateral femoral condyle friction syndrome and that should be distinguished from other causes of anterior or lateral knee pain. (orig.)

  3. Posteromedial knee friction syndrome: an entity with medial knee pain and edema between the femoral condyle, sartorius and gracilis.

    Science.gov (United States)

    Simeone, F Joseph; Huang, Ambrose J; Chang, Connie Y; Smith, Maximilian; Gill, Thomas J; Bredella, Miriam A; Torriani, Martin

    2015-04-01

    To describe MRI features of an entity consisting of medial knee pain and edema between the posteromedial femoral condyle (PMFC), sartorius and/or gracilis tendons and determine whether reduced tendon-bone distances may account for these findings. We retrospectively identified MRI cases of edema between the PMFC, sartorius and/or gracilis tendons (25 subjects, 26 knees). Two musculoskeletal radiologists independently graded edema and measured the sartorius- and gracilis-PMFC distances and knee flexion angle. Age- and gender-matched subjects with normal knee MRIs (27 subjects, 27 knees) served as controls for measurements. Statistical analyses compared abnormal to control subjects. Sartorius-PMFC and gracilis-PMFC spaces were narrower in abnormal compared to control subjects (1.6 ± 1.0 vs. 2.1 ± 1.2 mm, P = 0.04; 2.3 ± 2.0 vs. 4.6 ± 3.0 mm, P = 0.002, respectively). The knee flexion angle was similar between groups (P > 0.05). In subjects with clinical information, medial knee pain was the main complaint in 58 % (15/26) of abnormal subjects, with 42 % (11/26) having clinical suspicion of medial meniscal tear. Edema between the PMFC, sartorius and/or gracilis was mild in 54 % (14/26), moderate in 35 % (9/26) and severe in 12 % (3/26), and it was most frequent deep to both the sartorius and gracilis (50 %, 13/26). Edema between the PMFC, sartorius and/or gracilis tendons identified on knee MRI may be associated with medial knee pain and may represent a friction syndrome.

  4. Posteromedial knee friction syndrome: an entity with medial knee pain and edema between the femoral condyle, sartorius and gracilis

    Energy Technology Data Exchange (ETDEWEB)

    Simeone, F.J.; Huang, Ambrose J.; Chang, Connie Y.; Smith, Maximilian; Bredella, Miriam A.; Torriani, Martin [Massachusetts General Hospital and Harvard Medical School, Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States); Gill, Thomas J. [Boston Sports Medicine and Research Institute, Boston, MA (United States)

    2014-12-20

    To describe MRI features of an entity consisting of medial knee pain and edema between the posteromedial femoral condyle (PMFC), sartorius and/or gracilis tendons and determine whether reduced tendon-bone distances may account for these findings. We retrospectively identified MRI cases of edema between the PMFC, sartorius and/or gracilis tendons (25 subjects, 26 knees). Two musculoskeletal radiologists independently graded edema and measured the sartorius- and gracilis-PMFC distances and knee flexion angle. Age- and gender-matched subjects with normal knee MRIs (27 subjects, 27 knees) served as controls for measurements. Statistical analyses compared abnormal to control subjects. Sartorius-PMFC and gracilis-PMFC spaces were narrower in abnormal compared to control subjects (1.6 ± 1.0 vs. 2.1 ± 1.2 mm, P = 0.04; 2.3 ± 2.0 vs. 4.6 ± 3.0 mm, P = 0.002, respectively). The knee flexion angle was similar between groups (P > 0.05). In subjects with clinical information, medial knee pain was the main complaint in 58 % (15/26) of abnormal subjects, with 42 % (11/26) having clinical suspicion of medial meniscal tear. Edema between the PMFC, sartorius and/or gracilis was mild in 54 % (14/26), moderate in 35 % (9/26) and severe in 12 % (3/26), and it was most frequent deep to both the sartorius and gracilis (50 %, 13/26). Edema between the PMFC, sartorius and/or gracilis tendons identified on knee MRI may be associated with medial knee pain and may represent a friction syndrome. (orig.)

  5. Posteromedial knee friction syndrome: an entity with medial knee pain and edema between the femoral condyle, sartorius and gracilis

    International Nuclear Information System (INIS)

    Simeone, F.J.; Huang, Ambrose J.; Chang, Connie Y.; Smith, Maximilian; Bredella, Miriam A.; Torriani, Martin; Gill, Thomas J.

    2015-01-01

    To describe MRI features of an entity consisting of medial knee pain and edema between the posteromedial femoral condyle (PMFC), sartorius and/or gracilis tendons and determine whether reduced tendon-bone distances may account for these findings. We retrospectively identified MRI cases of edema between the PMFC, sartorius and/or gracilis tendons (25 subjects, 26 knees). Two musculoskeletal radiologists independently graded edema and measured the sartorius- and gracilis-PMFC distances and knee flexion angle. Age- and gender-matched subjects with normal knee MRIs (27 subjects, 27 knees) served as controls for measurements. Statistical analyses compared abnormal to control subjects. Sartorius-PMFC and gracilis-PMFC spaces were narrower in abnormal compared to control subjects (1.6 ± 1.0 vs. 2.1 ± 1.2 mm, P = 0.04; 2.3 ± 2.0 vs. 4.6 ± 3.0 mm, P = 0.002, respectively). The knee flexion angle was similar between groups (P > 0.05). In subjects with clinical information, medial knee pain was the main complaint in 58 % (15/26) of abnormal subjects, with 42 % (11/26) having clinical suspicion of medial meniscal tear. Edema between the PMFC, sartorius and/or gracilis was mild in 54 % (14/26), moderate in 35 % (9/26) and severe in 12 % (3/26), and it was most frequent deep to both the sartorius and gracilis (50 %, 13/26). Edema between the PMFC, sartorius and/or gracilis tendons identified on knee MRI may be associated with medial knee pain and may represent a friction syndrome. (orig.)

  6. Friction

    Science.gov (United States)

    Matsuo, Yoshihiro; Clarke, Daryl D.; Ozeki, Shinichi

    Friction materials such as disk pads, brake linings, and clutch facings are widely used for automotive applications. Friction materials function during braking due to frictional resistance that transforms kinetic energy into thermal energy. There has been a rudimentary evolution, from materials like leather or wood to asbestos fabric or asbestos fabric saturated with various resins such as asphalt or resin combined with pitch. These efforts were further developed by the use of woven asbestos material saturated by either rubber solution or liquid resin binder and functioned as an internal expanding brake, similar to brake lining system. The role of asbestos continued through the use of chopped asbestos saturated by rubber, but none was entirely successful due to the poor rubber heat resistance required for increased speeds and heavy gearing demands of the automobile industry. The use of phenolic resins as binder for asbestos friction materials provided the necessary thermal resistance and performance characteristics. Thus, the utility of asbestos as the main friction component, for over 100 years, has been significantly reduced in friction materials due to asbestos identity as a carcinogen. Steel and other fibrous components have displaced asbestos in disk pads. Currently, non-asbestos organics are the predominate friction material. Phenolic resins continue to be the preferred binder, and increased amounts are necessary to meet the requirements of highly functional asbestos-free disk pads for the automotive industry. With annual automobile production exceeding 70 million vehicles and additional automobile production occurring in developing countries worldwide and increasing yearly, the amount of phenolic resin for friction material is also increasing (Fig. 14.1). Fig. 14.1 Worldwide commercial vehicle production In recent years, increased fuel efficiency of passenger car is required due to the CO2 emission issue. One of the solutions to improve fuel efficiency is to

  7. Osteochondroma involving mandibular condyle

    Directory of Open Access Journals (Sweden)

    Latika Bachani

    2017-01-01

    Full Text Available Osteochondroma is defined as an osteocartilagenous exostosis with cartilage capped exophytic lesion that arises from the bone cortex. It is a slow growing benign tumor that is rarely seen in the maxillofacial region. Osteochondroma of the mandibular condyle is a relatively rare condition that causes a progressive enlargement of the condyle, usually resulting in facial asymmetry, temporomandibular joint (TMJ dysfunction and malocclusion. Radiographically, there is a unilaterally enlarged condyle usually with an exophytic growth of the tumor from the condylar head. The treatment of osteochondroma is primarily surgical resection of the tumor. This paper reports a case of osteochondroma of the right mandibular condyle presenting as a painless restricted mouth opening.

  8. Intra-articular fibroma of tendon sheath in a knee joint associated with iliotibial band friction syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Dong Ho; Choi, Sun Seob; Kim, Soo Jin; Lih, Wang [Dong-A University Medical Center, Busan (Korea, Republic of)

    2015-02-15

    Iliotibial band (ITB) friction syndrome is a common overuse injury typically seen in the active athlete population. A nodular lesion on the inner side of the ITB as an etiology or an accompanying lesion from friction syndrome has been rarely reported. A 45-year-old male presented with recurrent pain and a movable nodule at the lateral joint area, diagnosed as ITB friction syndrome. The nodule was confirmed as a rare intra-articular fibroma of the tendon sheath (FTS) on the basis of histopathologic findings. We describe the MRI findings, arthroscopic and pathologic features, in this case of intra-articular FTS presenting with ITB friction syndrome.

  9. Intra-articular fibroma of tendon sheath in a knee joint associated with iliotibial band friction syndrome

    International Nuclear Information System (INIS)

    Ha, Dong Ho; Choi, Sun Seob; Kim, Soo Jin; Lih, Wang

    2015-01-01

    Iliotibial band (ITB) friction syndrome is a common overuse injury typically seen in the active athlete population. A nodular lesion on the inner side of the ITB as an etiology or an accompanying lesion from friction syndrome has been rarely reported. A 45-year-old male presented with recurrent pain and a movable nodule at the lateral joint area, diagnosed as ITB friction syndrome. The nodule was confirmed as a rare intra-articular fibroma of the tendon sheath (FTS) on the basis of histopathologic findings. We describe the MRI findings, arthroscopic and pathologic features, in this case of intra-articular FTS presenting with ITB friction syndrome.

  10. Overview of Mandibular Condyle Fracture

    OpenAIRE

    Park, Su-Seong; Lee, Keun-Cheol; Kim, Seok-Kwun

    2012-01-01

    The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  11. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  12. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing ofthe mouth, and because fracture causes functional and aesthetic problems such as facialasymmetry, it is very important to perform accurate reduction. Traditionally, there has beendisagreement on how to manage fracture of the mandibular condyle. This review exploresthe misunderstanding of mandibular condyle fracture treatment and modern-day treatmentstrategies.

  13. Osteochondroma of the mandibular condyle

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2011-01-01

    Full Text Available Osteochondroma (OC of the mandibular condyle is a relatively rare condition that causes a progressive enlargement of the condyle, usually resulting in facial asymmetry, temporomandibular joint (TMJ dysfunction, and malocclusion. Radiographically, there is a unilaterally enlarged condyle usually with an exophytic outgrowth of the tumor from the condylar head. We present a case of a left mandibular condylar OC that created a major facial asymmetry, malocclusion, and TMJ dysfunction. Discussion includes the rationale for treatment and the method used in this case. In actively growing OCs, surgical intervention is indicated to remove the tumor stopping the benign growth process and improve facial symmetry, occlusion, and jaw function.

  14. MR imaging findings of medial tibial crest friction

    International Nuclear Information System (INIS)

    Klontzas, Michail E.; Akoumianakis, Ioannis D.; Vagios, Ilias; Karantanas, Apostolos H.

    2013-01-01

    Objective: Medial tibial condyle bone marrow edema (BME), associated with soft tissue edema (STe) surrounding the medial collateral ligament, was incidentally observed in MRI examinations of young and athletic individuals. The aim of the present study was to 1. Prospectively investigate the association between these findings and coexistence of localized pain, and 2. Explore the possible contribution of the tibial morphology to its pathogenesis. Methods: The medial tibial condyle crest was evaluated in 632 knee MRI examinations. The angle and depth were measured by two separate evaluators. The presence of STe and BME was recorded. A third evaluator blindly assessed the presence of pain at this site. Results: BME associated with STe was found in 24 patients (with no history of previous trauma, osteoarthritis, tumor or pes anserine bursitis). The mean crest angle was 151.3° (95%CI 147.4–155.3°) compared to 159.4° (95%CI 158.8–160°) in controls (Mann–Whitney test, P < 0.0001). MRI findings were highly predictive of localized pain (sensitivity 92% specificity 99%, Fisher's exact test, P < 0.0001). Conclusion: Friction at the medial tibial condyle crest is a painful syndrome. MRI is a highly specific and sensitive imaging modality for its diagnosis

  15. MR imaging findings of medial tibial crest friction

    Energy Technology Data Exchange (ETDEWEB)

    Klontzas, Michail E., E-mail: miklontzas@gmail.com; Akoumianakis, Ioannis D., E-mail: ioannis.akoumianakis@gmail.com; Vagios, Ilias, E-mail: iliasvagios@gmail.com; Karantanas, Apostolos H., E-mail: akarantanas@gmail.com

    2013-11-01

    Objective: Medial tibial condyle bone marrow edema (BME), associated with soft tissue edema (STe) surrounding the medial collateral ligament, was incidentally observed in MRI examinations of young and athletic individuals. The aim of the present study was to 1. Prospectively investigate the association between these findings and coexistence of localized pain, and 2. Explore the possible contribution of the tibial morphology to its pathogenesis. Methods: The medial tibial condyle crest was evaluated in 632 knee MRI examinations. The angle and depth were measured by two separate evaluators. The presence of STe and BME was recorded. A third evaluator blindly assessed the presence of pain at this site. Results: BME associated with STe was found in 24 patients (with no history of previous trauma, osteoarthritis, tumor or pes anserine bursitis). The mean crest angle was 151.3° (95%CI 147.4–155.3°) compared to 159.4° (95%CI 158.8–160°) in controls (Mann–Whitney test, P < 0.0001). MRI findings were highly predictive of localized pain (sensitivity 92% specificity 99%, Fisher's exact test, P < 0.0001). Conclusion: Friction at the medial tibial condyle crest is a painful syndrome. MRI is a highly specific and sensitive imaging modality for its diagnosis.

  16. Fracture of the occipital condyle

    International Nuclear Information System (INIS)

    Wessels, L.S.

    1990-01-01

    The term fracture of the occipital condyle is a misnomer and and usually represents an extensive fracture of the posterior fossa skull base extending onto the squamous portion of the occipital bone and even further forward. These fractures should be suspected when the lower cranial nerves are affected after severe cranial trauma. Conservative management appears to be indicated. 2 figs., 5 refs

  17. Os peroneum friction syndrome complicated by sesamoid fatigue fracture: a new radiological diagnosis? Case report and literature review

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    Bashir, Waseem A.; Connell, David A. [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, London, Middlesex (United Kingdom); Lewis, Steve [Craven Cottage, Fulham Football Club, London (United Kingdom); Cullen, Nicholas [The Royal National Orthopaedic Hospital NHS Trust, Department of Orthopaedics, London, Middlesex (United Kingdom)

    2009-02-15

    Injuries to the peroneal tendons are relatively common worldwide but tendon rupture without significant trauma is uncommon. Ankle mechanics can be seriously affected by disruption of one or both of the peroneal tendons although complete rupture can also remain asymptomatic. Accessory ossicles are sesamoid bones and are common findings in routine radiology of the foot and ankle. Although in the vast majority these ''os'' are normal variants of anatomy, they can lead to painful syndromes and suffer fractures and even undergo degenerative changes in response to overuse and trauma. Although similar syndromes have been discussed in the surgical literature, there is a lack of literature describing the use of modern imaging in the accurate diagnosis and its subsequent assistance towards appropriate management of os peroneum friction syndrome complicated by sesamoid fatigue syndrome. This article presents the plain film, sonographic and magnetic resonance imaging findings in a case of os peroneum friction syndrome complicated by a sesamoid fatigue fracture as well as reviewing the pertinent literature. (orig.)

  18. Os peroneum friction syndrome complicated by sesamoid fatigue fracture: a new radiological diagnosis? Case report and literature review.

    Science.gov (United States)

    Bashir, Waseem A; Lewis, Steve; Cullen, Nicholas; Connell, David A

    2009-02-01

    Injuries to the peroneal tendons are relatively common worldwide but tendon rupture without significant trauma is uncommon. Ankle mechanics can be seriously affected by disruption of one or both of the peroneal tendons although complete rupture can also remain asymptomatic. Accessory ossicles are sesamoid bones and are common findings in routine radiology of the foot and ankle. Although in the vast majority these "os" are normal variants of anatomy, they can lead to painful syndromes and suffer fractures and even undergo degenerative changes in response to overuse and trauma. Although similar syndromes have been discussed in the surgical literature, there is a lack of literature describing the use of modern imaging in the accurate diagnosis and its subsequent assistance towards appropriate management of os peroneum friction syndrome complicated by sesamoid fatigue syndrome. This article presents the plain film, sonographic and magnetic resonance imaging findings in a case of os peroneum friction syndrome complicated by a sesamoid fatigue fracture as well as reviewing the pertinent literature.

  19. Os peroneum friction syndrome complicated by sesamoid fatigue fracture: a new radiological diagnosis? Case report and literature review

    International Nuclear Information System (INIS)

    Bashir, Waseem A.; Connell, David A.; Lewis, Steve; Cullen, Nicholas

    2009-01-01

    Injuries to the peroneal tendons are relatively common worldwide but tendon rupture without significant trauma is uncommon. Ankle mechanics can be seriously affected by disruption of one or both of the peroneal tendons although complete rupture can also remain asymptomatic. Accessory ossicles are sesamoid bones and are common findings in routine radiology of the foot and ankle. Although in the vast majority these ''os'' are normal variants of anatomy, they can lead to painful syndromes and suffer fractures and even undergo degenerative changes in response to overuse and trauma. Although similar syndromes have been discussed in the surgical literature, there is a lack of literature describing the use of modern imaging in the accurate diagnosis and its subsequent assistance towards appropriate management of os peroneum friction syndrome complicated by sesamoid fatigue syndrome. This article presents the plain film, sonographic and magnetic resonance imaging findings in a case of os peroneum friction syndrome complicated by a sesamoid fatigue fracture as well as reviewing the pertinent literature. (orig.)

  20. Bilateral double-headed condyles: A rare case report

    Directory of Open Access Journals (Sweden)

    Swati Phore

    2018-01-01

    Full Text Available Bifid mandibular condyle is characterized by the duplicity of the head of the mandibular condyle, so the name double-headed condyle. It is usually diagnosed on routine radiographic examination and is described as a rare entity. Usually, bifid condyle is an incidental finding and its etiology is controversial, with no predilection for sex or ethnic background. Herein, we report a case of bilateral bifid condyles.

  1. Eosinophilic granuloma of the mandibular condyle

    International Nuclear Information System (INIS)

    Huh, Kyung Hoe; Yi, Won Jin; Oh, Sung Won; Lee, Sam Sun; Choi, Mun Kyung

    2008-01-01

    The present study reports a case of eosinophilic granuloma of the mandibular condyle. Eosinophilic granulomas on the mandibular condyle are very rare, but there are several common clinical and radiographic presentations. The clinical presentations involve swelling on preauricular area, limitation of opening, TMJ pain, etc. The radiographic presentations involve radiolucent lytic condylar lesion with or without pathologic fracture. Sometimes new bone formations are observed. The purpose of the article is to add new cases to the literatures.

  2. Eosinophilic granuloma of the mandibular condyle

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Kyung Hoe; Yi, Won Jin; Oh, Sung Won; Lee, Sam Sun [Department of Oral and Maxillofacial Radiology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul (Korea, Republic of); Choi, Mun Kyung [Department of Oral and Maxillofacial Surgery, College of Medicine, Inje University Sanggye Paik Hospital, Seoul (Korea, Republic of)

    2008-03-15

    The present study reports a case of eosinophilic granuloma of the mandibular condyle. Eosinophilic granulomas on the mandibular condyle are very rare, but there are several common clinical and radiographic presentations. The clinical presentations involve swelling on preauricular area, limitation of opening, TMJ pain, etc. The radiographic presentations involve radiolucent lytic condylar lesion with or without pathologic fracture. Sometimes new bone formations are observed. The purpose of the article is to add new cases to the literatures.

  3. Mandibular Condyle Fractures and Treatment Modalities

    Directory of Open Access Journals (Sweden)

    Halil ibrahim Kisa

    2014-08-01

    Full Text Available Maxillofacial injuries are most commonly associated with falls, motor and vehicle accidents, sports-related trauma, and interpersonel violence. The complexity of mandibular condyle region and its anatomic proximity to other craniofacial structures complicate diagnosis and treatment. Thus, treatment approaches of mandibular condyle fracture are still controversial. In the literature, different success rates are reported about observation versus treatment, closed reduction versus open reduction and fixation methods. In the present article, controversial issues related to mandibular condyle fractures were reviewed under the light of current literature. In conclusion, the simplest way that can be done with the least risk of complication should be chosen during treatment planning. In addition, current adjunctive treatment methods accelerating healing of fracture should be considered. [Archives Medical Review Journal 2014; 23(4.000: 658-671

  4. 21 CFR 872.3960 - Mandibular condyle prosthesis.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3960 Mandibular condyle prosthesis. (a) Identification. A mandibular condyle prosthesis is a device that is intended to be implanted in the human jaw to... requirement for premarket approval for any mandibular condyle prosthesis intended to be implanted in the human...

  5. Neurovascular structures of the mandibular angle and condyle: a comprehensive anatomical review.

    Science.gov (United States)

    Yang, Hun-Mu; Won, Sung-Yoon; Kim, Hee-Jin; Hu, Kyung-Seok

    2015-11-01

    Various surgical interventions including esthetic surgery, salivary gland excision, and open reduction of fracture have been performed in the area around the mandibular angle and condyle. This study aimed to comprehensively review the anatomy of the neurovascular structures on the angle and condyle with recent anatomic and clinical research. We provide detailed information about the branching and distributing patterns of the neurovascular structures at the mandibular angle and condyle, with reported data of measurements and proportions from previous anatomical and clinical research. Our report should serve to help practitioners gain a better understanding of the area in order or reduce potential complications during local procedures. Reckless manipulation during mandibular angle reduction could mutilate arterial branches, not only from the facial artery, but also from the external carotid artery. The transverse facial artery and superficial temporal artery could be damaged during approach and incision in the condylar area. The marginal mandibular branch of the facial nerve can be easily damaged during submandibular gland excision or facial rejuvenation treatment. The main trunk of the facial nerve and its upper and lower distinct divisions have been damaged during parotidectomy, rhytidectomy, and open reductions of condylar fractures. By revisiting the information in the present study, surgeons will be able to more accurately prevent procedure-related complications, such as iatrogenic vascular accidents on the mandibular angle and condyle, complete and partial facial palsy, gustatory sweating (Frey syndrome), and traumatic neuroma after parotidectomy.

  6. Comparison of impacts of friction massage, stretching exercises and analgesics on pain relief in primary fibromyalgia syndrome: a randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Amanollahi A

    2013-01-01

    Full Text Available Background: Stretching exercises and massage therapy are both suggested for pain relief in fibromyalgia syndrome. Previous studies have not proved their superiority over each other. This study compared the therapeutic effects of friction massage, stretching exercises, and analgesics on pain relief in patients with fibromyalgia syndrome.Methods: We evaluated 129 female patients with the diagnosis of primary fibromyalgia visited at the physical medicine clinics of Baqiyatallah Hospital in Tehran, Iran during 2010- 2011. Patients were randomly divided into three groups: the first group received 400 mg ibuprofen P.O. (3 times per day and 25 mg nortriptyline (daily P.O. as analgesic, the second group was treated by friction massage and the third group performed stretching exercises. Patients were assessed three times (initially, after one and four weeks by visual analogue scale (VAS.Results: The mean age of participants was 60.46 years. The mean age in each treatment group was 46.66 years in medication group, 46.73 years in stretching group and 46.65 years in friction massage group. Changes in VAS score over 4 weeks were 2.4, 3.1 and 1.9, in the first, second, and third groups, respectively. The changes in VAS were significantly different in the first and second groups rather than the controls (P<0.05.Conclusion: The effect of stretch exercise on pain relief was similar to analgesics, but it was more effective than friction massage. Moreover, the therapeutic effect of stretching exercise on pain relief upon four weeks was more permanent than friction massage but it was similar to analgesics.

  7. [Computer assisted orthognathic surgery: Condyle repositioning.

    Science.gov (United States)

    Bettega, G; Leitner, F

    2013-07-17

    Computer aided surgery has become a standard in many fields. It is rarely used in orthognathic surgery. Twenty years ago, we developed a navigation system adapted to this surgery, especially for mandibular condyle repositioning. The system has been improved along with technological progress. The authors of several clinical studies have validated this system. It is now routinely used in our department, because of its educational virtues among other assets. Copyright © 2013. Published by Elsevier Masson SAS.

  8. The radiologic spectrum of occipital condyle fractures

    International Nuclear Information System (INIS)

    Hanson, J.A.; Deliganis, A.V.; Baxter, A.B.; Cohen, W.A.; Wilson, A.J.; Mann, F.A.

    2002-01-01

    Full text: Occipital condyle fractures (OCFs) are increasingly diagnosed in survivors of high energy blunt trauma, and may be associated with craniocervical junction disruption.We aimed to describe and classify the imaging appearances of occipital condyle fractures in a large series of trauma patients. We reviewed conventional radiographs, computed tomography (CT), and magnetic resonance (MR) imaging in 95 patients with 107 OCFs, who were treated at a level 1 trauma centre (1992-1999). We described fracture patterns according to two current classification systems (Anderson and Montesano, and Tuli), and correlated imaging appearances with clinical findings, neurosurgical management and patient outcome. Fracture morphology and craniocervical junction integrity were best assessed by 1-1.5mm collimation CT. Inferomedial occipital condyle avulsion fractures (Anderson and Montesano type III) were the commonest OCF category, comprising 80/107 (75%). Unilateral OCFs were found in 73/95 (77%) patients, 58 of whom were managed by cervical orthotic brace or collar. Bilateral OCFs or occipito-atlanto-axial joint injuries were seen in the remaining 22/95 (23%) patients. Occipitocervical fusion or craniocervical halo traction were required in 12 patients, all of whom had CT evidence of bilateral occipito-atlanto-axial joint disruption. Associated cervical spine injuries were present in 29/95 (31%) patients. Ten (10/95, 10.5%) patients died in hospital, and 30/95 (32%) showed continuing disability. The remaining 55/95 (57.5%) patients showed good outcome and functional independence at 1 month. Occipital condyle fractures are rare injuries with a wide range of morphology, stability and clinical significance. Thorough radiological evaluation of all components of the occipito-atlanto-axial joint complex must be performed in order to determine the full extent of injury. In this series, most unilateral OCFs were managed by non-operative immobilisation, whereas bilateral occipito

  9. Glycosaminoglycan synthesis in the mandibular condyle during growth adaptation.

    Science.gov (United States)

    Kantomaa, T; Pirttiniemi, P; Tuominen, M; Poikela, A

    1994-01-01

    Condylar growth was studied after an operation simulating functional orthodontic appliances. Twenty-five rabbits underwent a surgical operation for the induction of premature synostosis to displace the glenoid fossa posteriorly during growth. Twenty-five control rabbits underwent sham operations. At the age of 15 days, 10 experimental and 10 control animals and, at the age of 20 days, 5 experimental and 5 control animals were killed. Their mandibular condyles were organ-cultured for 3 h in the presence of radiolabelled sulphur. The condyles were used for autoradiographic purposes. Digital image analysis of autoradiograms of histological sections showed synthesis of glycosaminoglycans to have increased from the anterior to the posterior direction. This increase was more marked in experimental animals than in the condyles of control animals. Ten experimental and 10 control animals were killed at the age of 15 days, and mandibular condyles were organ-cultured for 1, 4 and 7 days. Differentiation of proliferating prechondroblasts into hypertrophied chondrocytes continued under organ culture conditions. A marked decrease in the proliferating cell layer was noticed, especially in control condyles. Hypertrophy was faster and came closer to the surface of the condyle in the anterior region of the condyle. This was most marked in the condyles of experimental animals. The results indicate that a procedure carried out on the glenoid fossa with the same effect as functional appliances increases the synthesis of extracellular matrix in the posterosuperior region of the mandibular condyle.

  10. Coronal views of the paediatric mandibular condyle on ...

    African Journals Online (AJOL)

    This article highlights the importance of routinely reviewing the mandibular condyle on computerised tomography brain studies in a trauma setting, that often extends to involve the mandibular condyles in the scan parameters. We discuss 4 cases seen over the last 18 months at our institution, and review the relevant ...

  11. Mandibular condyle position in cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Hyoung Joo; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Kyung Hee Univ. School of Dentistry, Seoul (Korea, Republic of)

    2006-06-15

    To evaluate position of the mandibular condyle within articular fossa in an asymptomatic population radiographically by a cone beam computed tomography. Cone beam computed tomography of 60 temporomandibular joints was performed on 15 males and 15 females with no history of any temporomandibular disorders, or any other orthodontic or photoconductors treatments. Position of mandibular condyle within articular fossa at centric occlusion was evaluated. A statistical evaluation was done using a SPSS. In the sagittal views, mandibular condyle within articular fossa was laterally located at central section. Mandibular condyles in the right and left sides were showed asymmetric positional relationship at medial, central, and lateral sections. Mandibular condyle within articular fossa in an asymptomatic population was observed non-concentric position in the sagittal and coronal views.

  12. A tomographic study of the condyle position in temporomandibular disorders

    International Nuclear Information System (INIS)

    Choi, Sung Youn; Ryu, Young Kyu

    1988-01-01

    The aim of this study was to determine whether T.M.J. tomographic examination yielded significant difference in condyle positions among asymptomatic, myalgia, derangement, and arthrosis group of T.M.J. disorders. The author obtained sagittal linear tomograms of right and left T.M.Js. of 36 asymptomatic, 22 myalgia, 54 derangement, and 31 arthrosis patients taken at serial lateral, central, and medial sections in the intercuspal position after submentovertex radiographs analyzed. With the dual linear measurements of the posterior and anterior interarticular space, condyle positions were mathematically expressed as proportion. All data from these analysis was recorded and processed statistically. The results were obtained as follows: 1. In asymptomatic group, radiographically concentric condyle position was found in 50.0% to 65.4% of subjects, with a substance range of variability. No significant differences existed between men and women and also between right and left T.M.Js. for condyle position. 2. In women, significant difference for mean condyle position of left lateral section of each diagnostic category existed between derangement and myalgia groups (P< .05). Also that of left central section existed between derangement and myalgia group, and that of left medial section existed between derangement and myalgia groups (P< . 05). 3. In main-symptom side, condyle position in myalgia group was more concentric, and condyle position in derangement and group was more posterior. This showed significant differences between derangement and myalgia groups in lateral, central, and medial sections of main symptom side, and only between derangement and myalgia groups in central section of contra-lateral sides (P< .05). Condyle position in arthrosis group was broadly distributed among all positions. 4. In contra-lateral side, significant difference for mean condyle position of central section of each symptomatic group existed between derangement and myalgia group (P< .05

  13. A tomographic study of the condyle position in temporomandibular disorders

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sung Youn; Ryu, Young Kyu [Dept. of Oral Radiology, College of Dentistry, Yonsei University, Seoul (Korea, Republic of)

    1988-11-15

    The aim of this study was to determine whether T.M.J. tomographic examination yielded significant difference in condyle positions among asymptomatic, myalgia, derangement, and arthrosis group of T.M.J. disorders. The author obtained sagittal linear tomograms of right and left T.M.Js. of 36 asymptomatic, 22 myalgia, 54 derangement, and 31 arthrosis patients taken at serial lateral, central, and medial sections in the intercuspal position after submentovertex radiographs analyzed. With the dual linear measurements of the posterior and anterior interarticular space, condyle positions were mathematically expressed as proportion. All data from these analysis was recorded and processed statistically. The results were obtained as follows: 1. In asymptomatic group, radiographically concentric condyle position was found in 50.0% to 65.4% of subjects, with a substance range of variability. No significant differences existed between men and women and also between right and left T.M.Js. for condyle position. 2. In women, significant difference for mean condyle position of left lateral section of each diagnostic category existed between derangement and myalgia groups (P< .05). Also that of left central section existed between derangement and myalgia group, and that of left medial section existed between derangement and myalgia groups (P< . 05). 3. In main-symptom side, condyle position in myalgia group was more concentric, and condyle position in derangement and group was more posterior. This showed significant differences between derangement and myalgia groups in lateral, central, and medial sections of main symptom side, and only between derangement and myalgia groups in central section of contra-lateral sides (P< .05). Condyle position in arthrosis group was broadly distributed among all positions. 4. In contra-lateral side, significant difference for mean condyle position of central section of each symptomatic group existed between derangement and myalgia group (P< .05

  14. Simultaneous avascular necrosis of both medial and lateral femoral condyles

    International Nuclear Information System (INIS)

    Mansberg, R.

    2002-01-01

    Full text: Avascular necrosis (AVN) of a femoral condyle is a common orthopaedic condition. While both medial and lateral femoral condyles may be involved either singly or sequentially the simultaneous occurrence of AVN of both femoral condyles is extremely uncommon. A 57-year-old male is presented who developed the onset of severe left sided knee pain suddenly at rest. Plain and tomographic radiography was unremarkable and a bone scan was performed. Markedly increased vascularity was demonstrated in the left knee with intense osteoblastic activity in the left medial and femoral condyles more marked in the lateral femoral condyle. A diagnosis of AVN of both femoral condyles was made and a MRI exam was performed to confirm this unusual diagnosis. The MRI showed a diffuse increase in intensity bilaterally with subtle bony change in the subarticular bone consistent with AVN more marked in the left lateral femoral condyle. The patients' symptoms resolved with supportive treatment. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  15. Radiographic study of morphology of mandibular condyle

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hyung Kyu [Department of Oral Radiology, College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    1985-11-15

    Anatomical anomaly of temporo-mandibular joint and its dysfunction is becoming one of the important problem in dentistry because the number of these cases are increasing rapidly. Applying 'Lateral Transcranial Technic', 'Updegrave method' and 'Denar Accuard 100' to skull and adult with normal occlusion the author obtained following results: 1. Grewcock method combined with cephalos tat as one of 'Lateral Transcranial Technic' revealed clear picture but the image of condyle head was tend to incline downward. 2. Direction of central radiation in 'Updegrave method' should be 2 recommended inch upward from auditorial mearus. 3. For functional analysis and correct diagnosis 'Denar Accuard 100' should be highly recommended.

  16. Avascular osteonecrosis of the femoral condyle after arthroscopic surgery

    International Nuclear Information System (INIS)

    Al-Kaar, M.; Garcia, J.; Fritschy, D.; Bonvin, J.C.

    1997-01-01

    Avascular osteonecrosis of the femoral condyle after arthroscopic surgery. Retrospective review of 10 patients who presented with avascular necrosis of the ipsilateral femoral condyle following arthroscopic meniscectomy (9 medial, 1 lateral). The bone lesions were evaluated by radiography and MRI, which were repeated for few patients. MRI allows earlier diagnosis of avascular necrosis of the femoral condyle and offers an evaluation of extent of the lesions whose evolution is variable: 3 patients required a knee prosthesis, the other 7 patients were treated medically. (authors)

  17. Avascular osteonecrosis of the femoral condyle after arthroscopic surgery; Osteonecrose aseptique du condyle femoral apres meniscectomie par voie arthroscopique

    Energy Technology Data Exchange (ETDEWEB)

    Al-Kaar, M.; Garcia, J. [Hopital Cantonal Geneve, Geneva (Switzerland); Fritschy, D.; Bonvin, J.C. [Policlinique de Chirurgie, Hopital Cantonal Universitaire, Geneve (Switzerland)

    1997-04-01

    Avascular osteonecrosis of the femoral condyle after arthroscopic surgery. Retrospective review of 10 patients who presented with avascular necrosis of the ipsilateral femoral condyle following arthroscopic meniscectomy (9 medial, 1 lateral). The bone lesions were evaluated by radiography and MRI, which were repeated for few patients. MRI allows earlier diagnosis of avascular necrosis of the femoral condyle and offers an evaluation of extent of the lesions whose evolution is variable: 3 patients required a knee prosthesis, the other 7 patients were treated medically. (authors). 21 refs.

  18. Incomplete (bending) fractures of the mandibular condyle in children

    International Nuclear Information System (INIS)

    Ahrendt, D.; Swischuk, L.E.; Hayden, C.K. Jr.; Texas Univ., Galveston

    1984-01-01

    Incomplete, bending or bowing fractures of the mandibular condyle in children frequently go undetected. The reason is that the bending deformity often is subtle and passes for normal. This is especially true if the fractures are bilateral. (orig.)

  19. Observation of condyles by roentgenographic cephalogram

    International Nuclear Information System (INIS)

    Ahn, Hyung Kyu

    1984-01-01

    In spite of many projections of TMJ, there are rarely satisfactory projections of TMJ. The author traced and measured the P-A cephalograms, which number is 70 in each male and female, them finding the following results. 1. The long axis of the condyle is 19.80 mm on the right, and 19.89 mm on the left in male, and that of 18.65 mm on the right and 18.10 mm on the left in female. 2. The intercondylar distance is 119.09 mm in male, and 108.20 mm in female, resulting that the intercondylar distance in male is much longer than that in female. 3. The right and left deviation of the midline passing through the center of the intercondylar distance and prosthion is +0.37 mm in male, +0.64 mm in female, and its range is from -4.6 to +5.7 mm in male, and from -3.2 to +6.1 mm in female, resulting that prosthion nearly coincides with midline. 4. The angle of the intercondylar distance and the long axis (vertical angle) is +5.48 degrees in male, and +6.02 degrees in female, resulting that there is a little difference between male and female and the angle of the right is greater than that of the left in both male and female. 5. The typology of the condyle in sum of male and female is; Right: A type 55 (39.3%), B type 66 (47.1%), C type 12 (8 .6%), D type 7 (5.0%), E type 0 (0%) Left: A type 60 (42.9%), B type 58 (41.4%), C type 14 (10.0%), D type 8 (5.7%), E type 0 (0%) 6. The distribution of the typology between the right and the left is; AA 26 (18.6%), AB 50 (35.7%), AC 10 (7.1%), AD 3 (2.1%) BB 26 (18.6%), BC 13 (9.3%), BD 9 (6.4%), CC 0 (0%), CD 3 (2.1%).

  20. Bone changes of mandibular condyle using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Un; Kim, Hyung Seop; Song, Ju Seop; Kim, Kyoung A; Koh, Kwang Joon [Chonbuk National Univ., Chonju (Korea, Republic of)

    2007-09-15

    To assess bone changes of mandibular condyle using cone beam computed tomography (CBCT) in temporomandibualr disorder (TMD) patients. 314 temporomandibular joints (TMJs) images of 163 TMD patients were examined at the Department of Oral and Maxillofacial Radiology, Chonbuk National University. The images were obtained by PSR9000N (Asahi Roentgen Co., Japan) and reconstructed by using Asahivision software (Asahi Roentgen Co., Japan). The CBCT images were examined three times with four weeks interval by three radiologists. Bone changes of mandibular condyle such as flattening, sclerosis, erosion and osteophyte formation were observed in sagittal, axial, coronal and 3 dimensional images of the mandibular condyle. The statistical analysis was performed using SPSS 12.0. Intra-and interobserver agreement were performed by 3 radiologists without the knowledge of clinical information. Osteopathy (2.9%) was found more frequently on anterior surface of the mandibular condyle. Erosion (31.8%) was found more frequently on anterior surface of the mandibular condyle. The intraobserver agreement was good to excellent (k=0.78{sub 0}.84), but interobserver agreement was fair (k=0.45). CBCT can provide high qualified images of bone changes of the TMJ with axial, coronal and 3 dimensional images.

  1. Bone changes of mandibular condyle using cone beam computed tomography

    International Nuclear Information System (INIS)

    Lee, Ji Un; Kim, Hyung Seop; Song, Ju Seop; Kim, Kyoung A; Koh, Kwang Joon

    2007-01-01

    To assess bone changes of mandibular condyle using cone beam computed tomography (CBCT) in temporomandibualr disorder (TMD) patients. 314 temporomandibular joints (TMJs) images of 163 TMD patients were examined at the Department of Oral and Maxillofacial Radiology, Chonbuk National University. The images were obtained by PSR9000N (Asahi Roentgen Co., Japan) and reconstructed by using Asahivision software (Asahi Roentgen Co., Japan). The CBCT images were examined three times with four weeks interval by three radiologists. Bone changes of mandibular condyle such as flattening, sclerosis, erosion and osteophyte formation were observed in sagittal, axial, coronal and 3 dimensional images of the mandibular condyle. The statistical analysis was performed using SPSS 12.0. Intra-and interobserver agreement were performed by 3 radiologists without the knowledge of clinical information. Osteopathy (2.9%) was found more frequently on anterior surface of the mandibular condyle. Erosion (31.8%) was found more frequently on anterior surface of the mandibular condyle. The intraobserver agreement was good to excellent (k=0.78 0 .84), but interobserver agreement was fair (k=0.45). CBCT can provide high qualified images of bone changes of the TMJ with axial, coronal and 3 dimensional images

  2. Feasibility of purely endoscopic intramedullary fixation of mandibular condyle fractures.

    Science.gov (United States)

    Frake, Paul C; Goodman, Joseph F; Joshi, Arjun S

    2015-01-01

    The investigators of this study hypothesized that fractures of the mandibular condyle can be repaired using short-segment intramedullary implants and purely endoscopic surgical technique, using a basic science, human cadaver model in an academic center. Endoscopic instrumentation was used through a transoral mucosal incision to place intramedullary implants of 2 cm in length into osteotomized mandibular condyles. The surgical maneuvers that required to insert these implants, including condyle positioning, reaming, implant insertion, and seating of the mandibular ramus, are described herein. Primary outcome was considered as successful completion of the procedure. Ten cadaveric mandibular condyles were successfully repaired with rigid intramedullary internal fixation without the use of external incisions. Both insertion of a peg-type implant and screwing a threaded implant into the condylar head were possible. The inferior portion of the implant remained exposed, and the ramus of the mandible was manipulated into position on the implant using retraction at the sigmoid notch. The results of this study suggest that purely endoscopic repair of fractures of the mandibular condyle is possible by using short-segment intramedullary titanium implants and a transoral endoscopic approach without the need for facial incisions or punctures. The biomechanical advantages of these intramedullary implants, including improved strength and resistance to mechanical failure compared with miniplates, have been recently established. The combination of improved implant design and purely endoscopic technique may allow for improved fixation and reduced surgical- and implant-related morbidity in the treatment of condylar fractures.

  3. Iliotibial band friction syndrome after anterior cruciate ligament reconstruction using the transfix device: report of two cases and review of the literature.

    Science.gov (United States)

    Pelfort, Xavier; Monllau, Joan C; Puig, Lluís; Cáceres, Enric

    2006-06-01

    The use of hamstrings is increasing as a treatment for anterior cruciate ligament (ACL) injuries. There are a lot of new devices and techniques that try to fix the graft without causing further injury or increased morbidity. We report two cases in relation to the transfix device for reconstructing the ACL. The first case is a 38-year-old female who was treated with an autologous hamstring graft for chronic ACL instability brought on by a sport trauma. The patient developed iliotibial band friction syndrome 3 months after the operation. MRI showed incorrect positioning and a rupture of the femoral bio-absorbable cross-pin. The hamstring graft always had good fixation and did not produce instability of the knee. We removed the cross-pin fragment in a second surgery and the patient returned to her daily lifestyle after 3 weeks. The second case is a 52-year-old female with a painful and unstable knee due to a previous lateral meniscectomy and failure of an ACL reconstruction. We performed an ACL reconstruction with an autologous hamstring graft and a lateral meniscus transplantation. Some months after the procedure she also developed this syndrome. MRI showed the same features as shown in the first case and a second surgery was needed. To our knowledge this clinical and technical problem has not been previously described.

  4. Conservative orthodontic treatment of mandibular bilateral condyle fracture.

    Science.gov (United States)

    Gašpar, Goran; Brakus, Ivan; Kovačić, Ivan

    2014-09-01

    Maxillofacial trauma is rare in children younger than the age of 5 years (range 0.6%-1.2%), and they can require different clinical treatment strategies compared with fractures in the adult population because of concerns regarding mandibular growth and development of dentition. A 5-year-old girl with a history of falling from a bicycle 7 hours earlier was referred to the department of oral and maxillofacial surgery. Multislice computed tomographic examination demonstrated a bilateral fracture of the mandibular condyle neck associated with minimal fracture of the alveolar ridge of the maxilla. The multislice computed tomographic scan also demonstrated dislocation on the right condyle neck and, on the left side, a medial inclination of approximately 45 degrees associated with greenstick fracture of the right parasymphysis region. In this particular case, orthodontic rubber elastics in combination with fixed orthodontic brackets provided good results in the treatment of bilateral condyle neck fractures associated with greenstick fracture of parasymphysis.

  5. A clinico-radiologic study of bony remodeling of the fractured condyles in children

    International Nuclear Information System (INIS)

    Cho, Jeong Shin; Park, Chang Seo

    1995-01-01

    Bony remodeling pattern of condyle fractures in children are different from in adult for growing of condyle, also might affect treatment and prognosis of the condyle fracture. Subjects of this clinical and radiologic study were 26 temporomandibular joints diagnosed as condyle fracture in 23 patients under 15 years old age, They were treated with conservative method at Dental Hospital of Yonsei University from Jan., 1986 to Oct., 1994. Bony remodeling related with fracture pattern was evaluated. The results obtained are as follows: 1. The ratio of male to female in patients with condyle fracture was 1 : 0.9 and the difference of sex ratio was not noted. Comparing with preschool-age group and school-age group, age frequency was higher in preschool-age group (83%). 2. Fallen down (54%) was the most frequent cause of condyle fractures. Traffic accident and slip down were followed. 3. The most common clinical sign of condyle fractures was tenderness to palpation (19 cases). Mouth opening limitation (17 cases), swelling (7 cases), malocclusion (3 cases) were next in order. 4. According to sites of condyle fractures, unilateral fractures were in 20 patients and bilateral fractures in 3 patients, therefore total 23 patients-26 cases of condyle fracture were observed. According to fracture distribution, condyle fractures were in 10 patients (44%). Condyle fractures with symphysis fracture (9 patients, 39%), condyle fractures with ascending ramus fracture (2 patients, 9%), condyle fracture with mandibular body fracture (1 patient, 4%), and condyle fractures with mandibular angle fracture (1 patient, 4%) were followed. 5. In displacement pattern of fractured fragment of mandibular condyle, displacement (17 cases, 66%) was most common. Dislocation (5 cases, 19%) and deviation (4 cases, 15%) were next in order. 6. During the observation period of fractured condyles, remodeling patterns of fracture sites related with articular fossa were observed with usual congealer shape in 23

  6. Relation between anterior displacement of the temporomandibular joint disc and size of the condyle

    International Nuclear Information System (INIS)

    Ohgushi, Masatoshi; Kubota, Hisashi; Yamaguchi, Kouichi; Shibata, Takanori

    1996-01-01

    To elucidate the cause of anterior displacement of the disc, we evaluated the relation between anterior displacement and the size of the condyle from MR images in 301 patients (602 TMJs) with clinical diagnosis of internal derangement. We found that the size of condyles with anterior displacement of the disc was significantly smaller than that of condyles without anterior displacement. This result suggests that small condyles may give rise to anterior displacement of the disc. (author)

  7. A clinico-radiologic study of bony remodeling of the fractured condyles in children

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jeong Shin; Park, Chang Seo [Department of Dentistry, The Graduate School, Yonsei University, Seoul (Korea, Republic of)

    1995-08-15

    Bony remodeling pattern of condyle fractures in children are different from in adult for growing of condyle, also might affect treatment and prognosis of the condyle fracture. Subjects of this clinical and radiologic study were 26 temporomandibular joints diagnosed as condyle fracture in 23 patients under 15 years old age, They were treated with conservative method at Dental Hospital of Yonsei University from Jan., 1986 to Oct., 1994. Bony remodeling related with fracture pattern was evaluated. The results obtained are as follows: 1. The ratio of male to female in patients with condyle fracture was 1 : 0.9 and the difference of sex ratio was not noted. Comparing with preschool-age group and school-age group, age frequency was higher in preschool-age group (83%). 2. Fallen down (54%) was the most frequent cause of condyle fractures. Traffic accident and slip down were followed. 3. The most common clinical sign of condyle fractures was tenderness to palpation (19 cases). Mouth opening limitation (17 cases), swelling (7 cases), malocclusion (3 cases) were next in order. 4. According to sites of condyle fractures, unilateral fractures were in 20 patients and bilateral fractures in 3 patients, therefore total 23 patients-26 cases of condyle fracture were observed. According to fracture distribution, condyle fractures were in 10 patients (44%). Condyle fractures with symphysis fracture (9 patients, 39%), condyle fractures with ascending ramus fracture (2 patients, 9%), condyle fracture with mandibular body fracture (1 patient, 4%), and condyle fractures with mandibular angle fracture (1 patient, 4%) were followed. 5. In displacement pattern of fractured fragment of mandibular condyle, displacement (17 cases, 66%) was most common. Dislocation (5 cases, 19%) and deviation (4 cases, 15%) were next in order. 6. During the observation period of fractured condyles, remodeling patterns of fracture sites related with articular fossa were observed with usual congealer shape in 23

  8. Robust femur condyle disambiguation on biplanar X-rays.

    Science.gov (United States)

    Serrurier, Antoine; Quijano, Sergio; Nizard, Remy; Skalli, Wafa

    2012-12-01

    Three-dimensional (3D) reconstruction of the skeleton from biplanar X-rays relies on scarce information digitalised by an operator on both frontal and lateral radiographs. In clinical routine, difficulties occur for non-skilled operators to discriminate the medial from the lateral femur condyle on the lateral view. Our study proposes an algorithm able to detect automatically a possible inversion of the two condyles by the operator at an early stage of the reconstruction process. It relies on the computation of two 3D femur surfaces, one directly from the operator digitalisation and the other from the same digitalisation with medial and lateral condyles automatically swapped. Pairs of virtual biplanar X-rays are computed for both reconstructions and the closest pair to the original X-rays is selected on the basis of similarity measures, pointing the correct 3D surface. The algorithm shows a success rate higher than 85% for both asymptomatic and pathological femurs whatever the initial condyle digitalisation of the operator, bringing automatically non-skilled operators acting in clinical routine to the level of skilled operators. This study validates moreover the proof-of-concept of automatic shape adjustments of a 3D surface on the basis of similarity measures in the process of 3D reconstruction from biplanar X-rays. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  9. Evaluation of mandibular condyles in children with unilateral posterior crossbite.

    Science.gov (United States)

    Illipronti-Filho, Edson; Fantini, Solange Mongelli de; Chilvarquer, Israel

    2015-01-01

    The relationship of mandibular condyle dimensions and its association with unilateral posterior crossbite (UPXB) has been suggested in the literature. The purpose of this prospective study was to evaluate mandibular condyles on the left and right sides and between crossed and non-crossed sides in the sagittal and coronal planes, using cone-beam computed tomography (CBCT). Twenty CBCT images of 40 temporo mandibular joints (TMJs) in individuals in mixed dentition phase, which included 9 males (mean 7.9 years) and 11 females (mean 8.2 years), with unilateral posterior crossbite without premature contacts and functional mandibular shifts and with transverse maxillary deficiency. The criteria for sample exclusion included the presence of painful symptoms, facial trauma history, systemic diseases such as juvenile rheumatoid arthritis, mouth opening limitation (anomalies, and skeletal asymmetries that may result in TMJ disorders. Dimensional measurements of the condyles between the right and left sides and crossed and non-crossed sides in sagittal and coronal view were made. There was no significant difference between the measurements of the crossed and non-crossed sides in both sagittal and coronal view. These findings suggest that the presence of unilateral posterior crossbite in children with UPXB did not result in changes between the mandibular condyles in the right and left sides or between the crossed and non-crossed sides in the coronal or sagittal plane.

  10. Evaluation of mandibular condyles in children with unilateral posterior crossbite

    Directory of Open Access Journals (Sweden)

    Edson ILLIPRONTI-FILHO

    2015-01-01

    Full Text Available The relationship of mandibular condyle dimensions and its association with unilateral posterior crossbite (UPXB has been suggested in the literature. The purpose of this prospective study was to evaluate mandibular condyles on the left and right sides and between crossed and non-crossed sides in the sagittal and coronal planes, using cone-beam computed tomography (CBCT. Twenty CBCT images of 40 temporo mandibular joints (TMJs in individuals in mixed dentition phase, which included 9 males (mean 7.9 years and 11 females (mean 8.2 years, with unilateral posterior crossbite without premature contacts and functional mandibular shifts and with transverse maxillary deficiency. The criteria for sample exclusion included the presence of painful symptoms, facial trauma history, systemic diseases such as juvenile rheumatoid arthritis, mouth opening limitation (< 40 mm, congenital or genetic anomalies, and skeletal asymmetries that may result in TMJ disorders. Dimensional measurements of the condyles between the right and left sides and crossed and non-crossed sides in sagittal and coronal view were made. There was no significant difference between the measurements of the crossed and non-crossed sides in both sagittal and coronal view. These findings suggest that the presence of unilateral posterior crossbite in children with UPXB did not result in changes between the mandibular condyles in the right and left sides or between the crossed and non-crossed sides in the coronal or sagittal plane.

  11. Elderly patients with maxillofacial trauma: study of mandibular condyle fractures.

    Science.gov (United States)

    Nogami, Shinnosuke; Yamauchi, Kensuke; Yamashita, Toshio; Kataoka, Yoshihiro; Hirayama, Bunichi; Tanaka, Kenko; Takahashi, Tetsu

    2015-02-01

    The aim of this study was to investigate the trends and characteristic features of mandibular condyle fractures in elderly patients in terms of etiology, patterns, and treatment modalities. Records of 201 patients aged 65 years and older, who were treated for maxillofacial fractures at the Department of Oral and Maxillofacial Surgery, Kyushu Dental University, and Tohoku University from January 2002 to December 2013, were retrospectively analyzed. Patient records and radiographs were examined, with the following information: relevant medical history, cause of fracture, the presence and state of premolars and molars in the maxilla and mandible, number and location of mandible fracture, and method of treatment. As for the state of premolars and molars, premolars or molars in the mandible in contact with the maxilla were regarded as contacted. A fall was responsible for the majority of the fractures (173/201). With condyle fractures, there was a significant difference between the contacted and non-contacted group in regard to incidence. Furthermore, there was a significantly greater number of cases with symphysis and condyle combination fractures in the non-contacted group (70.9%) than in the contacted group (51.9%). As for the method of treatment, arthrocentesis was the most commonly employed. The present findings suggest that contacted molars in the maxilla and mandible have an influence on condyle fractures in elderly individuals. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Occipital condyle fracture and ligament injury: imaging by CT

    International Nuclear Information System (INIS)

    Bloom, A.I.; Neeman, Z.; Floman, Y.; Gomori, J.; Bar-Ziv, J.

    1996-01-01

    The true incidence of fracture of the occipital condyles is unknown. It may be associated with instability at the craniocervical joint. CT is the modality of choice for the demonstration of these fractures, but its use for imaging of the associated ligament injury has not been reported. In order to demonstrate normal anatomy, occipital condyle fracture and ligament injury, and to estimate the incidence of this lesion, 21 children and young adults with high-energy blunt craniocervical injury were examined prospectively. Thin-slice, axial, contiguous, CT was performed from the base of C2 to above the foramen magnum. Bone and soft tissue windows and coronal, sagittal, and curvilinear 2D reconstructions were performed. Five occipital condyle fractures were identified in four patients (19 %), with demonstration of alar ligament injury in two cases and local hematoma in one. In four, artifacts or rotation precluded assessment of ligaments. In all remaining cases normal bone and ligament anatomy was demonstrated. Fracture of the occipital condyles following craniocervical injury is not uncommon in children and young adults. Normal bone and ligament anatomy and pathology can be safely and clearly demonstrated in seriously injured patients and others using this CT technique. Increased awareness of this entity and a low threshold for performing CT should avoid the potentially serious consequences of a missed diagnosis. (orig.). With 8 figs., 2 tabs

  13. CT-based morphometric analysis of the occipital condyle: focus on occipital condyle screw insertion.

    Science.gov (United States)

    Zhou, Jinsong; Espinoza Orías, Alejandro A; Kang, Xia; He, Jade; Zhang, Zhihai; Inoue, Nozomu; An, Howard S

    2016-11-01

    OBJECTIVE The segmental occipital condyle screw (OCS) is an alternative fixation technique in occipitocervical fusion. A thorough morphological study of the occipital condyle (OC) is critical for OCS placement. The authors set out to introduce a more precise CT-based method for morphometric analysis of the OC as it pertains to the placement of the segmental OCS, and they describe a novel preoperative simulation method for screw placement. Two new clinically relevant parameters, the height available for the OCS and the warning depth, are proposed. METHODS CT data sets from 27 fresh-frozen human cadaveric occipitocervical spines were used. All measurements were performed using a commercially available 3D reconstruction software package. The length, width, and sagittal angle of the condyle were measured in the axial plane at the base of the OC. The height of the OC and the height available for the segmental OCS were measured in the reconstructed oblique sagittal plane, fitting the ideal trajectory of the OCS recommended in the literature. The placement of a 3.5-mm-diameter screw that had the longest length of bicortical purchase was simulated into the OC in the oblique sagittal plane, with the screw path not being blocked by the occiput and not violating the hypoglossal canal cranially or the atlantooccipital joint caudally. The length of the simulated screw was recorded. The warning depth was measured as the shortest distance from the entry point of the screw to the posterior border of the hypoglossal canal. RESULTS The mean length and width of the OC were found to be larger in males: 22.2 ± 1.7 mm and 12.1 ± 1.0 mm, respectively, overall (p < 0.0001 for both). The mean sagittal angle was 28.0° ± 4.9°. The height available for the OCS was significantly less than the height of the OC (6.2 ± 1.3 mm vs 9.4 ± 1.5 mm, p < 0.0001). The mean screw length (19.3 ± 1.9 mm) also presented significant sex-related differences: male greater than female (p = 0.0002). The

  14. Goldenhar syndrome

    Directory of Open Access Journals (Sweden)

    Neeraj Sharma

    2013-01-01

    Full Text Available Goldenhar syndrome is a syndrome of complex structures developing from first and second branchial arches during blastogenesis. The etiology of this rare disease is not fully understood, as it has shown itself variable genetically and of unclear causes. The disorder is characterized by a wide spectrum of symptoms and physical features that may vary greatly in range and severity from case to case. Here we present a unique case of Goldenhar syndrome with absence of left condyle, hypoplasia of the zygomatic bone, no pneumatization of the mastoid process, underdeveloped mandible, bifid tongue and the skin tags in the preauricular area.

  15. Friction dampers, the positive side of friction

    NARCIS (Netherlands)

    Lopez Arteaga, I.; Nijmeijer, H.; Busturia, J.M.; Sas, P.; Munck, de M.

    2004-01-01

    Friction is frequently seen as an unwanted phenomenon whose influence has to be either minimised or controlled. In this work one of the positive sides of friction is investigated: friction damping. Friction dampers can be a cheap and efficient way to reduce the vibration levels of a wide range of

  16. Recurrent osteochondroma of the mandibular condyle: A case report

    International Nuclear Information System (INIS)

    Kwon, Young Eun; Choi, Karp Shik; An, Chang Hyeon; Choi, So Young; An, Seo Young; Lee, Jae Seo

    2017-01-01

    A 21-year-old woman presented with facial asymmetry. Crepitus and clicking of the temporomandibular joint were noted. The midline deviated 5.5 mm to the left, and secondary malocclusion was observed. Panoramic and cone-beam computed tomographic images showed an irregular and exophytic bony mass on the anteromedial surface of the right mandibular condyle. A 3-phase bone scan revealed increased tracer uptake on the affected side. The lesion was treated with excision and reshaping under the diagnosis of osteochondroma confirmed by a histopathological examination. The lesion recurred after 3 years, and the patient underwent condylectomy. Mandibular condylar osteochondroma is often resected because it causes functional and aesthetic problems, but it rarely recurs. To the best of our knowledge, only 2 cases of recurrent osteochondromas of the mandibular condyle have been reported previously. Surgical treatment of the osteochondroma should be performed considering the possibility of recurrence, and long-term follow-up is recommended

  17. Recurrent osteochondroma of the mandibular condyle: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Eun; Choi, Karp Shik; An, Chang Hyeon; Choi, So Young; An, Seo Young [School of Dentistry, Kyungpook National University, Daegu (Korea, Republic of); Lee, Jae Seo [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Chonnam National University, Gwangju (Korea, Republic of)

    2017-03-15

    A 21-year-old woman presented with facial asymmetry. Crepitus and clicking of the temporomandibular joint were noted. The midline deviated 5.5 mm to the left, and secondary malocclusion was observed. Panoramic and cone-beam computed tomographic images showed an irregular and exophytic bony mass on the anteromedial surface of the right mandibular condyle. A 3-phase bone scan revealed increased tracer uptake on the affected side. The lesion was treated with excision and reshaping under the diagnosis of osteochondroma confirmed by a histopathological examination. The lesion recurred after 3 years, and the patient underwent condylectomy. Mandibular condylar osteochondroma is often resected because it causes functional and aesthetic problems, but it rarely recurs. To the best of our knowledge, only 2 cases of recurrent osteochondromas of the mandibular condyle have been reported previously. Surgical treatment of the osteochondroma should be performed considering the possibility of recurrence, and long-term follow-up is recommended.

  18. Multiple-slice spiral CT evaluation of occipital condyle fractures

    International Nuclear Information System (INIS)

    Wang Xifu; Zhang Guixiang; Li Kang'an; Zhao Jinglong; Wang Han; Feng Yan; Zheng Linfeng

    2011-01-01

    Objective: To explore the MSCT findings of occipital condyle fracture (OCF) and improve its diagnostic accuracy. Methods: Nineteen patients with OCF, selected from 110 patients suffering high energy injuries at the craniocervical junction, were enrolled into the study. The MSCT appearances of OCFs were retrospectively analyzed by two experienced radiologists. OCF had four types: type Ⅰ was a comminuted fracture, type Ⅱ was a extension of basilar skull fracture, type Ⅲ was an avulsion fracture at the attachment site of alar ligament on occipital condyle, type Ⅳ was a fracture of mixed pattern consisting of two or more above fracture types. Results: In 19 patients, the left, right and bilateral OCFs were seen in 7, 11 cases, and 1 case, respectively. Type Ⅰ was found in one case, which was a comminution of the left occipital condyle. Type Ⅱ was found in 5 cases, which involved the middle and posterior parts of occipital condyles with 2 on the left and 3 on the right, Type Ⅲ was found in 12 cases which showed various degree of fragment displacement with 3 occurring on the left, 8 on the right, 1 involving bilateral sides, 6 involving articular surfaces and 7 accompanying by enlargement of alar ligaments. Type Ⅳ was found in one case, with coexistence of Type Ⅱ and type Ⅲ In addition, OCFs were accompanied by head and (or) cervical spine injuries in 14 cases, which included cranial fracture in 8 cases, epidural hematoma in 4 cases, subarachnoid hemorrhage in one case, cerebral contusion and laceration in one case, subfalcial hernia in one case, cervical spine fracture and dislocation in 9 cases, and so on. Conclusion: OCFs can be accurately diagnosed by MSCT, which is important for selection of treatment protocols. (authors)

  19. Fractured condyle in a 3-month-old infant.

    Science.gov (United States)

    Cambell, R L; Moore, R F

    1975-07-01

    A 3-month-old infant sustained trauma to the mandibular symphysis resulting in radiographic evidence of a fracture of the right condylar head. This presented the diffculty of performing a clinical examination and total reliance on history of a trauma and subsequent swelling. Multiple radiographs of the condyles were used to establish the diagnosis and rule out a film artifact. No definitive treatment was required other than muscle exercises and parental instruction as to potential problems.

  20. An Atypical Variant of Superolateral Dislocation of the Mandibular Condyle: A Case Report.

    Science.gov (United States)

    Malik, Kapil; Debnath, Subhas C; Adhyapok, Apurba K; Hazarika, Kriti

    2017-10-01

    Dislocation of the mandibular condyle from the glenoid fossa can occur in anterior, posterior, lateral, and superior directions. Posterior, lateral, and superior dislocations are rare. Superolateral dislocation is seldom encountered in clinical practice. It is generally associated with fracture of the anterior or contralateral side of the mandible. The occurrence of superolateral dislocation of the condyle hooked above the zygomatic arch with an associated fracture of the medial pole of the condyle is rare and has been reported only once in the literature. This report describes another case in which the patient had superolateral dislocation of the mandibular condyle with a fractured medial pole without any associated fracture of the anterior or contralateral side of the mandible. The condyle was hooked laterally above the zygomatic arch. Open reduction of the dislocated condyle was performed and a good outcome was obtained. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Osteoarthritis of the patella, lateral femoral condyle and posterior medial femoral condyle correlate with range of motion.

    Science.gov (United States)

    Suzuki, Takashi; Motojima, Sayaka; Saito, Shu; Ishii, Takao; Ryu, Keinosuke; Ryu, Junnosuke; Tokuhashi, Yasuaki

    2013-11-01

    The type of osteoarthritis and the degree of severity which causes restriction of knee range of motion (ROM) is still largely unknown. The objective of this study was to analyse the location and the degree of cartilage degeneration that affect knee range of motion and the connection, if any, between femorotibial angle (FTA) and knee ROM restriction. Four hundreds and fifty-six knees in 230 subjects with knee osteoarthritis undergoing knee arthroplasty were included. Articular surface was divided into eight sections, and cartilage degeneration was evaluated macroscopically during the operation. Cartilage degeneration was classified into four grades based on the degree of exposure of subchondral bone. A Pearson correlation was conducted between FTA and knee flexion angle to determine whether high a degree of FTA caused knee flexion restriction. A logistic regression analysis was also conducted to detect the locations and levels of cartilage degeneration causing knee flexion restriction. No correlation was found between FTA and flexion angle (r = -0.08). Flexion angle was not restricted with increasing FTA. Logistic regression analysis showed significant correlation between restricted knee ROM and levels of knee cartilage degeneration in the patella (odds ratio (OR) = 1.77; P = 0.01), the lateral femoral condyle (OR = 1.62; P = 0.03) and the posterior medial femoral condyle (OR = 1.80; P = 0.03). For clinical relevance, soft tissue release and osteophyte resection around the patella, lateral femoral condyle and posterior medial femoral condyle might be indicated to obtain a higher degree of knee flexion angle.

  2. Vacuum friction

    Science.gov (United States)

    Barnett, Stephen M.; Sonnleitner, Matthias

    2018-03-01

    We know that in empty space there is no preferred state of rest. This is true both in special relativity but also in Newtonian mechanics with its associated Galilean relativity. It comes as something of a surprise, therefore, to discover the existence a friction force associated with spontaneous emission. The resolution of this paradox relies on a central idea from special relativity even though our derivation of it is non-relativistic. We examine the possibility that the physics underlying this effect might be explored in an ion trap, via the observation of a superposition of different mass states.

  3. A Rare Case Report of an Unusual Dislocation of Fractured Mandibular Condyle

    OpenAIRE

    Mishra, Madan; Singh, Gaurav

    2015-01-01

    Several cases have been reported regarding superolateral, posterior, or superior dislocation of mandibular condyle. The anteromedial dislocation of fractured condyle is the most common among all. This article reports an unusual and unique case of dislocated fractured mandibular condyle wherein the fractured left condylar head was dislocated to the left anatomic angle of mandible. We have not found a single such case in the world English literature published till date. The presented case falls...

  4. Superolateral Dislocation of Intact Mandibular Condyle: A Case Report and Review of Literature

    OpenAIRE

    Saikrishna, Degala; Shyam Sundar, S.; Mamata, K. S.

    2015-01-01

    Anteromedial fracture dislocation of the mandibular condyle is common but a superolateral dislocation of an intact condyle is quite rare. This type of dislocation is often misdiagnosed or completely overlooked and hence inadequately addressed. We report a case of a 41-year-old male patient who experienced superolateral dislocation of the intact condyle with symphysis fracture and panfacial fracture following a road-traffic accident, and review of literature of superolateral dislocations from ...

  5. Preauricular transmasseteric anteroparotid approach for extracorporeal fixation of mandibular condyle fractures

    Directory of Open Access Journals (Sweden)

    Rajasekhar Gali

    2016-01-01

    Full Text Available Introduction: Free grafting or extracorporeal fixation of traumatically displaced mandibular condyles is sometimes required in patients with severe anteromedial displacement of condylar head. Majority of the published studies report the use of a submandibular, retromandibular or preauricular incisions for the access which have demerits of limited visibility, access and potential to cause damage to facial nerve and other parotid gland related complications. Purpose: This retrospective clinical case record study was done to evaluate the preauricular transmasseteric anteroparotid (P-TMAP approach for open reduction and extracorporeal fixation of displaced and dislocated high condylar fractures of the mandible. Patients and Methods: This retrospective study involved search of clinical case records of seven patients with displaced and dislocated high condylar fractures treated by open reduction and extracorporeal fixation over a 3-year period. The parameters assessed were as follows: a the ease of access for retrieval, reimplantation and fixation of the proximal segment; b the postoperative approach related complications; c the adequacy of anatomical reduction and stability of fixation; d the occlusal changes; and the e TMJ function and radiological changes. Results: Accessibility and visibility were good. Accurate anatomical reduction and fixation were achieved in all the patients. The recorded complications were minimal and transient. Facial nerve (buccal branch palsy was noted in one patient with spontaneous resolution within 3 months. No cases of sialocele or Frey's syndrome were seen. Conclusion: The P-TMAP approach provides good access for open reduction and extracorporeal fixation of severely displaced condylar fractures. It facilitates retrieval, transplantation, repositioning, fixing the condyle and also reduces the chances of requirement of a vertical ramus osteotomy. It gives straight-line access to condylar head and ramus thereby

  6. Preauricular transmasseteric anteroparotid approach for extracorporeal fixation of mandibular condyle fractures.

    Science.gov (United States)

    Gali, Rajasekhar; Devireddy, Sathya Kumar; Venkata, Kishore Kumar Rayadurgam; Kanubaddy, Sridhar Reddy; Nemaly, Chaithanyaa; Dasari, Mallikarjuna

    2016-01-01

    Free grafting or extracorporeal fixation of traumatically displaced mandibular condyles is sometimes required in patients with severe anteromedial displacement of condylar head. Majority of the published studies report the use of a submandibular, retromandibular or preauricular incisions for the access which have demerits of limited visibility, access and potential to cause damage to facial nerve and other parotid gland related complications. This retrospective clinical case record study was done to evaluate the preauricular transmasseteric anteroparotid (P-TMAP) approach for open reduction and extracorporeal fixation of displaced and dislocated high condylar fractures of the mandible. This retrospective study involved search of clinical case records of seven patients with displaced and dislocated high condylar fractures treated by open reduction and extracorporeal fixation over a 3-year period. The parameters assessed were as follows: a) the ease of access for retrieval, reimplantation and fixation of the proximal segment; b) the postoperative approach related complications; c) the adequacy of anatomical reduction and stability of fixation; d) the occlusal changes; and the e) TMJ function and radiological changes. Accessibility and visibility were good. Accurate anatomical reduction and fixation were achieved in all the patients. The recorded complications were minimal and transient. Facial nerve (buccal branch) palsy was noted in one patient with spontaneous resolution within 3 months. No cases of sialocele or Frey's syndrome were seen. The P-TMAP approach provides good access for open reduction and extracorporeal fixation of severely displaced condylar fractures. It facilitates retrieval, transplantation, repositioning, fixing the condyle and also reduces the chances of requirement of a vertical ramus osteotomy. It gives straight-line access to condylar head and ramus thereby permitting perpendicular placement of screws with minimal risk of damage to the facial

  7. Superolateral dislocation of an intact mandibular condyle into the temporal fossa: case report and literature review.

    Science.gov (United States)

    Sharma, Divashree; Khasgiwala, Ankit; Maheshwari, Bharat; Singh, Charanpreet; Shakya, Neelam

    2017-02-01

    Temporomandibular joint dislocation refers to the dislodgement of mandibular condyle from the glenoid fossa. Anterior and anteromedial dislocations of the mandibular condyle are frequently reported in the literature, but superolateral dislocation is a rare presentation. This report outlines a case of superolateral dislocation of an intact mandibular condyle that occurred in conjunction with an ipsilateral mandibular parasymphysis fracture. A review of the clinical features of superolateral dislocation of the mandibular condyle and the possible techniques of its reduction ranging from the most conservative means to extensive surgical interventions is presented. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Open versus closed reduction: diacapitular fractures of the mandibular condyle.

    Science.gov (United States)

    Chrcanovic, Bruno Ramos

    2012-09-01

    The purpose of the study was to review the literature regarding the evolution of current thoughts on management of diacapitular fractures (DFs) of the mandibular condyle. An electronic search in PubMed was undertaken in March 2012. The titles and abstracts from these results were read to identify studies within the selection criteria. Eligibility criteria included studies reporting clinical series of DFs, including both animal and human studies, without date or language restrictions. The search strategy initially yielded 108 references. Twenty-eight studies were identified without repetition within the selection criteria. Additional hand-searching of the reference lists of selected studies yielded three additional papers. The current indications for open reduction and internal fixation (ORIF) of DFs described in the literature are: (a) fractures affecting the lateral condyle with reduction of mandibular height; (b) fractures in which the proximal fragment dislocates laterally out of the glenoid fossa, which cannot be reduced by closed or open treatment of another part of the mandibular fracture. The indications for conservative treatment are: (a) fractures that do not shorten the condylar height (a fracture with displacement of the medial parts of the condyle); (b) undisplaced fractures; (c) comminution of the condylar head, when the bony fragments are too small for stable fixation; and (d) fractures in children. As the temporomandibular joint disk plays an important role as a barrier preventing ankylosis, it is important to reposition the disk (if displaced/dislocated) during the surgical treatment of DFs. The lateral pterygoid muscle should never be stripped from the medially displaced fragment because its desinsertion disrupts circulation to the medial bony fragment, and also because this muscle helps to restore the muscle function after surgery. ORIF of selected DFs improves prognosis by anatomical bone and soft tissue recovery when combined with physical

  9. Femoral Condyle Fracture during Anterior Cruciate Ligament Reconstruction

    Directory of Open Access Journals (Sweden)

    Selahattin Ozyurek

    2015-07-01

    Full Text Available Dear Editor,We have greatly enjoyed reading the case report entitled “‘Femoral Condyle Fracture during Revision of Anterior Cruciate Ligament Reconstruction: Case Report and a Review of Literature in the issue of Arch Bone Jt Surg. 2015;3(2 with great interest. We would like to commend the authors for their detailed and valuable work. Although various case reports have described postoperative distal femur fracture at a range of time intervals (1,2 intraoperative intra-articular distal femur fracture is a unique entity.However, we believe that some important additional observations seem necessary to be contributed through this study. In this article, the authors stated that, to the best of their knowledge, there is no other case report in the literature introducing a femoral condyle fracture during arthroscopic ACL reconstruction or revision reconstruction. Nevertheless, we would like to call the attention of the readers to the fact that that the literature contains one additional case report re‌porting on intraoperative distal femoral coronal plane (Hoffa fracture during primary ACL reconstruction (2. Werner BC and Miller MD presented of case report of an intraoperative distal femoral coronal plane (Hoffa fracture that occurred during independent femoral tunnel drilling and dilation in a primary ACL reconstruction. As in the their case, this type of fracture can occur with appropriately placed femoral tunnels, but the risk can increase with larger graft diameters in patients with smaller lateral femoral condyles The patient was treated with open reduction and internal fixation, without compromise of graft stability and with good recovery of function. We believe that tailoring graft size to the size of the patient is important to prevent similar adverse events.

  10. Operative treatment of lateral humeral condyle fractures in children.

    Science.gov (United States)

    Wirmer, Johannes; Kruppa, Christian; Fitze, Guido

    2012-08-01

    The operative treatment of lateral humeral condyle fractures in children remains controversial. The result of incorrectly treated fractures may lead to complications such as pseudoarthrosis and severe deformity, with considerable functional and cosmetic restrictions. The aim of this study was to determine whether operative treatment of lateral humeral condyle fractures in children using Screw-wires (Orthofix GmbH, Ottobrunn, Germany) has any advantage over treatment with Kirschner wires ("K-wires") (aap-Implantate AG, Berlin, Germany). These results were then compared with operative treatment using lag-screw osteosynthesis. We treated surgically 76 cases of fracture of the lateral humeral condyle in children at the Department of Pediatric Surgery in Dresden between 1989 to 2002 and 2004 to 2008, from which 42 were available for follow-up examination. Within this group, there were seven children that were followed-up twice (in 1996 to 2002). Of these, 21 patients were treated with Screw-wires, and another 21 had K-wires inserted. The results were evaluated according to the Dhillon criteria. Only seven patients (17%) had a fair result in the overall grading according to the Dhillon criteria, four after K-wire and three after Screw-wire osteosyntheses. The remaining patients scored good to excellent results. There were no pseudoarthroses. Six patients (14%) had a varisation in the carrying angle between 10 and 16 degrees (three each procedure), and 15 patients (36%) had no difference in the carrying angle at all. Of these 15 patients, 10 were treated with Screw-wire osteosynthesis. Only one patient (2.4%) had a deficit of more than 10 degrees in elbow joint flexion, while only two (4.8%, one each procedure) had a deficit of more than 10 degrees in elbow joint extension, compared with the uninjured arm. Our results demonstrate that the employment of Screw-wire osteosynthesis is superior to the use of K-wires concerning the carrying angle while scoring alike on the

  11. 78 FR 9010 - Dental Devices; Reclassification of Temporary Mandibular Condyle Prosthesis

    Science.gov (United States)

    2013-02-07

    .... FDA-2012-N-1239] Dental Devices; Reclassification of Temporary Mandibular Condyle Prosthesis AGENCY... condyle prostheses into class III, based on the recommendation of a Dental Products Panel (the Panel... Administration, Dental Products Advisory Panel Meeting Transcript, February 12, 1997; http://www.accessdata.fda...

  12. Function impairment and pain after closed treatment of fractures of the mandibular condyle

    NARCIS (Netherlands)

    Dijkstra, P.U.; Stegenga, B.; de Bont, L.G.; Bos, R.R.

    Background: To determine the prognosis of fractures of the mandibular condyle after closed treatment. Methods: Patients (n = 144) with a fracture of the mandibular condyle, all treated closed, were included in the study. Fracture types and position of the fracture parts were determined on

  13. Osteochondroma of the mandibular condyle: surgical excision followed by occlusal stabilization.

    Science.gov (United States)

    Yoo, Ji-Yeon; Choi, Byung-Joon; Kwon, Yong-Dae; Lee, Deok-Won; Ohe, Joo-Young; Suh, Joon-Ho

    2012-03-01

    Osteochondroma of the mandibular condyle in adults can be treated by surgical excision, condylectomy followed by costochondral graft or orthognathic surgery. Such complex treatment plan may not be appropriate for patients with old age, affected with chronic osteochondroma of the condyle. In this clinical report, we present a patient with osteochondroma of the condyle treated by surgical excision. The patient's postoperative occlusion was a contraindication for orthognathic surgery because of the severe abrasion of the teeth and the chronic compensation of the dentition to the deviated mandible. Surgical excision of the lesion was carried out under general anesthesia, and the remaining condylar head was salvaged as much as possible. No graft materials or posthodontic condyle reconstruction was carried out. Because there was no occlusal stop to secure the mandible in a centric relation position of the condyle, a stabilization splint was delivered to position the condyle in a relatively stable position. The stability of the condyle position was evaluated by follow-up cone beam computed tomographic scans of the pathologic and the contralateral condyle, along with clinical factors such as occlusal contact points and mandible movements assayed by ARCUSdigma (KaVo). After significant condylar position was achieved, full prosthodontic reconstruction was performed to both the patient's and the dentist's satisfaction.

  14. Acoustics of friction

    Science.gov (United States)

    Akay, Adnan

    2002-04-01

    This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of

  15. The application of the Risdon approach for mandibular condyle fractures.

    Science.gov (United States)

    Nam, Seung Min; Lee, Jang Hyun; Kim, Jun Hyuk

    2013-07-06

    Many novel approaches to mandibular condyle fracture have been reported, but there is a relative lack of reports on the Risdon approach. In this study, the feasibility of the Risdon approach for condylar neck and subcondylar fractures of the mandible is demonstrated. A review of patients with mandibular condylar neck and subcondylar fractures was performed from March 2008 to June 2012. A total of 25 patients, 19 males and 6 females, had 14 condylar neck fractures and 11 subcondylar fractures. All of the cases were reduced using the Risdon approach. For subcondylar fractures, reduction and fixation with plates was done under direct vision. For condylar neck fractures, reduction and fixation was done with the aid of a trochar in adults and a percutaneous threaded Kirschner wire in children. There were no malunions or nonunions revealed in follow-up care. Mild transient neuropraxia of the marginal mandibular nerve was seen in 4 patients, which was resolved within 1-2 months. The Risdon approach is a technique for reducing the condylar neck and subcondylar fractures that is easy to perform and easy to learn. Its value in the reduction of mandibular condyle fractures should be emphasized.

  16. Biomechanical and morphometric evaluation of occipital condyle for occipitocervical segmental fixation

    International Nuclear Information System (INIS)

    Hong, Jae-Taek; Takigaya, Tomoyuki; Sugisaki, Keizo; Orias, A.A.E.; Inoue, Nozomu; An, H.S.

    2011-01-01

    Two recent novel techniques of occipital fixation are the occipitoatlantal (C0-C1) transarticular screw technique and the direct occipital condyle screw technique. The present study evaluated and compared the biomechanical stability of the direct occipital condyle screw and C0-C1 transarticular screw with the established method for craniocervical spine fixation using the midline occipital keel screw and C1 lateral mass screw. Morphometric evaluation of the occipital condyle and the hypoglossal canal was performed to avoid hypoglossal nerve injury during the screw placement. Thirteen recently frozen cadaveric specimens were used. The occipital condyle anatomy and the hypoglossal canal dimension were measured using reconstructed computed tomography images. Insertion torque and pullout strength were evaluated to compare the midline occipital keel screw, C0-C1 transarticular screw, C1 lateral mass screw, and direct occipital condyle screw. The dimensions of the occipital condyle allow use of a 3.5 or 4.0-mm diameter screw. Mean pullout strength was 1619.6 N for the midline occipital keel screw, 870.7 N for the C0-C1 transarticular screw, 707.0 N for the C1 lateral mass screw, and 431.7 N for the direct occipital condyle screw. Mean insertion torque was 0.55 Nm for the midline occipital keel screw, 0.32 Nm for the C0-C1 transarticular screw, 0.14 Nm for the C1 lateral mass screw, and 0.11 Nm for the direct occipital condyle screw. The condylar anatomy allows direct insertion of the occipital condyle screw and C0-C1 transarticular screw. These techniques are suitable options for the treatment of craniovertebral junction instabilities in selected patients. (author)

  17. Three-dimensional computerized tomography in mandibular condyle fractures

    International Nuclear Information System (INIS)

    Bermeo, Fausto; Salazar, Abad

    2003-01-01

    Now, car accidents are so commons, this associated to the high technology in produce automobiles make this type of accidents so serious and the consequences of mandibular condyle fractures are more commons and with more gravity, some of these patients, generally need a traqueostomy to be operated, that is why every second that we can save during the surgery is important. The normal exams as X rays and simple TAC give as an important idea but no complete, on the contrary the three-dimensional TAC permits to observe every damages and its exact location, this contribute to make a better surgery organization, the number and type of plates that we have to put and the better way to treat each case, that contribute to reduce time in operating theatre which is in benefit of the patient, diminishing risks in serious patients as they are, that is why we recommend the utilization of the three-dimensional TAC. (The author)

  18. Medial Condyle Fracture (Kilfoyle Type III of the Distal Humerus with Transient Fishtail Deformity after Surgery

    Directory of Open Access Journals (Sweden)

    Motoki Sonohata

    2017-01-01

    Full Text Available A “Fishtail deformity” is one of the well-known complications following pediatric lateral condyle or supracondylar fractures of the humerus. We herein report a case of medial condyle fracture (Kilfoyle type III in an 11-year-old boy. He had a transient “fishtail deformity” of the trochlear groove after open reduction and internal fixation. As occurred in the current case, the bone remodeling and the improvement of ischemia of the trochlea after medial condyle fracture may be associated with the likelihood of recovery from transient “fishtail deformity.”

  19. [Biomechanical analysis on healing process of sagittal fracture of the mandibular condyle after rigid fixation].

    Science.gov (United States)

    Jing, Jie; Qu, Ai-li; Ding, Xiao-mei; Hei, Yu-na

    2015-04-01

    To analyze the biomechanical healing process on rigid fixation of sagittal fracture of the mandibular condyle (SFMC), and to provide guidelines for surgical treatment. Three-dimensional finite element model (3D-FEAM) of mandible and condyle was established. The right condyle was simulated as SFMC with 0.1 mm space across the condyle length ways. The 3D-FEAM of rigid fixation was established. The biomechanical factors such as stress distribution of condylar surface, displacement around fracture, stress on the plate and stress shielding were calculated during 0, 4, 8 and 12-week after rigid fixation. The maximum equivalent stress of normal condyle was located at the area of middle 1/3 of condylar neck. The maximum equivalent stress at 0-week after fixation was 23 times than that on normal condyle. They were located at the condylar stump and the plate near inferior punctual areas of fracture line. There were little stress on the other areas. The maximum equivalent stress at 4, 8 and 12-week was approximately 6 times than that on normal condyle. They were located at the areas same as the area at 0-week. There were little stress on the other areas at the condyle. The maximum total displacement and maximum total corner were increased 0.57-0.75 mm and 0.01-0.09° respectively during healing process. The maximum equivalent stress at 0-week on the condylar trump was 5-6 times compared with that at 4, 8, and 12-week. The maximum equivalent stress, maximum total displacement and maximum total corner on the fractured fragment were not changed significantly during healing process. The maximum equivalent stress at 0-week on the plate was 7-9 times compared with that at 4, 8, 12-week. The stress of the condyle and stress shielding of the plate may be the reasons of absorbing and rebuilding on the condyle in healing process of SFMC. The biomechanical parameters increase obviously at 4-week after fixation. Elastic intermaxillary traction is necessary to decrease total displacement

  20. Recurrent simple bone cyst of the mandibular condyle: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung A; Koh, Kwang Joon [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, and Institute of Oral Bio Science, Chonbuk National University, Jeonju (Korea, Republic of)

    2013-03-15

    Cysts of the mandibular condyle are rare and can be difficult to diagnose and treat. Clinically, a simple bone cyst is asymptomatic and often discovered incidentally on routine radiographic examination. This report shows an atypical simple bone cyst occurring in the mandibular condyle showing recurrence after surgical curettage. Radiologically, this lesion involving the mandibular condyle should be distinguished from other similar lesions such as a chondriome, a central giant cell granuloma, and an aneurysmal bone cyst. Radiographic assessment was useful for forecasting the prognosis of a simple bone cyst. Possible reasons for the recurrence were discussed radiographically.

  1. Radiographic changes in the condyle of the temporomandibular joint in psoriatic arthritis

    International Nuclear Information System (INIS)

    Koenoenen, M.; Helsinki Univ.

    1987-01-01

    One hundred and ten patients with psoriatic arthritis (PA) and 100 matched control patients were examined by using orthopantomography to discover radiographic changes in the condyle of the temporomandibular joint (TMJ). 31% of the PA patients and 13% of the control patients had radiographic changes in the condyle of the TMJ. The most common radiographic finding in PA patients was unilateral erosion of the condyle. Of the radiographic changes in the PA group, cortical erosions correlated negatively with age, whereas osteophytes correlated positively with the duration of PA. (orig.)

  2. Occipital condyle metastasis: an unusual clinical presentation in carcinoma of the lung

    International Nuclear Information System (INIS)

    Pasricha, R.; Mohanty, P.P.; Madan, R.C.; Datta, N.R.

    2005-01-01

    Metastases to the base of the skull and occipital condyle metastases are uncommon as a presenting feature of malignancy. Lung cancers are known for their metastatic potential to various sites, some of which could be the only presenting feature of the underlying malignancy. However, occipital condyle metastases are very rare and to the best of our knowledge, metastases to this site from carcinoma of the lung, as a presenting feature, have never been reported in the literature. The present case report describes the clinical, radiological and the therapeutic interventions that were undertaken in a patient presenting with lung cancer who had solely the features of occipital condyle metastasis

  3. Origins of Rolling Friction

    Science.gov (United States)

    Cross, Rod

    2017-01-01

    When a hard object rolls on a soft surface, or vice versa, rolling friction arises from deformation of the soft object or the soft surface. The friction force can be described in terms of an offset in the normal reaction force or in terms of energy loss arising from the deformation. The origin of the friction force itself is not entirely clear. It…

  4. Mucoid degeneration of the anterior cruciate ligament with erosion of the lateral femoral condyle

    International Nuclear Information System (INIS)

    Melloni, Pietro; Valls, Rafael; Yuguero, Mariano; Saez, Amparo

    2004-01-01

    We report a case of a mucoid degeneration of the anterior cruciate ligament (ACL) that produced osseous erosion of the medial aspect of the lateral femoral condyle. The MRI findings and differential diagnosis are discussed. (orig.)

  5. AN ANATOMICAL PERSPECTIVE OF HUMAN OCCIPITAL CONDYLES AND FORAMEN MAGNUM WITH NEUROSURGICAL CORRELATES

    OpenAIRE

    Gaurav; Divya; Abha

    2014-01-01

    AIMS: Knowledge of condylar anatomy helps the surgeon in making important decisions regarding extent and direction of condylar drilling and minimizing injury and retraction of neural structures. Important preoperative information includes length, width, axis/directions and overriding of occipital condyle in foramen magnum, relationships of condyles to foramen magnum and to hypoglossal canal. The antero-posterior and transverse diameters of foramen magnum and amount of over...

  6. Dislocation of a mandibular condyle in the middle cranial fossa, diagnosed 54 years after trauma

    OpenAIRE

    De Mol, Antoni; Nicolielo, Laura; Ghekiere, Olivier; Jacobs, Reinhilde; Politis, Constantinus

    2017-01-01

    Abstract Dislocation of the mandibular condyle into the middle cranial fossa is a rare complication of mandibular trauma. We report the remarkable case of a 63-year-old patient in whom trauma 54 years prior to consultation resulted in intrusion of the right mandibular condyle into the middle cranial fossa. The diagnosis was missed because of insufficient data provided by conventional radiographies. Failure of timely diagnosis and lack of appropriate treatment resulted in temporomandibular joi...

  7. A study of repair cartilage from osteochondrotic humeral condyles of swine: preliminary report.

    OpenAIRE

    Nakano, T; Aherne, F X

    1992-01-01

    A total of 16 animals, including 12 lame and four normal boars, were used. All lame boars had severe osteochondrotic humeral condyles in which repair cartilage tissues originating from subchondral bone were observed. Quantitative chemical studies of repair cartilage and normal cartilage were carried out using humeral condyles from four selected animals (two lame and two normal boars, respectively). The repair cartilage contained a higher concentration of collagen and lower concentration of pr...

  8. [Design and fabrication of the custom-made titanium condyle by selective laser melting technology].

    Science.gov (United States)

    Chen, Jianyu; Luo, Chongdai; Zhang, Chunyu; Zhang, Gong; Qiu, Weiqian; Zhang, Zhiguang

    2014-10-01

    To design and fabricate the custom-made titanium mandibular condyle by the reverse engineering technology combined with selective laser melting (SLM) technology and to explore the mechanical properties of the SLM-processed samples and the application of the custom-made condyle in the temporomandibular joint (TMJ) reconstruction. The three-dimensional model of the mandibular condyle was obtained from a series of CT databases. The custom-made condyle model was designed by the reverse engineering software. The mandibular condyle was made of titanium powder with a particle size of 20-65 µm as the basic material and the processing was carried out in an argon atmosphere by the SLM machine. The yield strength, ultimate strength, bending strength, hardness, surface morphology and roughness were tested and analyzed. The finite element analysis (FEA) was used to analyze the stress distribution. The complex geometry and the surface of the custom-made condyle can be reproduced precisely by the SLM. The mechanical results showed that the yield strength, ultimate strength, bending strength and hardness were (559±14) MPa, (659±32) MPa, (1 067±42) MPa, and (212±4)HV, respectively. The surface roughness was reduced by sandblast treatment. The custom-made titanium condyle can be fabricated by SLM technology which is time-saving and highly digitized. The mechanical properties of the SLM sample can meet the requirements of surgical implant material in the clinic. The possibility of fabricating custom-made titanium mandibular condyle combined with the FEA opens new interesting perspectives for TMJ reconstruction.

  9. Anatomic variability of the vascularized composite osteomyocutaneous flap from the medial femoral condyle: an anatomical study

    Directory of Open Access Journals (Sweden)

    Trung-Hau Le Thua

    2014-12-01

    Full Text Available Aim: The anatomical study and clinical application for the vascularized corticoperiosteal flap from the medial femoral condyle have been performed and described previously. Although prior studies have described the composite osteomyocutaneous flap from the medial femoral condyle, a detailed analysis of the vascularity of this region has not yet been fully evaluated. Methods: This anatomical study described the variability of the arteries from the medial femoral condyle in 40 cadaveric specimens. Results: The descending genicular artery (DGA was found in 33 of 40 cases (82.5%. The  superomedial genicular artery (SGA was present in 10 cases (25%. All 33 cases (100% of the DGA had articular branches to the periosteum of the medial femoral condyle. Muscular branches and saphenous branches of the DGA were present in 25 cases (62.5% and 26 cases (70.3%, respectively. Conclusion: The current study demonstrates that the size and length of the vessels to the medial femoral condyle are sufficient for a vascularized bone flap. A careful preoperative vascular assessment is essential prior to use of the vascularized composite osteomyocutaneous flap from the medial femoral condyle, because of the considerable anatomical variations in different branches of the DGA.

  10. Overlooked metastatic lesions of the occipital condyle: a missed case treasure trove.

    Science.gov (United States)

    Loevner, L A; Yousem, D M

    1997-01-01

    Radiologic images obtained in nine patients with known primary cancer and occipital or head and neck pain were retrospectively reviewed after having been initially interpreted as normal. Imaging studies included head computed tomography (CT) in five cases, brain magnetic resonance (MR) imaging in six cases, cervical spine CT and MR imaging in five cases, radiography in two cases, and scintigraphy in two cases. This reevaluation demonstrated lesions of the occipital condyles in all patients. Seven patients had unilateral occipital condyle masses, and two patients had bilateral condyle lesions. Lesions were found to either involve only the occipital condyle (n = 4), extend to the adjacent occipital bone (n = 3), or extend to the ipsilateral clivus (n = 2). Misinterpretation of radiologic examinations resulted in an average delay in diagnosis of 10 weeks from the onset of symptoms to definitive therapy (irradiation). It is important to evaluate the occipital condyles in all patients with occipital pain, especially those with cancer. Neoplastic disease involving the occipital condyles is not common; however, it is frequently missed at imaging. Careful review of unenhanced sagittal and axial T1-weighted MR images and of the inferior sections from axial head CT studies will make it possible to avoid this potential pitfall.

  11. [Evaluation of the clinical results of non-surgical treatment for pediatric sagittal fracture of mandibular condyle].

    Science.gov (United States)

    Liu, Chang-kui; Tan, Xin-ying; Xu, Juan; Liu, Hua-wei; Liu, San-xia; Hu, Min

    2013-11-01

    To investigate the clinical results of occlusal splint in the treatment of sagittal fracture of mandibular condyle (SFMC) in children. Thirty-nine patients (48 condyles)aged 3-8 years with sagittal fracture of mandibular condyle were included in this study. All the patients were treated by occlusal splint.Slight open occlusion was maintained by occlusal splint for 3-6 months. Clinical and radiological examination was performed six mouths and every year after treatment. Good mandibular function was observed in 39 patients. Maximal mouth opening over 35 mm was achieved at 6 months. But 11 of the 39 patients presented with deviation on mouth opening at 6 months. The radiology showed an complete remodeling in 32 condyles (28 patients) and partial remodeling in 16 condyles (11 patients). Poor remodelling was not observed in any patients. Good clinical results can be obtained by using occlusal splint in the treatment of pediatric sagittal fracture of mandibular condyle.

  12. Diagnosis of occipital condyle fractures; Diagnostik von Frakturen der Okzipitalkondylen

    Energy Technology Data Exchange (ETDEWEB)

    Hefele-Roedel, B. [Radiologische Klinik Innenstadt, Univ. Muenchen (Germany); Vogl, T.J. [Radiologische Klinik Innenstadt, Univ. Muenchen (Germany); Lochbuehler, H. [Dr. v. Haunersches Kinderspital, Kinderchirurgische Klinik, Univ. Muenchen (Germany); Lissner, J. [Radiologische Klinik Innenstadt, Univ. Muenchen (Germany)

    1995-01-01

    Following the conventional X-ray diagnosis of the skull and upper cervical spine, CT proved to be the primary diagnostic method after a skull and brain injury: For all 4 cases we succeeded in detecting the occipital condyle fracture and in determing its size and location by reconstructions (coronal, sagittal, 3-D). In the case of complex occompanying injuries like soft tissue hematomas (cerebral, in the spinal cord, and the soft tissue of the neck) or for the detection of brain stem contusion, MRT had significant advantages. MRT can offer a higher image quality in soft tissue, especially in the spinal cord and the brain. (orig.) [Deutsch] Im Anschluss an die konventionelle Roentgendiagnostik des Schaedels und der Halswirbelsaeule, erwies sich die Computertomographie als primaer einzusetzendes diagnostisches Verfahren, nach erlittenem Schaedel-Hirn-Trauma. In allen Faellen gelang der exakte Frakturnachweis an den Okzipitalkondylen, die Bestimmung des Frakturausmasses und die genaue Frakturlokalisation in Rekonstruktionen (koronar, sagittal, 3-D). Bei komplexen Begleitverletzungen, wie Blutungen (zerebral, spinal und in den Halsweichteilen) oder zum Nachweis einer Hirnstammkontusion, erwies sich der Einsatz der MRT als vorteilhaft. Mit der MRT laesst sich ein deutlich hoeherer Weichteilkontrast, insbesondere spinal und zerebral, erzielen. (orig.)

  13. Nontraumatic bifid mandibular condyles in asymptomatic and symptomatic temporomandibular joint subjects

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Bong Hae; Jung, Yun Hoa [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2013-03-15

    This study was performed to determine the prevalence of bifid mandibular condyles (BMCs) in asymptomatic and symptomatic temporomandibular joint (TMJ) subjects with no traumatic history, and to assess their impact on clinical and radiographic manifestations of TMJ. A total of 3,046 asymptomatic and 4,378 symptomatic patients were included in the study. Cone-beam computed tomography (CBCT) images were reviewed for bifid condyles. T-tests were used to compare the frequency of BMCs when stratified by symptom, gender, and side. In BMC patients, the clinical features of pain and noise, osseous changes, and parasagittal positioning of the condyles were compared between the normally shaped condyle side and the BMC side using chi-squared tests. Fifteen (0.49%) asymptomatic and 22 (0.50%) symptomatic patients were found to have BMCs. Among the bilateral cases, the number of condyles were 19 (0.31%) and 25 (0.29%), respectively. No statistically significant differences were found between asymptomatic and symptomatic patients, between female and male patients, or between the right and left sides (p>0.05). Compared with the normally shaped condyle side, the BMC side showed no statistically significant differences in the distribution of pain and noise, parasagittal condylar position, or condylar osseous changes, with the exception of osteophytes. In the symptomatic group, osteophytes were found more frequently on the normally shaped condyle side than the BMC side (p<0.05). BMCs tended to be identified as an incidental finding. The presence of BMC would not lead to any TMJ symptoms or cause osseous changes.

  14. Nontraumatic bifid mandibular condyles in asymptomatic and symptomatic temporomandibular joint subjects

    International Nuclear Information System (INIS)

    Cho, Bong Hae; Jung, Yun Hoa

    2013-01-01

    This study was performed to determine the prevalence of bifid mandibular condyles (BMCs) in asymptomatic and symptomatic temporomandibular joint (TMJ) subjects with no traumatic history, and to assess their impact on clinical and radiographic manifestations of TMJ. A total of 3,046 asymptomatic and 4,378 symptomatic patients were included in the study. Cone-beam computed tomography (CBCT) images were reviewed for bifid condyles. T-tests were used to compare the frequency of BMCs when stratified by symptom, gender, and side. In BMC patients, the clinical features of pain and noise, osseous changes, and parasagittal positioning of the condyles were compared between the normally shaped condyle side and the BMC side using chi-squared tests. Fifteen (0.49%) asymptomatic and 22 (0.50%) symptomatic patients were found to have BMCs. Among the bilateral cases, the number of condyles were 19 (0.31%) and 25 (0.29%), respectively. No statistically significant differences were found between asymptomatic and symptomatic patients, between female and male patients, or between the right and left sides (p>0.05). Compared with the normally shaped condyle side, the BMC side showed no statistically significant differences in the distribution of pain and noise, parasagittal condylar position, or condylar osseous changes, with the exception of osteophytes. In the symptomatic group, osteophytes were found more frequently on the normally shaped condyle side than the BMC side (p<0.05). BMCs tended to be identified as an incidental finding. The presence of BMC would not lead to any TMJ symptoms or cause osseous changes.

  15. [Outcome of endoscopically assisted surgical treatment of mandibular condyle fractures: a retrospective study of 22 patients].

    Science.gov (United States)

    Prade, V; Seguin, P; Boutet, C; Alix, T

    2014-12-01

    The condylar region is a frequent localization of mandibular fractures; there are various types of management. Mini-invasive endoscopic surgery is an alternative to open reduction. We had as goal to evaluate the outcome of this technique. We performed a monocentric retrospective study of patients consecutively operated for a condylar fracture (type II to V in the Spiessl and Schroll classification) with intraoral route and endoscopic assistance, during 30 months. We assessed the functional and radiological outcomes, and the complications. Twenty-two patients (25 fractures) were included. Seventeen patients (19 fractures) could be followed (mean follow-up: 16.7 months). The mean values were: interincisal opening, 45mm (±8.4); protrusion, 8.3mm (±1.9); ipsilateral excursion of the jaw: 8.6mm (±2); contralateral excursion: 8.7mm (±4). Three routes were used combined with a preauricular approach. The fracture reduction was good for 10 of the 19 fractures and poor for 3. The complications were: 3 cases of infection, 1 case of fixation failure with good consolidation; for combined approaches: 2 cases of temporary facial palsy and 2 cases of Frey syndrome. Endoscopic assistance for the surgical management of the fracture of mandibular condyle is a reliable technique, with a good functional outcome, and a low rate of specific complications, especially for facial nerve lesion or esthetic outcome. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  16. Proximity friction reexamined

    International Nuclear Information System (INIS)

    Krappe, H.J.

    1989-01-01

    The contribution of inelastic excitations to radial and tangential friction form-factors in heavy-ion collisions is investigated in the frame-work of perturbation theory. The dependence of the form factors on the essential geometrical and level-density parameters of the scattering system is exhibited in a rather closed form. The conditions for the existence of time-local friction coefficients are discussed. Results are compared to form factors from other models, in particular the transfer-related proximity friction. For the radial friction coefficient the inelastic excitation mechanism seems to be the dominant contribution in peripheral collisions. (orig.)

  17. Volumetric analysis of the mandibular condyle using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bayram, Mehmet, E-mail: dtmehmetbayram@yahoo.com [Karadeniz Technical University, Faculty of Dentistry, Department of Orthodontics, 61080 Trabzon (Turkey); Kayipmaz, Saadettin; Sezgin, Oemer Said [Karadeniz Technical University, Faculty of Dentistry, Department of Oral Radiology, Trabzon (Turkey); Kuecuek, Murat [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Chemistry, Trabzon (Turkey)

    2012-08-15

    Objective: The aim was to determine the accuracy of volumetric analysis of the mandibular condyle using cone-beam computed tomography (CBCT). Materials and methods: Five dry mandibles containing 9 condyles were used. CBCT scans of the mandibles and an impression of each condylar area were taken. The physical volumes of the condyles were calculated as the gold standard using the water displacement technique. After isolating, the condylar volume was sectioned in the sagittal plane, and 0.3 mm thick sections with 0.9 mm intervals were obtained from 3D reconstructions. Using the Cavalieri principle, the volume of each condyle was estimated from the CBCT images by three observers. The accuracy of the CBCT volume measurements and the relation agreements between the results of the three observers were assessed using the Wilcoxon Signed Rank test and Pearson correlation test. The level of statistical significance was set at 0.05. Results: The results of the Pearson correlation showed that there were highly significant positive correlations between the observers' measurements. According to the results of the Wilcoxon Signed Rank test comparing the physical and observers' measurements, there were no statistically significant differences (p > 0.05). Conclusion: The Cavalieri principle, used in conjunction with a planimetry method, is a valid and effective method for volume estimation of the mandibular condyle on CBCT images.

  18. Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Alexandre Perez; Perrella, Andreia; Arita, Emiko Saito; Pereira, Marlene Fenyo Soeiro de Matos; Cavalcanti, Marcelo de Gusmao Paraiso, E-mail: alexperez34@gmail.co [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Odontologia. Dept. de Estomatologia

    2010-10-15

    There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: axial, coronal and sagittal multiplanar reconstruction (MPR); and sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill no.1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis. (author)

  19. Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars.

    Science.gov (United States)

    Mah, Deuk-Hyun; Kim, Su-Gwan; Moon, Seong-Yong; Oh, Ji-Su; You, Jae-Seek

    2015-02-01

    We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures. This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured. Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; Pcondyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; Pfractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures.

  20. Volumetric analysis of the mandibular condyle using cone beam computed tomography

    International Nuclear Information System (INIS)

    Bayram, Mehmet; Kayipmaz, Saadettin; Sezgin, Ömer Said; Küçük, Murat

    2012-01-01

    Objective: The aim was to determine the accuracy of volumetric analysis of the mandibular condyle using cone-beam computed tomography (CBCT). Materials and methods: Five dry mandibles containing 9 condyles were used. CBCT scans of the mandibles and an impression of each condylar area were taken. The physical volumes of the condyles were calculated as the gold standard using the water displacement technique. After isolating, the condylar volume was sectioned in the sagittal plane, and 0.3 mm thick sections with 0.9 mm intervals were obtained from 3D reconstructions. Using the Cavalieri principle, the volume of each condyle was estimated from the CBCT images by three observers. The accuracy of the CBCT volume measurements and the relation agreements between the results of the three observers were assessed using the Wilcoxon Signed Rank test and Pearson correlation test. The level of statistical significance was set at 0.05. Results: The results of the Pearson correlation showed that there were highly significant positive correlations between the observers’ measurements. According to the results of the Wilcoxon Signed Rank test comparing the physical and observers’ measurements, there were no statistically significant differences (p > 0.05). Conclusion: The Cavalieri principle, used in conjunction with a planimetry method, is a valid and effective method for volume estimation of the mandibular condyle on CBCT images.

  1. Analysis of patterns and treatment strategies for mandibular condyle fractures: review of 175 condyle fractures with review of literature.

    Science.gov (United States)

    Reddy, N Viveka V; Reddy, P Bhaskar; Rajan, Ritesh; Ganti, Srinivas; Jhawar, D K; Potturi, Abhinand; Pradeep

    2013-09-01

    This study aims to evaluate incidence, patterns and epidemiology of mandibular condylar fractures (MCF) to propose a treatment strategy for managing MCF and analyze the factors which influence the outcome. One hundred and seventy-five MCF's were evaluated over a four year period and their pattern was recorded in terms of displacement, level of fracture, age of incidence and dental occlusion. Of the 2,718 facial bone fractures, MCF incidence was the third most common at 18.39 %. Of 175 MCF 58.8 % were unilateral and 41.12 % were bilateral. 67 % of bilateral fractures and 43.8 % of unilateral fractures were associated with midline symphysis and contralateral parasymphysis fractures respectively. Most of the MCF was seen in the age group of above 16 years and 50 % of them were at subcondylar level (below the neck of the condyle). Majority of MCF sustained due to inter personal violence were undisplaced (72.7 %) and contrary to this majority of MCF sustained during road traffic accident were displaced. 62.9 % of total fractures required open reduction and rigid fixation and 37.1 % were managed with closed reduction. 80 % of MCF managed with closed reduction were in the age group of below 16 years. From this study it can be concluded that the treatment algorithm proposed for managing MCF is reliable and easy to adopt. We observed that absolute indication for open reduction of MCF is inability to achieve satisfactory occlusion by closed method and absolute contraindication for open reduction is condylar head fracture irrespective of the age of the patient.

  2. Sex Prediction using Foramen Magnum and Occipital Condyles Computed Tomography Measurements in Sudanese Population

    Directory of Open Access Journals (Sweden)

    Usama Mohamed El-Barrany

    2016-12-01

    Full Text Available Sex determination is important in establishing the identity of an individual. The foramen magnum is an important landmark of the skull base. The present research aimed to study the value of foramen magnum measurements to determine sex using computed tomography (CT among Sudanese individuals. Foramen magnum CT scans of 400 Sudanese individuals (200 males and 200 females aged 18 - 83 years were included in this study. Foramen magnum (length and width, right occipital condyle (length and width, left occipital condyle (length and width, minimum intercondylar distance, maximum bicondylar distance and maximum medial intercondylar distance were measured. All data were subjected to discriminant functions analysis. All nine measurements were significantly higher in males than females. Among these measurements, the right condyle length, minimum intercondylar distance, and foramen magnum width were able to determine sex in Sudanese individuals with an accuracy rate of 83 %.

  3. Morphological changes of the mandibular condyle in patients with temporomandibular joint disorder using magnetic resonance imaging

    International Nuclear Information System (INIS)

    Itoh, Shiori

    1994-01-01

    The morphological changes of the mandibular condyle in patients with temporomandibular joint disorder were studied. The subjects were 420 patients (103 males and 317 females, 8 to 80 years of age, mean age 39.8 years) who were clinically diagnosed as temporomandibular joint disorder. MR imaging was performed with a GE-Signa 1.5 Tesla MR imaging system using the body coil as a transmitter and 3-inch bilateral surface coils. The patients were examined by a multiplanar gradient echo technique in a closed-loop cine fashion on both sagittal and coronal planes. The results obtained were as follows: 1) Morphological changes of the mandibular condyle were detected in 47.0% of the patients. The predominant morphological changes were then formation of osteophyte and marginal proliferation (65.8%). 2) The incidence of morphological changes in the mandubular condyle did not show any significant difference between male and female, and tended to be higher in patients over 40 years of age, and the incidence in patients under 20 years of age was lower, compared to that in patients from 20 to 39 years of age. 3) The incidence of morphological changes in patients with anterior disk displacement without reduction was higher than in those with anterior disk displacement with reduction (P<0.001). The incidence of morphological changes in patients with rotational disk displacement was higher than in those with medial disk displacement (P<0.001). 4) The anterior translation of mandibular condyle was influenced more by anterior disk displacement rather than by morphological changes. From these results. it is suggested that simultaneous bilateral condyle pseudodynamic MR imaging was useful in the diagnosis of internal derangement, evaluation of morphological changes and assessment of motional abnormality of the condyle. (author)

  4. Size, shape and age-related changes of the mandibular condyle during childhood

    Energy Technology Data Exchange (ETDEWEB)

    Karlo, Christoph A. [University Children' s Hospital Zurich, Department of Diagnostic Imaging, Zurich (Switzerland); University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Stolzmann, Paul [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Habernig, Sandra; Kellenberger, Christian J. [University Children' s Hospital Zurich, Department of Diagnostic Imaging, Zurich (Switzerland); Mueller, Lukas [University of Zurich, Clinics for Orthodontics and Paediatric Dentistry, Zurich (Switzerland); Saurenmann, Traudel [University Children' s Hospital Zurich, Department of Rheumatology, Zurich (Switzerland)

    2010-10-15

    To determine age-related differences in the size and shape of the mandibular condyle in children to establish anatomical reference values. A total of 420 mandibular condyles in 210 children (mean age, 7 years) were retrospectively analysed by using computed tomography (CT) imaging. The greatest left-right (LRD) and anterior-posterior (APD) diameters and the anteversion angles (AA) were measured by two readers. An APD/LRD ratio was calculated. The shape of the condyles was graded into three types on sagittal images. Correlations of parameters with the children's age were assessed by using Pearson's correlation analyses. The LRD (mean, 14.1 {+-} 2.4 mm), APD (mean, 7.3 {+-} 1.0 mm) and LRD/APD ratio (mean, 1.9 {+-} 0.3) increased (r{sub LRD} = 0.70, p < 0.01; r{sub APD} = 0.56, p < 0.01; r{sub rat} = 0.28, p < 0.01) while the AA (mean, 27 {+-} 7 ) decreased significantly (r{sub antang} = -0.26, p < 0.001) with age. The condylar shape as determined on sagittal images correlated significantly with age (r = 0.69, p < 0.05). Boys had significantly higher anteversion angles (p < 0.01), greater LRDs (p < 0.05) and greater mean ratios (p < 0.05). The mandibular condyle is subject to significant age-related changes in size and shape during childhood. As the size of the condyles increases with age, the anteversion angles decrease and the shape of the condyle turns from round to oval. (orig.)

  5. Post-traumatic bifid mandibular condyle: A case report and literature review

    International Nuclear Information System (INIS)

    Woo, Min Ho; Yoon, Kyu Ho; Park, Kwan Soo; Park, Jae An

    2016-01-01

    Bifid mandibular condyle (BMC) is an uncommon morphological variant of the mandibular condyle. Although authors have proposed various etiologies for BMC, no consensus has emerged. In addition, varying findings have been reported regarding the epidemiological parameters of BMC (e.g., prevalence, gender ratio, and age), possibly due to its low incidence. BMC is occasionally associated with symptoms of the temporomandibular joint, such as ankylosis, pain, and trismus; however, it is difficult to detect this condition on conventional radiographs. This study reports a case of BMC with radiographic findings, and reviews the literature on the epidemiology of BMC

  6. Post-traumatic bifid mandibular condyle: A case report and literature review

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Min Ho; Yoon, Kyu Ho; Park, Kwan Soo; Park, Jae An [Dept. of Oral and Maxillofacial Surgery, Sanggye Paik Hospital, College of Medicine, Inje University, Seoul (Korea, Republic of)

    2016-09-15

    Bifid mandibular condyle (BMC) is an uncommon morphological variant of the mandibular condyle. Although authors have proposed various etiologies for BMC, no consensus has emerged. In addition, varying findings have been reported regarding the epidemiological parameters of BMC (e.g., prevalence, gender ratio, and age), possibly due to its low incidence. BMC is occasionally associated with symptoms of the temporomandibular joint, such as ankylosis, pain, and trismus; however, it is difficult to detect this condition on conventional radiographs. This study reports a case of BMC with radiographic findings, and reviews the literature on the epidemiology of BMC.

  7. Morphology of the lateral pterygoid muscle associated to the mandibular condyle in the human prenatal stage.

    Science.gov (United States)

    Carranza, Miriam L; Carda, Carmen; Simbrón, Alicia; Quevedo, María C Sánchez; Celaya, Gabriela; de Ferraris, Maria Elsa Gómez

    2006-01-01

    The lateral pterygoid muscle (LPM) inserts at the condyle and the articular disc and plays a central role in mandibular movement via the Temporomandibular Articular Complex. The aim of this study was to examine the association between the morphology of LPM muscular fascicles and the degree of mineralization of the mandibular condyle in the prenatal stage employing structural, ultrastructural and microanalytical evaluation. Sixteen human fetuses at 11-37 weeks of gestation, with no apparent pathology and resulting from spontaneous abortions, were included in the study. Samples from lateral pterygoid muscle and the mandibular condyle were processed for light microscopy and electron microscopy and microanalysis. Desmin immunolabeling (dilution 1: 25 Dako) and alpha sarcomeric actin immunolabeling (dilution 1:50 Dako) employing the avidin-biotin system were used in paraffin embedded samples. Contralateral samples were examine by transmission electron microscopy. Four condyles (at 17-21 weeks of gestation) were used to measure the relative content of calcium and phosphorous employing the X-ray diffraction microanalytical technique. At 11-16 weeks of gestation, the LPM was composed of secondary myotubes associated to satellite cells and nerve fibers. At 18 weeks, the muscle exhibited multiple compact fascicles and the condyle showed a thin, external, subperiostal mineralized layer with few central bone spicules. At 20 weeks, at the site of insertion of the LPM, the bone trabeculae of the condyle contained an electrondense matrix with abundant mineralization nuclei. At 17-21 weeks of gestation no significant variations in the contents of phosphorous and calcium were observed. At 24 weeks, transmission electron calcium and microscopy studies revealed a marked increase in the functional units of the muscle fascicles. Also, at this age muscle fibers exhibited differences in the expression of desmin and alpha sarcomeric actin. At 37 weeks the muscle became multipennate in

  8. Characterizing occipital condyle loads under high-speed head rotation.

    Science.gov (United States)

    Pintar, Frank A; Yoganandan, Narayan; Baisden, Jamie

    2005-11-01

    Because of the need to evaluate anthropomorphic test device (ATD) biofidelity under high-head angular accelerations, the purpose of the present investigation was to develop appropriate instrumentation for intact post mortem human subject (PMHS) testing, validate the instrumentation, and obtain information to characterize the response of the head-neck complex under this loading scenario. A series of rigid-arm pendulum, inertially loaded ATD tests was conducted. Head and neck ATD hydraulic piston chin pull tests were conducted. Subsequently, a series of PMHS tests was conducted to derive the response of the human head-neck under high-rate chin loading. Finally, Hybrid III and THOR-NT ATD head-neck systems were evaluated under the same scenario as the PMHS. A parametric analysis for center of gravity (CG) location and accelerometer orientation determined that even small errors (+/- 3 mm or 2 degrees), produced errors in the force and moment calculations by as much as 17 %. If the moment of inertia (MOI) term was varied by 5 %, resulting moment calculations were affected by as much as 8 %. If the 5 % error in MOI was used to compute occipital condyle moments, and results compared to upper load cell derived moments, peaks differed by as much as 24 %. The head CG and mass MOI should be directly measured for each preparation to obtain accurate results. The injury run on each specimen resulted in predominantly C1-C2 separations or partial separations. The 50(th) percentile probability of AIS=2+ neck injury using tensile force was about 2400 N; for AIS=3+ neck injury the 50(th) percentile risk was about 3180 N. When inserting extension moment as the criteria, the 50(th) percentile probability of an AIS=2+ injury was 51 Nm. The AIS=3+ extension moment at the 50(th) percentile probability was 75 Nm. The new THOR-NT ATD head-neck produced more biofidelic responses with an alternate head-neck junction design compared to the Hybrid III ATD.

  9. Evaluation of surgical treatment in mandibular condyle fractures.

    Science.gov (United States)

    Vesnaver, Aleš; Ahčan, Uroš; Rozman, Janez

    2012-12-01

    In the past, fractures of the mandibular condylar process were, as a rule, treated conservatively. At the Department of Maxillofacial and Oral Surgery of the University Medical Centre Ljubljana, Slovenia, our doctrine was changed in 2002 on the basis of preliminary results and reports in the literature, and these fractures were started to be treated surgically by open reduction and internal fixation with miniplates and screws, which led to good results and a shorter rehabilitation period. The goal of this study was to determine the safety and efficiency of surgical treatment, as well as to compare long-term results of surgical and conservative treatment, as objectively as possible. Two groups of patients, which had all sustained a unilateral, extra-articular mandibular condyle fracture, were compared. In the test group, there were 42 surgically treated patients, and in the control group, 20 conservatively treated patients. Clinical parameters and X-ray images were assessed in both groups and compared by the two tailed Student t test, and in case of attributive variables by the χ(2) test. Within the surgically treated group, postoperative and intraoperative complications were noted: temporary facial nerve palsy, development of a parotid salivary fistula, disturbance of auricle sensibility due to injury of the greater auricular nerve, miniplate fracture, as well as intraoperative bleeding, postoperative haematoma formation, infection, reoperation due to fragment malposition and other complications. Postoperative scars were also assessed. Statistically significant differences between the surgically and conservatively treated patients were found when comparing clinical parameters as well as X-ray images, the results being better in the surgically treated group. Complications of surgical treatment were also noted, the most important among them temporary paresis of facial nerve branches, which occurred in 10 patients (24%). Plate fractures occurred in five patients (12

  10. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  11. Science 101: What Causes Friction?

    Science.gov (United States)

    Robertson, Bill

    2014-01-01

    Defining friction and asking what causes it might seem like a trivial question. Friction seems simple enough to understand. Friction is a force between surfaces that pushes against things that are moving or tending to move, and the rougher the surfaces, the greater the friction. Bill Robertson answers this by saying, "Well, not exactly".…

  12. Paediatric treadmill friction injuries.

    Science.gov (United States)

    Jeremijenko, Luke; Mott, Jonathan; Wallis, Belinda; Kimble, Roy

    2009-05-01

    The aim of this study was to report on the severity and incidence of children injured by treadmills and to promote the implementation of safety standards. This retrospective review of children with treadmill friction injuries was conducted in a single tertiary-level burns centre in Australia between January 1997 and June 2007. The study revealed 37 children who sustained paediatric treadmill friction injuries. This was a presentation of 1% of all burns. Thirty-three (90%) of the injuries occurred in the last 3.5 years (January 2004 to June 2007). The modal age was 3.2 years. Thirty-three (90%) injuries were either full thickness or deep partial friction burns. Eleven (30%) required split thickness skin grafts. Of those who became entrapped, 100% required skin grafting. This study found that paediatric treadmill friction injuries are severe and increasing in incidence. Australian standards should be developed, implemented and mandated to reduce this preventable and severe injury.

  13. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  14. A new condyle implant design concept for an alloplastic temporomandibular joint in bone resorption cases.

    Science.gov (United States)

    Ramos, António; Mesnard, Michel

    2016-10-01

    The purpose of this article is to present and evaluate an innovative intramedullary implant concept developed for total alloplastic reconstruction in bone resorption cases. The main goal of this innovative concept is to avoid the main problems experienced with temporomandibular (TMJ) devices on the market, associated with bone fixation and changes in kinematics. A three-dimensional finite element model was developed based on computed tomography (CT) scan images, before and after implantation of the innovative implant concept. To validate the numerical model, a clean cadaveric condyle was instrumented with four rosettes and loaded before and after implantation with the innovative concept TMJ implant. The experimental results validate the numerical models comparing the intact and implanted condyles, as they present good correlation. They show that the most critical region is around rosette #1, with an increase in strains in the proximal region of the condyle of 140%. The maximum principal strain and stress generated with the implant is less than 2200 με and 75 MPa in the posterior region of the cortical bone. Shortly after insertion of this press-fit implant, stress and strain results appear to be within the normal limits and show some similarities with the intact condyle. If these responses do not change over time, the screw fixation used at present could be avoided or replaced. This solution reduces bone resection and lessens surgical damage to the muscles. Copyright © 2016 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  15. Changed morphology and mechanical properties of cancellous bone in the mandibular condyles of edentate people

    DEFF Research Database (Denmark)

    Ding, Ming

    2004-01-01

    Since edentate subjects have a reduced masticatory function, it can be expected that the morphology of the cancellous bone of their mandibular condyles has changed according to the altered mechanical environment. In the present study, the morphology of cylindrical cancellous bone specimens...

  16. Interpretation of mandibular condyle fractures using 2D- and 3D-computed tomography

    Directory of Open Access Journals (Sweden)

    Costa e Silva Adriana Paula de Andrade da

    2003-01-01

    Full Text Available Computed tomography (CT has been increasingly used in the examination of patients with craniofacial trauma. This technique is useful in the examination of the temporomandibular joint and allows the diagnosis of fractures of the mandibular condyle. Aiming to verify whether the three-dimensional reconstructed images from CT (3D-CT produce more effective visual information than the two-dimensional (2D-CT ones, we evaluated 2D-CT and 3D-CT examinations of 18 patients with mandibular condyle fractures. We observed that 2D-CT and 3D-CT reconstructed images produced similar information for the diagnosis of fractures of the mandibular condyle, although the 3D-CT allowed a better visualization of the position and displacement of bone fragments, as well as the comminution of fractures. These results, together with the possibility of refining and manipulating perspectives in 3D images, reinforce the importance of its use in the surgical planning and evaluation of treatment. We concluded that 3D-CT presented supplementary information for a more effective diagnosis of mandibular condyle fractures.

  17. Rate of displacement for Jakob Type 1 lateral condyle fractures treated with a cast.

    Science.gov (United States)

    Zale, C; Winthrop, Z A; Hennrikus, W

    2018-04-01

    The aim of this retrospective study is to report the rate of displacement of Jakob Type 1 lateral condyle fractures that were initially treated in a cast. We performed a retrospective review of all patients that were treated for a non-displaced (Jakob Type 1 displaced and were converted to a closed pinning treatment plan with a conversion rate of 8.5%. There was a mean of 13.2 days (4 to 21) between treatment by initial casting and closed pinning. This study demonstrates an 8.5% displacement and conversion rate from cast treatment to closed pinning for initially non-displaced Jakob Type 1 lateral condyle fractures of the humerus. The internal oblique radiograph is most accurate to determine displacement. We recommend obtaining an internal oblique view at initial evaluation and at follow-up in the cast for lateral condyle fractures. To minimize movement at the fracture site, we recommend treating Jakob Type 1 lateral condyle fractures with a long arm cast with the elbow at 90° and the forearm in the supine position with a sling-loop design. IV - retrospective therapeutic study.

  18. 78 FR 79308 - Dental Devices; Reclassification of Temporary Mandibular Condyle Prosthesis

    Science.gov (United States)

    2013-12-30

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 872 [Docket No. FDA-2012-N-1239] Dental Devices; Reclassification of Temporary Mandibular Condyle Prosthesis AGENCY... delegated to the Commissioner of Food and Drugs, 21 CFR part 872 is amended as follows: PART 872--DENTAL...

  19. Ossification variants of the femoral condyles are not associated with osteochondritis dissecans

    Energy Technology Data Exchange (ETDEWEB)

    Jans, L., E-mail: lennartjans@hotmail.com [Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Jaremko, J., E-mail: jjaremko@gmail.com [Department of Radiology, University of Alberta Hospital, 8440-112 Street, Edmonton T6G 2B7, Alberta (Canada); Ditchfield, M., E-mail: Michael.ditchfield@southernhealth.org.au [Department of Radiology, Monash University Clayton Campus, Wellington Road, Clayton 3800, VIC (Australia); De Coninck, T., E-mail: Tinekedeconinck@ugent.be [Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Huysse, W., E-mail: Wouter.huysse@ugent.be [Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium); Moon, A., E-mail: Anna.moon@rch.org.au [Department of Radiology, Royal Children' s Hospital, Flemington Road, Parkville 3052, VIC (Australia); Verstraete, K., E-mail: Koenraad.verstraete@ugent.be [Department of Radiology and Medical Imaging, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium)

    2012-11-15

    Purpose: To determine if ossification variants of the femoral condyles involving the subchondral bone plate are associated with osteochondritis dissecans (OCD). Materials and methods: The prevalence of ossification variants of the unaffected femoral condyle in 116 patients (aged 9-14 years) with unicondylar OCD on MRI (magnetic resonance imaging) of the knee was compared to a control group of 579 patients (aged 9-14 years) without OCD. The evolution of the ossification variants in both groups was studied by reviewing follow-up MR imaging side by side with the baseline study. Results: The prevalence of ossification variants in the unaffected condyle in patients with OCD (12.9%) and in the control group of patients without OCD (12.6%) was similar (p = 0.88). Evolution of ossification variants to OCD was not seen on follow-up MRI examinations. All variants had decreased in size or were no longer visible. Conclusion: Ossification variants of the femoral condyle that involve the subchondral bone plate are not associated with OCD. Clinical relevance statement: Ossification variants are not associated with OCD, indicating that routine MRI follow-up in affected children is not mandatory.

  20. Complaints related to mandibular function impairment after closed treatment of fractures of the mandibular condyle

    NARCIS (Netherlands)

    Niezen, E. T.; Bos, R. R. M.; de Bont, L. G. M.; Stegenga, B.; Dijkstra, P. U.

    This study analysed the relationship between complaints and mandibular function after closed treatment of fractures of the mandibular condyle in a prospective study. In a I-year follow-up, complaints were assessed during physical examination and function was assessed using the mandibular function

  1. The correlation between mineralization degree and bone tissue stiffness in the porcine mandibular condyle

    NARCIS (Netherlands)

    Willems, N.M.B.K.; Mulder, L.; Toonder, den J.M.J.; Zentner, A.; Langenbach, G.E.J.

    2014-01-01

    The aim of this study was to correlate the local tissue mineral density (TMD) with the bone tissue stiffness. It was hypothesized that these variables are positively correlated. Cancellous and cortical bone samples were derived from ten mandibular condyles taken from 5 young and 5 adult female pigs.

  2. Ossification variants of the femoral condyles are not associated with osteochondritis dissecans

    International Nuclear Information System (INIS)

    Jans, L.; Jaremko, J.; Ditchfield, M.; De Coninck, T.; Huysse, W.; Moon, A.; Verstraete, K.

    2012-01-01

    Purpose: To determine if ossification variants of the femoral condyles involving the subchondral bone plate are associated with osteochondritis dissecans (OCD). Materials and methods: The prevalence of ossification variants of the unaffected femoral condyle in 116 patients (aged 9–14 years) with unicondylar OCD on MRI (magnetic resonance imaging) of the knee was compared to a control group of 579 patients (aged 9–14 years) without OCD. The evolution of the ossification variants in both groups was studied by reviewing follow-up MR imaging side by side with the baseline study. Results: The prevalence of ossification variants in the unaffected condyle in patients with OCD (12.9%) and in the control group of patients without OCD (12.6%) was similar (p = 0.88). Evolution of ossification variants to OCD was not seen on follow-up MRI examinations. All variants had decreased in size or were no longer visible. Conclusion: Ossification variants of the femoral condyle that involve the subchondral bone plate are not associated with OCD. Clinical relevance statement: Ossification variants are not associated with OCD, indicating that routine MRI follow-up in affected children is not mandatory.

  3. Reflections on Friction in Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Yair Rezek

    2010-08-01

    Full Text Available Distinctly quantum friction effects of three types are surveyed: internalfriction, measurement-induced friction, and quantum-fluctuation-induced friction. We demonstrate that external driving will lead to quantum internal friction, and critique the measurement-based interpretation of friction. We conclude that in general systems will experience internal and external quantum friction over and beyond the classical frictional contributions.

  4. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  5. Accuracy and Reliability of Cone-Beam Computed Tomography for Linear and Volumetric Mandibular Condyle Measurements. A Human Cadaver Study.

    Science.gov (United States)

    García-Sanz, Verónica; Bellot-Arcís, Carlos; Hernández, Virginia; Serrano-Sánchez, Pedro; Guarinos, Juan; Paredes-Gallardo, Vanessa

    2017-09-20

    The accuracy of Cone-Beam Computed Tomography (CBCT) on linear and volumetric measurements on condyles has only been assessed on dry skulls. The aim of this study was to evaluate the reliability and accuracy of linear and volumetric measurements of mandibular condyles in the presence of soft tissues using CBCT. Six embalmed cadaver heads were used. CBCT scans were taken, followed by the extraction of the condyles. The water displacement technique was used to calculate the volumes of the condyles and three linear measurements were made using a digital caliper, these measurements serving as the gold standard. Surface models of the condyles were obtained using a 3D scanner, and superimposed onto the CBCT images. Condyles were isolated on the CBCT render volume using the surface models as reference and volumes were measured. Linear measurements were made on CBCT slices. The CBCT method was found to be reliable for both volumetric and linear measurements (CV  0.90). Highly accurate values were obtained for the three linear measurements and volume. CBCT is a reliable and accurate method for taking volumetric and linear measurements on mandibular condyles in the presence of soft tissue, and so a valid tool for clinical diagnosis.

  6. Evaluation of condyle defects using different reconstruction protocols of cone-beam computed tomography

    International Nuclear Information System (INIS)

    Bastos, Luana Costa; Campos, Paulo Sergio Flores; Ramos-Perez, Flavia Maria de Moraes; Pontual, Andrea dos Anjos; Almeida, Solange Maria

    2013-01-01

    This study was conducted to investigate how well cone-beam computed tomography (CBCT) can detect simulated cavitary defects in condyles, and to test the influence of the reconstruction protocols. Defects were created with spherical diamond burs (numbers 1013, 1016, 3017) in superior and / or posterior surfaces of twenty condyles. The condyles were scanned, and cross-sectional reconstructions were performed with nine different protocols, based on slice thickness (0.2, 0.6, 1.0 mm) and on the filters (original image, Sharpen Mild, S9) used. Two observers evaluated the defects, determining their presence and location. Statistical analysis was carried out using simple Kappa coefficient and McNemar’s test to check inter- and intra-rater reliability. The chi-square test was used to compare the rater accuracy. Analysis of variance (Tukey's test) assessed the effect of the protocols used. Kappa values for inter- and intra-rater reliability demonstrate almost perfect agreement. The proportion of correct answers was significantly higher than that of errors for cavitary defects on both condyle surfaces (p < 0.01). Only in identifying the defects located on the posterior surface was it possible to observe the influence of the 1.0 mm protocol thickness and no filter, which showed a significantly lower value. Based on the results of the current study, the technique used was valid for identifying the existence of cavities in the condyle surface. However, the protocol of a 1.0 mm-thick slice and no filter proved to be the worst method for identifying the defects on the posterior surface. (author)

  7. Evaluation of condyle defects using different reconstruction protocols of cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, Luana Costa; Campos, Paulo Sergio Flores, E-mail: bastosluana@ymail.com [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Fac. de Odontologia. Dept. de Radiologia Oral e Maxilofacial; Ramos-Perez, Flavia Maria de Moraes [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Fac. de Odontologia. Dept. de Clinica e Odontologia Preventiva; Pontual, Andrea dos Anjos [Universidade Federal de Pernambuco (UFPE), Camaragibe, PE (Brazil). Fac. de Odontologia. Dept. de Radiologia Oral; Almeida, Solange Maria [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Fac. de Odontologia. Dept. de Radiologia Oral

    2013-11-15

    This study was conducted to investigate how well cone-beam computed tomography (CBCT) can detect simulated cavitary defects in condyles, and to test the influence of the reconstruction protocols. Defects were created with spherical diamond burs (numbers 1013, 1016, 3017) in superior and / or posterior surfaces of twenty condyles. The condyles were scanned, and cross-sectional reconstructions were performed with nine different protocols, based on slice thickness (0.2, 0.6, 1.0 mm) and on the filters (original image, Sharpen Mild, S9) used. Two observers evaluated the defects, determining their presence and location. Statistical analysis was carried out using simple Kappa coefficient and McNemar’s test to check inter- and intra-rater reliability. The chi-square test was used to compare the rater accuracy. Analysis of variance (Tukey's test) assessed the effect of the protocols used. Kappa values for inter- and intra-rater reliability demonstrate almost perfect agreement. The proportion of correct answers was significantly higher than that of errors for cavitary defects on both condyle surfaces (p < 0.01). Only in identifying the defects located on the posterior surface was it possible to observe the influence of the 1.0 mm protocol thickness and no filter, which showed a significantly lower value. Based on the results of the current study, the technique used was valid for identifying the existence of cavities in the condyle surface. However, the protocol of a 1.0 mm-thick slice and no filter proved to be the worst method for identifying the defects on the posterior surface. (author)

  8. Management of neglected lateral condyle fractures of humerus in children: A retrospective study

    Directory of Open Access Journals (Sweden)

    Anil Agarwal

    2012-01-01

    Full Text Available Background: Late presentation of humeral lateral condylar fracture in children is a surgical dilemma. Osteosynthesis of the fracture fragment or correction of elbow deformity with osteotomies and ulnar nerve transposition or sometimes both procedures combined is a controversial topic. We retrospectively evaluated open reduction and fixation cases in late presentation of lateral humeral condyle fracture in pediatric cases with regards to union and functional results. Materials and Methods: Twenty two pediatric (≤12 years patients with fractures of lateral condyle presenting 4 weeks or more post injury between the study period of 2006 and 2010 were included. Multiple K-wires / with or without screws along with bone grafting were used. At final evaluation, union (radiologically and elbow function (Liverpool Elbow Score, LES was assessed. Results: There were 19 boys and 3 girls. Followup averaged 33 months. Pain (n=9, swelling (n=6, restriction of elbow motion (n=6, prominence of lateral condylar region (n=4, valgus deformity (n=4 were the main presenting symptoms. Ulnar nerve function was normal in all patients. There were nine Milch type I and 13 type II fractures. Union occurred in 20 cases. One case had malunion and in another case there was resorption of condyle following postoperative infection and avascular necrosis. Prominent lateral condyles (4/12, fish tail appearance (n=7, premature epiphyseal closure (n=2 were other observations. LES averaged 8.12 (range, 6.66-9.54 at final followup. Conclusions: There is high rate of union and satisfactory elbow function in late presenting lateral condyle fractures in children following osteosynthesis attempt. Our study showed poor correlation between patient′s age, duration of late presentation or Milch type I or II and final elbow function as determined by LES.

  9. Normal Development and Measurements of the Occipital Condyle-C1 Interval in Children and Young Adults.

    Science.gov (United States)

    Smith, P; Linscott, L L; Vadivelu, S; Zhang, B; Leach, J L

    2016-05-01

    Widening of the occipital condyle-C1 interval is the most specific and sensitive means of detecting atlanto-occipital dislocation. Recent studies attempting to define normal measurements of the condyle-C1 interval in children have varied substantially. This study was performed to test the null hypothesis that condyle-C1 interval morphology and joint measurements do not change as a function of age. Imaging review of subjects undergoing CT of the upper cervical spine for reasons unrelated to trauma or developmental abnormality was performed. Four equidistant measurements were obtained for each bilateral condyle-C1 interval on sagittal and coronal images. The cohort was divided into 7 age groups to calculate the mean, SD, and 95% CIs for the average condyle-C1 interval in both planes. The prevalence of a medial occipital condyle notch was calculated. Two hundred forty-eight joints were measured in 124 subjects with an age range of 2 days to 22 years. The condyle-C1 interval varies substantially by age. Average coronal measurements are larger and more variable than sagittal measurements. The medial occipital condyle notch is most prevalent from 1 to 12 years and is uncommon in older adolescents and young adults. The condyle-C1 interval increases during the first several years of life, is largest in the 2- to 4-year age range, and then decreases through late childhood and adolescence. A single threshold value to detect atlanto-occipital dissociation may not be sensitive and specific for all age groups. Application of this normative data to documented cases of atlanto-occipital injury is needed to determine clinical utility. © 2016 by American Journal of Neuroradiology.

  10. Chemical origins of frictional aging.

    Science.gov (United States)

    Liu, Yun; Szlufarska, Izabela

    2012-11-02

    Although the basic laws of friction are simple enough to be taught in elementary physics classes and although friction has been widely studied for centuries, in the current state of knowledge it is still not possible to predict a friction force from fundamental principles. One of the highly debated topics in this field is the origin of static friction. For most macroscopic contacts between two solids, static friction will increase logarithmically with time, a phenomenon that is referred to as aging of the interface. One known reason for the logarithmic growth of static friction is the deformation creep in plastic contacts. However, this mechanism cannot explain frictional aging observed in the absence of roughness and plasticity. Here, we discover molecular mechanisms that can lead to a logarithmic increase of friction based purely on interfacial chemistry. Predictions of our model are consistent with published experimental data on the friction of silica.

  11. Application of Normative Occipital Condyle-C1 Interval Measurements to Detect Atlanto-Occipital Injury in Children.

    Science.gov (United States)

    Corcoran, B; Linscott, L L; Leach, J L; Vadivelu, S

    2016-05-01

    Prior studies have found that widening or asymmetry of the occipital condyle-C1 interval on CT is a sensitive and specific marker for atlanto-occipital dislocation. Previously reported abnormal occipital condyle-C1 interval values are not age-specific, possibly leading to false-positive findings in younger children, in whom this joint space is normally larger than that in adults. This study assesses the utility of applying age-specific normative occipital condyle-C1 interval ranges to documented cases of atlanto-occipital injury compared with previously reported abnormal cutoff values. Retrospective review of CT and MR imaging of 14 subjects with atlanto-occipital injury was performed, and occipital condyle-C1 interval measurements were made for each subject. Sensitivities and specificities of proposed occipital condyle-C1 interval cutoffs of 2 and 3 SDs above the mean and previously published occipital condyle-C1 interval cutoffs for atlanto-occipital injury were then calculated on the basis of occipital condyle-C1 interval measurements for each subject. An occipital condyle-C1 interval 2 SDs above the age-specific mean has a sensitivity of 50% and specificity of 89%-100%, depending on the age group. An occipital condyle-C1 interval 3 SDs above the age-specific mean has a sensitivity of 50% and a specificity of 95%-100%. A 4.0-mm occipital condyle-C1 interval has a sensitivity of 36% and a specificity of 100% in all age groups. A 2.5-mm occipital condyle-C1 interval has a sensitivity of 93% and a specificity of 18%-100%. Occipital condyle-C1 interval widening cutoffs used to establish atlanto-occipital injury lack both sensitivity and specificity in children and young teenagers. MR imaging is necessary to establish a diagnosis of atlanto-occipital injury in children and young teenagers when the appropriate mechanism of injury is present. © 2016 by American Journal of Neuroradiology.

  12. Frictional coefficient depending on active friction radius with BPV ...

    African Journals Online (AJOL)

    Frictional coefficient depending on active friction radius with BPV and BTV in automobile disc braking system. ... International Journal of Engineering, Science and Technology. Journal Home · ABOUT ... AJOL African Journals Online. HOW TO ...

  13. Internal friction in uranium

    International Nuclear Information System (INIS)

    Selle, J.E.

    1975-01-01

    Results are presented of studies conducted to relate internal friction measurements in U to allotropic transformations. It was found that several internal friction peaks occur in α-uranium whose magnitude changed drastically after annealing in the β phase. All of the allotropic transformations in uranium are diffusional in nature under slow heating and cooling conditions. Creep at regions of high stress concentration appears to be responsible for high temperature internal friction in α-uranium. The activation energy for grain boundary relaxation in α-uranium was found to be 65.1 +- 4 kcal/mole. Impurity atoms interfere with the basic mechanism for grain boundary relaxation resulting in a distribution in activation energies. A considerable distribution in ln tau 0 was also found which is a measure of the distribution in local order and in the Debye frequency around a grain boundary

  14. Anatomical study of the radius and center of curvature of the distal femoral condyle

    KAUST Repository

    Kosel, Jü rgen; Giouroudi, Ioanna; Scheffer, Cornie; Dillon, Edwin Mark; Erasmus, Pieter J.

    2010-01-01

    In this anatomical study, the anteroposterior curvature of the surface of 16 cadaveric distal femurs was examined in terms of radii and center point. Those two parameters attract high interest due to their significance for total knee arthroplasty. Basically, two different conclusions have been drawn in foregoing studies: (1) The curvature shows a constant radius and (2) the curvature shows a variable radius. The investigations were based on a new method combining three-dimensional laser-scanning and planar geometrical analyses. This method is aimed at providing high accuracy and high local resolution. The high-precision laser scanning enables the exact reproduction of the distal femurs - including their cartilage tissue - as a three-dimensional computer model. The surface curvature was investigated on intersection planes that were oriented perpendicularly to the surgical epicondylar line. Three planes were placed at the central part of each condyle. The intersection of either plane with the femur model was approximated with the help of a b-spline, yielding three b-splines on each condyle. The radii and center points of the circles, approximating the local curvature of the b-splines, were then evaluated. The results from all three b-splines were averaged in order to increase the reliability of the method. The results show the variation in the surface curvatures of the investigated samples of condyles. These variations are expressed in the pattern of the center points and the radii of the curvatures. The standard deviations of the radii for a 90 deg arc on the posterior condyle range from 0.6 mm up to 5.1 mm, with an average of 2.4 mm laterally and 2.2 mm medially. No correlation was found between the curvature of the lateral and medial condyles. Within the range of the investigated 16 samples, the conclusion can be drawn that the condyle surface curvature is not constant and different for all specimens when viewed along the surgical epicondylar axis. For the portion

  15. Solitary Langerhans cell histiocytosis of the occipital condyle: a case report and review of the literature.

    Science.gov (United States)

    Teranishi, Yu; Shin, Masahiro; Yoshino, Masanori; Saito, Nobuhito

    2016-02-01

    Despite the recent advent of various radiographic imaging techniques, it is still very difficult to correctly distinguish a pediatric osteolytic lesion in the occipital condyle, which makes it further complicated to decide on the necessity of and the adequate timing for radical resection and craniocervical fusions. To establish a legitimate therapeutic strategy for this deep-seated lesion, surgical biopsy is a reasonable choice for first-line intervention. The choice of surgical approach becomes very important because a sufficient amount of histological specimen must be obtained to confirm the diagnosis but, ideally, the residual bony structures and the muscular structures should be preserved so as not to increase craniocervical instability. In this report, we present our experience with a case of solitary Langerhans cell histiocytosis (LCH) involving the occipital condyle that was successfully treated with minimally invasive surgical biopsy with a far lateral condylar approach supported by preoperative 3D computer graphic simulation. An 8-year-old girl presented with neck pain. Magnetic resonance imaging and computed tomography (CT) revealed an osteolytic lesion of the left occipital condyle. At surgery, the patient was placed in the prone position. A 3-cm skin incision was made in the posterior auricular region, and the sternocleidomastoid and splenius capitis muscles were dissected in the middle of the muscle bundle along the direction of the muscle fiber. Under a navigation system, we approached the occipital condyle through the space between the longissimus capitis muscle and the posterior belly of the digastric muscle and lateral to the superior oblique muscle, verifying each muscle at each depth of the surgical field and, finally, obtained sufficient surgical specimen. After the biopsy, her craniocervical instability had not worsened, and chemotherapy was performed. Twelve weeks after chemotherapy, her neck pain had gradually disappeared along with her

  16. Labour market frictions and migration

    NARCIS (Netherlands)

    Cremers, Jan

    2016-01-01

    The 4th contribution to the series INT-AR papers is dedicated to the methods of assessing labour market frictions. The paper provides a (brief) international comparison of the role of labour migration in solving these frictions.

  17. Metrical analysis of disc-condyle relation with different splint treatment positions in patients with TMJ disc displacement

    Directory of Open Access Journals (Sweden)

    Mu-Qing Liu

    Full Text Available Abstract Objective: To evaluate the effect of bite positions characterizing different splint treatments (anterior repositioning and stabilization splints on the disc-condyle relation in patients with TMJ disc displacement with reduction (DDwR, using magnetic resonance imaging (MRI. Material and Methods: 37 patients, with a mean age of 18.8±4.3 years (7 male and 30 females and diagnosed with DDwR based on the RDC/TMD, were recruited. MRI metrical analysis of the spatial changes of the disc/condyle, as well as their relationships, was done in three positions: maximum intercuspation (Position 1, anterior repositioning splint position (Position 2, and stabilization splint position (Position 3. Disc/condyle coordinate measurements and disc condyle angles were determined and compared. Results: In Position 1, the average disc-condyle angle was 53.4° in the 60 joints with DDwR, while it was −13.3° with Position 2 and 30.1° with Position 3. The frequency of successful "disc recapture" with Position 2 was significantly higher (58/60, 96.7% than Position 3 (20/60, 33.3%. In Positions 2 and 3, the condyle moved forward and downward while the disc moved backward. The movements were, however, more remarkable with Position 2. Conclusions: Anterior repositioning of the mandible improves the spatial relationship between the disc and condyle in patients with DDwR. In addition to anterior and inferior movement of the condyle, transitory posterior movement of the disc also occurred.

  18. Friction in sheet metal forming

    DEFF Research Database (Denmark)

    Wiklund, D.; Liljebgren, M.; Berglund, J.

    2010-01-01

    and calls for functional tool surfaces that are durable in these severe tribological conditions. In this study the influence of tool surface topography on friction has been investigated. The frictional response was studied in a Bending Under Tension test. The results did show that a low frictional response...

  19. Oral-motor and electromyographic characterization of patients submitted to open a nd closed reductions of mandibular condyle fracture.

    Science.gov (United States)

    Silva, Amanda Pagliotto da; Sassi, Fernanda Chiarion; Andrade, Claudia Regina Furquim de

    To characterize the oral-motor system of adults with mandibular condyle facture comparing the performance of individuals submitted to open reduction with internal fixation (ORIF) and closed reduction with mandibulomaxillary fixation (CRMMF). Study participants were 26 adults divided into three groups: G1 - eight individuals submitted to ORIF for correction of condyle fracture; G2 - nine individuals submitted to CRMMF for correction of condyle fracture; CG - nine healthy volunteers with no alterations of the orofacial myofunctional system. All participants underwent the same clinical protocol: assessment of the orofacial myofunctional system; evaluation of the mandibular range of motion; and surface electromyography (sEMG) of the masticatory muscles. Results indicated that patients with condyle fractures from both groups presented significant differences compared with those from the control group in terms of mobility of the oral-motor organs, mastication, and deglutition. Regarding the measures obtained for mandibular movements, participants with facial fractures from both groups showed significant differences compared with those from the control group, indicating greater restrictions in mandibular motion. As for the analysis of sEMG results, G1 patients presented more symmetrical masseter activation during the task of maximal voluntary teeth clenching. Patients with mandibular condyle fractures present significant deficits in posture, mobility, and function of the oral-motor system. The type of medical treatment does not influence the results of muscle function during the first six months after fracture reduction. Individuals submitted to ORIF of the condyle fracture present more symmetrical activation of the masseter muscle.

  20. Intelligent Flow Friction Estimation.

    Science.gov (United States)

    Brkić, Dejan; Ćojbašić, Žarko

    2016-01-01

    Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ). In the present study, a noniterative approach using Artificial Neural Network (ANN) was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re) and the relative roughness of pipe (ε/D) were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re) and the relative roughness (ε/D) ranging between 5000 and 10(8) and between 10(-7) and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  1. Student figures in friction

    DEFF Research Database (Denmark)

    Nielsen, Gritt B.

    , students' room for participation in their own learning, influenced by demands for efficiency, flexibility and student-centred education. The thesis recasts the anthropological endeavour as one of ‘figuration work'. That is, ‘frictional events' are explored as moments when conflicting figures...

  2. Skin tribology: Science friction?

    NARCIS (Netherlands)

    van der Heide, Emile; Zeng, Xiangqiong; Masen, Marc Arthur

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is

  3. Coulomb Friction Damper

    Science.gov (United States)

    Appleberry, W. T.

    1983-01-01

    Standard hydraulic shock absorber modified to form coulomb (linear friction) damper. Device damps very small velocities and is well suited for use with large masses mounted on soft springs. Damping force is easily adjusted for different loads. Dampers are more reliable than fluid dampers and also more economical to build and to maintain.

  4. Intelligent Flow Friction Estimation

    Directory of Open Access Journals (Sweden)

    Dejan Brkić

    2016-01-01

    Full Text Available Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ. In the present study, a noniterative approach using Artificial Neural Network (ANN was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re and the relative roughness of pipe (ε/D were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re and the relative roughness (ε/D ranging between 5000 and 108 and between 10−7 and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  5. Friction welding method

    International Nuclear Information System (INIS)

    Ishida, Ryuichi; Hatanaka, Tatsuo.

    1969-01-01

    A friction welding method for forming a lattice-shaped base and tie plate supporter for fuel elements is disclosed in which a plate formed with a concavity along its edge is pressure welded to a rotating member such as a boss by longitudinally contacting the projecting surfaces remaining on either side of the concavity with the rotating member during the high speed rotation thereof in the presence of an inert gas. Since only the two projecting surfaces of the plate are fused by friction to the rotary member, heat expansion is absorbed by the concavity to prevent distortion; moreover, a two point contact surface assures a stable fitting and promotes the construction of a rigid lattice in which a number of the abovementioned plates are friction welded between rotating members to form any desired complex arrangement. The inert has serves to protect the material quality of the contacting surfaces from air during the welding step. The present invention thus provides a method in which even Zircaloy may be friction welded in place of casting stainless steel in the construction of supporting lattices to thereby enhance neutron economy. (K. J. Owens)

  6. Intra- and interobserver agreement of computed tomography in assessment of the mandibular condyle

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Bong Hae; Jung, Yun Hoa [Pusan National Univ. College of Dentistry, Pusan (Korea, Republic of)

    2007-12-15

    To study the intra- and interobserver agreement of multidetector row computed tomography (MDCT) in interpretation of degenerative changes of the mandibular condyle. Five observers independently evaluated one hundred temporomandibular joint MDCT images for signs of osteophytes, erosion, sclerosis and flattening. The intra- and interobserve agreements were calculated by using Kappa statistics. The intraobserver agreement was substantial for erosion (k=0.75), flattening (k=0.74) and sclerosis (k=0.72) and almost perfect for osteophytes (k=0.84). The interobserver agreement was fair for flattening (k=0.39), moderate for erosion (k=0.58) and sclerosis (k=0.48) and substantial for osteophytes (k=0.75). This study shows that we can expert good agreement for the presence of osteophytes, but not for flattening in the interpretation of MDCT images of the condyle.

  7. Subchondral Impaction Fractures of the Medial Femoral Condyle in Weightlifters: A Report of 5 Cases.

    Science.gov (United States)

    Grzelak, Piotr; Podgórski, Michał Tomasz; Stefańczyk, Ludomir; Krochmalski, Marek; Domżalski, Marcin

    2016-01-01

    Although subchondral impaction fractures have already been reported in the non-weight-bearing portion of the lateral femoral condyle, this study reveals the presence of an intra-articular impaction fracture of the postero-superior region of the non-weight-bearing portion of the medial femoral condyle recognized in 5 of a group of 22 representatives of the Polish national Olympic weightlifting team, who underwent 1.5T magnetic resonance imaging examination. Articular cartilage lesions varied with regard to the type of injury and its severity ranging from healed or subchronic injuries to acute trauma. All described individuals had no clinical history of acute knee trauma and only 3 of them had minor pain symptoms. The accumulation of microtraumas occurring during participation in particular activities associated with weightlifting training seems to be responsible for the development of this type of contusion. This is the first description of impaction fracture observed in this location in professional weightlifters.

  8. The effects of the low calcium diet and irradiation on the mandibular condyle of rats

    International Nuclear Information System (INIS)

    Ahn, Hee Mun; Lee, Sang Rae

    1993-01-01

    This study was performed to investigate the changes of mandibular condyle by low diet and the effects of irradiation on the bone in ofteoporotic state. In order to carry out this experiment, 80 served-week old Sprague-Dawley strain rats about 150gm were selected and equally divided into one experimental group of 40 rats and one control group with the remainder. The experimental group and the control group of 40 rats and one control group with the remainder. The experimental group and the control group were then subdivided into two group and exposed to irradiation. The two irradiation groups received a single dose of 20 Gy on the jaw area only and irradiated with a cobalt-60 teletherapy unit. The rats in the control and experimental groups were serially terminated by fours on the 3rd, the 7th, the 14th, and the 21st day after irradiation. After termination, both sides of the dead rats mandibular condyle were removed and fixed with 10% neutral formalin. The bone mineral density of mandibular condle was measured by use of dual energy X-ray with Hitex HA-80 (Hitex Co., Japan). Thereafter, the obtained radiographs were observed, and the mandibular condyle was further decalcified and embedded in paraffin as the general method. The specimen sectioned and stained with hematoxylin-eosin, PAS and Rabbit Anti-Human Tumor Necrosis Factor-α observed by a light microscope. The obtained results were as follows: 1. In the non-irradiated group with low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days, and decrease the number of trabeculae of the condyle and resorption of the calcified cartilaginous zone were observed after 3 days. On microscopic observation, the number and size of trabecular were decreased after 7 days of experiment. 2. In the irradiated group with the low calcium diet, the bone mineral density of the condyle was markedly decreased after 14 days and resorption of the calcified cartilaginous zone and decrease the number and

  9. Inflammatory pseudotumor of the occipital condyle imitating a malignant neoplasm - a case report

    International Nuclear Information System (INIS)

    Sznajder, K.; Skrzelewski, S.

    2007-01-01

    Inflammatory pseudotumor is a non-neoplastic process of unknown etiology characterized by proliferation of connective tissue with an inflammatory infiltrate. IPT most frequently arises in the orbit, but can also be found in the larynx, the paranasal sinus and rarely in the skull base. We present the case of a 20-year-old patient with a 4-month history of headache and insomnia. Neurological examination showed limited head mobility and hypoglossal nerve dysfunction. The patient was afebrile and no abnormalities in blood tests were found. CT revealed the presence of a tumor mass destructing the right occipital condyle. MRI was performed and the mass was surgically removed. The histological diagnosis was non-specific chronic inflammatory granulation tissue. Inflammatory pseudotumors can often mimic malignant neoplasms, especially in cases where bone destruction is observed. IPT of the occipital condyle is a rare but aggressive lesion that should be treated by surgical excision. (author)

  10. Effect of occlusal (mechanical) stimulus on bone remodelling in rat mandibular condyle.

    Science.gov (United States)

    Gazit, D; Ehrlich, J; Kohen, Y; Bab, I

    1987-09-01

    Mechanical load influences the remodelling of skeletal tissues. In the mandibular condyle, occlusal alterations and the consequent mechanical stimulus induce changes in chondrocytes and cartilage mineralization. In the present study we quantified in the mandibular condyle the effect of occlusal interference on remodelling of the subchondral bone. Computerized histomorphometry after 5-21-day exposure to the influence of a unilateral occlusal splint revealed an increased rate of trabecular remodelling, consisting of enhancement in osteoblast and osteoclast numbers and activities. The bone formation parameters reached their high values on Days 5 or 9 and remained stable thereafter. Bone resorption showed a gradual increase throughout the experimental period. These results further characterize the temporomandibular joint reaction to occlusal alterations. It is suggested that the present increase in bone turnover together with the known enhancement in chondrogenesis are part of a process of functional adaptation in response to mechanical stimulus.

  11. Increased friction coefficient and superficial zone protein expression in patients with advanced osteoarthritis.

    Science.gov (United States)

    Neu, C P; Reddi, A H; Komvopoulos, K; Schmid, T M; Di Cesare, P E

    2010-09-01

    To quantify the concentration of superficial zone protein (SZP) in the articular cartilage and synovial fluid of patients with advanced osteoarthritis (OA) and to further correlate the SZP content with the friction coefficient, OA severity, and levels of proinflammatory cytokines. Samples of articular cartilage and synovial fluid were obtained from patients undergoing elective total knee replacement surgery. Additional normal samples were obtained from donated body program and tissue bank sources. Regional SZP expression in cartilage obtained from the femoral condyles was quantified by enzyme-linked immunosorbent assay (ELISA) and visualized by immunohistochemistry. Friction coefficient measurements of cartilage plugs slid in the boundary lubrication system were obtained. OA severity was graded using histochemical analyses. The concentrations of SZP and proinflammatory cytokines in synovial fluid were determined by ELISA. A pattern of SZP localization in knee cartilage was identified, with load-bearing regions exhibiting high SZP expression. SZP expression patterns were correlated with friction coefficient and OA severity; however, SZP expression was observed in all samples at the articular surface, regardless of OA severity. SZP expression and aspirate volume of synovial fluid were higher in OA patients than in normal controls. Expression of cytokines was elevated in the synovial fluid of some patients. Our findings indicate a mechanochemical coupling in which physical forces regulate OA severity and joint lubrication. The findings of this study also suggest that SZP may be ineffective in reducing joint friction in the boundary lubrication mode at an advanced stage of OA, where other mechanisms may dominate the observed tribological behavior.

  12. Influence of occlusal splints on TMJ condyle-fossa relationship and disc shape

    OpenAIRE

    Braun, Barbara Victoria

    2012-01-01

    Background. Occlusal splints are nowadays commonly used in dentistry to treat symptoms of myoarthropathies of the masticatory system, but also to treat simple occlusal parafunctions. Still, the exact mechanism by which the treatment works is unknown. The aim of this study was to find out the answers to following questions: 1. is there an immediate change of the minimum condyle-fossa distance and accompanying disc thickness by inserting a Michigan splint and 2. is it possible to displace the m...

  13. Remodeling process of the streptozotocln-induced diabetic rat's resected condyle

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jung Pyo; Kim, Won Cheol; Hwang, Eui Hwan; Lee, Sang Rae [Dept. of Oral and Maxillofacial Radiology, Oral Diagnosis and Oral Medicine, College of Dentistry, Kyung Hee University, Seoul (Korea, Republic of)

    1994-08-15

    The purpose of this study was to investigate the remodeling process of the streptozotocin-induced diabetic rat's resected condyle. The experiment was performed with male Sprague-Dawley strain rats weighing approximately 250 gm, which were rendered diabetic by an intravenous injection of streptozotocin (70 mg/kg body weight). After condylectomy, experimental rats were serially terminated on the 1st week, the 2nd week, the 3rd week, and the 4th week. The following termination, the mandible were dissected out to make specimens. Each mandibular condyle was radiographed with Hitex HA-80 (Hitex Co., Ltd. Japan). In addition to radiographic observation, the mandibular condyles, further decalcified and embedded in paraffin, were sectioned and stained with Hematoxylin and Eosin, Toluidine blue and Masson's trichrome. They were observed with a light microscope and a polarizing microscope. The results were as follows. 1. Soft X-ray radiograms revealed proliferation of bone after 1 week in both groups. Irregularly repaired bones and dense trabeculae were clearly observed in experimental group. 2. The resected condyles were repaired by intramembraneous and endochondral bone formation in both groups. 3. Bone tissue repair was initiated from the adjacent margin of resected bone, and cartilaginous tissues were observed at the top of repaired bone in both groups. 4. The number of osteoblasts of experimental group was small, compared with control group. Each osteoblast was small and flat. The thin trabeculae were irregularly formed. 5. Collagens of bone were gradually matured in both groups but the degree of maturation was lower in experimental group. 6. Fibrous tissues covered the upper parts of repaired bone were densely arranged in the both groups. Conclusively, atrophied osteoblasts, immature collagen of bone, and thin and irregular trabeculae function and caused disturbance of remodeling process of bone.

  14. Bifid mandibular condyle with temporomandibular joint ankylosis: report of two cases and review of literature

    Energy Technology Data Exchange (ETDEWEB)

    Gulati, Ajay; Virmani, V.; Ramanathan, S.; Khandelwal, N. [Postgraduate Institute of Medical Education and Research, PGIMER, Department of Radiodiagnosis and Imaging, Chandigarh (India); Verma, L. [Gian Sagar Dental College and Hospital, Department of Pedodontics, Patiala (India)

    2009-10-15

    Bifid mandibular condyle is an uncommon entity with a controversial etiology. It can be developmental or acquired and rarely may be associated with temporomandibular joint (TMJ) ankylosis. Although the patient may be asymptomatic, the radiologist should be aware of this entity and its clinical implications. We report two cases of BMC, one developmental and the other secondary to trauma. Both were diagnosed using computed tomography, which additionally revealed the associated ankylosis of TMJ in both the patients. (orig.)

  15. Bifid mandibular condyle with temporomandibular joint ankylosis: report of two cases and review of literature

    International Nuclear Information System (INIS)

    Gulati, Ajay; Virmani, V.; Ramanathan, S.; Khandelwal, N.; Verma, L.

    2009-01-01

    Bifid mandibular condyle is an uncommon entity with a controversial etiology. It can be developmental or acquired and rarely may be associated with temporomandibular joint (TMJ) ankylosis. Although the patient may be asymptomatic, the radiologist should be aware of this entity and its clinical implications. We report two cases of BMC, one developmental and the other secondary to trauma. Both were diagnosed using computed tomography, which additionally revealed the associated ankylosis of TMJ in both the patients. (orig.)

  16. Current Concepts in the Mandibular Condyle Fracture Management Part II: Open Reduction Versus Closed Reduction

    OpenAIRE

    Choi, Kang-Young; Yang, Jung-Dug; Chung, Ho-Yun; Cho, Byung-Chae

    2012-01-01

    In the treatment of mandibular condyle fracture, conservative treatment using closed reduction or surgical treatment using open reduction can be used. Management of mandibular condylar fractures remains a source of ongoing controversy in oral and maxillofacial trauma. For each type of condylar fracture,the treatment method must be chosen taking into consideration the presence of teeth, fracture height, patient'sadaptation, patient's masticatory system, disturbance of occlusal function, and de...

  17. Current Concepts in the Mandibular Condyle Fracture Management Part I: Overview of Condylar Fracture

    OpenAIRE

    Choi, Kang-Young; Yang, Jung-Dug; Chung, Ho-Yun; Cho, Byung-Chae

    2012-01-01

    The incidence of condylar fractures is high, but the management of fractures of the mandibular condyle continues to be controversial. Historically, maxillomandibular fixation, external fixation, and surgical splints with internal fixation systems were the techniques commonly used in the treatment of the fractured mandible. Condylar fractures can be extracapsular or intracapsular, undisplaced, deviated, displaced, or dislocated. Treatment depends on the age of the patient, the co-existence of ...

  18. Endoscope-Assisted Transoral Fixation of Mandibular Condyle Fractures: Submandibular Versus Transoral Endoscopic Approach.

    Science.gov (United States)

    Hwang, Na-Hyun; Lee, Yoon-Hwan; You, Hi-Jin; Yoon, Eul-Sik; Kim, Deok-Woo

    2016-07-01

    In recent years, endoscope-assisted transoral approach for condylar fracture treatment has attracted much attention. However, the surgical approach is technically challenging: the procedure requires specialized instruments and the surgeons experience a steep learning curve. During the transoral endoscopic (TE) approach several instruments are positioned through a narrow oral incision making endoscope maneuvering very difficult. For this reason, the authors changed the entry port of the endoscope from transoral to submandibular area through a small stab incision. The aim of this study is to assess the advantage of using the submandibular endoscopic intraoral approach (SEI).The SEI approach requires intraoral incision for fracture reduction and fixation, and 4 mm size submandibular stab incision for endoscope and traction wires. Fifteen patients with condyle neck and subcondyle fractures were operated under the submandibular approach and 15 patients with the same diagnosis were operated under the standard TE approach.The SEI approach allowed clear visualization of the posterior margin of the ramus and condyle, and the visual axis was parallel to the condyle ramus unit. The TE approach clearly shows the anterior margin of the condyle and the sigmoid notch. The surgical time of the SEI group was 128 minutes and the TE group was 120 minutes (P >0.05). All patients in the TE endoscope group were fixated with the trocar system, but only 2 lower neck fracture patients in the SEI group required a trocar. The other 13 subcondyle fractures were fixated with an angulated screw driver (P <0.05). There were no differences in complication and surgical outcomes.The submandibular endoscopic approach has an advantage of having more space with good visualization, and facilitated the use of an angulated screw driver.

  19. Changes in the main masticatory muscles in CT after mandibular condyle fracture

    International Nuclear Information System (INIS)

    Raustia, A.M.; Oikarinen, K.S.; Pyhtinen, J.

    1990-01-01

    The aim was to study changes in the main masticatory muscles after mandibular condyle fracture as seen by CT, comparing the densities and sizes of the masseter, medial pterygoid and lateral pterygoid muscles on the fractured side with those on the non-fractured side. More or less permanent muscular changes are detectable several years after the accident, especially in the lateral pterygoid muscle, which is attached to the condylar head. This muscle was statistically significantly smaller (p [de

  20. Aneurysmal bone cyst of the mandibular condyle with condylar neck fracture

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Hoon [Department of Biomedical Engineering, College of Medicine and Healthcare Industry Research Institute, Kyung Hee University, Seoul (Korea, Republic of); Yu, Jae Jung; Kang, Ju Han; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Department of Oral and Maxillofacial Radiology, School of Dentistry and Institute of Oral Biology, Kyung Hee University, Seoul (Korea, Republic of)

    2009-12-15

    Aneurysmal bone cyst (ABC) is relatively rare, non-neoplastic expansible lesion of bone. The case of a 15-year-old male with a ABC of the left mandibular condyle is presented. Panoramic radiograph showed a unilocular radiolucency with thinned coritces and a subcondylar fracture which was due to the trauma. Computed tomography (CT) revealed expansible lesion which had similar attenuation soft tissue. The patient was treated surgically including iliac crestal bone graft.

  1. Aneurysmal bone cyst of the mandibular condyle with condylar neck fracture

    International Nuclear Information System (INIS)

    Park, Jeong Hoon; Yu, Jae Jung; Kang, Ju Han; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan

    2009-01-01

    Aneurysmal bone cyst (ABC) is relatively rare, non-neoplastic expansible lesion of bone. The case of a 15-year-old male with a ABC of the left mandibular condyle is presented. Panoramic radiograph showed a unilocular radiolucency with thinned coritces and a subcondylar fracture which was due to the trauma. Computed tomography (CT) revealed expansible lesion which had similar attenuation soft tissue. The patient was treated surgically including iliac crestal bone graft.

  2. PEBBLES Simulation of Static Friction and New Static Friction Benchmark

    International Nuclear Information System (INIS)

    Cogliati, Joshua J.; Ougouag, Abderrafi M.

    2010-01-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

  3. Internal rotor friction instability

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  4. Spontaneous osteonecrosis of the knee associated with tibial plateau and femoral condyle insufficiency stress fracture

    Energy Technology Data Exchange (ETDEWEB)

    Narvaez, J.A.; Narvaez, J.; Lama, E.De; Sanchez, A. [Department of Magnetic Resonance Imaging, IDI Hospital Duran i Reynals, Ciutat Sanitaria i Universitaria de Bellvitge, Gran Via s/n, 08907, L' Hospitalet de Llobregat (Barcelona) (Spain)

    2003-08-01

    The purpose of this article is to describe the association between spontaneous osteonecrosis and insufficiency stress fractures of the knee. To determine whether insufficiency stress fracture is associated with spontaneous osteonecrosis of the knee, we retrospectively reviewed the medical charts and imaging studies of all patients with spontaneous osteonecrosis of the knee, studied by MR imaging, seen in a tertiary hospital over an 8-year period. Four women (age range 66-84 years) presented spontaneous osteonecrosis of the knee associated with insufficiency stress fracture of the medial tibial plateau. One of these patients also presented a concomitant insufficiency stress fracture of the medial femoral condyle. Radiographs were diagnostic of spontaneous osteonecrosis of the medial femoral condyle in three cases, and insufficiency stress fracture of the medial tibial plateau was detected in one case. Magnetic resonance imaging allows the diagnosis of both conditions in all four cases. Spontaneous osteonecrosis of the knee may be associated with insufficiency stress fracture of the medial femoral condyle and the medial tibial plateau. This association provides additional arguments in favor of the traumatic etiology of spontaneous osteonecrosis of knee. (orig.)

  5. Condyle and mandibular bone change after unilateral condylar neck fracture in growing rats.

    Science.gov (United States)

    Hu, Y; Yang, H-f; Li, S; Chen, J-z; Luo, Y-w; Yang, C

    2012-08-01

    Unilateral fracture of the condylar neck in immature subjects might lead to mandible asymmetry and condyle remodelling. A rat model was used to investigate mandibular deviation and condylar remodelling associated with condyle fracture. 72 4-week-old male rats were randomly divided into three groups: an experimental group (unilateral transverse condylar fracture induced surgically), a sham operation group (surgical exposure but no fracture), and a non-operative control group (no operation). The rats were killed at intervals up to 9weeks after surgery, and outcomes were assessed using various measures of mandible deviation, histological and X-ray observation, and immunohistochemical measures of expression levels of connective tissue growth factor (CTGF) and type II collagen (Col II). The fracture led to the degeneration of mandibular size, associated with atrophy of fractured condylar process. Progressive remodelling of cartilage and increasing expression levels of CTGF and Col II were found. The authors conclude that condylar fracture can lead to asymmetries in mandible and condyle remodelling and expression of CTGF and Col II in condylar cartilage on both the ipsilateral and the contralateral sides. Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  6. Current Concepts in the Mandibular Condyle Fracture Management Part I: Overview of Condylar Fracture

    Science.gov (United States)

    Yang, Jung-Dug; Chung, Ho-Yun; Cho, Byung-Chae

    2012-01-01

    The incidence of condylar fractures is high, but the management of fractures of the mandibular condyle continues to be controversial. Historically, maxillomandibular fixation, external fixation, and surgical splints with internal fixation systems were the techniques commonly used in the treatment of the fractured mandible. Condylar fractures can be extracapsular or intracapsular, undisplaced, deviated, displaced, or dislocated. Treatment depends on the age of the patient, the co-existence of other mandibular or maxillary fractures, whether the condylar fracture is unilateral or bilateral, the level and displacement of the fracture, the state of dentition and dental occlusion, and the surgeonnds on the age of the patient, the co-existence of othefrom which it is difficult to recover aesthetically and functionally;an appropriate treatment is required to reconstruct the shape and achieve the function ofthe uninjured status. To do this, accurate diagnosis, appropriate reduction and rigid fixation, and complication prevention are required. In particular, as mandibular condyle fracture may cause long-term complications such as malocclusion, particularly open bite, reduced posterior facial height, and facial asymmetry in addition to chronic pain and mobility limitation, great caution should be taken. Accordingly, the authors review a general overview of condyle fracture. PMID:22872830

  7. Strength of titanium intramedullary implant versus miniplate fixation of mandibular condyle fractures.

    Science.gov (United States)

    Frake, Paul C; Howell, Rebecca J; Joshi, Arjun S

    2012-07-01

    To test the strength of internal fixation of mandibular condyle fractures repaired with titanium miniplates versus titanium intramedullary implants. Prospective laboratory experimentation in urethane mandible models and human cadaveric mandibles. Materials testing laboratory at an academic medical center. Osteotomies of the mandibular condyle were created in 40 urethane hemimandible models and 24 human cadaveric specimens. Half of the samples in each group were repaired with traditional miniplates, and the other half were repaired with intramedullary titanium implants. Anteroposterior and mediolateral loads were applied to the samples, and the displacement was measured with reference to the applied force. Titanium intramedullary implants demonstrated statistically significant improved strength and stiffness versus miniplates in the urethane model experimental groups. Despite frequent plastic deformation and mechanical failures of the miniplates, a 1.6-mm-diameter titanium intramedullary pin did not mechanically fail in any of the cases. Intramedullary implantation failures were due to secondary fracture of the adjacent cortical bone or experimental design limitations including rotation of the smooth pin implant. Mechanical implant failures that were encountered with miniplate fixation were not seen with titanium intramedullary implants. These intramedullary implants provide stronger and more rigid fixation of mandibular condyle fractures than miniplates in this in vitro model.

  8. Current Concepts in the Mandibular Condyle Fracture Management Part I: Overview of Condylar Fracture

    Directory of Open Access Journals (Sweden)

    Kang-Young Choi

    2012-07-01

    Full Text Available The incidence of condylar fractures is high, but the management of fractures of the mandibular condyle continues to be controversial. Historically, maxillomandibular fixation, external fixation, and surgical splints with internal fixation systems were the techniques commonly used in the treatment of the fractured mandible. Condylar fractures can be extracapsular or intracapsular, undisplaced, deviated, displaced, or dislocated. Treatment depends on the age of the patient, the co-existence of other mandibular or maxillary fractures, whether the condylar fracture is unilateral or bilateral, the level and displacement of the fracture, the state of dentition and dental occlusion, and the surgeonnds on the age of the patient, the co-existence of othefrom which it is difficult to recover aesthetically and functionally;an appropriate treatment is required to reconstruct the shape and achieve the function ofthe uninjured status. To do this, accurate diagnosis, appropriate reduction and rigid fixation, and complication prevention are required. In particular, as mandibular condyle fracture may cause long-term complications such as malocclusion, particularly open bite, reduced posterior facial height, and facial asymmetry in addition to chronic pain and mobility limitation, great caution should be taken. Accordingly, the authors review a general overview of condyle fracture.

  9. Anomalies of ossification in the posterolateral femoral condyle: assessment by MRI

    Energy Technology Data Exchange (ETDEWEB)

    Nawata, K.; Teshima, Ryota; Morio, Yasuo; Hagino, Hiroshi [Department of Orthopaedic Surgery, Faculty of Medicine, Tottori University, Yonaga (Japan)

    1999-10-01

    Background. Anomalies of ossification in the lower femoral epiphysis are often radiographically indistinguishable from juvenile osteochondritis dissecans. Objective. To clarify the MRI characteristics of the anomalies of ossification in the posterolateral femoral condyle that distinguish it from juvenile osteochondritis dissecans. Materials and methods. We retrospectively examined the medical records, plain radiographs (n = 4), MRI (n = 4) and follow-up MRI (n = 2) of four boys (age 8-11 years) with anomalies of ossification in the posterolateral femoral condyle. Results. Plain radiography showed symmetrical marginal irregularity of the posterolateral femoral condyles of both knees. These lesions were asymptomatic, and the areas of irregular radiographic appearances reduced in size or disappeared without treatment within a mean observation period of 3.5 months. MRI showed a clearly demarcated low-intensity islet with the same signal intensity as subchondral bone (which was considered to be an accessory ossification nucleus) in a high-signal area in which the signal intensity was equal to that of normal articular cartilage. The areas observed as radiolucent zones on plain radiography were visualised at the same signal intensity as articular cartilage, and were continuous with articular cartilage on MRI; thus they were regarded as uncalcified cartilage. These MR findings are different from MR images of osteochondritis dissecans. Conclusions. MRI is considered to be the most effective non-invasive diagnostic method for these two conditions. (orig.) With 3 figs., 1 tab., 10 refs.

  10. Mandibular condyle dimensions in Peruvian patients with Class II and Class III skeletal patterns.

    Directory of Open Access Journals (Sweden)

    Hugo Zegarra-Baquerizo

    2017-10-01

    Full Text Available Objective: To compare condylar dimensions of young adults with Class II and Class III skeletal patterns using cone-beam computed tomography (CBCT. Materials and methods: 124 CBCTs from 18-30 year-old patients, divided into 2 groups according to skeletal patterns (Class II and Class III were evaluated. Skeletal patterns were classified by measuring the ANB angle of each patient. The anteroposterior diameter (A and P of the right and left mandibular condyle was assessed from a sagittal view by a line drawn from point A (anterior to P (posterior. The coronal plane allowed the evaluation of the medio-lateral diameter by drawing a line from point M (medium to L (lateral; all distances were measured in mm. Results: In Class II the A-P diameter was 9.06±1.33 and 8.86±1.56 for the right and left condyles respectively, in Class III these values were 8.71±1.2 and 8.84±1.42. In Class II the M-L diameter was 17.94±2.68 and 17.67±2.44 for the right and left condyles respectively, in Class III these values were 19.16±2.75 and 19.16±2.54. Conclusion: Class III M-L dimensions showed higher values than Class II, whereas these differences were minimal in A-P.

  11. Spontaneous osteonecrosis of the knee associated with tibial plateau and femoral condyle insufficiency stress fracture

    International Nuclear Information System (INIS)

    Narvaez, J.A.; Narvaez, J.; Lama, E.De; Sanchez, A.

    2003-01-01

    The purpose of this article is to describe the association between spontaneous osteonecrosis and insufficiency stress fractures of the knee. To determine whether insufficiency stress fracture is associated with spontaneous osteonecrosis of the knee, we retrospectively reviewed the medical charts and imaging studies of all patients with spontaneous osteonecrosis of the knee, studied by MR imaging, seen in a tertiary hospital over an 8-year period. Four women (age range 66-84 years) presented spontaneous osteonecrosis of the knee associated with insufficiency stress fracture of the medial tibial plateau. One of these patients also presented a concomitant insufficiency stress fracture of the medial femoral condyle. Radiographs were diagnostic of spontaneous osteonecrosis of the medial femoral condyle in three cases, and insufficiency stress fracture of the medial tibial plateau was detected in one case. Magnetic resonance imaging allows the diagnosis of both conditions in all four cases. Spontaneous osteonecrosis of the knee may be associated with insufficiency stress fracture of the medial femoral condyle and the medial tibial plateau. This association provides additional arguments in favor of the traumatic etiology of spontaneous osteonecrosis of knee. (orig.)

  12. CAD-CAM-generated hydroxyapatite scaffold to replace the mandibular condyle in sheep: preliminary results.

    Science.gov (United States)

    Ciocca, Leonardo; Donati, Davide; Fantini, Massimiliano; Landi, Elena; Piattelli, Adriano; Iezzi, Giovanna; Tampieri, Anna; Spadari, Alessandro; Romagnoli, Noemi; Scotti, Roberto

    2013-08-01

    In this study, rapid CAD-CAM prototyping of pure hydroxyapatite to replace temporomandibular joint condyles was tested in sheep. Three adult animals were implanted with CAD-CAM-designed porous hydroxyapatite scaffolds as condyle substitutes. The desired scaffold shape was achieved by subtractive automated milling machining (block reduction). Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Using the same technique, fixation plates were created and applied to the scaffold pre-operatively to firmly secure the condyles to the bone and to assure primary stability of the hydroxyapatite scaffolds during masticatory function. Four months post-surgery, the sheep were sacrificed. The hydroxyapatite scaffolds were explanted, and histological specimens were prepared. Different histological tissues penetrating the scaffold macropores, the sequence of bone remodeling, new apposition of bone and/or cartilage as a consequence of the different functional anatomic role, and osseointegration at the interface between the scaffold and bone were documented. This animal model was found to be appropriate for testing CAD-CAM customization and the biomechanical properties of porous, pure hydroxyapatite scaffolds used as joint prostheses.

  13. Condyle-Specific Matching Does Not Improve Midterm Clinical Outcomes of Osteochondral Allograft Transplantation in the Knee.

    Science.gov (United States)

    Wang, Dean; Jones, Kristofer J; Eliasberg, Claire D; Pais, Mollyann D; Rodeo, Scott A; Williams, Riley J

    2017-10-04

    Condyle-specific matching for osteochondral allograft transplantation (OCA) pairs donor and recipient condyles in an attempt to minimize articular incongruity. While the majority of cartilage defects are located on the medial femoral condyle, lateral femoral condyles are more commonly available as a graft source. The purpose of this study was to compare the clinical outcomes of patients treated with non-orthotopic (lateral-to-medial condyle or medial-to-lateral condyle) OCA with those treated with traditional orthotopic (medial-to-medial condyle or lateral-to-lateral condyle) OCA. We hypothesized that clinical outcomes would be similar between groups at midterm follow-up. A retrospective review of prospectively collected data on patients treated with OCA from 2000 to 2014 was conducted. Seventy-seven patients with a full-thickness cartilage defect of a femoral condyle were treated with either orthotopic (n = 50) or non-orthotopic (n = 27) OCA. A minimum follow-up of 2 years was required for analysis. Patients in each group were matched according to sex, age, and total chondral defect size. Reoperations and patient responses to validated outcome measures were reviewed. Failure was defined as any revision cartilage procedure or conversion to knee arthroplasty. The mean duration of follow-up was 4.0 years (range, 2 to 16 years). The orthotopic and non-orthotopic OCA groups were comparable in terms of demographics, the mean number of prior ipsilateral knee operations, and the percentage of concomitant procedures at baseline. Reoperation (p = 0.427) and failure (p = 0.917) rates did not differ significantly between groups. Both groups demonstrated significant increases in the Short Form-36 (SF-36) physical functioning and pain, International Knee Documentation Committee (IKDC), and Knee Outcome Survey-Activities of Daily Living (KOS-ADL) scores compared with baseline (p OCA and those treated with non-orthotopic OCA, suggesting that condyle-specific matching may not be

  14. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  15. Bioinspired orientation-dependent friction.

    Science.gov (United States)

    Xue, Longjian; Iturri, Jagoba; Kappl, Michael; Butt, Hans-Jürgen; del Campo, Aránzazu

    2014-09-23

    Spatular terminals on the toe pads of a gecko play an important role in directional adhesion and friction required for reversible attachment. Inspired by the toe pad design of a gecko, we study friction of polydimethylsiloxane (PDMS) micropillars terminated with asymmetric (spatular-shaped) overhangs. Friction forces in the direction of and against the spatular end were evaluated and compared to friction forces on symmetric T-shaped pillars and pillars without overhangs. The shape of friction curves and the values of friction forces on spatula-terminated pillars were orientation-dependent. Kinetic friction forces were enhanced when shearing against the spatular end, while static friction was stronger in the direction toward the spatular end. The overall friction force was higher in the direction against the spatula end. The maximum value was limited by the mechanical stability of the overhangs during shear. The aspect ratio of the pillar had a strong influence on the magnitude of the friction force, and its contribution surpassed and masked that of the spatular tip for aspect ratios of >2.

  16. Identification of GMS friction model without friction force measurement

    International Nuclear Information System (INIS)

    Grami, Said; Aissaoui, Hicham

    2011-01-01

    This paper deals with an online identification of the Generalized Maxwell Slip (GMS) friction model for both presliding and sliding regime at the same time. This identification is based on robust adaptive observer without friction force measurement. To apply the observer, a new approach of calculating the filtered friction force from the measurable signals is introduced. Moreover, two approximations are proposed to get the friction model linear over the unknown parameters and an approach of suitable filtering is introduced to guarantee the continuity of the model. Simulation results are presented to prove the efficiency of the approach of identification.

  17. Friction surfaced Stellite6 coatings

    International Nuclear Information System (INIS)

    Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

    2012-01-01

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  18. Micromechanical study of macroscopic friction and dissipation in idealised granular materials: the effect of interparticle friction

    NARCIS (Netherlands)

    Kruyt, Nicolaas P.; Gutkowski, Witold; Rothenburg, L.; Kowalewski, Tomasz A.

    2004-01-01

    Using Discrete Element Method (DEM) simulations with varying interparticle friction coefficient, the relation between interparticle friction coefficient and macroscopic continuum friction and dissipation is investigated. As expected, macroscopic friction and dilatancy increase with interparticle

  19. The description of condyle position in disc displacement with reduction using Cone Beam Computed Tomography 3D radiographic analysis

    Directory of Open Access Journals (Sweden)

    Liana Rahmayani

    2009-07-01

    Full Text Available One of the temporomandibular joint disorders that mostly occurs is disc displacement with reduction. Disc displacement that causes the displacement of condyle position can be evaluated by using radiograph. The Cone Beam Computed Tomography (CBCT-3D is a radiograph equipment which is able to capture the condyle position from many directions. This research was aimed to see the condyle position in patients with disc displacement with reduction symptoms. This research was conducted to 11 patients with symptoms of disc displacement with reduction and 3 patients without symptoms of disc displacement with reduction as the counterpart. What was conducted to the sample was the radiographic imaging using CBCT-3D radiography, followed by measuring the joint space distance in the sagittal and coronal directions. The result of the research was analyzed using the T-test. Statistically, the result of the test showed a significant difference ( = 0.05 between patients with disc displacement with reduction symptoms and the patients without symptoms, in sagittal and coronal views. The conclusion led to the difference in condyle positions in patients with the disc displacement with reduction and patients without the symptoms which meant there was a condyle position displacement that caused the distance alteration in joint space in sagittal and coronal directions.

  20. Evaluation of reference gene suitability for quantitative expression analysis by quantitative polymerase chain reaction in the mandibular condyle of sheep.

    Science.gov (United States)

    Jiang, Xin; Xue, Yang; Zhou, Hongzhi; Li, Shouhong; Zhang, Zongmin; Hou, Rui; Ding, Yuxiang; Hu, Kaijin

    2015-10-01

    Reference genes are commonly used as a reliable approach to normalize the results of quantitative polymerase chain reaction (qPCR), and to reduce errors in the relative quantification of gene expression. Suitable reference genes belonging to numerous functional classes have been identified for various types of species and tissue. However, little is currently known regarding the most suitable reference genes for bone, specifically for the sheep mandibular condyle. Sheep are important for the study of human bone diseases, particularly for temporomandibular diseases. The present study aimed to identify a set of reference genes suitable for the normalization of qPCR data from the mandibular condyle of sheep. A total of 12 reference genes belonging to various functional classes were selected, and the expression stability of the reference genes was determined in both the normal and fractured area of the sheep mandibular condyle. RefFinder, which integrates the following currently available computational algorithms: geNorm, NormFinder, BestKeeper, and the comparative ΔCt method, was used to compare and rank the candidate reference genes. The results obtained from the four methods demonstrated a similar trend: RPL19, ACTB, and PGK1 were the most stably expressed reference genes in the sheep mandibular condyle. As determined by RefFinder comprehensive analysis, the results of the present study suggested that RPL19 is the most suitable reference gene for studies associated with the sheep mandibular condyle. In addition, ACTB and PGK1 may be considered suitable alternatives.

  1. The role of the lateral pterygoid muscle in the sagittal fracture of mandibular condyle (SFMC) healing process.

    Science.gov (United States)

    Liu, Chng-Kui; Liu, Ping; Meng, Fan-Wen; Deng, Bang-Lian; Xue, Yang; Mao, Tian-Qiu; Hu, Kai-Jin

    2012-06-01

    The aim of this study was to examine the role of the lateral peterygoid muscle in the reconstruction of the shape of the condyle during healing of a sagittal fracture of the mandibular condyle. Twenty adult sheep were divided into 2 groups: all had a unilateral operation on the right side when the anterior and posterior attachments of the discs were cut, and an oblique vertical osteotomy was made from the lateral pole of the condyle to the medial side of the condylar neck. Ten sheep had the lateral pterygoid muscle cut, and the other 10 sheep did not. Sheep were killed at 4 weeks (n=2 from each group), 12 weeks (n=4), and 24 weeks (n=4) postoperatively. Computed tomograms (CT) were taken before and after operations. We dissected the joints, and recorded with the naked eye the shape, degree of erosion, and amount of calcification of the temporomandibular joint (TMJ). In the group in which the lateral peterygoid muscle had not been cut the joints showed overgrowth of new bone and more advanced ankylosis. Our results show that the lateral pterygoid muscle plays an important part in reconstructing the shape of the condyle during the healing of a sagittal fracture of the mandibular condyle, and combined with the dislocated and damaged disc is an important factor in the aetiology of traumatic ankylosis of the TMJ. Copyright © 2011. Published by Elsevier Ltd.

  2. The effect of extracapsular injuries on growth and development of the mandible condyle: an experimental study in growing dogs.

    Science.gov (United States)

    Liu, Siying; Tian, Lei; Ding, Mingchao; Liu, Yanpu; Li, Guiyu; Chen, Jinwu; Ding, Yin

    2016-11-01

    To investigate the effects of condylar extracapsular injuries on the development of the mandibular condyle and try to find a way to treat condylar hyperplasia by electively using such injuries to restrict the overdeveloped mandibular condyle. Sixty 6-month-old beagle puppies were divided randomly into five groups: blank control; unilateral fracture to the condylar neck; unilateral fracture to the condylar neck treated with rigid internal fixation; unilateral periosteum injury; unilateral decortication of the condylar neck. Computed tomography, 99 m Tc single-photon emission computed tomography, and tetracycline-calcein double-labeling were performed after surgery. The puppies were sacrificed 12 and 24 weeks after surgery. Morphologic analyses and examination of growth activity were done. Unilateral fracture of the condylar neck without fixation caused local morphologic changes during the early postoperative period, but compensatory growth of the condyle altered such changes after healing. The other types of injury failed to inhibit the growth of the condyle and the mandible, whereas functional deviation of the chin was found after unilateral fracture of the condylar neck with or without fixation. The four types of extracapsular injury described here failed to inhibit the growth of the mandibular condyle and could not be selected as alternatives to treat condylar hyperplasia. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Argo packing friction research update

    International Nuclear Information System (INIS)

    VanTassell, D.M.

    1994-01-01

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  4. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  5. Displaced humeral lateral condyle fractures in children: should we bury the pins?

    Science.gov (United States)

    Das De, Soumen; Bae, Donald S; Waters, Peter M

    2012-09-01

    The purpose of this investigation was to determine if leaving Kirschner wires exposed is more cost-effective than burying them subcutaneously after open reduction and internal fixation (ORIF) of humeral lateral condyle fractures. A retrospective cohort study of all lateral condyle fractures treated over a 10-year period at a single institution was performed. Data on surgical technique, fracture healing, and complications were analyzed, as well as treatment costs. A decision analysis model was then constructed to compare the strategies of leaving the pins exposed versus buried. Finally, sensitivity analyses were performed, assessing cost-effectiveness when infection rates and costs of treating deep infections were varied. A total of 235 children with displaced fractures were treated with ORIF using Kirschner wires. Pins were left exposed in 41 cases (17.4%) and buried in 194 cases (82.6%); the age, sex, injury mechanisms, and fracture patterns were similar in both the groups. The median time to removal of implants was shorter with exposed versus buried pins (4 vs. 6 wk, Pfracture union or loss of reduction rates. The rate of superficial infection was higher with exposed pins (9.8% vs. 3.1%), but this was not statistically significant (P=0.076). There were no deep infections with exposed pins, whereas the rate of deep infection was 0.5% with buried pins (P=1.00). Buried pins were associated with additional complications, including symptomatic implants (7.2%); pins protruding through the skin (16%); internal pin migration necessitating additional surgery (1%); and skin necrosis (1%). The decision analysis revealed that leaving pins exposed resulted in an average cost savings of $3442 per patient. This strategy remained cost-effective even when infection rates with exposed pins approached 40%. Leaving the pins exposed after ORIF of lateral condyle fractures is safe and more cost-effective than burying the pins subcutaneously. Retrospective cohort study (level III).

  6. Surgical treatment of sagittal fracture of mandibular condyle using long-screw osteosynthesis.

    Science.gov (United States)

    Luo, Shufang; Li, Bo; Long, Xing; Deng, Mohong; Cai, Hengxing; Cheng, Yong

    2011-07-01

    The retrospective study evaluated long-screw (bicortical screw) osteosynthesis used in the surgical treatment of sagittal fracture of the mandibular condyle and compared it with titanium plates and removal of the condylar fragment. Ninety-five patients with sagittal fracture of the mandibular condyle received open surgical treatment from 1997 to 2008. Among these patients, the condylar fragments were fixed with long screws in 56 cases (group A), were fixed with titanium plates in 12 cases (group B), and were completely removed in 24 cases (group C). Follow-up was carried out clinically and radiologically. The clinical features included limitation of mandibular mobility, occlusion disturbance, lateral deviation on mouth opening, joint pain, clicking, facial asymmetry, and patient's subjective evaluation. The radiologic parameters consisted of degree of bony resorption, bony change, change of osteosynthesis material, and shortening of mandibular ramus height. Anatomic reduction and functional restoration were obtained and no severe complication was detected in group A. However, 3 of 14 patients had severe osteoarthrosis and 2 of 14 patients had ankylosis in group B. In group C 3 of 24 patients had mandibular retrusion, 4 of 24 patients had front teeth open bite, 4 of 24 patients had severe osteoarthrosis, and 1 of 24 patients had ankylosis. The long-screw fixation group had a more favorable prognosis than the titanium plate group and the group in which removal of the condylar fragment was performed. The long-screw fixation technique might be suitable for use in the surgical treatment of sagittal fractures of the mandibular condyle. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  7. Facilitation of bone resorption activities in synovial lavage fluid patients with mandibular condyle fractures.

    Science.gov (United States)

    Takano, H; Takahashi, T; Nakata, A; Nogami, S; Yusa, K; Kuwajima, S; Yamazaki, M; Fukuda, M

    2016-05-01

    The aim of this study was to investigate the bone resorption effect of the mediators delivered in joint cavity of patients with mandibular condyle fractures by detecting osteoclast markers using cellular biochemistry methods, and by analysing bone resorption activities via inducing osteoclast differentiation of the infiltrated cells from arthrocentesis. Sixteen joints in 10 patients with mandibular condyle fractures were evaluated. The control group consisted of synovial fluid (SF) samples from seven joints of four volunteers who had no clinical signs or symptoms involving the temporomandibular joint (TMJ) or disc displacement. We collected SF cells from all patients during therapeutic arthrocentesis. The infiltrating cells from TMJ SF were cultured, differentiated into tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells and examined bone resorption activities. We also investigated factors related to osteoclast induction of SF, using ELISA procedures. Osteoclast-like cells were induced from the SF cells obtained from all patients with condylar fractures. These multinucleated giant cells were positive for TRAP and actin, and had the ability to absorb dentin slices. The levels of macrophage colony-stimulating factor (M-CSF), prostaglandin E2 (PGE2), soluble form of receptor activator of nuclear factor kappa-B ligand (sRANKL) and osteoprotegerin (OPG), in SF samples from the patients, were significantly higher than in the controls. These findings indicate that bone resorption activities in SF from patients with mandibular condyle fractures were upregulated and may participate in the pathogenesis and wound healing. © 2016 The Authors. Journal of Oral Rehabilitation Published by John Wiley & Sons Ltd.

  8. Analysis of two different surgical approaches for fractures of the mandibular condyle.

    Science.gov (United States)

    Kumaran, S; Thambiah, L J

    2012-01-01

    Fractures of the condyle account for one third of all the mandibular fractures. Different surgical approaches to the condyle described hitherto testify to the advantages and disadvantages of the different surgical techniques used for approaching the condyle in such cases of fractures. We have described and compared two of such surgical techniques in this study. The aim of this study is to compare the outcome of dealing with condylar fractures by two different surgical techniques: the mini retromandibular approach, and the preauricular approach. A prospective study of 31 patients who had suffered with mandibular condylar fractures was carried out. Of these, 26 patients had unilateral condylar fractures, and 5 patients had a bilateral fracture. Further, 19 of these patients were treated by the mini retromandibular approach and 12 by the preauricular approach. The treated patients were followed up and evaluated for a minimum period of 1 year and assessed for parameters such as the maximum mouth opening, lateral movement on the fractured side, mandibular movements such as protrusion, dental occlusion, scar formation, facial nerve weakness, salivary fistula formation and time taken for the completion of the surgical procedure. t- test was used for statistical analysis of the data obtained in the study. Dental occlusion was restored in all the cases, and good anatomical reduction was achieved. The mean operating time was higher 63.53 (mean) ± 18.12 minutes standard deviation (SD) in the preauricular approach compared to 45.22 (mean) ± 18.86 minutes SD in the mini retromandibular approach. Scar formation was satisfactory in almost all the cases.

  9. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  10. Friction in levitated superconductors

    International Nuclear Information System (INIS)

    Brandt, E.H.

    1988-01-01

    A type I superconductor levitated above a magnet of low symmetry has a unique equilibrium position about which it may oscillate freely. In contrast, a type II superconductor has a continuous range of stable equilibrium positions and orientations where it floats rigidly without swinging or orbiting as if it were stuck in sand. A strong internal friction conspicuously indicates the existence and unpinning of flux lines in oxide superconductors levitated above liquid nitrogen. It is shown how these effects follow from the hysteretic magnetization curves and how the energy is dissipated

  11. Mechanical properties of cancellous bone in the human mandibular condyle are anisotropic

    DEFF Research Database (Denmark)

    Giesen, EB; Ding, Ming; Dalstra, M

    2001-01-01

    The objective of the present study was (1) to test the hypothesis that the elastic and failure properties of the cancellous bone of the mandibular condyle depend on the loading direction, and (2) to relate these properties to bone density parameters. Uniaxial compression tests were performed......). Archimedes' principle was applied to determine bone density parameters. The cancellous bone was in axial loading 3.4 times stiffer and 2.8 times stronger upon failure than in transverse loading. High coefficients of correlation were found among the various mechanical properties and between them...

  12. A paediatric case of bilateral mandibular condyle fracture presenting with bloody otorrhoea following trauma.

    Science.gov (United States)

    Chan, Yat Chun; Au-Yeung, Kwan Leong

    2017-04-22

    A 7-year-old boy presented to the emergency department with bilateral bloody otorrhoea after falling from his scooter. Skull base fracture was suspected. CT showed no evidence of skull base fracture but bilateral mandibular condyle and external acoustic canals fractures. We report this case to illustrate a rare possibility of bilateral external acoustic canal fracture associated with condylar fracture in trauma patients presented with bloody otorrhoea. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. Changes in the main masticatory muscles in CT after mandibular condyle fracture

    Energy Technology Data Exchange (ETDEWEB)

    Raustia, A.M. (Oulu Univ. Central Hospital (Finland). Dept. of Prosthodontics and Stomatognathic Physiology); Oikarinen, K.S. (Oulu Univ. Central Hospital (Finland). Dept. of Oral and Maxillofacial Surgery); Pyhtinen, J. (Oulu Univ. Central Hospital (Finland). Dept. of Diagnostic Radiology)

    1990-11-01

    The aim was to study changes in the main masticatory muscles after mandibular condyle fracture as seen by CT, comparing the densities and sizes of the masseter, medial pterygoid and lateral pterygoid muscles on the fractured side with those on the non-fractured side. More or less permanent muscular changes are detectable several years after the accident, especially in the lateral pterygoid muscle, which is attached to the condylar head. This muscle was statistically significantly smaller (p<0,001) on the fractured side. Examination of the masticatory muscles immediately after the fracture and at intervals afterwards could reveal more about the pathogenesis of the changes in these muscles. (orig.).

  14. Architectural Measures of the Cancellous Bone of the Mandibular Condyle Identified by Principal Components Analysis

    DEFF Research Database (Denmark)

    Giese, E.B.; Ding, M.; Dalstra, M.

    2003-01-01

    embalmed mandibular condyles; the angle of the first principal direction and the axis of the specimen, expressing the orientation of the trabeculae, ranged from 10 degrees to 87 degrees. Morphological parameters were determined by a method based on Archimedes' principle and by micro-CT scanning......-like trabeculae, and not with more or thicker trabeculae. The trabecular orientation was most determinative (about 50%) in explaining stiffness, strength, and failure energy. The amount of bone was second most determinative and increased the explained variance to about 72%. These results suggest that trabecular...

  15. Friction analysis of kinetic schemes : the friction coefficient

    NARCIS (Netherlands)

    Lolkema, Juke S.

    1995-01-01

    Friction analysis is proposed as the application of general control analysis to single enzymes to describe the control of elementary kinetic steps on the overall catalytic rate. For each transition, a friction coefficient is defined that measures the sensitivity of the turnover rate to the free

  16. Frictional behaviour of high performance fibrous tows: Friction experiments

    NARCIS (Netherlands)

    Cornelissen, Bo; Rietman, Bert; Akkerman, Remko

    2013-01-01

    Tow friction is an important mechanism in the production and processing of high performance fibrous tows. The frictional behaviour of these tows is anisotropic due to the texture of the filaments as well as the tows. This work describes capstan experiments that were performed to measure the

  17. Consensus or controversy? The classification and treatment decision-making by 491 maxillofacial surgeons from around the world in three cases of a unilateral mandibular condyle fracture

    NARCIS (Netherlands)

    Kommers, S.C.; Boffano, P.; Forouzanfar, T.

    2015-01-01

    Purpose Many studies are available in the literature on both classification and treatment of unilateral mandibular condyle fractures. To date however, controversy regarding the best treatment for unilateral mandibular condyle fractures remains. Material and methods In this study, an attempt was made

  18. Internal friction, microstructure, and radiation effects

    International Nuclear Information System (INIS)

    Wechsler, M.S.; Sommer, W.F.; Davidson, D.R.

    1984-01-01

    A brief review is given of internal friction relaxation peaks and background internal friction. The microstructural origin of the internal friction is discussed. Particular emphasis is placed on radiation effects

  19. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  20. Blades Couple Dry Friction Connection

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk; Radolfová, Alena

    2015-01-01

    Roč. 9, č. 1 (2015), s. 31-40 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : stick-slip dry friction * 3D friction characteristic * tangential contact stiffness * hysterezis loop * response curves Subject RIV: BI - Acoustics

  1. Friction laws at the nanoscale.

    Science.gov (United States)

    Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

    2009-02-26

    Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

  2. Corrosion effects on friction factors

    International Nuclear Information System (INIS)

    Magleby, H.L.; Shaffer, S.J.

    1996-01-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly

  3. [Intramedullary nailing combined with cannulated screw in treating femoral condyles fractures].

    Science.gov (United States)

    Shen, Guo-Qing; Zhang, Hao; Long, Da-Fu; Li, Zheng-Wen; Tan, Ying-Dong

    2017-07-25

    To observe the clinical effects of retrograde intramedullary nailing and cannulated screws in the treatment of femoral condylar fracture. From June 2009 to June 2015, 13 patients with femoral condyles fracture were treated by retrograde intramedullary nailing and cannulated screws including 6 males and 7 females with an average age of 46.1 years old ranging from 16 to 76 years old. There were 10 cases of closed fractures, 3 cases of open fraetures. According to AO classification criteriam, 4 cases were type C1, 7 cases were type C2, 2 cases were type C3. Postoperative reduction of fracture and the knee joint function recovery were observed. All patients were followed up for 12 to 36 months with a mean of 24 months. X-ray examination showed that the union time of fracture was 18 to 24 weeks, 21 weeks on average. There were no cases of loosening, breakage of internal fixators and re-fracture. Hospital for Special Surgery(HSS) knee score was 90.07±4.99 at 1 year after the operation. The clinical efficacy for retrograde intramedullary nailing and cannulated screw for the treatment of femoral condyles fracture was excellent. It can improve the anatomical reattachment rate and reduce the complications and promote the knee functional recovery.

  4. Current Concepts in the Mandibular Condyle Fracture Management Part II: Open Reduction Versus Closed Reduction

    Science.gov (United States)

    Yang, Jung-Dug; Chung, Ho-Yun; Cho, Byung-Chae

    2012-01-01

    In the treatment of mandibular condyle fracture, conservative treatment using closed reduction or surgical treatment using open reduction can be used. Management of mandibular condylar fractures remains a source of ongoing controversy in oral and maxillofacial trauma. For each type of condylar fracture,the treatment method must be chosen taking into consideration the presence of teeth, fracture height, patient'sadaptation, patient's masticatory system, disturbance of occlusal function, and deviation of the mandible. In the past, closed reduction with concomitant active physical therapy conducted after intermaxillary fixation during the recovery period had been mainly used, but in recent years, open treatment of condylar fractures with rigid internal fixation has become more common. The objective of this review was to evaluate the main variables that determine the choice of an open or closed method for treatment of condylar fractures, identifying their indications, advantages, and disadvantages, and to appraise the current evidence regarding the effectiveness of interventions that are used in the management of fractures of the mandibular condyle. PMID:22872831

  5. Epidemiology and treatment outcome of surgically treated mandibular condyle fractures. A five years retrospective study.

    Science.gov (United States)

    Zrounba, Hugues; Lutz, Jean-Christophe; Zink, Simone; Wilk, Astrid

    2014-09-01

    Surgical management of mandibular condyle fractures is still controversial. Although it provides better outcome than closed treatment questions still remain about the surgical approach and the osteosynthesis devices to be used. Between 2005 and 2010, we managed 168 mandibular condyle fractures with open treatment. Two surgical approaches were used in this study, a pre-auricular and a high submandibular approach (one or the other or as a combined approach). Internal fixation was performed using TCP(®) plates (Medartis, Basel, Switzerland) or with two lag screws (15 and 17 mm). Delta plates were used in 15 cases (8.9%). We report the epidemiology of these fractures and the outcomes of the surgical treatment. We assessed the complications related to the surgical procedure and those related to the osteosynthesis material. The facial nerve related complication rate was very low and the osteosynthesis materials used proved to be strong enough to realize a stable fixation. The two approaches used in this study appeared to be safe with good aesthetic results. Most of the surgical procedure failures occurred in high subcondylar fractures especially when bilateral. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  6. Current Concepts in the Mandibular Condyle Fracture Management Part I: Overview of Condylar Fracture

    Directory of Open Access Journals (Sweden)

    Kang-Young Choi

    2012-07-01

    Full Text Available The incidence of condylar fractures is high,but the management of fractures of the mandibularcondyle continues to be controversial. Historically, maxillomandibular fixation, externalfixation, and surgical splints with internal fixation systems were the techniques commonlyused in the treatment of the fractured mandible. Condylar fractures can be extracapsularor intracapsular, undisplaced, deviated, displaced, or dislocated. Treatment depends on theage of the patient, the co-existence of other mandibular or maxillary fractures, whether thecondylar fracture is unilateral or bilateral, the level and displacement of the fracture, thestate of dentition and dental occlusion, and the surgeonnds on the age of the patient, theco-existence of othefrom which it is difficult to recover aesthetically and functionally;anappropriate treatment is required to reconstruct the shape and achieve the function oftheuninjured status. To do this, accurate diagnosis, appropriate reduction and rigid fixation, andcomplication prevention are required. In particular, as mandibular condyle fracture may causelong-term complications such as malocclusion, particularly open bite, reduced posterior facialheight, and facial asymmetry in addition to chronic pain and mobility limitation, great cautionshould be taken. Accordingly, the authors review a general overview of condyle fracture.

  7. Dislocation of the mandibular condyle into the middle cranial fossa causing an epidural haematoma.

    Science.gov (United States)

    Struewer, Johannes; Kiriazidis, Ilias; Figiel, Jens; Dukatz, Thomas; Frangen, Thomas; Ziring, Ewgeni

    2012-07-01

    Dislocation of the mandibular condyle into the middle cranial fossa is a rare complication of mandibular trauma due to anatomical and biomechanical factors. Owing to the proximity of the temporal glenoid fossa to the middle meningeal artery, there is the risk of serious sequelae in case of trauma. The authors report the case of a 36-year-old male patient, who was beaten up in a family dispute and presented with complex mandibular and maxillofacial fractures, including mandibular condyle intrusion into the middle cranial fossa causing extensive meningeal bleeding. The patient underwent immediate surgery, with evacuation of the epidural haematoma via a temporal approach. In addition open reduction and reconstruction of the temporal glenoid fossa via anatomic reduction of the fragments was performed. A functional occlusion was re-established via miniplate reconstruction of the complex mandibular body and ramus fractures. Prompt diagnosis and a multidisciplinary approach are essential to minimize the complications. Advanced imaging modalities of computed tomography are indicated. Treatment options should be individualized in particular in case of suspected neurological injury. Copyright © 2011 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  8. Current Concepts in the Mandibular Condyle Fracture Management Part II: Open Reduction Versus Closed Reduction

    Directory of Open Access Journals (Sweden)

    Kang-Young Choi

    2012-07-01

    Full Text Available In the treatment of mandibular condyle fracture, conservative treatment using closedreduction or surgical treatment using open reduction can be used. Management of mandibularcondylar fractures remains a source of ongoing controversy in oral and maxillofacial trauma.For each type of condylar fracture,the treatment method must be chosen taking intoconsideration the presence of teeth, fracture height, patient’sadaptation, patient’s masticatorysystem, disturbance of occlusal function, and deviation of the mandible. In the past, closedreduction with concomitant active physical therapy conducted after intermaxillary fixationduring the recovery period had been mainly used, but in recent years, open treatment ofcondylar fractures with rigid internal fixation has become more common. The objectiveof this review was to evaluate the main variables that determine the choice of an open orclosed method for treatment of condylar fractures, identifying their indications, advantages,and disadvantages, and to appraise the current evidence regarding the effectiveness ofinterventions that are used in the management of fractures of the mandibular condyle.

  9. Current Concepts in the Mandibular Condyle Fracture Management Part II: Open Reduction Versus Closed Reduction

    Directory of Open Access Journals (Sweden)

    Kang-Young Choi

    2012-07-01

    Full Text Available In the treatment of mandibular condyle fracture, conservative treatment using closed reduction or surgical treatment using open reduction can be used. Management of mandibular condylar fractures remains a source of ongoing controversy in oral and maxillofacial trauma. For each type of condylar fracture,the treatment method must be chosen taking into consideration the presence of teeth, fracture height, patient'sadaptation, patient's masticatory system, disturbance of occlusal function, and deviation of the mandible. In the past, closed reduction with concomitant active physical therapy conducted after intermaxillary fixation during the recovery period had been mainly used, but in recent years, open treatment of condylar fractures with rigid internal fixation has become more common. The objective of this review was to evaluate the main variables that determine the choice of an open or closed method for treatment of condylar fractures, identifying their indications, advantages, and disadvantages, and to appraise the current evidence regarding the effectiveness of interventions that are used in the management of fractures of the mandibular condyle.

  10. Shape and Site Dependent in Vivo Degradation of Mg-Zn Pins in Rabbit Femoral Condyle

    Directory of Open Access Journals (Sweden)

    Pei Han

    2014-02-01

    Full Text Available A type of specially designed pin model of Mg-Zn alloy was implanted into the full thickness of lesions of New Zealand rabbits’ femoral condyles. The recovery progress, outer surface healing and in vivo degradation were characterized by various methods including radiographs, Micro-CT scan with surface rendering, SEM (scanning electron microscope with EDX (Energy Dispersive X-ray analysis and so on. The in vivo results suggested that a few but not sufficient bridges for holding force were formed between the bone and the implant if there was a preexisting gap between them. The rapid degradation of the implantation in the condyle would result in the appearance of cavities. Morphological evaluation of the specially designed pins indicated that the cusp was the most vulnerable part during degradation. Furthermore, different implantation sites with distinct components and biological functions can lead to different degradation rates of Mg-Zn alloy. The rate of Mg-Zn alloy decreases in the following order: implantation into soft tissue, less trabecular bone, more trabecular bone, and cortical bone. Because of the complexities of in vivo degradation, it is necessary for the design of biomedical Mg-Zn devices to take into consideration the implantation sites used in clinics.

  11. Radiographic structural findings in the mandibular condyles of young individuals receiving orthodontic treatment

    International Nuclear Information System (INIS)

    Peltola, J.S.; Nystroem, M.; Koenoenen, M.; Wolf, J.

    1995-01-01

    Radiographic findings in mandibular condyles were studied from the pre- and post-treatment panoramic radiographs of 625 orthodontic patients. The subjects' mean age was 11 years at the start and 14 years at the end of active orthodontic treatment. Radiographic condylar findings were seen in 14 subjects before treatment and in 54 subjects after treatment. In age-related controls condylar findings were seen in 3%. The condylar findings was ''flattening only'' in half of the patients and in one-third of the controls with condylar findings. Activator treatment was associated with condylar findings. Condylar findings increased with age in the orthodontically treated subjects, but not in the unselected population controls. This may mean that condyles become more sensitive with age in children. Increase with age may be partly due to the radiographic interpretation, since minor condylar findings are difficult to observe in young children, and partly due to differences in treatment modalities and the duration of treatment. 44 refs., 1 fig., 3 tabs

  12. Tactile friction of topical formulations.

    Science.gov (United States)

    Skedung, L; Buraczewska-Norin, I; Dawood, N; Rutland, M W; Ringstad, L

    2016-02-01

    The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Frictional Heating with Time-Dependent Specific Power of Friction

    Directory of Open Access Journals (Sweden)

    Topczewska Katarzyna

    2017-06-01

    Full Text Available In this paper analytical solutions of the thermal problems of friction were received. The appropriate boundary-value problems of heat conduction were formulated and solved for a homogeneous semi–space (a brake disc heated on its free surface by frictional heat fluxes with different and time-dependent intensities. Solutions were obtained in dimensionless form using Duhamel's theorem. Based on received solutions, evolution and spatial distribution of the dimensionless temperature were analyzed using numerical methods. The numerical results allowed to determine influence of the time distribution of friction power on the spatio-temporal temperature distribution in brake disc.

  14. Wave friction factor rediscovered

    Science.gov (United States)

    Le Roux, J. P.

    2012-02-01

    The wave friction factor is commonly expressed as a function of the horizontal water particle semi-excursion ( A wb) at the top of the boundary layer. A wb, in turn, is normally derived from linear wave theory by {{U_{{wb}}/T_{{w}}}}{{2π }} , where U wb is the maximum water particle velocity measured at the top of the boundary layer and T w is the wave period. However, it is shown here that A wb determined in this way deviates drastically from its real value under both linear and non-linear waves. Three equations for smooth, transitional and rough boundary conditions, respectively, are proposed to solve this problem, all three being a function of U wb, T w, and δ, the thickness of the boundary layer. Because these variables can be determined theoretically for any bottom slope and water depth using the deepwater wave conditions, there is no need to physically measure them. Although differing substantially from many modern attempts to define the wave friction factor, the results coincide with equations proposed in the 1960s for either smooth or rough boundary conditions. The findings also confirm that the long-held notion of circular water particle motion down to the bottom in deepwater conditions is erroneous, the motion in fact being circular at the surface and elliptical at depth in both deep and shallow water conditions, with only horizontal motion at the top of the boundary layer. The new equations are incorporated in an updated version (WAVECALC II) of the Excel program published earlier in this journal by Le Roux et al. Geo-Mar Lett 30(5): 549-560, (2010).

  15. Friction and anchorage loading revisited.

    Science.gov (United States)

    Dholakia, Kartik D

    2012-01-01

    Contemporary concepts of sliding mechanics explain that friction is inevitable. To overcome this frictional resistance, excess force is required to retract the tooth along the archwire (ie, individual retraction of canines, en masse retraction of anterior teeth), in addition to the amount of force required for tooth movement. The anterior tooth retraction force, in addition to excess force (to overcome friction), produces reciprocal protraction force on molars, thereby leading to increased anchorage loading. However, this traditional concept was challenged in recent literature, which was based on the finite element model, but did not bear correlation to the clinical scenario. This article will reinforce the fact that clinically, friction increases anchorage loading in all three planes of space, considering the fact that tooth movement is a quasistatic process rather than a purely continuous or static one, and that conventional ways of determining the effects of static or dynamic friction on anchorage load cannot be applied to clinical situations (which consist of anatomical resistance units and a complex muscular force system). The article does not aim to quantify friction and its effect on the amount of anchorage load. Rather, a new perspective regarding the role of various additional factors (which is not explained by contemporary concept) that may influence friction and anchorage loading is provided..

  16. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  17. IMF-screws or arch bars as conservative treatment for mandibular condyle fractures: Quality of life aspects

    NARCIS (Netherlands)

    van den Bergh, B.; van Otterloo, J.J.D.M.; van der Ploeg, T.; Tuinzing, D.B.; Forouzanfar, T.

    2015-01-01

    Objective Arch bars as treatment for a fractured mandibular condyle are inconvenient to patients and lead to lowered quality of life (QOL). To overcome these inconveniences, IMF-screws (IMFS) to facilitate intermaxillary fixation during surgery have been developed. The purpose of the present study

  18. Conservative treatment of a mandibular condyle fracture: comparing intermaxillary fixation with screws or arch bar. A randomised clinical trial

    NARCIS (Netherlands)

    van den Bergh, B.; Blankestijn, J.; van der Ploeg, T.; Tuinzing, D.B.; Forouzanfar, T.

    2015-01-01

    Introduction A mandibular condyle fracture can be treated conservatively by intermaxillary fixation (IMF) or by open reposition and internal fixation (ORIF). Many IMF-modalities can be chosen, including IMF-screws (IMFS). This prospective multi-centre randomised clinical trial compared the use of

  19. Conservative treatment of a mandibular condyle fracture: Comparing intermaxillary fixation with screws or arch bar. A randomised clinical trial

    NARCIS (Netherlands)

    van den Bergh, B.; Blankestijn, J.; van der Ploeg, T.; Tuinzing, D.B.; Forouzanfar, T.

    2015-01-01

    Introduction A mandibular condyle fracture can be treated conservatively by intermaxillary fixation (IMF) or by open reposition and internal fixation (ORIF). Many IMF-modalities can be chosen, including IMF-screws (IMFS). This prospective multi-centre randomised clinical trial compared the use of

  20. Recovery of mouth-opening after closed treatment of a fracture of the mandibular condyle : a longitudinal study

    NARCIS (Netherlands)

    Niezen, E. T.; Stuive, I.; Post, W. J.; Bos, R. R. M.; Dijkstra, P. U.

    The aim of this retrospective study was to assess recovery of mouth opening after closed treatment of fractures of the mandibular condyle, and analyse which characteristics might influence recovery. We measured mouth opening in 142 patients (mean (SD) age 30 (14) years, 96 of whom were male) during

  1. Clinical and radiological outcomes after treatment of sagittal fracture of mandibular condyle (SFMC) by using occlusal splint in children.

    Science.gov (United States)

    Liu, Chang-Kui; Meng, Fan-Wen; Tan, Xin-Ying; Xu, Juan; Liu, Hua-Wei; Liu, San-Xia; Huang, Hai-Tao; Yan, Rong-Zeng; Hu, Min; Hu, Kai-Jin

    2014-02-01

    This study was designed to investigate the effects of occlusal splints in the treatment of sagittal fractures of the mandibular condyle in children. From January 1995 to December 2011, 37 sagittal fractures of the mandibular condyle in 30 patients aged 4-8 years old were included in this study. All the patients were treated with 1-2mm occlusal splints in the molar region. The mouths of the patients were kept slightly open by the occlusal splints for 3-6 months, and we reviewed the clinical and radiological remodelling of the affected condyles after treatment. Excellent (n=20) and good (n=10) clinical outcomes were achieved with full radiological remodelling seen in 19 and partial remodelling in 11. Treatment with occlusal splints is effective in delivering good results and function with minimal morbidity in children with sagittal fractures of the condyle, while permitting ongoing remodelling and growth in the short term. Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  2. IMF-screws or arch bars as conservative treatment for mandibular condyle fractures: quality of life aspects

    NARCIS (Netherlands)

    van den Bergh, B.; de Mol van Otterloo, J.J.; van der Ploeg, T.; Tuinzing, D.B.; Forouzanfar, T.

    2015-01-01

    Objective Arch bars as treatment for a fractured mandibular condyle are inconvenient to patients and lead to lowered quality of life (QOL). To overcome these inconveniences, IMF-screws (IMFS) to facilitate intermaxillary fixation during surgery have been developed. The purpose of the present study

  3. Radiographic evaluation of the canine elbow joint with special reference to the medial humeral condyle and the medial coronoid process

    International Nuclear Information System (INIS)

    Voorhout, G.; Hazewinkel, H.A.W.

    1987-01-01

    The results of radiographic examination of clinically affected elbow joints in 14 young, large-breed dogs, including standard and oblique projections and linear tomography, were compared with the findings of medial arthrotomy. Radiographs revealed arthrosis (13 dogs), osteochondrosis of the medial humeral condyle (2 dogs), fragmentation of the medial coronoid process (5 dogs), and a combination of osteochondrosis of the medial humeral condyle and fragmentation of the medial coronoid process (2 dogs). In one dog fissures in the medial coronoid process and in another dog a linear radiopacity along the articular surface of the medial coronoid process were found. In three dogs both medial humeral condyle and medial coronoid process appeared normal. The radiographic findings were confirmed during surgery in 11 dogs. Cartilage erosion of the medial humeral condyle in two dogs and of the medial coronoid process in one dog had not resulted in radiographically visible abnormalities. Radiographic examination of the elbow joints in young, large-breed dogs should include standard mediolateral and craniocaudal projections, a mediolateral projection with the joint maximally extended and the leg supinated 15°, and a craniolateral-to-caudomedial projection

  4. The prevalence, radiographic appearance and gender predilection of bifid mandibular condyles in Punjabi population of North India: A retrospective study

    Directory of Open Access Journals (Sweden)

    Bhawandeep Kaur

    2017-01-01

    Full Text Available Aim: The aim of this study was to determine the prevalence and gender predilection of bifid mandibular condyle (BMC in Indian population using extra oral radiographs. Material and Methods: Previous record of 800 patients was evaluated by the observers who had undergone extra oral radiography for any diagnostic or treatment purposes between years 2012 and 2014. Results: Out of 800 extra oral radiographs, bifid condyles were found in 28, giving an overall prevalence of 3.5%. Out of 28 bifid condyles, 20 were in females (2.5% and eight were in males (1.7%. The prevalence of BMC was found to be more in females as compared to the males and this difference was statistically significant with P value equivalent to 0.001. Among 28 bifid condyles, 19 were unilateral (2.4% and nine were bilateral 1.5%. Chi-square test shows non-significant P value. Conclusion: It is possible that BMC is a more frequent condition than is commonly perceived. However, because of the minimal symptoms associated with this condition, the authors believe that it will remain an incidental finding upon routine radiographic examination, rather than a clinical observation.

  5. Flow Friction or Spontaneous Ignition?

    Science.gov (United States)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  6. [Friction: self-ligating brackets].

    Science.gov (United States)

    Thermac, Guilhem; Morgon, Laurent; Godeneche, Julien

    2008-12-01

    The manufacturers of self-ligating brackets advertise a reduction of the friction engendered between the wire and the bracket, which is an essential parameter for treatment's speed and comfort. We have compared the friction obtained with four types of self-ligating brackets - In-Ovation R, Damon 3, Smart Clip and Quick - with that of a standard bracket Omniarch associated with an elastomeric ligature. All bracket were tested on a bench of traction with three types of wires: steel .019"x.025", TMA .019"x.025" and NEO sentalloy F300 .020"x.020". The results confirm a clear friction reduction for all tested wire.

  7. Late presentation of fractures of the lateral condyle of the humerus in children

    Directory of Open Access Journals (Sweden)

    Shyam K Saraf

    2011-01-01

    Full Text Available Background: The current controversy regarding the management of fractures of the lateral condyle of the humerus presenting between 3 to 12 weeks prompted us to evaluate our results of open reduction and internal fixation of such fractures. Patients and Methods: Twenty-one patients operated between March 1995 and February 2001 qualified for this study. Five patients presented between 3-4 weeks, nine between 5-8 weeks and seven between 9-12 weeks post injury. Ten fractures were classified as stage II and eleven as stage III (Jacob et al. criteria. The mean age was 8 years (range: 4-14 years. All patients underwent surgery (open reduction and internal fixation with K-wires/screw, with or without bone grafting. The results were assessed by the modified criteria of Agarwal et al. after an average follow-up of 2.3 years. Results: Excellent to good results were observed in all the five patients presenting at 3-4 weeks post injury. In the patients presenting at 5-8 weeks, the results were excellent in one, good in four, fair in three, and poor in one patient. The fracture united in all cases; however, malunion was observed in four patients. The fractures that were operated at 9-12 weeks showed good results in one case, fair result in three cases, and poor result in three cases. Avascular necrosis of the lateral condyle in one patient, premature fusion in two patients, pin tract infection in three patients, and gross restriction of elbow movements in three patients were the major complications in this group. Accurate reduction was difficult as a result of new bone formation and remodeling at the fracture surfaces. Multiple incisions over the common extensor aponeurosis and bone graft supplementation were helpful for achieving acceptable reduction. Conclusion: Open reduction and internal fixation is recommended in all cases of displaced fractures of the lateral condyle of the humerus presenting at up to 12 weeks post injury. However, the results become

  8. Surgical treatment on displaced and dislocated sagittal fractures of the mandibular condyle.

    Science.gov (United States)

    Jing, Jie; Han, Yu; Song, Yu; Wan, Yingbiao

    2011-06-01

    The purpose of this study was to evaluate the effect of surgical treatment on displaced and dislocated sagittal fractures of the mandibular condyle (SFMC). Twenty-four patients with 28 displaced and dislocated SFMCs were distinguished into type M, type C, and type L fractures according the location of the fracture line. The fractured fragment was reduced and fixated with two 0.6-mm 4-hole micro-plates via a preauricular temporal incision. The fragment was extirpated when it was too small to be fixated. The postoperative position and profile of the fragment was examined by orthopantomogram radiograph or computed tomography (CT). The function of the temporal and zygomatic branches of the facial nerve was inspected. The occluding relation was surveyed, the interincisal distance at maximum mouth opening was measured, and the deviation from the midline during mouth opening was recorded. Twenty-three condyles (82%) suffered dislocated fractures with the condylar fragment out of the glenoid fossa. Five condyles (18%) were displaced, but not dislocated. There were 2 (7%) type M, 19 (68%) type C (3 comminuted), and 7 (25%) type L fractures (1 comminuted), respectively. Twenty-one (75%) fractured fragments received free-graft procedures with 2 micro-plates. Four (14%) fragments were reduced and fixated without being dissected free of their attachments. Three (11%) fragments were extirpated. There were no permanent facial never branch injuries. Micro-plate removal was necessary because of postoperative infection and necrosis of the fractured fragment in 1 condylar process. No other patients could be found with obvious postoperative bone resorption. The average postoperative maximum mouth opening and deviation at 6 months were improved significantly. The postoperative occlusion was good in 22 cases. Access with the preauricular incision, and the dislocated and displaced fragment can be reduced and fixated to its normal position easily. Free-graft procedure is a suitable

  9. Showing Area Matters: A Work of Friction

    Science.gov (United States)

    Van Domelen, David

    2010-01-01

    Typically, we teach the simplified friction equation of the form F[subscript s] = [mu][subscript s]N for static friction, where F[subscript s] is the maximum static friction, [mu][subscript s] is the coefficient of static friction, and "N" is the normal force pressing the surfaces together. However, this is a bit too simplified, and…

  10. A Pedagogical Model of Static Friction

    OpenAIRE

    Pickett, Galen T.

    2015-01-01

    While dry Coulombic friction is an elementary topic in any standard introductory course in mechanics, the critical distinction between the kinetic and static friction forces is something that is both hard to teach and to learn. In this paper, I describe a geometric model of static friction that may help introductory students to both understand and apply the Coulomb static friction approximation.

  11. Multimodal Friction Ignition Tester

    Science.gov (United States)

    Davis, Eddie; Howard, Bill; Herald, Stephen

    2009-01-01

    The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term multimodal in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen test conditions approximating conditions expected to be encountered in proposed composite material oxygen tanks aboard aircraft and spacecraft in flight. The MFIT includes a stainless-steel pressure vessel capable of retaining the required test atmosphere. Mounted atop the vessel is a pneumatic cylinder containing a piston for exerting the specified normal force between the two specimens. Through a shaft seal, the piston shaft extends downward into the vessel. One of the specimens is mounted on a block, denoted the pressure block, at the lower end of the piston shaft. This specimen is pressed down against the other specimen, which is mounted in a recess in another block, denoted the slip block, that can be moved horizontally but not vertically. The slip block is driven in reciprocating horizontal motion by an electrodynamic vibration exciter outside the pressure vessel. The armature of the electrodynamic exciter is connected to the slip block via a horizontal shaft that extends into the pressure vessel via a second shaft seal. The reciprocating horizontal

  12. Friction induced hunting limit cycles : a comparison between the LuGre and switch friction model

    NARCIS (Netherlands)

    Hensen, R.H.A.; Molengraft, van de M.J.G.; Steinbuch, M.

    2003-01-01

    In this paper, friction induced limit cycles are predicted for a simple motion system consisting of a motor-driven inertia subjected to friction and a PID-controlled regulator task. The two friction models used, i.e., (i) the dynamic LuGre friction model and (ii) the static switch friction model,

  13. Comparison of conventional panoramic radiography and panoramic digital subtraction radiography in detection of simulated lesions of mandibular condyle

    Directory of Open Access Journals (Sweden)

    Panjnoush M.

    2008-12-01

    Full Text Available "n  "nBackground and Aim: Digital subtraction Radiography (DSR is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assesment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl. "nMaterials and Methods: this was a process reaserch study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher's Exact test. "nResults: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6% vs 41.9% (p<0.0001. "nConclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

  14. Treatment of mandibular condyle fractures using a modified transparotid approach via the parotid mini-incision: experience with 31 cases.

    Directory of Open Access Journals (Sweden)

    Jun Shi

    Full Text Available Surgery for mandibular condyle fractures must allow direct vision of the fracture, reduce surgical trauma and achieve reduction and fixation while avoiding facial nerve injury. This prospective study was conducted to introduce a new surgical approach for open reduction and internal fixation of mandibular condyle fractures using a modified transparotid approach via the parotid mini-incision, and surgical outcomes were evaluated. The modified transparotid approach via the parotid mini-incision was applied and rigid internal fixation using a small titanium plate was carried out for 36 mandibular condyle fractures in 31 cases. Postoperative follow-up of patients ranged from 3 to 26 months; in the first 3 months after surgery, outcomes for all patients were analyzed by evaluating the degree of mouth opening, occlusal relationship, facial nerve function and results of imaging studies. The occlusal relationships were excellent in all patients and none had symptoms of intraoperative ipsilateral facial nerve injury. The mean degree of mouth opening was 4.0 (maximum 4.8 cm, minimum 3.0 cm. No mandibular deviations were noted in any patient during mouth opening. CT showed complete anatomical reduction of the mandibular condyle fracture in all patients. The modified transparotid approach via the smaller, easily concealed parotid mini-incision is minimally invasive and achieves anatomical reduction and rigid internal fixation with a simplified procedure that directly exposes the fracture site. Study results showed that this procedure is safe and feasible for treating mandibular condyle fracture, and offers a short operative path, protection of the facial nerve and satisfactory aesthetic outcomes.

  15. Comparison of accuracy of uncorrected and corrected sagittal tomography in detection of mandibular condyle erosions: An exvivo study

    Directory of Open Access Journals (Sweden)

    Asieh Zamani Naser

    2010-01-01

    Full Text Available Background: Radiographic examination of TMJ is indicated when there are clinical signs of pathological conditions, mainly bone changes that may influence the diagnosis and treatment planning. The purpose of this study was to evaluate and to compare the validity and diagnostic accuracy of uncorrected and corrected sagittal tomographic images in the detection of simulated mandibular condyle erosions. Methods : Simulated lesions were created in 10 dry mandibles using a dental round bur. Using uncorrected and corrected sagittal tomography techniques, mandibular condyles were imaged by a Cranex Tome X-ray unit before and after creating the lesions. The uncorrected and corrected tomography images were examined by two independent observers for absence or presence of a lesion. The accuracy for detecting mandibular condyle lesions was expressed as sensitivity, specificity, and validity values. Differences between the two radiographic modalities were tested by Wilcoxon for paired data tests. Inter-observer agreement was determined by Cohen′s Kappa. Results: The sensitivity, specificity and validity were 45%, 85% and 30% in uncorrected sagittal tomographic images, respectively, and 70%, 92.5% and 60% in corrected sagittal tomographic images, respectively. There was a significant statistical difference between the accuracy of uncorrected and corrected sagittal tomography in detection of mandibular condyle erosions (P = 0.016. The inter-observer agreement was slight for uncorrected sagittal tomography and moderate for corrected sagittal tomography. Conclusion: The accuracy of corrected sagittal tomography is significantly higher than that of uncorrected sagittal tomography. Therefore, corrected sagittal tomography seems to be a better modality in detection of mandibular condyle erosions.

  16. Assessment of osteoarthrosis of the temporomandibular joint associated with avascular necrosis of the condyle on magnetic resonance imaging

    International Nuclear Information System (INIS)

    Segami, Natsuki; Murakami, Ken-ichiro; Hosaka, Hideo; Moriya, Yoshiyuki; Miyaki, Katsuaki; Chen, Wen-Hsi; Iizuka, Tadahiko

    1993-01-01

    Osteoarthrosis associated with findings of avascular necrosis of the mandibular condyle on magnetic resonance imaging was clinically evaluated. The subjects consisted of 5 female unilateral cases, with an average age of 55.4 years who had a mean duration of illness of 15.2 months. The symptoms were a mean interincisal opening distance of 32.8 mm with arthralgia in mild to moderate degree, and joint noise (crepitation) in all joints. MRI documented decreasing signal intensity of the condyle with 2 joints in high degree and 3 joints in moderate, as well as variable low signal density of the articular eminence, associated with concomitant anterior disk displacement. X-ray showed deformity of the condyle and eminence. The operative findings disclosed disk rupture and comparatively smooth cartilage with minimum remodeling of the condylar surface; however, avascular evidence was suggested when corticotomy was performed. 4 joints underwent diskectomy, condylar shaving, auricular cartilage grafts and corticotomy of the condyle. Arthroscopic corticotomy was applied for 1 joint with mild symptoms. Postoperative symptoms improved to mean opening distance of 41.4 mm and disappeared arthralgia in 4 joints. The surgical outcome was excellent in 3 joints and good in 2 joints. Follow-up MRI in 2 cases disclosed increasing signal intensity, which suggested recovery of condylar vascularity following corticotomy. It is suggested that the low-signal intensity on MRI in osteoarthrosis might indicate avascular lesions of the condyle, secondary to degenerative change. Histological investigations are required to evaluate avascular necrosis of the temporomandibular joints. (author)

  17. Assessment of osteoarthrosis of the temporomandibular joint associated with avascular necrosis of the condyle on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Segami, Natsuki; Murakami, Ken-ichiro; Hosaka, Hideo; Moriya, Yoshiyuki; Miyaki, Katsuaki; Chen, Wen-Hsi; Iizuka, Tadahiko [Kyoto Univ. (Japan). Faculty of Medicine

    1993-02-01

    Osteoarthrosis associated with findings of avascular necrosis of the mandibular condyle on magnetic resonance imaging was clinically evaluated. The subjects consisted of 5 female unilateral cases, with an average age of 55.4 years who had a mean duration of illness of 15.2 months. The symptoms were a mean interincisal opening distance of 32.8 mm with arthralgia in mild to moderate degree, and joint noise (crepitation) in all joints. MRI documented decreasing signal intensity of the condyle with 2 joints in high degree and 3 joints in moderate, as well as variable low signal density of the articular eminence, associated with concomitant anterior disk displacement. X-ray showed deformity of the condyle and eminence. The operative findings disclosed disk rupture and comparatively smooth cartilage with minimum remodeling of the condylar surface; however, avascular evidence was suggested when corticotomy was performed. 4 joints underwent diskectomy, condylar shaving, auricular cartilage grafts and corticotomy of the condyle. Arthroscopic corticotomy was applied for 1 joint with mild symptoms. Postoperative symptoms improved to mean opening distance of 41.4 mm and disappeared arthralgia in 4 joints. The surgical outcome was excellent in 3 joints and good in 2 joints. Follow-up MRI in 2 cases disclosed increasing signal intensity, which suggested recovery of condylar vascularity following corticotomy. It is suggested that the low-signal intensity on MRI in osteoarthrosis might indicate avascular lesions of the condyle, secondary to degenerative change. Histological investigations are required to evaluate avascular necrosis of the temporomandibular joints. (author).

  18. Rubber friction and tire dynamics

    International Nuclear Information System (INIS)

    Persson, B N J

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  19. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  20. Size scaling of static friction.

    Science.gov (United States)

    Braun, O M; Manini, Nicola; Tosatti, Erio

    2013-02-22

    Sliding friction across a thin soft lubricant film typically occurs by stick slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Here we formulate a scaling law of the static friction force, which for a soft lubricant is predicted to decrease as f(m)+Δf/A(γ) for increasing contact area A, with γ>0. Our main finding is that the value of f(m), controlling the survival of stick slip at large size, can be evaluated by simulations of comparably small size. MD simulations of soft lubricant sliding are presented, which verify this theory.

  1. Rubber friction and tire dynamics.

    Science.gov (United States)

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  2. Nuclear friction and chaotic motion

    International Nuclear Information System (INIS)

    Srokowski, T.; Szczurek, A.; Drozdz, S.

    1990-01-01

    The concept of nuclear friction is considered from the point of view of regular versus chaotic motion in an atomic nucleus. Using a realistic nuclear Hamiltonian it is explicitly shown that the frictional description of the gross features of nuclear collisions is adequate if the system behaves chaotically. Because of the core in the Hamiltonian, the three-body nuclear system already reveals a structure of the phase space rich enough for this concept to be applicable

  3. Slipforming - Materials effect on friction

    OpenAIRE

    Busterud, Jørgen Thomasgaard

    2016-01-01

    Master's thesis in Structural engineering Slipforming is a construction method for concrete and it is especially suited for tall constructions with simple geometry. This method have occasionally caused lifting cracks and other surface damages, due to the friction between the slipform panel and the concrete has become to high. The thesis will look at how the choice of material composition in concrete mixes in the combination of a given slipform rate would affect the friction between the ...

  4. Slow rupture of frictional interfaces

    OpenAIRE

    Sinai, Yohai Bar; Brener, Efim A.; Bouchbinder, Eran

    2011-01-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not comple...

  5. Labor Supply and Optimization Frictions

    DEFF Research Database (Denmark)

    Søgaard, Jakob Egholt

    In this paper I investigate the nature of optimization frictions by studying the labor market of Danish students. This particular labor market is an interesting case study as it features a range of special institutional settings that affect students’ incentive to earn income and comparing outcomes...... theory. More concretely I find the dominate optimization friction to be individuals’ inattention about their earnings during the year, while real adjustment cost and gradual learning appears to be of less importance....

  6. Comparative study of manufacturing condyle implant using rapid prototyping and CNC machining

    Science.gov (United States)

    Bojanampati, S.; Karthikeyan, R.; Islam, MD; Venugopal, S.

    2018-04-01

    Injuries to the cranio-maxillofacial area caused by road traffic accidents (RTAs), fall from heights, birth defects, metabolic disorders and tumors affect a rising number of patients in the United Arab Emirates (UAE), and require maxillofacial surgery. Mandibular reconstruction poses a specific challenge in both functionality and aesthetics, and involves replacement of the damaged bone by a custom made implant. Due to material, design cycle time and manufacturing process time, such implants are in many instances not affordable to patients. In this paper, the feasibility of designing and manufacturing low-cost, custom made condyle implant is assessed using two different approaches, consisting of rapid prototyping and three-axis computer numerically controlled (CNC) machining. Two candidate rapid prototyping techniques are considered, namely fused deposition modeling (FDM) and three-dimensional printing followed by sand casting The feasibility of the proposed manufacturing processes is evaluated based on manufacturing time, cost, quality, and reliability.

  7. Quantitative Assessment of Radioisotope Uptake in Condyles by SPECT Bone Scintigraphy

    Directory of Open Access Journals (Sweden)

    Z. Dalili

    2006-03-01

    Full Text Available Statement of problem: Condylar hyperplasia of the mandible is a self limiting abnormality which can cause facial asymmetry, temporomandibular joint (TMJdysfunction and esthetic problems. Treatment planning is based on the results of isotope scanning, clinical findings and patient age. Single photon emission tomography(SPECT is considered to be a sensitive method in the calculation of condylar uptake differences.Purpose: The aim of this study was to determine the growth activity occurring in the mandibular condyles, and to devise an index of side-to-side differences in condylar activity in different individuals.Material and Methods: 38 patients, with an age range of 13 to 34 years, undergoing skeletal scintigraphy for a variety of conditions, were chosen for this study. 25 mci TC-99 was injected to all subjects in order to assess the difference between right (Rt andleft (Lt condylar uptake percentage and to calculate the Lt to Rt condylar uptake ratio.The normal index was determined.Results: The maximum amount of difference between the uptake of Rt and Lt condyles was 6.2 percent (Lt side and Rt side were 53.1 % and 46.9 %, respectively in the male patients and 5.7 percent in the female patients (Lt side and Rt side were 52.85 % and 47.15 %, respectively. The condylar activity difference and ratio of Lt to Rt condylar uptakes did not show a significant difference between the male and female groups.Conclusion: The difference between the growth activity of RT and LT normal TMJs was less than 6.2 percent.

  8. Condyle-fossa modifications and muscle interactions during herbst treatment, part 1. New technological methods.

    Science.gov (United States)

    Voudouris, John C; Woodside, Donald G; Altuna, Gurkan; Kuftinec, Mladen M; Angelopoulos, Gerassimos; Bourque, Paul J

    2003-06-01

    Changes in the condyle, the glenoid fossa, and the muscles of mastication were investigated in subjects undergoing continuous orthopedic advancement of the mandible with a Herbst-block appliance. The total sample consisted of 56 subjects and included 15 nonhuman primates (in the middle mixed, early permanent, and permanent dentitions), 17 human Herbst patients in the early permanent dentition, and 24 human controls from the Burlington Growth Center. The 8 nonhuman primates in the middle mixed dentition were the focus of this study. Mandibular advancement was obtained progressively in 5 animals by adding stops to the telescopic arms of fixed functional Herbst appliances with occlusal coverage; activations of 5.0 mm, 7.0 mm, and 8.0 mm were achieved. Two primates served as controls, and the third was a sham control. Two experimental animals and the 2 controls also wore surgically implanted electromyographic electrodes in the superior and inferior heads of the lateral pterygoid muscles and in the superficial masseter and anterior digastric muscles. Changes in condylar growth direction and amount were assessed with the Björk method from measurements made on serial cephalometric tracings superimposed on metallic implants. Undecalcified sections, treated with intravenous tetracycline vital staining, were viewed with fluorescence microscopy to examine histologic changes in the condyle and the glenoid fossa. New bone formation in the fossa associated with continuous mandibular protrusion was quantified by using computerized histomorphometric analysis of decalcified histological sections and polarized light. The unique combination of permanently implanted electromyographic electrodes, tetracycline vital staining, and histomorphometry represents a significant technological advancement in methods and materials. Together, they demonstrated different muscle-bone interaction results for functional appliances than those reported in previous studies. In Part 1 of this study, we

  9. A modified surgical technique for neglected fracture of lateral humeral condyle in children.

    Science.gov (United States)

    Sulaiman, Abdul Razak; Munajat, Ismail; Mohd, Emil Fazliq

    2011-11-01

    Operative treatment for neglected fracture of lateral humeral condyle (LHC) is difficult because of contracted muscle, fibrous tissue formation, and indistinct bony edges. Its success depends on the ability to preserve blood supply during the surgery. We retrospectively reviewed eight cases of neglected fracture of LHC in children treated with open reduction with selected multiple 'V' lengthening of common extensor muscle and internal fixation. The patients were between 3 and 8 years of age. The period of neglect was between 3 and 20 weeks. Four patients with displacement of more than 10 mm and neglect for 5 weeks or more required lengthening of common extensor muscle aponeurosis. The follow-up assessments were between 1 and 6.3 years with a mean of 4.4 years. All patients had union by 2 months. They gained improvement of flexion range of motion between 60° and 120° with a mean of 86.3°. Loss of final range of motion compared with the normal side was between 5° and 35° with a mean of 10°. No patient had limitation of activities or pain. Six cases had excellent and two cases had good Dillon functional score. All patients had lateral condyle prominent with different severities. There was one mild avascular necrosis and one fishtail deformity. Both of them had almost full range of motion. All patients had early physeal closure, except one, who had only 1 year follow-up. There was no case of progressive valgus deformity. Children with neglected fracture of LHC would benefit from anatomical reduction and internal fixation through a proper exposure and if indicated combined with multiple 'V' lengthening of common extensor muscle aponeurosis. This is a level IV study.

  10. Femoral condyle insufficiency fractures: associated clinical and morphological findings and impact on outcome

    Energy Technology Data Exchange (ETDEWEB)

    Plett, Sara K.; Hackney, Lauren A.; Heilmeier, Ursula; Nardo, Lorenzo; Zhang, Chiyuan A.; Link, Thomas M. [Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA (United States); Yu, Aihong [Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA (United States); 4th Medical College of Peking University, Department of Radiology, Beijing Jishuitan Hospital, Beijing (China)

    2015-12-15

    To determine the characteristics of femoral condyle insufficiency fracture (FCIF) lesions and their relative associations with the risk of clinical progression. This HIPAA-compliant retrospective study was approved by our Institutional Review Board. Seventy-three patients (age range, 19-95) were included after excluding patients with post-traumatic fractures, bone marrow infarct, osteochondritis dissecans, or underlying tumor. Two board-certified musculoskeletal radiologists classified morphologic findings including lesion diameter, associated bone marrow edema pattern, and associated cartilage/meniscus damage. Electronic medical charts were evaluated for symptoms, risk factors, and longitudinal outcomes, including total knee arthroplasty (TKA). Imaging characteristics were correlated with clinical findings, and comparison of outcome groups was performed using a regression model adjusted for age. The majority of patients with FCIF were women (64.4 %, 47/73), on average 10 years older than men (66.28 ± 15.86 years vs. 56.54 ± 10.39 years, p = 0.005). The most common location for FCIF was the central weight-bearing surface of the medial femoral condyle; overlying full thickness cartilage loss (75.7 %, 53/70) and ipsilateral meniscal injury (94.1 %, 64/68) were frequently associated. Clinical outcomes were variable, with 23.9 % (11/46) requiring TKA. Cartilage WORMS score, adjacent cartilage loss, and contralateral meniscal injury, in addition to decreased knee range of motion at presentation, were significantly associated with progression to TKA (p < 0.05). FCIF are frequently associated with overlying cartilage loss and ipsilateral meniscal injury. The extent of cartilage loss and meniscal damage, in addition to loss of knee range of motion at the time of presentation, are significantly associated with clinical progression. (orig.)

  11. Modeling Friction in Modelica with the Lund-Grenoble Friction Model

    OpenAIRE

    Aberger, Martin; Otter, Martin

    2002-01-01

    The properties of the Lund-Grenoble friction model are summarized and different types of friction elements - bearing friction, clutch, one-way clutch, are implemented in Modelica using this friction formulation. The dynamic properties of these components are determined in simulations and compared with the friction models available in the Modelica standard library. This includes also an automatic gearbox model where 6 friction elements are coupled dynamically.

  12. High speed friction microscopy and nanoscale friction coefficient mapping

    International Nuclear Information System (INIS)

    Bosse, James L; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S

    2014-01-01

    As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for friction coefficient mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm s −1 for microfabricated SiO 2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ∼1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 µm s −1 up to 2 cm s −1 . While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems. (paper)

  13. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  14. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  15. Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining

    Science.gov (United States)

    Zhang, Dekun; Chen, Kai; Guo, Yongbo

    2018-01-01

    This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions. The mixed-friction mechanism was in the period when the working conditions varied from high pressure and speed to low pressure and speed. PMID:29498677

  16. Prevalence and clinical significance of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease: observations at MR imaging.

    LENUS (Irish Health Repository)

    Chan, V O

    2013-08-01

    To determine the prevalence of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease in patients with anterior knee pain and to correlate it with patient demographics, patellar shape, and patellofemoral alignment.

  17. Structural Damping with Friction Beams

    Directory of Open Access Journals (Sweden)

    L. Gaul

    2008-01-01

    Full Text Available In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi-active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi-active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non-linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point-to-point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode

  18. Versatile Friction Stir Welding/Friction Plug Welding System

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  19. Slow rupture of frictional interfaces

    Science.gov (United States)

    Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

    2012-02-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

  20. Nonlinear friction model for servo press simulation

    Science.gov (United States)

    Ma, Ninshu; Sugitomo, Nobuhiko; Kyuno, Takunori; Tamura, Shintaro; Naka, Tetsuo

    2013-12-01

    The friction coefficient was measured under an idealized condition for a pulse servo motion. The measured friction coefficient and its changing with both sliding distance and a pulse motion showed that the friction resistance can be reduced due to the re-lubrication during unloading process of the pulse servo motion. Based on the measured friction coefficient and its changes with sliding distance and re-lubrication of oil, a nonlinear friction model was developed. Using the newly developed the nonlinear friction model, a deep draw simulation was performed and the formability was evaluated. The results were compared with experimental ones and the effectiveness was verified.

  1. Mesenchymal Stem Cells and Platelet Gel Improve Bone Deposition within CAD-CAM Custom-Made Ceramic HA Scaffolds for Condyle Substitution

    Directory of Open Access Journals (Sweden)

    L. Ciocca

    2013-01-01

    Full Text Available Purpose. This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs and CAD-CAM customized pure and porous hydroxyapatite (HA scaffolds to replace the temporomandibular joint (TMJ condyle. Methods. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Results. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P<0.05. The bone ingrowth (BI relative values of split-mouth comparison (right versus left side showed a significant difference between condyles with and without MSCs (P<0.05. Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. Conclusion. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs.

  2. Mesenchymal stem cells and platelet gel improve bone deposition within CAD-CAM custom-made ceramic HA scaffolds for condyle substitution.

    Science.gov (United States)

    Ciocca, L; Donati, D; Ragazzini, S; Dozza, B; Rossi, F; Fantini, M; Spadari, A; Romagnoli, N; Landi, E; Tampieri, A; Piattelli, A; Iezzi, G; Scotti, R

    2013-01-01

    This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs) and CAD-CAM customized pure and porous hydroxyapatite (HA) scaffolds to replace the temporomandibular joint (TMJ) condyle. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right) of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P < 0.05). The bone ingrowth (BI) relative values of split-mouth comparison (right versus left side) showed a significant difference between condyles with and without MSCs (P < 0.05). Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs.

  3. Distraction of the temporomandibular joint condyle in patients with unilateral non-reducing disc displacement: Fact or fiction?

    Science.gov (United States)

    Yıldız, Melih; Çağatay Dayan, Süleyman; Şakar, Olcay; Sülün, Tonguç

    2017-07-24

    This study investigated the distractive effect of a unilateral pivot splint on patients with unilateral disc displacement without reduction. The study group was comprised of 18 patients who had no history of treatment with removable prosthetic restorations of molars, premolars, or canine teeth, and no previous treatment for temporomandibular disorder. Joint spaces measurements made on magnetic resonance images indicated the affected side to be narrower than the healthy side. Unilateral distraction splints were made for all patients. An ultrasonic motion analyzer was used to measure the vertical shift occurring on the affected side as patients closed their mouths with maximal force with the splint in their mouths. Closing with maximal force on the unilateral distraction splint led to a noticeable downward movement of the affected condyle. The findings of this study indicate that the TMJ condyle of patients with unilateral disc displacement without reduction may be unilaterally distracted if the articular space is narrowed.

  4. Morphometric Evaluation of Occipital Condyles: Defining Optimal Trajectories and Safe Screw Lengths for Occipital Condyle-Based Occipitocervical Fixation in Indian Population.

    Science.gov (United States)

    Bosco, Aju; Venugopal, Prakash; Shetty, Ajoy Prasad; Shanmuganathan, Rajasekaran; Kanna, Rishi Mugesh

    2018-04-01

    Computed tomographic (CT) morphometric analysis. To assess the feasibility and safety of occipital condyle (OC)-based occipitocervical fixation (OCF) in Indians and to define anatomical zones and screw lengths for safe screw placement. Limitations of occipital squama-based OCF has led to development of two novel OC-based OCF techniques. Morphometric analysis was performed on the OCs of 70 Indian adults. The feasibility of placing a 3.5-mm-diameter screw into OCs was investigated. Safe trajectories and screw lengths for OC screws and C0-C1 transarticular screws without hypoglossal canal or atlantooccipital joint compromise were estimated. The average screw length and safe sagittal and medial angulations for OC screws were 19.9±2.3 mm, ≤6.4°±2.4° cranially, and 31.1°±3° medially, respectively. An OC screw could not be accommodated by 27% of the population. The safe sagittal angles and screw lengths for C0-C1 transarticular screw insertion (48.9°±5.7° cranial, 26.7±2.9 mm for junctional entry technique; 36.7°±4.6° cranial, 31.6±2.7 mm for caudal C1 arch entry technique, respectively) were significantly different than those in other populations. The risk of vertebral artery injury was high for the caudal C1 arch entry technique. Screw placement was uncertain in 48% of Indians due to the presence of aberrant anatomy. There were significant differences in the metrics of OC-based OCF between Indian and other populations. Because of the smaller occipital squama dimensions in Indians, OC-based OCF techniques may have a higher application rate and could be a viable alternative/salvage option in selected cases. Preoperative CT, including three-dimensional-CT-angiography (to delineate vertebral artery course), is imperative to avoid complications resulting from aberrant bony and vascular anatomy. Our data can serve as a valuable reference guide in placing these screws safely under fluoroscopic guidance.

  5. A new method of CT scanning for the diagnosis of mandibular fractures; A preliminary report: diagnosis of condyle fractures

    Energy Technology Data Exchange (ETDEWEB)

    Tsukagoshi, Taku; Satoh, Kaneshige; Onizuka, Takuya (Showa Univ., Tokyo (Japan). School of Medicine)

    1990-08-01

    The condylar neck of the mandible is one of the most common fracture sites in the facial skeleton. Such a fracture is routinely diagnosed by A-P, lateral oblique, and Towne projection roentgenography or orthopantomography. Despite the combination of these films, fracture of the neck of the mandible is still difficult to diagnose definitely. Therefore, a new CT scanning method was developed for diagnosing fractures of the neck of the condylar mandible. The CT axis is projected along the length of the mandible, extending from the condyle to the symphysis. This projection visualizes both the condyle and the mandibular symphysis in the same plane. The patient is placed in a supine position with the head fully extended. The base line, a line extending from the midpoint of the glenoid fossa to the menton, is determined with a lateral facial cephalogram. CT scanning with a 5 mm window is performed in parallel with and 2 cm anterior to and 2 cm posterior to the base line. When CT scanning was performed in a healthy volunteer, the condition of the condyle and the condylar neck of the mandible was clearly shown, and the view extended from the condyle to the symphysis. For automobile accident patients in whom fracture of the neck of the mandible was associated with fracture of the symphysis, two fractures were found in the same plane. A newly developed CT scanning technique is useful in the diagnosis of fractures of the condylar neck of the mandible and in the identification of fractures at other mandibular sites. It also allows scanning of patients in a supine position, which may aid in managing patients with multiple traumas. (N.K.).

  6. Machine Learning of Fault Friction

    Science.gov (United States)

    Johnson, P. A.; Rouet-Leduc, B.; Hulbert, C.; Marone, C.; Guyer, R. A.

    2017-12-01

    We are applying machine learning (ML) techniques to continuous acoustic emission (AE) data from laboratory earthquake experiments. Our goal is to apply explicit ML methods to this acoustic datathe AE in order to infer frictional properties of a laboratory fault. The experiment is a double direct shear apparatus comprised of fault blocks surrounding fault gouge comprised of glass beads or quartz powder. Fault characteristics are recorded, including shear stress, applied load (bulk friction = shear stress/normal load) and shear velocity. The raw acoustic signal is continuously recorded. We rely on explicit decision tree approaches (Random Forest and Gradient Boosted Trees) that allow us to identify important features linked to the fault friction. A training procedure that employs both the AE and the recorded shear stress from the experiment is first conducted. Then, testing takes place on data the algorithm has never seen before, using only the continuous AE signal. We find that these methods provide rich information regarding frictional processes during slip (Rouet-Leduc et al., 2017a; Hulbert et al., 2017). In addition, similar machine learning approaches predict failure times, as well as slip magnitudes in some cases. We find that these methods work for both stick slip and slow slip experiments, for periodic slip and for aperiodic slip. We also derive a fundamental relationship between the AE and the friction describing the frictional behavior of any earthquake slip cycle in a given experiment (Rouet-Leduc et al., 2017b). Our goal is to ultimately scale these approaches to Earth geophysical data to probe fault friction. References Rouet-Leduc, B., C. Hulbert, N. Lubbers, K. Barros, C. Humphreys and P. A. Johnson, Machine learning predicts laboratory earthquakes, in review (2017). https://arxiv.org/abs/1702.05774Rouet-LeDuc, B. et al., Friction Laws Derived From the Acoustic Emissions of a Laboratory Fault by Machine Learning (2017), AGU Fall Meeting Session S025

  7. Case report: multifocal subchondral stress fractures of the femoral heads and tibial condyles in a young military recruit.

    Science.gov (United States)

    Yoon, Pil Whan; Yoo, Jeong Joon; Yoon, Kang Sup; Kim, Hee Joong

    2012-03-01

    Subchondral stress fractures of the femoral head may be either of the insufficiency-type with poor quality bone or the fatigue-type with normal quality bone but subject to high repetitive stresses. Unlike osteonecrosis, multiple site involvement rarely has been reported for subchondral stress fractures. We describe a case of multifocal subchondral stress fractures involving femoral heads and medial tibial condyles bilaterally within 2 weeks. A 27-year-old military recruit began having left knee pain after 2 weeks of basic training, without any injury. Subsequently, right knee, right hip, and left hip pain developed sequentially within 2 weeks. The diagnosis of multifocal subchondral stress fracture was confirmed by plain radiographs and MR images. Nonoperative treatment of the subchondral stress fractures of both medial tibial condyles and the left uncollapsed femoral head resulted in resolution of symptoms. The collapsed right femoral head was treated with a fibular strut allograft to restore congruity and healed without further collapse. There has been one case report in which an insufficiency-type subchondral stress fracture of the femoral head and medial femoral condyle occurred within a 2-year interval. Because the incidence of bilateral subchondral stress fractures of the femoral head is low and multifocal involvement has not been reported, multifocal subchondral stress fractures can be confused with multifocal osteonecrosis. Our case shows that subchondral stress fractures can occur in multiple sites almost simultaneously.

  8. Shaft-Condylar Angle for surgical correction in neglected and displaced lateral humeral condyle fracture in children.

    Science.gov (United States)

    Mulpruek, Pornchai; Angsanuntsukh, Chanika; Woratanarat, Patarawan; Sa-Ngasoongsong, Paphon; Tawonsawatruk, Tulyapruek; Chanplakorn, Pongsthorn

    2015-09-01

    To assess the outcome after using the Shaft-Condylar angle (SCA) as intraoperative reference for sagittal plane correction in displaced lateral humeral condyle fractures in children presented 3-weeks after injury. Ten children, with delayed presentation of a displaced lateral humeral condyle fracture and undergoing surgery during 1999-2011, were reviewed. The goal was to obtain a smooth articular surface with an intraoperative SCA of nearly 40° and nearest-anatomical carrying angle. They were allocated into two groups according to the postoperative SCA [Good-reduction group (SCA=30-50°), and Bad-reduction group (SCA50°)] and the final outcomes were then compared. All fractures united without avascular necrosis. The Good-reduction group (n=7) showed a significant improvement in final range of motion and functional outcome compared to the Bad-reduction group (n=3) (p=0.02). However, there was no significant difference in pain, carrying angle and overall outcome between both groups. SCA is a possible intraoperative reference for sagittal alignment correction in late presented displaced lateral humeral condyle fractures.

  9. Impacted mandibular third molars and their influence on mandibular angle and condyle fractures--a retrospective study.

    Science.gov (United States)

    Gaddipati, Rajasekhar; Ramisetty, Sudhir; Vura, Nandagopal; Kanduri, Rajeev Reddy; Gunda, Vinay Kumar

    2014-10-01

    Previous retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle. A retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures. Hospital records and panoramic radiographs were used to determine and classify these variables. The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients. Database was constructed and analysed using SPSS version 10.0. This present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  10. Open reduction and internal fixation of intra-articular fractures of the mandibular condyle: our first experiences.

    Science.gov (United States)

    Vesnaver, Ales

    2008-10-01

    Treatment of intra-articular fractures of the mandibular condyle head is conservative at most institutions dealing with facial fractures. Recently, reports had been published about benefits of surgical treatment in these fractures. From July 2004 until the end of June 2006, 13 patients with 16 displaced intra-articular fractures of the mandibular condyle were treated with open reduction and internal fixation at the Department of Oral and Maxillofacial Surgery in Ljubljana, Slovenia, using the preauricular approach and the lag screw technique. Twelve of the 13 patients could open their mouths for 40 mm or more, and 10 had a deflection of the chin of less than 2 mm upon maximal opening. None of the patients experienced pain upon rest, palpation, or chewing. Occlusion was not noted as altered in any of the cases, neither subjectively, nor on examination. There were no cases of postoperative weakness of the temporal branch of the facial nerve. Surgical treatment of intra-articular condyle fractures using the preauricular approach achieves a good exposure and enables proper reduction. Stable fixation of fractured bony fragments can be achieved using the lag screw technique. Another benefit of open exposure is revision and repair of TMJ soft tissues. With the appropriate surgical technique, the surgical procedure is safe and leads to good results.

  11. Literature survey on microscopic friction modeling

    NARCIS (Netherlands)

    Hol, J.

    2010-01-01

    To better understand contact and friction conditions, experimental and theoretical studies have been performed in order to take microscopic dependencies into account. Friction is developed on microscopic level by adhesion between contacting asperities, the ploughing effect between asperities and the

  12. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. An asbestos free friction material composite for brake linings is synthesized containing fibrous re- inforcing ... every manufacturer of automotive friction materials uses phenolics as ... The resin binder is a critical compo- nent. The limits ...

  13. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    Directionality of grinding marks influences the coefficient of friction ... Menezes et al (2006a,b) studied the effect of roughness parameters and grinding angle on ... as coefficient of friction, sliding velocity, normal load, hardness and thermal.

  14. Methods and Devices used to Measure Friction

    DEFF Research Database (Denmark)

    Jeswiet, Jack; Arentoft, Mogens; Henningsen, Poul

    2004-01-01

    . To gain a good understanding of the mechanisms at the interface and to be able to verify the friction and tribology models that exist, friction sensors are needed. Designing sensors to measure friction-stress in metal working has been pursued by many researchers. This paper surveys methods, which have...... been tried in the past and discusses some of the recent sensor designs, which can now be used to measure Friction in both production situations and for research purposes....

  15. Advances on LuGre friction model

    OpenAIRE

    Fuad, Mohammad; Ikhouane, Fayçal

    2013-01-01

    LuGre friction model is an ordinary differential equation that is widely used in describing the friction phenomenon for mechanical systems. The importance of this model comes from the fact that it captures most of the friction behavior that has been observed including hysteresis. In this paper, we study some aspects related to the hysteresis behavior induced by the LuGre friction model.

  16. Apparatus for measurement of coefficient of friction

    Science.gov (United States)

    Slifka, A. J.; Siegwarth, J. D.; Sparks, L. L.; Chaudhuri, Dilip K.

    1990-01-01

    An apparatus designed to measure the coefficient of friction in certain controlled atmospheres is described. The coefficient of friction observed during high-load tests was nearly constant, with an average value of 0.56. This value is in general agreement with that found in the literature and also with the initial friction coefficient value of 0.67 measured during self-mated friction of 440C steel in an oxygen environment.

  17. A field theoretic model for static friction

    OpenAIRE

    Mahyaeh, I.; Rouhani, S.

    2013-01-01

    We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...

  18. Friction and dissipative phenomena in quantum mechanics

    International Nuclear Information System (INIS)

    Kostin, M.D.

    1975-01-01

    Frictional and dissipative terms of the Schroedinger equation are studied. A proof is given showing that the frictional term of the Schroedinger--Langevin equation causes the quantum system to lose energy. General expressions are derived for the frictional term of the Schroedinger equation. (U.S.)

  19. Adaptive friction compensation: a globally stable approach

    NARCIS (Netherlands)

    Verbert, K.A.; Tóth, R.; Babuska, R.

    2016-01-01

    In this paper, an adaptive friction compensation scheme is proposed. The friction force is computed as a timevarying friction coefficient multiplied by the sign of the velocity and an on-line update law is designed to estimate this coefficient based on the actual position and velocity errors.

  20. Multiscale friction modeling for sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.; Felder, Eric; Montmitonnet, Pierre

    2010-01-01

    The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes when

  1. A thermodynamic model of sliding friction

    Directory of Open Access Journals (Sweden)

    Lasse Makkonen

    2012-03-01

    Full Text Available A first principles thermodynamic model of sliding friction is derived. The model predictions are in agreement with the observed friction laws both in macro- and nanoscale. When applied to calculating the friction coefficient the model provides a quantitative agreement with recent atomic force microscopy measurements on a number of materials.

  2. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    An asbestos free friction material composite for brake linings is synthesized containing fibrous reinforcing constituents, friction imparting and controlling additives, elastomeric additives, fire retarding components and a thermosetting resin. The composite shows exemplary friction characteristics and has great resistance to ...

  3. Radiographic Study on the Bony Changes of Mandibular Condyle Head in Temporomandibular Disorder Patients

    International Nuclear Information System (INIS)

    Park, Moo Soon; You, Dong Soo

    1989-01-01

    The author has studied radiographic bony changes of mandibular condyle head in temporomandibular disorder patients using Oblique lateral transcranial projection, Orthopantomography, and Tomography. The bony change types and the frequencies of occurrence and the incidences of bony changes in three different radiographic techniques were examined. The coincidences of body change types between the Oblique lateral transcranial projection and the lateral part of Tomogram, the Orthopantomogram and the medial part of Tomogram were also examined. The results were as follows: 1. The mean age of patients was 31.7 years and under 40 years were 24 patients, women were 27 patients, men were 4 patients. 2. The observable cases of bony changes in all three radiographic techniques were 19 cases (50%) of 38 cases and the observable cases of bony changes in only Tomography were 5 cases (13.2%). 3. The most frequent radiographic bony change type was osteophyte and next orders were flattening, erosion, concavity. 4. The positional incidences of bony changes in Tomogram were 31 cases in lateral part and 27 cases in central part. 5. The coincidence of bony change types between the oblique lateral transcranial projection and the lateral part of Tomogram was 80%, and the coincidence between the Orthopantomogram and the medial part of Tomogram was 76.9%.

  4. Delayed presentation of popliteal artery transection following undisplaced lateral condyle fracture of tibia

    Directory of Open Access Journals (Sweden)

    Mohit Gupta

    2016-01-01

    Full Text Available Literature suggests that vascular damage occurring with orthopedic injury of the lower extremity is rare and uncommon. We present a case of a young adult male who presented to the emergency room with a history of road traffic accident with complaints of pain in the right ankle diagnosed as medial malleolus fracture and pain in the left knee diagnosed as undisplaced lateral tibial condyle fracture. At the time of presentation, the left leg appeared normal and was stabilized with a knee brace, which on the next day developed severe swelling with absence of distal pulses. Doppler revealed no blood flow distal to popliteal artery with severe soft tissue edema. The patient was posted for emergency basis vascular exploration where popliteal artery was surprisingly found transected and was repaired followed by timely fasciotomy. This case report has also been prepared to stress the importance of secondary survey in patients after high energy trauma as it can prevent the important injuries from being missed.

  5. Photoelastic analysis of bone deformation in the region of the mandibular condyle during mastication.

    Science.gov (United States)

    Meyer, Christophe; Kahn, Jean-Luc; Boutemi, Philippe; Wilk, Astrid

    2002-06-01

    The purpose of this experimental study was to demonstrate the stress patterns arising in the region of the mandibular condyle during mastication. Stress analysis was performed using reflection photoelasticity to demonstrate deformation occurring on the surface of the mandible. The rami of three fresh dentate human mandibles were coated with a shell of photoelastic resin. Using a novel loading device, these mandibles were then subjected to external forces (muscular traction, resultant mandibular forces and intra-articular reaction force) reproducing a unilateral biting task between the first right molars. Deformations were measured from the working side. The trace of isostatic lines from the isoclinic fringes revealed major differences in stress distributions between the three mandibles. These differences were attributed to differences in shape between the three mandibles. Conversely, we consistently found compressive stress patterns along the posterior border of the ramus and tensile stress patterns along the anterior border of the ramus and in the zone situated below the siqmoid notch. These findings suggest that during this particular task, the mandible is subjected to sagittal forces which tend to straighten the mandibular angle. This implies that new concepts are needed for the positioning of osteosynthesis plates in the condylar region, close to the tensile strain lines, as has been recommended also for other parts of the mandible when applying semi-rigid internal fixation. Copyright 2002 European Association for Cranio-Maxillofacial Surgery. Published by Elsevier Science Ltd.

  6. Finite element analysis of three patterns of internal fixation of fractures of the mandibular condyle.

    Science.gov (United States)

    Aquilina, Peter; Chamoli, Uphar; Parr, William C H; Clausen, Philip D; Wroe, Stephen

    2013-06-01

    The most stable pattern of internal fixation for fractures of the mandibular condyle is a matter for ongoing discussion. In this study we investigated the stability of three commonly used patterns of plate fixation, and constructed finite element models of a simulated mandibular condylar fracture. The completed models were heterogeneous in the distribution of bony material properties, contained about 1.2 million elements, and incorporated simulated jaw-adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. This model was considerably larger and more complex than previous finite element models that have been used to analyse the biomechanical behaviour of differing plating techniques. The use of two parallel 2.0 titanium miniplates gave a more stable configuration with lower mean element stresses and displacements over the use of a single miniplate. In addition, a parallel orientation of two miniplates resulted in lower stresses and displacements than did the use of two miniplates in an offset pattern. The use of two parallel titanium plates resulted in a superior biomechanical result as defined by mean element stresses and relative movement between the fractured fragments in these finite element models. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  7. Ankylosis Due Sequel Of Fracture Of The Mandibular Condyle: Case Report

    Directory of Open Access Journals (Sweden)

    Alina Alencar Ferreira Gomes

    2017-08-01

    Full Text Available The Ankylosis of the Temporomandibular joint (TMJ is a disorder of craniofacial complex that results in the merger between the condyle and the mandibular fossa, causing partial or complete immobilization of the mandible. The etiological factors are local and systemic inflammation, infection in the area of TMJ, rheumatic diseases and neoplasms, having the trauma as the main etiologic factor. The traumas are responsible for 31% to 98% of cases of ankylosis. The diagnosis is made from the anamnesis and imaging scans (computed tomography pointing to the union of joint components. The treatment of ankylosis is a big challenge due the high rate of recurrence that can be affected by factors such as type of ankylosis, surgical technique, age of the patient, post-operative physiotherapy and systematic follow-up of the patient. The various forms of treatment require careful analysis of type of ankylosis if it is intra or extra-articular, unilateral or bilateral and if it is bony or fibrous, There is no consensus in current literature regarding the best treatment. The aim of this work is to present through the report of a clinical case, a surgical treatment of Unilateral Temporomandibular joint Ankylosis, due to sequel of condylar fracture with re-establishment of the stomatognathic functions in postoperative follow-up.

  8. Pathology of the distal condyles of the third metacarpal and third metatarsal bones of the horse

    International Nuclear Information System (INIS)

    Riggs, C.M.; Whitehouse, G.H.; Boyde, A.

    1999-01-01

    This study examined material from Thoroughbred horses, the majority of which had been in race training, for evidence of pathology in the third metacarpal (McIII) and third metatarsal (MtIII) bones which might be related to the occurrence of distal condylar fractures. Whole bone samples were studied and documented by macrophotography prior to macroradiography and computed tomographic (CT) imaging. Microradiographs were made from 100 microm thick mediolateral sections cut perpendicular to the dorsal and palmar/plantar articular surfaces of distal condylar regions of McIII and MtIII. Blocks were prepared for morphological imaging using the backscattered electron mode of scanning electron microscopy (BSE SEM). Linear defects in mineralised articular cartilage and subchondral bone were found in the palmar/plantar aspects of the condylar grooves adjacent to the sagittal ridge. These were closely related to the pattern of densification of the subchondral bone and were associated with intense focal remodelling of the immediately adjacent and subjacent bone. Parasagittal fractures of the condyles originated in similar defects. A unifying hypothesis for the aetiopathogenesis of these fractures is presented

  9. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J

    2008-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively i...

  10. Improved Coulomb-Friction Damper

    Science.gov (United States)

    Campbell, G. E.

    1985-01-01

    Equal damping provided on forward and reverse strokes. Improved damper has springs and wedge rings symmetrically placed on both ends of piston wedge, so friction force same in both directions of travel. Unlike conventional automotive shock absorbers, they resemble on outside, both versions require no viscous liquid and operate over wide temperature range.

  11. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  12. Information frictions and monetary policy

    Czech Academy of Sciences Publication Activity Database

    Matějka, Filip

    2012-01-01

    Roč. 6, č. 1 (2012), s. 7-24 ISSN 1802-792X Institutional support: RVO:67985998 Keywords : nominal rigidity * information frictions * monetary economics Subject RIV: AH - Economics http://www.vsfs.cz/periodika/acta-2012-01.pdf

  13. Optimizing Functional Outcomes in Mandibular Condyle Reconstruction With the Free Fibula Flap Using Computer-Aided Design and Manufacturing Technology.

    Science.gov (United States)

    Lee, Z-Hye; Avraham, Tomer; Monaco, Casian; Patel, Ashish A; Hirsch, David L; Levine, Jamie P

    2018-05-01

    Mandibular defects involving the condyle represent a complex reconstructive challenge for restoring proper function of the temporomandibular joint (TMJ) because it requires precise bone graft alignment for full restoration of joint function. The use of computer-aided design and manufacturing (CAD/CAM) technology can aid in accurate reconstruction of mandibular condyle defects with a vascularized free fibula flap without the need for additional adjuncts. The purpose of this study was to analyze clinical and functional outcomes after reconstruction of mandibular condyle defects using only a free fibula graft with the help of virtual surgery techniques. A retrospective review was performed to identify all patients who underwent mandibular reconstruction with only a free fibula flap without any TMJ adjuncts after a total condylectomy. Three-dimensional modeling software was used to plan and execute reconstruction for all patients. From 2009 through 2014, 14 patients underwent reconstruction of mandibular defects involving the condyle with the aid of virtual surgery technology. The average age was 38.7 years (range, 11 to 77 yr). The average follow-up period was 2.6 years (range, 0.8 to 4.2 yr). Flap survival was 100% (N = 14). All patients reported improved facial symmetry, adequate jaw opening, and normal dental occlusion. In addition, they achieved good functional outcomes, including normal intelligible speech and the tolerance of a regular diet with solid foods. Maximal interincisal opening range for all patients was 25 to 38 mm with no lateral deviation or subjective joint pain. No patient had progressive joint hypomobility or condylar migration. One patient had ankylosis, which required release. TMJ reconstruction poses considerable challenges in bone graft alignment for full restoration of joint function. The use of CAD/CAM technology can aid in accurate reconstruction of mandibular condyle defects with a vascularized free fibula flap through precise

  14. Differences between the chewing and non-chewing sides of the mandibular first molars and condyles in the closing phase during chewing in normal subjects.

    Science.gov (United States)

    Tomonari, Hiroshi; Kwon, Sangho; Kuninori, Takaharu; Miyawaki, Shouichi

    2017-09-01

    This study aimed to assess differences between the closing paths of the chewing and non-chewing sides of mandibular first molars and condyles during natural mastication, using standardized model food in healthy subjects. Thirty-two healthy young adults (age: 19-25 years; 22 men, 10 women) with normal occlusion and function chewed on standardized gummy jelly. Using an optoelectric jaw-tracking system with six degrees of freedom, we recorded the path of the mandibular first molars and condyles on both sides for 10 strokes during unilateral chewing. Variables were compared between the chewing side and the non-chewing side of first molars and condyles on frontal, sagittal, and horizontal views during the early-, middle- and late-closing phases. On superior/inferior displacements, the chewing side first molar and condyle were positioned superior to those on the non-chewing side during the early- and middle-closing phases. Conversely, the first molar and condyle on the non-chewing side were positioned significantly superior to those on the chewing side during the late-closing phase. On anterior/posterior displacements, the chewing side mandibular first molar and condyle were positioned significantly posterior to those on the non-chewing side throughout all closing phases. Our results showed the differences between the mandibular first molars and condyles on both sides with respect to masticatory path during natural chewing of a model food. These differences can be useful for informing initial diagnostic tests for impaired masticatory function in the clinical environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Comparative study of the prognosis of an extracorporeal reduction and a closed treatment in mandibular condyle head and/or neck fractures.

    Science.gov (United States)

    Park, Jung-Min; Jang, Yong-Wook; Kim, Seong-Gon; Park, Young-Wook; Rotaru, Horatiu; Baciut, Grigore; Hurubeanu, Lucia

    2010-12-01

    The objective of this study was a comparison of the prognosis between an extracorporeal reduction technique and closed treatment of a mandibular condyle fracture. The relationship between condylar resorption and several clinical variables was also studied. Seventy-one patients who had a mandibular condyle fracture took part in this study. Thirty-five patients (female: 7, male: 28, age: 30.46 ± 14.27 years) were treated by extracorporeal reduction, and 36 patients (male: 24, female: 12, age: 24.28 ± 9.99 years) were treated using a closed treatment. The presence of complications such as condylar resorption, malocclusion, nerve disorder, and disc displacement was evaluated with panoramic radiographs and clinical examinations 12 months after treatment. The relationships between the complications and other clinical variables were evaluated statistically. The anatomic site and fracture type were closely related to condyle resorption in the bivariate analysis. Condylar head fractures showed significantly higher condyle resorption than condylar neck fractures (P = .023). A complex or compound fracture showed significantly higher condyle resorption compared with a simple fracture (P = .006). Patients who had a complex/compound fracture were 34.366 times more likely to have condyle resorption compared with those who had a simple fracture (P = .002). The patient's age and treatment method were also significant predictors for condyle resorption. Fracture type was the strongest predictor of condylar resorption. Because treatment method and patient age were also related to the prognosis, the optimal treatment for mandibular condylar head and/or neck fractures should be individualized according to the patient's condition. Copyright © 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  16. Pressure and Friction Injuries in Primary Care.

    Science.gov (United States)

    Phillips, Shawn; Seiverling, Elizabeth; Silvis, Matthew

    2015-12-01

    Pressure and friction injuries are common throughout the lifespan. A detailed history of the onset and progression of friction and pressure injuries is key to aiding clinicians in determining the underlying mechanism behind the development of the injury. Modifying or removing the forces that are creating pressure or friction is the key to both prevention and healing of these injuries. Proper care of pressure and friction injuries to the skin is important to prevent the development of infection. Patient education on positioning and ergonomics can help to prevent recurrence of pressure and friction injuries. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Friction, Free Axes of Rotation and Entropy

    Directory of Open Access Journals (Sweden)

    Alexander Kazachkov

    2017-03-01

    Full Text Available Friction forces acting on rotators may promote their alignment and therefore eliminate degrees of freedom in their movement. The alignment of rotators by friction force was shown by experiments performed with different spinners, demonstrating how friction generates negentropy in a system of rotators. A gas of rigid rotators influenced by friction force is considered. The orientational negentropy generated by a friction force was estimated with the Sackur-Tetrode equation. The minimal change in total entropy of a system of rotators, corresponding to their eventual alignment, decreases with temperature. The reported effect may be of primary importance for the phase equilibrium and motion of ubiquitous colloidal and granular systems.

  18. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  19. Internal friction in irradiated textolite

    International Nuclear Information System (INIS)

    Zajkin, Yu.A.; Kozhamkulov, B.A.; Koztaeva, U.P.

    1996-01-01

    Structural relaxation in irradiated textolite of ST and ST-EhTF trade marks presenting pressed material got by method of impregnation of fibreglass by phenole and epoxytriphenole binders relatively. Measuring of temperature dependences of internal friction (TDIF) is carried out in torsional pendulum at oscillation frequency 0.6-1.0 Hz before and after irradiation by stopped gamma-quanta with energy 3 MeV on electron accelerator EhLU-4. α and β peaks, related with segments motion in base and side chains of macromolecular have being observed on TDIF of all textolite. Growth of peaks height after irradiation evident about increase of segments mobility in base chain and about de-freezing of segments in side chains and it could be considered as qualitative measure of radiation destruction rate. Comparison of temperature dependences of internal friction indicates on higher radiation stability of textolite of ST-EhTF trade mark

  20. Magnetic resonance imaging of articular cartilage abnormalities of the far posterior femoral condyle of the knee

    Energy Technology Data Exchange (ETDEWEB)

    Ogino, Shuhei; Huang, Thomas; Watanabe, Atsuya; Iranpour-Boroujeni, Tannaz; Yoshioka, Hiroshi (Dept. of Radiology, Brigham and Women' s Hospital, Boston, MA (United States)), e-mail: hiroshi@uci.edu

    2010-01-15

    Background: Incidental articular cartilage lesions of the far posterior femoral condyle (FPFC) are commonly detected. Whether or not these cartilage lesions are symptomatic or clinically significant is unknown. Purpose: To characterize and assess prevalence of articular cartilage abnormalities of the FPFC and associated bone marrow edema (BME) and/or internal derangements through magnetic resonance (MR) images. Material and Methods: 654 knee MR examinations were reviewed retrospectively. Sagittal fast spin-echo proton density-weighted images with and without fat suppression were acquired with a 1.5T scanner, and were evaluated by two readers by consensus. The following factors were assessed: 1) the prevalence of cartilage abnormalities, 2) laterality, 3) the type of cartilage abnormalities, 4) cartilage abnormality grading, 5) associated BME, 6) complications such as meniscal injury and cruciate ligament injury, and 7) knee alignment (femorotibial angle [FTA]). Results: Articular cartilage abnormalities of the FPFC were demonstrated in 157 of the 654 patients (24%). Of these, 40 patients demonstrated medial and lateral FPFC cartilage abnormalities and were thus counted as 80 cases. Focal lateral FPFC abnormalities were demonstrated in 117 of 197 cases (59.4%), while diffuse lateral FPFC abnormalities were demonstrated in 24 of 197 cases (12.2%). Focal medial FPFC abnormalities were demonstrated in 23 of 197 cases (11.6%), while diffuse medial FPFC abnormalities were demonstrated in 33 of 197 cases (16.8%). No statistically significant pattern of associated BME, FTA, or internal derangements including meniscal and cruciate ligament injury was demonstrated. Conclusion: Articular cartilage abnormalities of the FPFC are common and were demonstrated in 24% of patients or 30% of cases. Lateral FPFC abnormalities occur 2.5 times more frequently than medial FPFC abnormalities and were more frequently focal compared with medial cohorts. BME is associated in 36.5% of cases

  1. Kissing contusion between the posterolateral tibial plateau and lateral femoral condyle: associated ligament and meniscal tears

    International Nuclear Information System (INIS)

    Hong, Hyun Pyo; Lee, Jae Gue; Park, Ji Seon; Ryu, Kyung Nam

    2004-01-01

    Kissing contusion between the posterolateral tibial plateau and lateral femoral condyle is frequently found in association with a tear of the anterior cruciate liagment (ACL). The purpose of this study was to determine which ligamentous and meniscal tears are associated with kissing contusion. We retrospectively reviewed the findings depicted by 323 consecutive MR images of the knee and confirmed at arthroscopy. For the diagnosis of disruption, ligaments, medial menisci (MM) and lateral menisci (LM) were evaluated using accepted criteria. We compared the prevalence and location of meniscal and ligamentous tears between group I (44 knees with kissing contusion) and group II (279 knees without kissing contusion). For statistical analysis the chi-square test was used. ACLs were torn in all 44 knees (100%) with kissing contusion, and 78 (28%) of 279 without kissing contusion. There were ten medial collateral ligament (MCL) tears (23%) in group I, and 17 MCL tears (6%), five lateral collateral ligament (LCL) tears (2%) and ten posterior cruciate ligament (PCL) tears (4%) in group II. In group I, meniscal tears were found in 22 MM (50%) and in 19 LM (43%), while in group II, they occurred in 128 MM (46%) and 128 LM (46%), In group I, 17 (77%) of 22 MM tears and 13 (68%) of 19 LM tears were located in the posterior horn, while in group II, the corresponding figures were 97/128 (76%) and 60 of 128 (47%). The differing prevalence of ACL and MCL tears between the groups was statistically significant (p 0.05). Although kissing contusion was a highly specific sign of ACL tears, its presence was also significant among MCL tears. There was no significant difference in meniscal tears with or without kissing contusion

  2. Consensus or controversy? The classification and treatment decision-making by 491 maxillofacial surgeons from around the world in three cases of a unilateral mandibular condyle fracture.

    Science.gov (United States)

    Kommers, Sofie C; Boffano, Paolo; Forouzanfar, Tymour

    2015-12-01

    Many studies are available in the literature on both classification and treatment of unilateral mandibular condyle fractures. To date however, controversy regarding the best treatment for unilateral mandibular condyle fractures remains. In this study, an attempt was made to quantify the level of agreement between a sample of maxillofacial surgeons worldwide, on the classification and treatment decisions in three different unilateral mandibular condyle fracture cases. In total, 491 of 3044 participants responded. In all three mandibular condyle fracture cases, a fairly high level of disagreement was found. Only in the case of a subcondylar fracture, assuming dysocclusion was present, more than 81% of surgeons agreed that the best treatment would be open reduction and internal fixation. Based on the study results, there is considerable variation among surgeons worldwide with regard to treatment of unilateral mandibular condyle fracture. 3D imaging in higher fractures tends to lead to more invasive treatment decisions. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  3. Internal friction in uranium dioxide

    International Nuclear Information System (INIS)

    Paulin Filho, Pedro Iris

    1979-01-01

    The uranium dioxide inelastic properties were studied measuring internal friction at low frequencies (of the order of 1 Hz). The work was developed in the 160 to 400 deg C temperature range. The effect of stoichiometry variation was studied oxidizing the sample with consequent change of the defect structure originally present in the non-stoichiometric uranium dioxide. The presence of a wide and irregular peak due to oxidation was observed at low temperatures. Activation energy calculations indicated the occurrence of various relaxation processes and assuming the existence of a peak between - 80 and - 70 deg C , the absolute value obtained for the activation energy (0,54 eV) is consistent with the observed values determined at medium and high frequencies for the stress induced reorientation of defects. The microstructure effect on the inelastic properties was studied for stoichiometric uranium dioxide, by varying grain size and porosity. These parameters have influence on the high temperature measurements of internal friction. The internal friction variation for temperatures higher than 340 deg C is thought to be due to grain boundary relaxation phenomena. (author)

  4. Friction of elastomer-on-glass system and direct observation of its frictional interface

    International Nuclear Information System (INIS)

    Okamoto, Yoshihiro; Nishio, Kazuyuki; Sugiura, Jun-ichi; Hirano, Motohisa; Nitta, Takahiro

    2007-01-01

    We performed a study on the static friction of PDMS elastomers with well-defined surface topography sliding over glass. An experimental setup for simultaneous measurements of friction force and direct observations of frictional interface has been developed. The static friction force was nearly proportional to normal load. The static friction force was independent of stick time. The simultaneous measurements revealed that the static friction force was proportional to the total area of contact. The coefficient was nearly independent of the surface topography of PDMS elastomers

  5. The effect of friction in coulombian damper

    Science.gov (United States)

    Wahad, H. S.; Tudor, A.; Vlase, M.; Cerbu, N.; Subhi, K. A.

    2017-02-01

    The study aimed to analyze the damping phenomenon in a system with variable friction, Stribeck type. Shock absorbers with limit and dry friction, is called coulombian shock-absorbers. The physical damping vibration phenomenon, in equipment, is based on friction between the cushioning gasket and the output regulator of the shock-absorber. Friction between them can be dry, limit, mixture or fluid. The friction is depending on the contact pressure and lubricant presence. It is defined dimensionless form for the Striebeck curve (µ friction coefficient - sliding speed v). The friction may damp a vibratory movement or can maintain it (self-vibration), depending on the µ with v (it can increase / decrease or it can be relative constant). The solutions of differential equation of movement are obtained for some work condition of one damper for automatic washing machine. The friction force can transfer partial or total energy or generates excitation energy in damper. The damping efficiency is defined and is determined analytical for the constant friction coefficient and for the parabolic friction coefficient.

  6. Kinetic Friction of Sport Fabrics on Snow

    Directory of Open Access Journals (Sweden)

    Werner Nachbauer

    2016-03-01

    Full Text Available After falls, skiers or snowboarders often slide on the slope and may collide with obstacles. Thus, the skier’s friction on snow is an important factor to reduce incidence and severity of impact injuries. The purpose of this study was to measure snow friction of different fabrics of ski garments with respect to roughness, speed, and contact pressure. Three types of fabrics were investigated: a commercially available ski overall, a smooth downhill racing suit, and a dimpled downhill racing suit. Friction was measured for fabrics taped on a short ski using a linear tribometer. The fabrics’ roughness was determined by focus variation microscopy. Friction coefficients were between 0.19 and 0.48. Roughness, friction coefficient, and friction force were highest for the dimpled race suit. The friction force of the fabrics was higher for the higher contact pressure than for the lower one at all speeds. It was concluded that the main friction mechanism for the fabrics was dry friction. Only the fabric with the roughest surface showed friction coefficients, which were high enough to sufficiently decelerate a sliding skier on beginner and intermediate slopes.

  7. Nano-friction behavior of phosphorene.

    Science.gov (United States)

    Bai, Lichun; Liu, Bo; Srikanth, Narasimalu; Tian, Yu; Zhou, Kun

    2017-09-01

    Nano-friction of phosphorene plays a significant role in affecting the controllability and efficiency of applying strain engineering to tune its properties. So far, the friction behavior of phosphorene has not been studied. This work studies the friction of single-layer and bilayer phosphorene on an amorphous silicon substrate by sliding a rigid tip. For the single-layer phosphorene, it is found that its friction is highly anisotropic, i.e. the friction is larger along the armchair direction than that along the zigzag direction. Moreover, pre-strain of the phosphorene also exhibits anisotropic effects. The friction increases with the pre-strain along the zigzag direction, but decreases with that along the armchair direction. Furthermore, the strong adhesion between the phosphorene and its substrate increases the friction between the phosphorene and the tip. For bilayer phosphorene, its friction highly depends on its stacking mode, which determines the contact interface with a commensurate or incommensurate pattern. This friction behavior is quite unique and greatly differs from that of graphene and molybdenum disulfide. Detailed analysis reveals that this behavior results from the combination effect of the friction contact area, the potential-energy profile of phosphorene, and its unique elongation.

  8. Exposed versus buried wires for fixation of lateral humeral condyle fractures in children: a comparison of safety and efficacy.

    Science.gov (United States)

    Chan, Lester Wai Mon; Siow, Hua Ming

    2011-10-01

    Displaced fractures of the lateral condyle of the humerus are usually treated with open reduction and fixation with smooth Kirschner wires. These may be passed through the skin and left exposed or buried subcutaneously. Exposed wires may be removed in the outpatient clinic, whereas buried wires require a formal procedure under anaesthesia. This advantage may be offset if there is a higher rate of complications with exposed wires. The aim of this study was to compare the safety and efficacy of exposed and buried wires. Retrospective cohort. Children with lateral condyle fractures of the humerus who had undergone surgery were identified from our departmental database. Case records and X-rays of 75 patients were reviewed. Forty-two patients had buried wires and 33 had exposed wires. There were no serious complications in either group. In the exposed wires group, 1 patient had a superficial wound infection that was treated effectively with 1 week of oral antibiotics, while 2 patients had hypergranulation of pin tracts treated with topical silver nitrate. None of the patients showed loss of reduction, deep infection, or any other complications requiring additional procedures. There was no statistically significant difference in the rate of complications between the buried and exposed groups. We conclude that open reduction and exposed wiring is a safe and effective option for lateral condyle fractures, and recommend a period of 4 weeks of K-wire fixation followed by 2 weeks of backslab immobilisation as adequate for union with minimal risk of infection.

  9. Friction coefficient dependence on electrostatic tribocharging

    Science.gov (United States)

    Burgo, Thiago A. L.; Silva, Cristiane A.; Balestrin, Lia B. S.; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers. PMID:23934227

  10. Friction Anisotropy with Respect to Topographic Orientation

    Science.gov (United States)

    Yu, Chengjiao; Wang, Q. Jane

    2012-01-01

    Friction characteristics with respect to surface topographic orientation were investigated using surfaces of different materials and fabricated with grooves of different scales. Scratching friction tests were conducted using a nano-indentation-scratching system with the tip motion parallel or perpendicular to the groove orientation. Similar friction anisotropy trends were observed for all the surfaces studied, which are (1) under a light load and for surfaces with narrow grooves, the tip motion parallel to the grooves offers higher friction coefficients than does that perpendicular to them, (2) otherwise, equal or lower friction coefficients are found under this motion. The influences of groove size relative to the diameter of the mating tip (as a representative asperity), surface contact stiffness, contact area, and the characteristic stiction length are discussed. The appearance of this friction anisotropy is independent of material; however, the boundary and the point of trend transition depend on material properties. PMID:23248751

  11. High temperature internal friction in pure aluminium

    International Nuclear Information System (INIS)

    Aboagye, J.K.; Payida, D.S.

    1982-05-01

    The temperature dependence of internal friction of nearly pure aluminium (99.99% aluminium) has been carefully measured as a function of annealing temperature and hence grain size. The results indicate that, provided the frequency and annealing temperature are held constant, the internal friction increases with temperature until some maximum value is attained and then begins to go down as the temperature is further increased. It is also noted that the internal friction decreases with annealing temperature and that annealing time has the same effect as annealing temperature. It is also noted that the internal friction peak is shifted towards higher temperatures as annealing temperature is increased. It is surmised that the grain size or the total grain boundary volume determines the height of the internal friction curve and that the order-disorder transitions at the grain boundaries induced by both entropy and energy gradients give rise to internal friction peaks in polycrystals. (author)

  12. Friction coefficient dependence on electrostatic tribocharging.

    Science.gov (United States)

    Burgo, Thiago A L; Silva, Cristiane A; Balestrin, Lia B S; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers.

  13. Static friction between rigid fractal surfaces.

    Science.gov (United States)

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  14. Investigation of squeal noise under positive friction characteristics condition provided by friction modifiers

    Science.gov (United States)

    Liu, Xiaogang; Meehan, Paul A.

    2016-06-01

    Field application of friction modifiers on the top of rail has been shown to effectively curb squeal and reduce lateral forces, but performance can be variable, according to other relevant research. Up to now, most investigations of friction modifiers were conducted in the field, where it is difficult to control or measure important parameters such as angle of attack, rolling speed, adhesion ratio etc. In the present investigation, the effect of different friction modifiers on the occurrence of squeal was investigated on a rolling contact two disk test rig. In particular, friction-creep curves and squeal sound pressure levels were measured under different rolling speeds and friction modifiers. The results show friction modifiers can eliminate or reduce the negative slope of friction-creep curves, but squeal noise still exists. Theoretical modelling of instantaneous creep behaviours reveals a possible reason why wheel squeal still exists after the application of friction modifiers.

  15. Friction measurement in a hip wear simulator.

    Science.gov (United States)

    Saikko, Vesa

    2016-05-01

    A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated. © IMechE 2016.

  16. Effect of grafted oligopeptides on friction.

    Science.gov (United States)

    Iarikov, Dmitri D; Ducker, William A

    2013-05-14

    Frictional and normal forces in aqueous solution at 25 °C were measured between a glass particle and oligopeptide films grafted from a glass plate. Homopeptide molecules consisting of 11 monomers of either glutamine, leucine, glutamic acid, lysine, or phenylalanine and one heteropolymer were each "grafted from" an oxidized silicon wafer using microwave-assisted solid-phase peptide synthesis. The peptide films were characterized using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. Frictional force measurements showed that the oligopeptides increased the magnitude of friction compared to that on a bare hydrophilic silicon wafer but that the friction was a strong function of the nature of the monomer unit. Overall we find that the friction is lower for more hydrophilic films. For example, the most hydrophobic monomer, leucine, exhibited the highest friction whereas the hydrophilic monomer, polyglutamic acid, exhibited the lowest friction at zero load. When the two surfaces had opposite charges, there was a strong attraction, adhesion, and high friction between the surfaces. Friction for all polymers was lower in phosphate-buffered saline than in pure water, which was attributed to lubrication via hydrated salt ions.

  17. Noise and vibration in friction systems

    CERN Document Server

    Sergienko, Vladimir P

    2015-01-01

    The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.

  18. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  19. The friction cost method: a comment.

    Science.gov (United States)

    Johannesson, M; Karlsson, G

    1997-04-01

    The friction cost method has been proposed as an alternative to the human-capital approach of estimating indirect costs. We argue that the friction cost method is based on implausible assumptions not supported by neoclassical economic theory. Furthermore consistently applying the friction cost method would mean that the method should also be applied in the estimation of direct costs, which would mean that the costs of health care programmes are substantially decreased. It is concluded that the friction cost method does not seem to be a useful alternative to the human-capital approach in the estimation of indirect costs.

  20. A Simple Device For Measuring Skin Friction

    Directory of Open Access Journals (Sweden)

    Gupta A.B

    1995-01-01

    Full Text Available A simple device for measuring skin friction in vivo is described. The frictional coefficient of normal Indian skin and the effect of hydration and application of talc and glycerol on the frictional coefficient and also the friction of ichthyotic skin have been determined with its help. The average value of friction of friction of normal India skin at forearm is found to be 0.41 +- 0.08, the hydration raises the value to 0.71 +- 0.11 and the effect of glycerol is also to school it up to 0.70+- 0.05, almost equal to that of water. The effect of talc however is opposite and its application lowers the friction to 0.21+-0.07. The mean coeff of friction for ichthyotic skin is found to be 0.21+- 0.0.5, which closely agrees with talc-treated normal skin. A good positive correlation (p<0.01 between friction and sebum level at skin site, with r = 0.64, has been observed.

  1. Servo Reduces Friction In Flexure Bearing

    Science.gov (United States)

    Clingman, W. Dean

    1991-01-01

    Proposed servocontrol device reduces such resistive torques as stiction, friction, ripple, and cogging in flexure bearing described in LAR-14348, "Flexure Bearing Reduces Startup Friction". Reduces frictional "bump" torque encountered when bearing ball runs into buildup of grease on bearing race. Also used as cable follower to reduce torque caused by cable and hoses when they bend because of motion of bearing. New device includes torquer across ball race. Torquer controlled by servo striving to keep flexure at null, removing torque to outer ring. In effect, device is inner control loop reducing friction, but does not control platforms or any outer-control-loop functions.

  2. "A" shape plate for open rigid internal fixation of mandible condyle neck fracture.

    Science.gov (United States)

    Kozakiewicz, Marcin; Swiniarski, Jacek

    2014-09-01

    Reduction of the fracture is crucial for proper outcome of the treatment. The stability of reduction is closed connected to the method of its fixation. The topic of condylar fracture osteosynthesis still remains highly controversial and challenging. That is why authors decided to propose novel design of the fixating plate and the example of its application. The aim of this study was to present A-shape plate dedicated to rigid fixation of mandible condyle neck fracture. A-shape condylar plate (ACP) design is prepared of 1.0 mm thick titanium alloy (grade 5) sheet: posterior and anterior bars are reinforced by widening to 2.5 mm and anatomically curved along the compression and traction lines in ramus and condylar neck. Superior three-hole-group has triangular organization and located on the level of condylar head. The inferior extensions of the bars are equipped in three holes located at each of lower tails. Connecting bar (2.0 mm wide) connects the first hole of each lower tails closing upper part of ACP in triangular shape. The connecting bar runs along compression line of condylar neck. Holes in ACP has 2.0 mm diameter for locking or normal screws. Height of ACP is 31 mm. The proposed new type of plate was compared by finite element analysis (FEA) to nowadays manufactured 9-hole trapezoid plate as the most similar device. ACP design was evaluated by finite element analysis (FEA) and later applied in patient affected with high condylar neck fracture complicated by fracture of coronoid process. FEA revealed high strength of ACP and more stabile fixation than trapezoid plate. The result was caused by multipoint fixation at three regions of the plate and reinforced bars supported by semi-horizontal connecting bar. Clinical application of ACP was as versatile as makes possible to simultaneous fixation of high condylar neck and coronoid process fracture. Application of proposed A-shape condylar plate would be possible in all levels of neck fractures and can be use

  3. Characterization of friction and wear behavior of friction modifiers used in wheel-rail contacts

    NARCIS (Netherlands)

    Oomen, M. A.; Bosman, R.; Lugt, P. M.

    2017-01-01

    Reliable traction between wheel and rail is an important issue in the railway industry. To reduce variations in the coefficient of friction, so-called “friction modifiers” (carrier with particles) are used. Twin-disk tests were done with three commercial friction modifiers, based on different

  4. Friction-induced Vibrations in an Experimental Drill-string System for Various Friction Situations

    NARCIS (Netherlands)

    Mihajlovic, N.; Wouw, van de N.; Hendriks, M.P.M.; Nijmeijer, H.

    2005-01-01

    Friction-induced limit cycling deteriorates system performance in a wide variety of mechanical systems. In this paper, we study the way in which essential friction characteristics affect the occurrence and nature of friction-induced limit cycling in flexible rotor systems. This study is performed on

  5. On the nature of the static friction, kinetic friction and creep

    DEFF Research Database (Denmark)

    Persson, B. N. J.; Albohr, O.; Mancosu, F.

    2003-01-01

    of capillary bridges. However, there is no single value of the static friction coefficient, since it depends upon the initial dwell time and on rate of starting.We argue that the correct basis for the Coulomb friction law, which states that the friction force is proportional to the normal load...

  6. A Physics-Based Rock Friction Constitutive Law: Steady State Friction

    Science.gov (United States)

    Aharonov, Einat; Scholz, Christopher H.

    2018-02-01

    Experiments measuring friction over a wide range of sliding velocities find that the value of the friction coefficient varies widely: friction is high and behaves according to the rate and state constitutive law during slow sliding, yet markedly weakens as the sliding velocity approaches seismic slip speeds. We introduce a physics-based theory to explain this behavior. Using conventional microphysics of creep, we calculate the velocity and temperature dependence of contact stresses during sliding, including the thermal effects of shear heating. Contacts are assumed to reach a coupled thermal and mechanical steady state, and friction is calculated for steady sliding. Results from theory provide good quantitative agreement with reported experimental results for quartz and granite friction over 11 orders of magnitude in velocity. The new model elucidates the physics of friction and predicts the connection between friction laws to independently determined material parameters. It predicts four frictional regimes as function of slip rate: at slow velocity friction is either velocity strengthening or weakening, depending on material parameters, and follows the rate and state friction law. Differences between surface and volume activation energies are the main control on velocity dependence. At intermediate velocity, for some material parameters, a distinct velocity strengthening regime emerges. At fast sliding, shear heating produces thermal softening of friction. At the fastest sliding, melting causes further weakening. This theory, with its four frictional regimes, fits well previously published experimental results under low temperature and normal stress.

  7. Quantum friction across the vacuum

    International Nuclear Information System (INIS)

    Ebelein, C.

    1998-01-01

    Friction is so ubiquitous that it seems to be almost trivially familiar. The rubbing of two solid surfaces is opposed by a resistance and accompanied by the production of heat. Engineers still dream of perfectly smooth surfaces that can be moved against each other without any friction. However, this dream has now been shattered by John Pendry of Imperial College, London, who has published a theory that shows that even two perfectly smooth surfaces can experience an appreciable friction when moved relative to each other (J. Phys.: Condens. Matter 1997 9 10301-10320). Moreover, the two surfaces he considers are not even in contact but separated by a gap a lattice constant or so wide. The explanation of this lies in what Pendry calls the shearing of the vacuum in the gap. In quantum physics the vacuum is not just empty nothingness; it is full of virtually everything. The vacuum abounds with virtual photons. These zero-point fluctuations cannot normally be seen, but they give the vacuum a structure that manifests itself in a variety of effects (for example, the Casimir effect). A more subtle, yet more familiar, manifestation of these zero-point fluctuations is the van der Waals force. The effect described by Pendry can be understood as a van der Waals interaction between two infinite slabs of dielectric material moving relative to each other. Each slab will be aware of the motion of the other because the virtual photons reflected from the moving surface are Doppler-shifted up or down, depending on the direction of the photon wave vector relative to the motion. Pendry shows that this asymmetry in the exchange of virtual photons can lead to an appreciable effect for materials of reasonably strong dispersion. (author)

  8. Stabilizing Stick-Slip Friction

    International Nuclear Information System (INIS)

    Capozza, Rosario; Barel, Itay; Urbakh, Michael; Rubinstein, Shmuel M.; Fineberg, Jay

    2011-01-01

    Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality.

  9. Job Heterogeneity and Coordination Frictions

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Daniel

    We develop a new directed search model of a frictional labor market with a continuum of heterogenous workers and firms. We estimate two versions of the model - auction and price posting - using Danish data on wages and productivities. Assuming heterogenous workers with no comparative advantage, we...... the job ladder, how the identification of assortative matching is fundamentally different in directed and undirected search models, how our theory accounts for business cycle facts related to inter-temporal changes in job offer distributions, and how our model could also be used to identify...

  10. Is 3D-CT reformation using free software applicable to diagnosis of bone changes in mandibular condyles?

    Directory of Open Access Journals (Sweden)

    Marília Gerhardt de Oliveira

    2009-06-01

    Full Text Available OBJECTIVES: This study evaluated the agreement of computed tomography (CT imaging using 3D reformations (3DR with shaded surface display (SSD and maximum intensity projection (MIP in the diagnosis of bone changes in mandibular condyles of patients with rheumatoid arthritis (RA, and compared findings with multiplanar reformation (MPR images, used as the criterion standard. MATERIAL AND METHODS: Axial CT images of 44 temporomandibular joints (TMJs of 22 patients with RA were used. Images were recorded in DICOM format and assessed using free software (ImageJ. Each sample had its 3DR-SSD and 3DR-MIP results compared in pairs with the MPR results. RESULTS: Slight agreement (k = 0.0374 was found in almost all comparisons. The level of agreement showed that 3DR-SSD and 3DR-MIP yielded a number of false-negative results that was statistically significant when compared with MPR. CONCLUSIONS: 3DR-SSD or 3DR-MIP should only be used as adjuvant techniques to MPR in the diagnosis of bone changes in mandibular condyles.

  11. An anatomical study of the proximal aspect of the medial femoral condyle to define the proximal-distal condylar length

    Directory of Open Access Journals (Sweden)

    Chia-Ming Chang

    2017-01-01

    Full Text Available Objective: Despite its possible role in knee arthroplasty, the proximal-distal condylar length (PDCL of the femur has never been reported in the literature. We conducted an anatomic study of the proximal aspect of the medial femoral condyle to propose a method for measuring the PDCL. Materials and Methods: Inspection of dried bone specimens was carried out to assure the most proximal condylar margin (MPCM as the eligible starting point to measure the PDCL. Simulation surgery was performed on seven pairs of cadaveric knees to verify the clinical application of measuring the PDCL after locating the MPCM. Interobserver reliability of this procedure was also analyzed. Results: Observation of the bone specimens showed that the MPCM is a concavity formed by the junction of the distal end of the supracondylar ridge and the proximal margin of the medial condyle. This anatomically distinctive structure made the MPCM an unambiguous landmark. The cadaveric simulation surgical dissection demonstrated that the MPCM is easily accessed in a surgical setting, making the measurement of the PDCL plausible. The intraclass correlation coefficient was 0.78, indicating good interobserver reliability for this technique. Conclusion: This study has suggested that the PDCL can be measured based on the MPCM in a surgical setting. PDCL measurement might be useful in joint line position management, selection of femoral component sizes, and other applications related to the proximal-distal dimension of the knee. Further investigation is required.

  12. Structural variation of the distal condyles of the third metacarpal and third metatarsal bones in the horse

    International Nuclear Information System (INIS)

    Riggs, C.M.; Whitehouse, G.H.; Boyde, A.

    1999-01-01

    This study examined 3-dimensional (3D) distribution of sectors with contrasting density in the equine third metacarpal (McIII) and third metatarsal (MtIII) bones with a view to explaining the aetiology of distal condylar fractures. Macroradiography and computed tomographic (CT) imaging were used in the nondestructive study of bones obtained from horses, most of which were Thoroughbreds in race training. Distal condylar regions of McIII and MtIII were also studied in microradiographs of 100 mu m thick mediolateral sections cut perpendicular to the dorsal and palmar/plantar articular surfaces. Qualitative and quantitative results from all methods used (radiography, CTand microradiographic stereology) demonstrated densification (sclerosis) of subchondral bone located in the palmar/plantar regions of the medial and lateral condyles of both McIII and MtIII, Substantial density gradients between the denser condyles and the subchondral bone of the sagittal groove were shown to equate with anatomical differences in loading intensity during locomotion. It is hypothesised that such differences in bone density results in stress concentration at the palmar/plantar aspect of the condylar grooves, which may predispose to fracture

  13. Recovery of mouth-opening after closed treatment of a fracture of the mandibular condyle: a longitudinal study.

    Science.gov (United States)

    Niezen, E T; Stuive, I; Post, W J; Bos, R R M; Dijkstra, P U

    2015-02-01

    The aim of this retrospective study was to assess recovery of mouth opening after closed treatment of fractures of the mandibular condyle, and analyse which characteristics might influence recovery. We measured mouth opening in 142 patients (mean (SD) age 30 (14) years, 96 of whom were male) during follow-up at 3, 6, 13, 26, and 52 weeks after the injury. Fractures were assessed on radiographs. Data were analysed using a multilevel analysis. Half the fractures were of the low condylar neck (n=71). Thirty-seven patients had bilateral condylar fractures, 29 had dislocated fractures, and in 80 the fracture was displaced. One or more additional mandibular fractures were present in 68. During follow-up mean (SD) mouth opening increased to: 33.6 (9.6) at 3 weeks, 40.1 (10.0) at 6 weeks, 45.1 (9.6) at 13 weeks, 49.8 (9.5) at 26 weeks, and 52.6 (7.5) at 52 weeks. Older age, female sex, displaced fracture, bilateral fractures, additional mandibular fractures, and the interaction between follow-up time and additional mandibular fractures, were predictors of a less favourable recovery of mouth opening. Clinicians can use the results of this study to predict recovery of mouth opening after closed treatment of fractures of the mandibular condyle at first consultation. Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  14. Conservative treatment of a mandibular condyle fracture: Comparing intermaxillary fixation with screws or arch bar. A randomised clinical trial.

    Science.gov (United States)

    van den Bergh, B; Blankestijn, J; van der Ploeg, T; Tuinzing, D B; Forouzanfar, T

    2015-06-01

    A mandibular condyle fracture can be treated conservatively by intermaxillary fixation (IMF) or by open reposition and internal fixation (ORIF). Many IMF-modalities can be chosen, including IMF-screws (IMFS). This prospective multi-centre randomised clinical trial compared the use of IMFS with the use of arch bars in the treatment of mandibular condyle fractures. The study population consisted of 50 patients (mean age: 31.8 years). Twenty-four (48%) patients were allocated in the IMFS group. Twenty-six (52%) patients were assigned to the arch bars group. In total 188 IMF-screws were used (5-12 screws per patient, mean 7.83 screws per patient). All pain scores were lower in the IMFS group. Three patients developed a malocclusion (IFMS-group: one patient, arch bars-group: two patients). Mean surgical time was significantly shorter in the IMFS group (59 vs. 126 min; pfractured on insertion (0.53%), one (0.53%) screw was inserted into a root. Six (3.2%) screws loosened spontaneously in four patients. Mucosal disturbances were seen in 22 patients, equally divided over both groups. Considering the advantages and the disadvantages of IMFS, and observing the results of this study, the authors conclude that IMFS provide a superior method for IMF. IMFS are safer for the patients and surgeons. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  15. Development plates for stable internal fixation: Study of mechanical resistance in simulated fractures of the mandibular condyle.

    Science.gov (United States)

    Celegatti Filho, Tóride Sebastião; Rodrigues, Danillo Costa; Lauria, Andrezza; Moreira, Roger William Fernandes; Consani, Simonides

    2015-01-01

    To develop Y-shaped plates with different thicknesses to be used in simulated fractures of the mandibular condyle. Ten plates were developed in Y shape, containing eight holes, and 30 synthetic polyurethane mandible replicas were developed for the study. The load test was performed on an Instron Model 4411 universal testing machine, applying load in the mediolateral and anterior-posterior positions on the head of the condyle. Two-way ANOVA with Tukey testing with a 5% significance level was used. It was observed that when the load was applied in the medial-lateral plate of greater thickness (1.5 mm), it gave the highest strength, while in the anteroposterior direction, the plate with the highest resistance was of the lesser thickness (0.6 mm). A plate with a thickness of 1.5 mm was the one with the highest average value for all displacements. In the anteroposterior direction, the highest values of resistance were seen in the displacement of 15 mm. After comparing the values of the biomechanical testing found in the scientific literature, it is suggested that the use of Y plates are suitable for use in subcondylar fractures within the limitations of the study. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  16. Closed reduction of displaced or dislocated mandibular condyle fractures in children using threaded Kirschner wire and external rubber traction.

    Science.gov (United States)

    Kim, J H; Nam, D H

    2015-10-01

    Most surgeons agree that closed treatment provides the best results for condylar fractures in children. Nevertheless, treatment of the paediatric mandibular condyle fracture that is severely displaced or dislocated is controversial. The purpose of this study was to investigate the long-term clinical and radiological outcomes following the treatment of displaced or dislocated condylar fractures in children using threaded Kirschner wire and external rubber traction. This procedure can strengthen the advantage of closed reduction and make up for the shortcomings of open reduction. From March 1, 2005 to December 25, 2011, 11 children aged between 4 and 12 years with displaced or dislocated mandibular condyle fractures were treated using threaded Kirschner wire and external rubber traction under portable C-arm fluoroscopy. All patients had unilateral displaced or dislocated condylar fractures. The follow-up period ranged from 24 to 42 months (mean 29.3 months). Normal occlusion and pain-free function of the temporomandibular joint, without deviation or limitation of jaw opening, was achieved in all patients. This closed reduction technique in displaced or dislocated condylar fractures in children offers a reliable solution in preventing the unfavourable sequelae of closed treatment and the open technique, such as altered morphology, functional disturbances, and facial nerve damage. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  17. Superolateral dislocation of the intact mandibular condyle associated with panfacial fracture: a case report and literature review.

    Science.gov (United States)

    Amaral, Márcio Bruno; Bueno, Sebastião Cristian; Silva, Alice Araújo Ferreira; Mesquita, Ricardo Alves

    2011-06-01

    Superolateral dislocation of the intact mandibular condyle (SDIMC) is rare. This case report focuses on a 15-year-old teenager who was involved in a motor vehicle accident as well a literature review regarding the SDIMC. Clinical examination demonstrated a diffuse edema in the midfacial area and a left lateral deflection of the mandible, including an open bite and a crepitation in the symphyseal region. Three-dimensional computed tomography scans were taken, which presented a superolateral dislocation of the left mandibular condyle as well as panfacial fracture. The patient was set in intermaxillary fixation for 2 weeks and underwent subsequent active jaw physiotherapy, the evaluation of which presented satisfactory results. This case study also presents a literature review, which demonstrated 21 well-documented cases of SDIMC. The patients' mean age was of 29 years. The male gender proved to be more prevalent, with road traffic collisions representing the most common form of accident. Type II, with unilateral dislocation, proved to be the most common. The mean reduction time was 7 days. The open methods were the most commonly used reduction methods. Mandible fracture was associated with dislocation in 82% of the cases, with other facial fractures appearing in only 23% of the cases. Patient follow up presented satisfactory results in 59% of the cases. © 2011 John Wiley & Sons A/S.

  18. Use of the medial femoral condyle vascularized bone flap in traumatic avascular necrosis of the navicular: a case report.

    Science.gov (United States)

    Holm, Janson; Vangelisti, Garrett; Remmers, Jared

    2012-01-01

    The medial femoral condyle vascularized bone flap has a high success rate in published literature regarding its use in nonunions and avascular necrosis of the upper and lower extremities. It is reported to have minimal donor site morbidity and the ability to provide structural support and torsional strength to load-bearing areas. The flap has found particular success in the treatment of scaphoid nonunions. The tarsal navicular, similar to the scaphoid, is largely articular cancellous bone with little surface area for vascular inflow. These anatomic features make the navicular prone to nonunion and avascular necrosis in traumatic scenarios. We describe a case of nonunion and avascular necrosis of the tarsal navicular occurring as sequelae of a high-impact midfoot injury sustained in an automobile accident. After an initial attempt at open reduction and internal fixation with midfoot bridge plating, subsidence and nonunion resulted. An attempt at arthrodesis of the talonavicular and naviculocuneiform joints was then undertaken. This too failed, leading to the development of additional collapse and avascular necrosis. The site was treated with a medial femoral condyle vascularized bone flap. In this single case, the patient returned to pain-free ambulation and reported excellent outcomes and functional capacity. Although we present a successful case, a larger case series is necessary to establish the use of this flap as a reliable option for the treatment of nonunion and avascular necrosis of the tarsal navicular. Copyright © 2012 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  19. [SPECIFIC DIAGNOSTIC SIGNIFICANCE OF "RIPPLE SIGN" OF MEDIAL FEMORAL CONDYLE UNDER ARTHROSCOPE IN MEDIAL LONGITUDINAL MENISCAL TEARS].

    Science.gov (United States)

    Ren Shiyou; Sun, Limang; Chen, Guofei; Jiang, Changqing; Zhang, Xintao; Zhang Wentao

    2015-01-01

    To investigate the reliability of the "ripple sign" on the upper surface of the medial femoral condyle in the diagnosis of medial longitudinal meniscal tears under arthroscope. Between June 2013 and June 2014, 56 patients with knee injuries were included. There were 35 males and 21 females with an average age of 22.2 years (range, 12-38 years). The causes of injury were sports in 40 cases, falling in 10 cases, and traffic accident in 6 cases. The injury was located at the left knee in 22 cases and at the right knee in 34 cases. The disease duration was 10-40 days (mean, 20.2 days). Of 56 patients, 15 cases had simple medial meniscal injury; 41 cases had combined injuries, including anterior cruciate ligament injury in 38 cases, posterior cruciate ligament injury in 2 cases, and patellar dislocation in 1 case. The "ripple sign" was observed under arthroscope before operation. Repair of medial meniscal injury and reconstruction of cruciate ligament were performed. The positive "ripple sign" was seen under arthroscope in all patients, who were diagnosed to have longitudinal meniscal tears, including 23 cases of mild "ripple sign" , 28 cases of moderate "ripple sign", and 5 cases of severe "ripple sign". The "ripple sign" on the upper surface of the medial femoral condyle is a reliable diagnostic evidence of medial longitudinal meniscal tears.

  20. Low-friction nanojoint prototype

    Science.gov (United States)

    Vlassov, Sergei; Oras, Sven; Antsov, Mikk; Butikova, Jelena; Lõhmus, Rünno; Polyakov, Boris

    2018-05-01

    High surface energy of individual nanostructures leads to high adhesion and static friction that can completely hinder the operation of nanoscale systems with movable parts. For instance, silver or gold nanowires cannot be moved on silicon substrate without plastic deformation. In this paper, we experimentally demonstrate an operational prototype of a low-friction nanojoint. The movable part of the prototype is made either from a gold or silver nano-pin produced by laser-induced partial melting of silver and gold nanowires resulting in the formation of rounded bulbs on their ends. The nano-pin is then manipulated into the inverted pyramid (i-pyramids) specially etched in a Si wafer. Due to the small contact area, the nano-pin can be repeatedly tilted inside an i-pyramid as a rigid object without noticeable deformation. At the same time in the absence of external force the nanojoint is stable and preserves its position and tilt angle. Experiments are performed inside a scanning electron microscope and are supported by finite element method simulations.

  1. Mathematical models of viscous friction

    CERN Document Server

    Buttà, Paolo; Marchioro, Carlo

    2015-01-01

    In this monograph we present a review of a number of recent results on the motion of a classical body immersed in an infinitely extended medium and subjected to the action of an external force. We investigate this topic in the framework of mathematical physics by focusing mainly on the class of purely Hamiltonian systems, for which very few results are available. We discuss two cases: when the medium is a gas and when it is a fluid. In the first case, the aim is to obtain microscopic models of viscous friction. In the second, we seek to underline some non-trivial features of the motion. Far from giving a general survey on the subject, which is very rich and complex from both a phenomenological and theoretical point of view, we focus on some fairly simple models that can be studied rigorously, thus providing a first step towards a mathematical description of viscous friction. In some cases, we restrict ourselves to studying the problem at a heuristic level, or we present the main ideas, discussing only some as...

  2. Effect of Process Parameters on Friction Model in Computer Simulation of Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    A. Yamileva

    2014-07-01

    Full Text Available The friction model is important part of a numerical model of linear friction welding. Its selection determines the accuracy of the results. Existing models employ the classical law of Amonton-Coulomb where the friction coefficient is either constant or linearly dependent on a single parameter. Determination of the coefficient of friction is a time consuming process that requires a lot of experiments. So the feasibility of determinating the complex dependence should be assessing by analysis of effect of approximating law for friction model on simulation results.

  3. Velocity Dependence in the Cyclic Friction Arising with Gears

    OpenAIRE

    García Armada, Elena; González de Santos, Pablo; Canudas de Wit, Carlos

    2002-01-01

    Recent research on friction in robot joints and transmission systems has considered meshing friction a position-dependent friction component. However, in this paper we show experimental evidence that meshing friction depends highly on joint speed.We identify the meshing friction in the gearboxes of a robotic leg, and we propose a new mathematical model that considers the rate dependency of meshing friction. The resulting model is validated through experimentation. Results...

  4. Friction Coefficient Determination by Electrical Resistance Measurements

    Science.gov (United States)

    Tunyagi, A.; Kandrai, K.; Fülöp, Z.; Kapusi, Z.; Simon, A.

    2018-01-01

    A simple and low-cost, DIY-type, Arduino-driven experiment is presented for the study of friction and measurement of the friction coefficient, using a conductive rubber cord as a force sensor. It is proposed for high-school or college/university-level students. We strongly believe that it is worthwhile planning, designing and performing Arduino…

  5. Rolling Friction on a Wheeled Laboratory Cart

    Science.gov (United States)

    Mungan, Carl E.

    2012-01-01

    A simple model is developed that predicts the coefficient of rolling friction for an undriven laboratory cart on a track that is approximately independent of the mass loaded onto the cart and of the angle of inclination of the track. The model includes both deformation of the wheels/track and frictional torque at the axles/bearings. The concept of…

  6. Magnetic Viscous Drag for Friction Labs

    Science.gov (United States)

    Gaffney, Chris; Catching, Adam

    2016-01-01

    The typical friction lab performed in introductory mechanics courses is usually not the favorite of either the student or the instructor. The measurements are not all that easy to make, and reproducibility is usually a troublesome issue. This paper describes the augmentation of such a friction lab with a study of the viscous drag on a magnet…

  7. ANALYSIS OF THE MAGNETIZED FRICTION FORCE.

    Energy Technology Data Exchange (ETDEWEB)

    FEDOTOV, A.V.; BRUHWILER, D.L.; SIDORIN, A.O.

    2006-05-29

    A comprehensive examination of theoretical models for the friction force, in use by the electron cooling community, was performed. Here, they present their insights about the models gained as a result of comparison between the friction force formulas and direct numerical simulations, as well as studies of the cooling process as a whole.

  8. Gimbaled-shoulder friction stir welding tool

    Science.gov (United States)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  9. Friction in textile thermoplastic composites forming

    NARCIS (Netherlands)

    Akkerman, Remko; ten Thije, R.H.W.; Sachs, Ulrich; de Rooij, Matthias B.; Binetruy, C.; Boussu, F.

    2010-01-01

    A previously developed mesoscopic friction model for glass/PP textile composite laminates during forming is evaluated for glass and carbon/PPS laminates, at higher temperatures and lower viscosities than before. Experiments were performed for tool/ply and ply/ply configurations in a new friction

  10. The role of friction in tow mechanics

    NARCIS (Netherlands)

    Cornelissen, Bo

    2013-01-01

    Friction plays and important role in the processing of fibrous materials: during production of tow materials, during textile manufacturing and during preforming operations for composite moulding processes. One of the poorly understood phenomena in these processes is the dynamic frictional behaviour

  11. High Friction Surface Treatments, Transportation Research Synthesis

    Science.gov (United States)

    2018-03-01

    MnDOT and local transportation agencies in Minnesota are considering the use of a high friction surface treatment (HFST) as a safety strategy. HFST is used as a spot pavement surfacing treatment in locations with high friction demand (for example, cr...

  12. Device measures static friction of magnetic tape

    Science.gov (United States)

    Cole, P. T.

    1967-01-01

    Device measures the coefficient of static friction of magnetic tape over a range of temperatures and relative humidities. It uses a strain gage to measure the force of friction between a reference surface and the tape drawn at a constant velocity of approximately 0.0001 inch per second relative to the reference surface.

  13. Friction brake cushions acceleration and vibration loads

    Science.gov (United States)

    Fraser, G. F.; Zawadski, G. Z.

    1966-01-01

    Friction brake cushions an object in a vehicle from axially applied vibration and steady-state acceleration forces. The brake incorporates a doubly tapered piston that applies a controlled radial force to friction brake segments bearing against the walls of a cylinder.

  14. Dynamic frictional contact for elastic viscoplastic material

    Directory of Open Access Journals (Sweden)

    Kenneth L. Kuttler

    2007-05-01

    Full Text Available Using a general theory for evolution inclusions, existence and uniqueness theorems are obtained for weak solutions to a frictional dynamic contact problem for elastic visco-plastic material. An existence theorem in the case where the friction coefficient is discontinuous is also presented.

  15. Prediction of friction coefficients for gases

    Science.gov (United States)

    Taylor, M. F.

    1969-01-01

    Empirical relations are used for correlating laminar and turbulent friction coefficients for gases, with large variations in the physical properties, flowing through smooth tubes. These relations have been used to correlate friction coefficients for hydrogen, helium, nitrogen, carbon dioxide and air.

  16. Advanced friction modeling for sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.

    2012-01-01

    The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a

  17. Advanced friction modeling in sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; Meinders, Vincent T.; Huetink, Han

    2011-01-01

    The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a

  18. Position-dependent friction in quantum mechanics

    International Nuclear Information System (INIS)

    Srokowski, T.

    1985-01-01

    The quantum description of motion of a particle subjected to position-dependent frictional forces is presented. The two cases are taken into account: a motion without external forces and in the harmonic oscillator field. As an example, a frictional barrier penetration is considered. 16 refs. (author)

  19. High-velocity frictional properties of gabbro

    Science.gov (United States)

    Tsutsumi, Akito; Shimamoto, Toshihiko

    High-velocity friction experiments have been performed on a pair of hollow-cylindrical specimens of gabbro initially at room temperature, at slip rates from 7.5 mm/s to 1.8 m/s, with total circumferential displacements of 125 to 174 m, and at normal stresses to 5 MPa, using a rotary-shear high-speed friction testing machine. Steady-state friction increases slightly with increasing slip rate at slip rates to about 100 mm/s (velocity strengthening) and it decreases markedly with increasing slip rate at higher velocities (velocity weakening). Steady-state friction in the velocity weakening regime is lower for the non-melting case than the frictional melting case, due perhaps to severe thermal fracturing. A very large peak friction is always recognized upon the initiation of visible frictional melting, presumably owing to the welding of fault surfaces upon the solidification of melt patches. Frictional properties thus change dramatically with increasing displacement at high velocities, and such a non-linear effect must be incorporated into the analysis of earthquake initiation processes.

  20. Trial manufacture of rotary friction tester and frictional force measurement of metals

    CERN Document Server

    Abe, T; Kanari, M; Tanzawa, S

    2002-01-01

    In the plasma confinement type fusion reactor, in-vessel structures such as a blanket module slide at the joints each other when plasma disruption occurs, and then frictional heat is generated there. Therefore, for the selection of material and the use as the design data, it is important to understand the frictional characteristics of metals and ceramic films in the vacuum. In the present study, we have manufactured a prototype of rotary friction tester and examined the performances of the tester. The frictional characteristics of metals in the room air was measured using the friction tester, and the results obtained are as follows. A drifting friction force for a constant time and a friction force during the idling were 98 mN and 225 mN, respectively. These values were sufficiently small as compared to pressing load (9.8 - 57.8 N) used in the friction test. In a friction force measurement of stainless steel, dynamic friction force obeyed Amontons' law which indicated that dynamic friction force is not depend...

  1. Frictional ageing from interfacial bonding and the origins of rate and state friction.

    Science.gov (United States)

    Li, Qunyang; Tullis, Terry E; Goldsby, David; Carpick, Robert W

    2011-11-30

    Earthquakes have long been recognized as being the result of stick-slip frictional instabilities. Over the past few decades, laboratory studies of rock friction have elucidated many aspects of tectonic fault zone processes and earthquake phenomena. Typically, the static friction of rocks grows logarithmically with time when they are held in stationary contact, but the mechanism responsible for this strengthening is not understood. This time-dependent increase of frictional strength, or frictional ageing, is one manifestation of the 'evolution effect' in rate and state friction theory. A prevailing view is that the time dependence of rock friction results from increases in contact area caused by creep of contacting asperities. Here we present the results of atomic force microscopy experiments that instead show that frictional ageing arises from the formation of interfacial chemical bonds, and the large magnitude of ageing at the nanometre scale is quantitatively consistent with what is required to explain observations in macroscopic rock friction experiments. The relative magnitude of the evolution effect compared with that of the 'direct effect'--the dependence of friction on instantaneous changes in slip velocity--determine whether unstable slip, leading to earthquakes, is possible. Understanding the mechanism underlying the evolution effect would enable us to formulate physically based frictional constitutive laws, rather than the current empirically based 'laws', allowing more confident extrapolation to natural faults.

  2. Novel friction law for the static friction force based on local precursor slipping.

    Science.gov (United States)

    Katano, Yu; Nakano, Ken; Otsuki, Michio; Matsukawa, Hiroshi

    2014-09-10

    The sliding of a solid object on a solid substrate requires a shear force that is larger than the maximum static friction force. It is commonly believed that the maximum static friction force is proportional to the loading force and does not depend on the apparent contact area. The ratio of the maximum static friction force to the loading force is called the static friction coefficient µM, which is considered to be a constant. Here, we conduct experiments demonstrating that the static friction force of a slider on a substrate follows a novel friction law under certain conditions. The magnitude of µM decreases as the loading force increases or as the apparent contact area decreases. This behavior is caused by the slip of local precursors before the onset of bulk sliding and is consistent with recent theory. The results of this study will develop novel methods for static friction control.

  3. Large Friction Anisotropy of a Polydiacetylene Monolayer

    International Nuclear Information System (INIS)

    Burns, A.R.; Carpick, R.W.; Sasaki, D.Y.

    1999-01-01

    Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbone. We propose that the backbones impose anisotropic packing of the hydrocarbon side chains which leads to the observed friction anisotropy. Friction anisotropy is therefore a sensitive, optically-independent indicator of polymer backbone direction and monolayer structural properties

  4. Friction Properties of Carbon Fiber Brush

    OpenAIRE

    大塚, 由佳; 月山, 陽介; 野老山, 貴行; 梅原, 徳次; OHTSUKA, Yuka; TSUKIYAMA, Yosuke; TOKOROYAMA, Takayuki; UMEHARA, Noritsugu

    2011-01-01

    直径数μmのカーボンファイバーを束ねたカーボンファイバーブラシ材料と金属材料のすべり摩擦におけるすべり出しの摩擦及び平均摩擦特性と,金属同士のそれらの摩擦特性の相違を調べ,カーボンファイバーブラシ材料の摩擦の特異性を明らかにした. Friction properties as initial and average friction coefficient were investigated for carbon brush materials. Experimental results shows that static friction coefficient of carbon fiber brush is smaller than kinetic friction after a macro slip. This phenomena is different from the usual friction properties between metals. I...

  5. Frictional properties of jointed welded tuff

    International Nuclear Information System (INIS)

    Teufel, L.W.

    1981-07-01

    The results of the experiments on simulated joints in welded tuff from the Grouse Canyon Member of the Belted Range Tuff warrant the following conclusions: (1) The coefficient of friction of the joints is independent of normal stress at a given sliding velocity. (2) The coefficient of friction increases with both increasing time of stationary contact and decreasing sliding velocity. (3) Time and velocity dependence of friction is due to an increase in the real area of contact on the sliding surface, caused by asperity creep. (4) Joints in water-saturated tuff show a greater time and velocity dependence of friction than those in dehydrated tuff. (5) The enhanced time and velocity dependence of friction with water saturation is a result of increased creep at asperity contacts, which is in turn due to a reduction in the surface indentation hardness by hydrolytic weakening and/or stress corrosion cracking

  6. On the geometric phenomenology of static friction.

    Science.gov (United States)

    Ghosh, Shankar; Merin, A P; Nitsure, Nitin

    2017-09-06

    In this note we introduce a hierarchy of phase spaces for static friction, which give a graphical way to systematically quantify the directional dependence in static friction via subregions of the phase spaces. We experimentally plot these subregions to obtain phenomenological descriptions for static friction in various examples where the macroscopic shape of the object affects the frictional response. The phase spaces have the universal property that for any experiment in which a given object is put on a substrate fashioned from a chosen material with a specified nature of contact, the frictional behaviour can be read off from a uniquely determined classifying map on the control space of the experiment which takes values in the appropriate phase space.

  7. Friction forces on phase transition fronts

    International Nuclear Information System (INIS)

    Mégevand, Ariel

    2013-01-01

    In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling

  8. Quantitative evaluation of subchondral bone injury of the plantaro-lateral condyles of the third metatarsal bone in Thoroughbred horses identified using nuclear scintigraphy: 48 cases.

    Science.gov (United States)

    Parker, R A; Bladon, B M; Parkin, T D H; Fraser, B S L

    2010-09-01

    Increased radio-isotope uptake (IRU) in the subchondral bone of the plantaro-lateral condyle of the third metatarsus (MTIII) is a commonly reported scintigraphic finding and potential cause of lameness in UK Thoroughbred racehorses in training and has not been fully documented. To characterise lameness attributable to IRU of the subchondral bone of MTIII, compare the scintigraphic findings of these horses with a normal population and evaluate the use of scintigraphy as an indicator of prognosis. IRU will be in significantly higher in horses with subchondral bone injury and will be related to prognosis and future racing performance. Data were analysed from 48 horses in which subchondral bone injury of the plantaro-lateral condyle of MTIII had been diagnosed using nuclear scintigraphy and that met the inclusion criteria. Data recorded included age, sex, trainer, racing discipline, lameness assessment, treatment regimes, radiographic and scintigraphic findings, response to diagnostic analgesia where performed and racing performance pre- and post diagnosis. Region of interest (ROI) counts were obtained for the plantar condyle and the mid diaphysis from the latero-medial view, the ratio calculated and then compared with a control group of clinically unaffected horses. The mean condyle mid-diaphysis ROI ratio was significantly (PThoroughbred racehorses. Nuclear scintigraphy is a useful diagnostic imaging modality in the detection of affected horses but is a poor indicator of prognosis for the condition. Better understanding of the clinical manifestations, diagnosis of and prognosis for subchondral bone injury will benefit the Thoroughbred industry in the UK.

  9. FRICTION-BOON OR BANE IN ORTHODONTICS

    Directory of Open Access Journals (Sweden)

    Sameer

    2015-11-01

    Full Text Available OBJECTIVE: Most fixed appliance techniques involve some degree of sliding between brackets and arch wires. A sound knowledge of the various factors affecting the magnitude of friction is of paramount importance to the clinician. The present study was performed to evaluate and compare the frictional resistance and characteristics between self-ligating brackets and pre-adjusted edgewise brackets with different types of ligation. MATERIALS AND METHODS: Tidy's frictional test design was used to simulate retraction of tooth along with artificial saliva to simulate wet conditions in oral cavity. The jig with this assembly was mounted on the Instron machine with the cross head moving upwards at a speed of 5mm/min. The movable bracket was suspended from the load cell of the testing machine, while the jig was mounted on cross head of machine and the load cell readings were recorded on digital display. Following wires are used 0.016 HANT, 0.019X 0.025HANT, 0.019X 0.025 SS, 0.021X 0.025 SS wires are used. The brackets used were 0.022 slot Damon, 0.022 Smart clip and 0.022 slot MBT system. RESULTS: Self ligating brackets were shown to produce lesser friction when compared to the conventional brackets used with modules, and stainless steel ligatures. Damon self-ligating brackets produce a least friction of all the brackets used in the study. Stainless steel ligatures produced the least friction compared to elastomeric. CONCLUSION: Self ligation brackets produce lesser friction than the conventional brackets ligated with elastomeric modules and stainless steel ligature. Damon self-ligating brackets produce a least friction of all the brackets used in the study width of the bracket was also found to be directly proportional to the friction produced 0.0016HANT with elastomeric modules produce more friction due increase in flexibility of wire.

  10. Anticipating the friction coefficient of friction materials used in automobiles by means of machine learning without using a test instrument

    OpenAIRE

    TİMUR, Mustafa; AYDIN, Fatih

    2013-01-01

    The most important factor for designs in which friction materials are used is the coefficient of friction. The coefficient of friction has been determined taking such variants as velocity, temperature, and pressure into account, which arise from various factors in friction materials, and by analyzing the effects of these variants on friction materials. Many test instruments have been produced in order to determine the coefficient of friction. In this article, a study about the use ...

  11. Effect of bone-soft tissue friction on ultrasound axial shear strain elastography.

    Science.gov (United States)

    Tang, Songyuan; Chaudhry, Anuj; Kim, Namhee; Reddy, J N; Righetti, Raffaella

    2017-07-12

    Bone-soft tissue friction is an important factor affecting several musculoskeletal disorders, frictional syndromes and the ability of a bone fracture to heal. However, this parameter is difficult to determine using non-invasive imaging modalities, especially in clinical settings. Ultrasound axial shear strain elastography is a non-invasive imaging modality that has been used in the recent past to estimate the bonding between different tissue layers. As most elastography methods, axial shear strain elastography is primarily used in soft tissues. More recently, this technique has been proposed to assess the bone-soft tissue interface. In this paper, we investigate the effect of a variation in bone-soft tissue friction coefficient in the resulting axial shear strain elastograms. Finite element poroelastic models of bone specimens exhibiting different bone-soft tissue friction coefficients were created and mechanically analyzed. These models were then imported to an ultrasound elastography simulation module to assess the presence of axial shear strain patterns. In vitro experiments were performed to corroborate selected simulation results. The results of this study show that the normalized axial shear strain estimated at the bone-soft tissue interface is statistically correlated to the bone-soft tissue coefficient of friction. This information may prove useful to better interpret ultrasound elastography results obtained in bone-related applications and, possibly, monitor bone healing.

  12. Friction Stir Welding and Processing

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Carsley, John; Clarke, Kester D.; Krajewski, Paul E.

    2015-05-01

    With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, which organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.

  13. Surface Friction of Polyacrylamide Hydrogel Particles

    Science.gov (United States)

    Cuccia, Nicholas; Burton, Justin

    Polyacrylamide hydrogel particles have recently become a popular system for modeling low-friction, granular materials near the jamming transition. Because a gel consists of a polymer network filled with solvent, its frictional behavior is often explained using a combination of hydrodynamic lubrication and polymer-surface interactions. As a result, the frictional coefficient can vary between 0.001 and 0.03 depending on several factors such as contact area, sliding velocity, normal force, and the gel surface chemistry. Most tribological measurements of hydrogels utilize two flat surfaces, where the contact area is not well-defined. We have built a custom, low-force tribometer to measure the single-contact frictional properties of spherical hydrogel particles on flat hydrogel surfaces under a variety of measurement conditions. At high velocities (> 1 cm/s), the friction coefficient depends linearly on velocity, but does not tend to zero at zero velocity. We also compare our measurements to solid particles (steel, glass, etc.) on hydrogel surfaces, which exhibit larger frictional forces, and show less dependence on velocity. A physical model for the friction which includes the lubrication layer between the deformed surfaces will be discussed. National Science Foundation Grant No. 1506446.

  14. FRICTION TORQUE IN THE SLIDE BEARINGS

    Directory of Open Access Journals (Sweden)

    BONDARENKO L. N.

    2016-09-01

    Full Text Available Summary. Problem statement. Until now slide bearings are used widely in engineering. But the calculation is made on obsolete method that is based on undetermined parameters such as wear of the bearing shell. It is accepted in the literature that if the shaft and liner material are homogeneous, the workpiece surface are cylindrical as they wear and contact between them occurs at all points contact arc. Research objective. The purpose of this study is determine a friction torque in the slide bearings of power-basis parameters. Conclusions. Since the friction is primarily responsible for wear of cinematic pairs “pin – liner” and “pivot – liner” slide bearings. It is shown that the friction torquesof angles wrap, that are obtained by the formulas and given in literature, are not only qualitatively but also quantitatively, namely, the calculation by literature to the formulas the friction torques are proportional to the angle wrap and the calculation by improved formulas the friction torques are inversely proportional to the angle wrap due to the reduction the normal pressure. Underreporting friction torque at large angle wrap is between 40 and 15 %. The difference in the magnitude of friction torque in the run-in and run-out cinematic pairs with real method of machining is 2...3 %, which it is possible to declare of reducing the finish of contacting surface of slide bearings.

  15. Amontonian frictional behaviour of nanostructured surfaces.

    Science.gov (United States)

    Pilkington, Georgia A; Thormann, Esben; Claesson, Per M; Fuge, Gareth M; Fox, Oliver J L; Ashfold, Michael N R; Leese, Hannah; Mattia, Davide; Briscoe, Wuge H

    2011-05-28

    With nanotextured surfaces and interfaces increasingly being encountered in technological and biomedical applications, there is a need for a better understanding of frictional properties involving such surfaces. Here we report friction measurements of several nanostructured surfaces using an Atomic Force Microscope (AFM). These nanostructured surfaces provide well defined model systems on which we have tested the applicability of Amontons' laws of friction. Our results show that Amontonian behaviour is observed with each of the surfaces studied. However, no correlation has been found between measured friction and various surface roughness parameters such as average surface roughness (R(a)) and root mean squared (rms) roughness. Instead, we propose that the friction coefficient may be decomposed into two contributions, i.e., μ = μ(0) + μ(g), with the intrinsic friction coefficient μ(0) accounting for the chemical nature of the surfaces and the geometric friction coefficient μ(g) for the presence of nanotextures. We have found a possible correlation between μ(g) and the average local slope of the surface nanotextures. This journal is © the Owner Societies 2011

  16. Nonmonotonicity of the Frictional Bimaterial Effect

    Science.gov (United States)

    Aldam, Michael; Xu, Shiqing; Brener, Efim A.; Ben-Zion, Yehuda; Bouchbinder, Eran

    2017-10-01

    Sliding along frictional interfaces separating dissimilar elastic materials is qualitatively different from sliding along interfaces separating identical materials due to the existence of an elastodynamic coupling between interfacial slip and normal stress perturbations in the former case. This bimaterial coupling has important implications for the dynamics of frictional interfaces, including their stability and rupture propagation along them. We show that while this bimaterial coupling is a monotonically increasing function of the bimaterial contrast, when it is coupled to interfacial shear stress perturbations through a friction law, various physical quantities exhibit a nonmonotonic dependence on the bimaterial contrast. In particular, we show that for a regularized Coulomb friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is a nonmonotonic function of the bimaterial contrast and provides analytic insight into the origin of this nonmonotonicity. We further show that for velocity-strengthening rate-and-state friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is also a nonmonotonic function of the bimaterial contrast. Results from simulations of dynamic rupture along a bimaterial interface with slip-weakening friction provide evidence that the theoretically predicted nonmonotonicity persists in nonsteady, transient frictional dynamics.

  17. Assessment of semi-active friction dampers

    Science.gov (United States)

    dos Santos, Marcelo Braga; Coelho, Humberto Tronconi; Lepore Neto, Francisco Paulo; Mafhoud, Jarir

    2017-09-01

    The use of friction dampers has been widely proposed for a variety of mechanical systems for which applying viscoelastic materials, fluid based dampers or other viscous dampers is impossible. An important example is the application of friction dampers in aircraft engines to reduce the blades' vibration amplitudes. In most cases, friction dampers have been studied in a passive manner, but significant improvements can be achieved by controlling the normal force in the contact region. The aim of this paper is to present and study five control strategies for friction dampers based on three different hysteresis cycles by using the Harmonic Balance Method (HBM), a numerical and experimental analysis. The first control strategy uses the friction force as a resistance when the system is deviating from its equilibrium position. The second control strategy maximizes the energy removal in each harmonic oscillation cycle by calculating the optimal normal force based on the last displacement peak. The third control strategy combines the first strategy with the homogenous modulation of the friction force. Finally, the last two strategies attempt to predict the system's movement based on its velocity and acceleration and our knowledge of its physical properties. Numerical and experimental studies are performed with these five strategies, which define the performance metrics. The experimental testing rig is fully identified and its parameters are used for numerical simulations. The obtained results show the satisfactory performance of the friction damper and selected strategy and the suitable agreement between the numerical and experimental results.

  18. Enhanced nanoscale friction on fluorinated graphene.

    Science.gov (United States)

    Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

    2012-12-12

    Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene.

  19. A large osteoid osteoma of the mandibular condyle causing conductive hearing loss: a case report and review of literature.

    Science.gov (United States)

    Richardson, Sunil; Khandeparker, Rakshit Vijay; Sharma, Kapil

    2017-04-01

    Osteoid osteomas are benign skeletal neoplasms that are commonly encountered in the bones of the lower extremities, but are exceedingly rare in jaw bones with a prevalence of less than 1%. This unique clinical entity is usually seen in younger individuals, with nocturnal pain and swelling as its characteristic clinical manifestations. The size of the lesion is rarely found to be more than 2 cm. We hereby report a rare case of osteoid osteoma originating from the neck of the mandibular condyle that grew to large enough proportions to result in conductive hearing loss in addition to pain, swelling and restricted mouth opening. In addition, an effort has been made to review all the documented cases of osteoid osteomas of the jaws that have been published in the literature thus far.

  20. Evaluation of an injectable bioactive borate glass cement to heal bone defects in a rabbit femoral condyle model

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xu [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Huang, Wenhai [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Zhang, Yadong, E-mail: zhangyadong6@126.com [Department of Spine Surgery, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai 200120 (China); Huang, Chengcheng; Yu, Zunxiong; Wang, Lei; Liu, Wenlong; Wang, Ting [Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Zhou, Jie; Wang, Hui; Zhou, Nai; Wang, Deping [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Pan, Haobo, E-mail: hb.pan@siat.ac.cn [Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Rahaman, Mohamed N., E-mail: rahaman@mst.edu [Department of Spine Surgery, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai 200120 (China); Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0340 (United States)

    2017-04-01

    There is a need for synthetic biomaterials to heal bone defects using minimal invasive surgery. In the present study, an injectable cement composed of bioactive borate glass particles and a chitosan bonding solution was developed and evaluated for its capacity to heal bone defects in a rabbit femoral condyle model. The injectability and setting time of the cement in vitro decreased but the compressive strength increased (8 ± 2 MPa to 31 ± 2 MPa) as the ratio of glass particles to chitosan solution increased (from 1.0 g ml{sup −1} to 2.5 g ml{sup −1}). Upon immersing the cement in phosphate-buffered saline, the glass particles reacted and converted to hydroxyapatite, imparting bioactivity to the cement. Osteoblastic MC3T3-E1 cells showed enhanced proliferation and alkaline phosphatase activity when incubated in media containing the soluble ionic product of the cement. The bioactive glass cement showed a better capacity to stimulate bone formation in rabbit femoral condyle defects at 12 weeks postimplantation when compared to a commercial calcium sulfate cement. The injectable bioactive borate glass cement developed in this study could provide a promising biomaterial to heal bone defects by minimal invasive surgery. - Highlights: • New class of injectable bone cement composed of bioactive borate glass particles and chitosan bonding phase was created. • The cement is biocompatible and bioactive, and has a much lower temperature increase during setting than PMMA cement. • The cement has a more controllable degradation rate and higher strength over a longer time than calcium sulfate cement. • The cement showed a better ability to heal bone defects than calcium sulfate over a twelve-week implantation period.

  1. Relationship between fracture of mandibular condyle and absence of unerupted mandibular third molar-a retrospective study.

    Science.gov (United States)

    Rajan, Ritesh; Verma, Dinesh Kumar; Borle, R M; Yadav, Abhilasha

    2016-06-01

    The purpose of the present study was to find, if there exists, a co-relation between presence of unerupted mandibular third molar and fracture of mandibular condyle. A retrospective, multicenter study was done collecting the data of all mandibular condyle fractures treated from November 2006 till August 2015. Data was collected from the patient's records and radiographs for the following information: age, sex, etiology of fracture, presence and state of lower third molars, and associated fracture. The results were subjected to statistical analysis. Out of 180 patients of condylar fracture, unerupted third molars were present in 35 (19.44 %) cases compared to 145 (80.55 %) cases of condylar fracture where the unerupted third molars were not present. The difference was statistically significant (p fracture was seen in 4 (11.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 9 (25.7 %) cases, isolated unilateral condylar fracture in 0 (0.0 %) cases, and unilateral condylar fracture associated with other mandibular fractures in 17 (48.5 %) cases and condylar fracture associated with mid face fractures in 5 (14.2 %) cases. In the unerupted third molar absent group, isolated bilateral condylar fracture was seen in 5 (3.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 30 (20.6 %) cases, isolated unilateral condylar fracture in 24 (16.5 %) cases, unilateral condylar fracture associated with other mandibular fractures in 73 (50.34 %) cases, and condylar fracture associated with mid face fractures in 13(8.96 %) cases. The difference between the groups was statistically significant (p = 0.032). This study suggests that the fractures of mandibular condylar region have a significantly higher incidence in patients without an unerupted mandibular third molar.

  2. IMF-screws or arch bars as conservative treatment for mandibular condyle fractures: Quality of life aspects.

    Science.gov (United States)

    van den Bergh, B; de Mol van Otterloo, J J; van der Ploeg, T; Tuinzing, D B; Forouzanfar, T

    2015-09-01

    Arch bars as treatment for a fractured mandibular condyle are inconvenient to patients and lead to lowered quality of life (QOL). To overcome these inconveniences, IMF-screws (IMFS) to facilitate intermaxillary fixation during surgery have been developed. The purpose of the present study is to investigate and compare QOL for patients treated for a fractured mandibular condyle with either IMFS or arch bars. This research trial was conducted from 2010 to 2014 as part of an earlier prospective, multicenter, randomized clinical trial in which the use of IMFS was compared to the use of arch bars in the treatment of mandibular condylar fractures. In total, 50 patients were included: 30 (60%) male patients and 20 (40%) female patients (mean age: 31.8 years, standard deviation [SD] = 13.9 years, range = 18-64 years). A total of 24 (48%) patients were allocated in the IMFS group, and 26 (52%) patients were assigned to the arch-bars control group. Significant results were observed in the subscales social isolation, possibility to eat and vary diet, influence on sleep, and satisfaction with the given treatment, all in favour of IMFS. In conclusion, using IMFS as a method for conservative treatment of condylar fractures led to a higher QOL during the 6-week period of fracture healing. In comparison to arch bars, patients treated with IMFS experienced less social isolation, had fewer problems with eating, and express the feeling they are able to continue their normal diet. Furthermore it seems that the use of IMFS has a lower negative impact on social and financial aspects of the patient. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  3. Anisotropy in cohesive, frictional granular media

    International Nuclear Information System (INIS)

    Luding, Stefan

    2005-01-01

    The modelling of cohesive, frictional granular materials with a discrete particle molecular dynamics is reviewed. From the structure of the quasi-static granular solid, the fabric, stress, and stiffness tensors are determined, including both normal and tangential forces. The influence of the material properties on the flow behaviour is also reported, including relations between the microscopic attractive force and the macroscopic cohesion as well as the dependence of the macroscopic friction on the microscopic contact friction coefficient. Related to the dynamics, the anisotropy of both structure and stress are exponentially approaching the maximum

  4. Internal Friction And Instabilities Of Rotors

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1992-01-01

    Report describes study of effects of internal friction on dynamics of rotors prompted by concern over instabilities in rotors of turbomachines. Theoretical and experimental studies described. Theoretical involved development of nonlinear mathematical models of internal friction in three joints found in turbomachinery - axial splines, Curvic(TM) splines, and interference fits between smooth cylindrical surfaces. Experimental included traction tests to determine the coefficients of friction of rotor alloys at various temperatures, bending-mode-vibration tests of shafts equipped with various joints and rotordynamic tests of shafts with axial-spline and interference-fit joints.

  5. NASA tire/runway friction projects

    Science.gov (United States)

    Yager, Thomas J.

    1995-01-01

    The paper reviews several aspects of NASA Langley Research Center's tire/runway friction evaluations directed towards improving the safety and economy of aircraft ground operations. The facilities and test equipment used in implementing different aircraft tire friction studies and other related aircraft ground performance investigations are described together with recent workshop activities at NASA Wallops Flight Facility. An overview of the pending Joint NASA/Transport Canada/FM Winter Runway Friction Program is given. Other NASA ongoing studies and on-site field tests are discussed including tire wear performance and new surface treatments. The paper concludes with a description of future research plans.

  6. Serotonin syndrome

    Science.gov (United States)

    Hyperserotonemia; Serotonergic syndrome; Serotonin toxicity; SSRI - serotonin syndrome; MAO - serotonin syndrome ... brain area. For example, you can develop this syndrome if you take migraine medicines called triptans together ...

  7. Comparisons of friction models in bulk metal forming

    DEFF Research Database (Denmark)

    Tan, Xincai

    2002-01-01

    A friction model is one of the key input boundary conditions in finite element simulations. It is said that the friction model plays an important role in controlling the accuracy of necessary output results predicted. Among the various friction models, which one is of higher accuracy is still...... unknown and controversial. In this paper, finite element analyses applying five different friction models to experiments of upsetting of AA 6082 lubricated with four lubricants are presented. Frictional parameter values are determined by fitness of data of friction area ratio from finite element analysis...... to experimental results. It is found that calibration curves of the friction area ratio for all of the five chosen friction models used in the finite element simulation do fit the experimental results. Usually, calbration curves of the friction area ratio are more sensitive to friction at the tool...

  8. Modeling Friction Performance of Drill String Torsional Oscillation Using Dynamic Friction Model

    Directory of Open Access Journals (Sweden)

    Xingming Wang

    2017-01-01

    Full Text Available Drill string torsional and longitudinal oscillation can significantly reduce axial drag in horizontal drilling. An improved theoretical model for the analysis of the frictional force was proposed based on microscopic contact deformation theory and a bristle model. The established model, an improved dynamic friction model established for drill strings in a wellbore, was used to determine the relationship of friction force changes and the drill string torsional vibration. The model results were in good agreement with the experimental data, verifying the accuracy of the established model. The analysis of the influence of drilling mud properties indicated that there is an approximately linear relationship between the axial friction force and dynamic shear and viscosity. The influence of drill string torsional oscillation on the axial friction force is discussed. The results indicated that the drill string transverse velocity is a prerequisite for reducing axial friction. In addition, low amplitude of torsional vibration speed can significantly reduce axial friction. Then, increasing the amplitude of transverse vibration speed, the effect of axial reduction is not significant. In addition, by involving general field drilling parameters, this model can accurately describe the friction behavior and quantitatively predict the frictional resistance in horizontal drilling.

  9. Novel Friction Law for the Static Friction Force based on Local Precursor Slipping

    OpenAIRE

    Katano, Yu; Nakano, Ken; Otsuki, Michio; Matsukawa, Hiroshi

    2014-01-01

    The sliding of a solid object on a solid substrate requires a shear force that is larger than the maximum static friction force. It is commonly believed that the maximum static friction force is proportional to the loading force and does not depend on the apparent contact area. The ratio of the maximum static friction force to the loading force is called the static friction coefficient µ M, which is considered to be a constant. Here, we conduct experiments demonstrating that the static fricti...

  10. Velocity dependence of friction of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.

    2009-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate, and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional...... shear stress for both cases. In our simulations, the polymer films are very thin (approx. 3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  11. Transient effects in friction fractal asperity creep

    CERN Document Server

    Goedecke, Andreas

    2013-01-01

    Transient friction effects determine the behavior of a wide class of mechatronic systems. Classic examples are squealing brakes, stiction in robotic arms, or stick-slip in linear drives. To properly design and understand mechatronic systems of this type, good quantitative models of transient friction effects are of primary interest. The theory developed in this book approaches this problem bottom-up, by deriving the behavior of macroscopic friction surfaces from the microscopic surface physics. The model is based on two assumptions: First, rough surfaces are inherently fractal, exhibiting roughness on a wide range of scales. Second, transient friction effects are caused by creep enlargement of the real area of contact between two bodies. This work demonstrates the results of extensive Finite Element analyses of the creep behavior of surface asperities, and proposes a generalized multi-scale area iteration for calculating the time-dependent real contact between two bodies. The toolset is then demonstrated both...

  12. Experimental studies of the magnetized friction force

    International Nuclear Information System (INIS)

    Fedotov, A. V.; Litvinenko, V. N.; Gaalnander, B.; Lofnes, T.; Ziemann, V.; Sidorin, A.; Smirnov, A.

    2006-01-01

    High-energy electron cooling, presently considered as an essential tool for several applications in high-energy and nuclear physics, requires an accurate description of the friction force which ions experience by passing through an electron beam. Present low-energy electron coolers can be used for a detailed study of the friction force. In addition, parameters of a low-energy cooler can be chosen in a manner to reproduce regimes expected in future high-energy operation. Here, we report a set of dedicated experiments in CELSIUS aimed at a detailed study of the magnetized friction force. Some results of the accurate comparison of experimental data with the friction force formulas are presented

  13. Fundamentals of Friction and Vapor Phase Lubrication

    National Research Council Canada - National Science Library

    Gellman, Andrew

    2004-01-01

    This is the final report for the three year research program on "Fundamentals of Friction and Vapor Phase Lubrication" conducted at Carnegie Mellon with support from AFOSR grant number F49630-01-1-0069...

  14. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.; Cohen, Claude; Agarwal, Praveen; Archer, Lynden A.

    2011-01-01

    higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased

  15. The coefficient of friction, particularly of ice

    International Nuclear Information System (INIS)

    Mills, Allan

    2008-01-01

    The static and dynamic coefficients of friction are defined, and values from 0.3 to 0.6 are quoted for common materials. These drop to about 0.15 when oil is added as a lubricant. Water ice at temperatures not far below 0 °C is remarkable for low coefficients of around 0.05 for static friction and 0.04–0.02 for dynamic friction, but these figures increase as the temperature diminishes. Reasons for the slipperiness of ice are summarized, but they are still not entirely clear. One hypothesis suggests that it is related to the transient formation of a lubricating film of liquid water produced by frictional heating. If this is the case, some composition melting a little above ambient temperatures might provide a skating rink that did not require expensive refrigeration. Various compositions have been tested, but an entirely satisfactory material has yet to be found

  16. Comparing numerically exact and modelled static friction

    Directory of Open Access Journals (Sweden)

    Krengel Dominik

    2017-01-01

    Full Text Available Currently there exists no mechanically consistent “numerically exact” implementation of static and dynamic Coulomb friction for general soft particle simulations with arbitrary contact situations in two or three dimension, but only along one dimension. We outline a differential-algebraic equation approach for a “numerically exact” computation of friction in two dimensions and compare its application to the Cundall-Strack model in some test cases.

  17. Hedging, arbitrage and optimality with superlinear frictions

    OpenAIRE

    Guasoni, Paolo; Rásonyi, Miklós

    2015-01-01

    In a continuous-time model with multiple assets described by c\\`{a}dl\\`{a}g processes, this paper characterizes superhedging prices, absence of arbitrage, and utility maximizing strategies, under general frictions that make execution prices arbitrarily unfavorable for high trading intensity. Such frictions induce a duality between feasible trading strategies and shadow execution prices with a martingale measure. Utility maximizing strategies exist even if arbitrage is present, because it is n...

  18. Political frictions and public policy outcomes

    OpenAIRE

    Grechyna, Daryna

    2016-01-01

    We study the role of political frictions in public policy outcomes. We propose a simple model of fiscal policy that combines a lack of commitment by the government, political turnover, and another political friction that can be interpreted either as political polarization or as public rent-seeking. We show that political turnover increases public debt levels, while political polarization or public rent-seeking leads to higher public spending. We evaluate the importance of different political ...

  19. Probing friction in actin-based motility

    International Nuclear Information System (INIS)

    Marcy, Yann; Joanny, Jean-Francois; Prost, Jacques; Sykes, Cecile

    2007-01-01

    Actin dynamics are responsible for cell protrusion and certain intracellular movements. The transient attachment of the actin filaments to a moving surface generates a friction force that resists the movement. We probe here the dynamics of these attachments by inducing a stick-slip behavior via micromanipulation of a growing actin comet. We show that general principles of adhesion and friction can explain our observations

  20. Friction Stir Welding Process: A Green Technology

    OpenAIRE

    Esther T. Akinlabi; Stephen A. Akinlabi

    2012-01-01

    Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materia...

  1. Macroeconomics with Financial Frictions: A Survey

    OpenAIRE

    Markus K. Brunnermeier; Thomas M. Eisenbach; Yuliy Sannikov

    2012-01-01

    This article surveys the macroeconomic implications of financial frictions. Financial frictions lead to persistence and when combined with illiquidity to non-linear amplification effects. Risk is endogenous and liquidity spirals cause financial instability. Increasing margins further restrict leverage and exacerbate downturns. A demand for liquid assets and a role for money emerges. The market outcome is generically not even constrained efficient and the issuance of government debt can lead t...

  2. Friction Welding of Titanium and Carbon Steel

    OpenAIRE

    Atsushi, HASUI; Yoichi, KIRA; Faculty of Science and Technology, Keio University; Ishikawajima-Harima Heavy Industries, Co., Ltd.

    1985-01-01

    Titanium-steel is a combination of dissimilar materials, which are difficult to weld in general, owing to inevitable formation of brittle intermetallic compounds. A prominent feature of friction welding process is ability to weld dissimilar materials in many kinds of combinations. This report deals with friction weldabilily of pure titanium and S25C steel, which are 12 mm in diameter. Main results are summarized as follows; (1) Suitable welding conditions to obtain a sound weld, which has a j...

  3. On high temperature internal friction in metallic glasses

    International Nuclear Information System (INIS)

    Zolotukhin, I.V.; Kalinin, Yu.E.; Roshchupkin, A.M.

    1992-01-01

    High temperature background of internal friction in amorphous lanthanum-aluminium alloys was investigated. More rapid growth of internal friction was observed at temperature ∼ 453 K reaching maximal value at 495 K. Crystallization process was accompanied by decrease of internal friction. Increase of mechanical vibration frequency to 1000 Hz leads to rise of internal friction background in the range of room temperatures and to decrease at temperatures above 370 K. Bend was observed on temperature dependence of internal friction at 440 K

  4. Regularized friction and continuation: Comparison with Coulomb's law

    OpenAIRE

    Vigué, Pierre; Vergez, Christophe; Karkar, Sami; Cochelin, Bruno

    2016-01-01

    International audience; Periodic solutions of systems with friction are difficult to investigate because of the irregular nature of friction laws. This paper examines periodic solutions and most notably stick-slip, on a simple one-degre-of-freedom system (mass, spring, damper, belt), with Coulomb's friction law, and with a regularized friction law (i.e. the friction coefficient becomes a function of relative speed, with a stiffness parameter). With Coulomb's law, the stick-slip solution is co...

  5. Internal friction in irradiated silicon

    International Nuclear Information System (INIS)

    Kalanov, M.U.; Pajzullakhanov, M.S.; Khajdarov, T.; Ummatov, Kh.

    1999-01-01

    The submicroscopic heterogeneities in mono- and polycrystal silicon and the influence of X-ray radiation on them were investigated using the ultrasound resonance method. Disk-shaped samples of 27.5 mm in diameter and 4 mm in thickness, with the flat surface parallel to crystallographic plane (111), were irradiated by X-ray beam of 1 Wt/cm 2 (50 KeV, Mo K α ) during 10 hours. Relations of internal frictions (Q -1 ) of samples and their relative attitude (ψ) - Q -1 (ψ) show that there is a presence of double-humped configuration for monocrystal silicon with the peaks at ψ=900 and 270 degrees. The relations Q -1 (ψ) remain the same after the irradiation. However, the peak width becomes larger. This data show that the configuration and attitude of the heterogeneities remain the same after the irradiation. The double-humped configuration was not discovered for the relations Q -1 (ψ) of polycrystal silicon. It is explained by the fact that there is an isotropic distribution in the content of many blocks and granules

  6. Flexible Friction Stir Joining Technology

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lim, Yong Chae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mahoney, Murray [MegaStir Technologies LLC, Orem, UT (United States); Sanderson, Samuel [MegaStir Technologies LLC, Orem, UT (United States); Larsen, Steve [MegaStir Technologies LLC, Orem, UT (United States); Steel, Russel [MegaStir Technologies LLC, Orem, UT (United States); Fleck, Dale [MegaStir Technologies LLC, Orem, UT (United States); Fairchild, Doug P [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Wasson, Andrew J [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Babb, Jon [MegaStir Technologies LLC, Orem, UT (United States); Higgins, Paul [MegaStir Technologies LLC, Orem, UT (United States)

    2015-07-23

    Reported herein is the final report on a U.S. Department of Energy (DOE) Advanced Manufacturing Office (AMO) project with industry cost-share that was jointly carried out by Oak Ridge National Laboratory (ORNL), ExxonMobil Upstream Research Company (ExxonMobil), and MegaStir Technologies (MegaStir). The project was aimed to advance the state of the art of friction stir welding (FSW) technology, a highly energy-efficient solid-state joining process, for field deployable, on-site fabrications of large, complex and thick-sectioned structures of high-performance and high-temperature materials. The technology innovations developed herein attempted to address two fundamental shortcomings of FSW: 1) the inability for on-site welding and 2) the inability to weld thick section steels, both of which have impeded widespread use of FSW in manufacturing. Through this work, major advance has been made toward transforming FSW technology from a “specialty” process to a mainstream materials joining technology to realize its pervasive energy, environmental, and economic benefits across industry.

  7. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    OpenAIRE

    Senai YALCINKAYA

    2017-01-01

    Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the s...

  8. Fluoroscopically guided closed reduction and internal fixation of fractures of the lateral portion of the humeral condyle: prospective clinical study of the technique and results in ten dogs.

    Science.gov (United States)

    Cook, J L; Tomlinson, J L; Reed, A L

    1999-01-01

    To report a technique for fluoroscopically guided closed reduction with internal fixation of fractures of the lateral portion of the humeral condyle (FLHC) and determine the long-term results in 10 clinical cases. Prospective clinical case study. Ten dogs with 11 fractures. Fractures of the lateral portion of the humeral condyle were stabilized with transcondylar screws and Kirschner wires. Closed reduction and implant placement were achieved using intraoperative fluoroscopic guidance. After fracture repair, postoperative radiographs were evaluated for articular alignment and implant placement. Dogs were evaluated after surgery by means of lameness scores, elbow range of motion (ROM), radiographic assessment, and owner evaluation of function. Postoperative reduction was considered anatomic in 6 fractures with all other fractures having ROM values between affected and unaffected elbows. All of the dogs in this study regained 90-100% of full function, based on owner assessment. Fluoroscopic guidance for closed reduction and internal fixation of FLHC in dogs is an effective technique.

  9. Osseous changes and condyle position in TMJ tomograms: impact of RDC/TMD clinical diagnoses on agreement between expected and actual findings.

    Science.gov (United States)

    Wiese, Mie; Wenzel, Ann; Hintze, Hanne; Petersson, Arne; Knutsson, Kerstin; Bakke, Merete; List, Thomas; Svensson, Peter

    2008-08-01

    The objective of this study was to evaluate the impact of clinical TMJ diagnosis, gender, and age on the agreement between expected and actual radiographic findings. A total of 204 patients with TMJ symptoms were examined using the Research Diagnostic Criteria (RDC/TMD). Expected radiographic findings were recorded. TMJ tomograms in closed and open mouth position were assessed for osseous changes and condyle position. Expected and actual findings were compared. Logistic regression analyses were performed with agreement on radiographic findings as the dependent variable and with clinical RDC/TMD diagnoses, gender and age as the independent variables. The number of radiographic findings was mostly underestimated. A clinical diagnosis of osteoarthritis and age increased the chance of overestimating osseous changes. Disc displacement and age decreased the chance of agreement on certain condyle positions. Tomography often revealed unexpected findings. It was not possible to select particular patient groups who would benefit more or less from a radiographic examination.

  10. Occipital Condyle Fracture with Accompanying Meningeal Spinal Cysts as a result of Cervical Spine Injury in 15-Year-Old Girl

    Directory of Open Access Journals (Sweden)

    Łukasz Wiktor

    2015-01-01

    Full Text Available The occipital condyle fracture is rare injury of the craniocervical junction. Meningeal spinal cysts are rare tumors of the spinal cord. Depending on location, these lesions may be classified as extradural and subdural, but extradural spinal cysts are more common. We present the case of a 15-year-old girl who suffered from avulsion occipital condyle fracture treated with use of “halo-vest” system. We established that clinical effect after completed treatment is very good. Control MRI evaluation was performed 12 months after removal of “halo-vest” traction, and clinically silent extradural meningeal spinal cysts were detected at the ventral side of the spinal cord in the cervical segment of the spine. Due to clinically silent course of the disease, we decided to use the conservative treatment. The patient remains under control of our department.

  11. Development of a penetration friction apparatus (PFA) to measure the frictional performance of surgical suture.

    Science.gov (United States)

    Zhang, Gangqiang; Ren, Tianhui; Lette, Walter; Zeng, Xiangqiong; van der Heide, Emile

    2017-10-01

    Nowadays there is a wide variety of surgical sutures available in the market. Surgical sutures have different sizes, structures, materials and coatings, whereas they are being used for various surgeries. The frictional performances of surgical sutures have been found to play a vital role in their functionality. The high friction force of surgical sutures in the suturing process may cause inflammation and pain to the person, leading to a longer recovery time, and the second trauma of soft or fragile tissue. Thus, the investigation into the frictional performance of surgical suture is essential. Despite the unquestionable fact, little is actually known on the friction performances of surgical suture-tissue due to the lack of appropriate test equipment. This study presents a new penetration friction apparatus (PFA) that allowed for the evaluation of the friction performances of various surgical needles and sutures during the suturing process, under different contact conditions. It considered the deformation of tissue and can realize the puncture force measurements of surgical needles as well as the friction force of surgical sutures. The developed PFA could accurately evaluate and understand the frictional behaviour of surgical suture-tissue in the simulating clinical conditions. The forces measured by the PFA showed the same trend as that reported in literatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Kalker's algorithm Fastsim solves tangential contact problems with slip-dependent friction and friction anisotropy

    Science.gov (United States)

    Piotrowski, J.

    2010-07-01

    This paper presents two extensions of Kalker's algorithm Fastsim of the simplified theory of rolling contact. The first extension is for solving tangential contact problems with the coefficient of friction depending on slip velocity. Two friction laws have been considered: with and without recuperation of the static friction. According to the tribological hypothesis for metallic bodies shear failure, the friction law without recuperation of static friction is more suitable for wheel and rail than the other one. Sample results present local quantities inside the contact area (division to slip and adhesion, traction) as well as global ones (creep forces as functions of creepages and rolling velocity). For the coefficient of friction diminishing with slip, the creep forces decay after reaching the maximum and they depend on the rolling velocity. The second extension is for solving tangential contact problems with friction anisotropy characterised by a convex set of the permissible tangential tractions. The effect of the anisotropy has been shown on examples of rolling without spin and in the presence of pure spin for the elliptical set. The friction anisotropy influences tangential tractions and creep forces. Sample results present local and global quantities. Both extensions have been described with the same language of formulation and they may be merged into one, joint algorithm.

  13. Status of Stellite 6 friction testing

    International Nuclear Information System (INIS)

    Watkins, J.C.; DeWall, K.G.

    1998-01-01

    For the past several years, researchers at the Idaho National Engineering and Environmental Laboratory, under the sponsorship of the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, have been investigating the performance of motor-operated valves subjected to design basis flow and pressure loads. Part of this research addresses the friction that occurs at the interface between the valve disc and the valve body seats during operation of a gate valve. In most gate valves, these surfaces are hardfaced with Stellite 6, a cobalt-based alloy. Analytical methods exist for predicting the thrust needed to operate these valves at specific pressure conditions. To produce accurate valve thrust predictions, the analyst must have a reasonably accurate, though conservative, estimate of the coefficient of friction at the disc-to-seat interface. One of the questions that remains to be answered is whether, and to what extent, aging of the disc and seat surfaces effects the disc-to-seat coefficient of friction. Specifically, does the environment in a nuclear plants piping system cause the accumulation of an oxide film on these surfaces that increases the coefficient of friction; and if so, how great is the increase? This paper presents results of specimen tests addressing this issue, with emphasis on the following: (1) the characteristics and thickness of the oxide film that develops on Stellite 6 as it ages; (2) the change in the friction coefficient of Stellite 6 as it ages, including the question of whether the friction coefficient eventually reaches a plateau; and (3) the effect in-service cycling has on the characteristics and thickness of the oxide film and on the friction coefficient

  14. Thermal effects in static friction: thermolubricity.

    Science.gov (United States)

    Franchini, A; Bortolani, V; Santoro, G; Brigazzi, M

    2008-10-01

    We present a molecular dynamics analysis of the static friction between two thick slabs. The upper block is formed by N2 molecules and the lower block by Pb atoms. We study the effects of the temperature as well as the effects produced by the structure of the surface of the lower block on the static friction. To put in evidence the temperature effects we will compare the results obtained with the lower block formed by still atoms with those obtained when the atoms are allowed to vibrate (e.g., with phonons). To investigate the importance of the geometry of the surface of the lower block we apply the external force in different directions, with respect to a chosen crystallographic direction of the substrate. We show that the interaction between the lattice dynamics of the two blocks is responsible for the strong dependence of the static friction on the temperature. The lattice dynamics interaction between the two blocks strongly reduces the static friction, with respect to the case of the rigid substrate. This is due to the large momentum transfer between atoms and the N2 molecules which disorders the molecules of the interface layer. A further disorder is introduced by the temperature. We perform calculations at T = 20K which is a temperature below the melting, which for our slab is at 50K . We found that because of the disorder the static friction becomes independent of the direction of the external applied force. The very low value of the static friction seems to indicate that we are in a regime of thermolubricity similar to that observed in dynamical friction.

  15. Gimballed Shoulders for Friction Stir Welding

    Science.gov (United States)

    Carter, Robert; Lawless, Kirby

    2008-01-01

    In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

  16. Beals Syndrome

    Science.gov (United States)

    ... the syndrome. How does Beals syndrome compare with Marfan syndrome? People with Beals syndrome have many of the ... bone) and aortic enlargement problems as people with Marfan syndrome, and treatments for these problems are the same. ...

  17. Prevalence and clinical significance of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease: observations at MR imaging.

    Science.gov (United States)

    Chan, V O; Moran, D E; Mwangi, I; Eustace, S J

    2013-08-01

    To determine the prevalence of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease in patients with anterior knee pain and to correlate it with patient demographics, patellar shape, and patellofemoral alignment. Retrospective study over a 1-year period reviewing the MR knee examinations of all patients who were referred for assessment of anterior knee pain. Only patients with isolated lateral patellofemoral disease were included. Age, gender, distribution of lateral patellofemoral chondromalacia, and grade of cartilaginous defects were documented for each patient. Correlation between the distribution of lateral patellofemoral chondromalacia and patient demographics, patellar shape, and indices of patellar alignment (femoral sulcus angle and modified Q angle) was then ascertained. There were 50 patients (22 males, 28 females) with anterior knee pain and isolated patellofemoral disease. The majority of the patients (78 %) had co-existent disease with grade 1 chondromalacia. No significant correlation was found between patients with chondromalacia isolated to the anterior margin of the lateral femoral condyle and age, gender, patellar shape, or modified Q angle (p > 0.05). However, patients with chondromalacia isolated to the anterior margin of the lateral femoral condyle had a shallower femoral sulcus angle (mean 141.8°) compared to the patients with lateral patellar facet disease (mean 133.8°) (p = 0.002). A small percentage of patients with anterior knee pain have chondromalacia isolated to the anterior margin of the lateral femoral condyle. This was associated with a shallower femoral sulcus angle.

  18. A lateral approach to the repair of propagating fractures of the medial condyle of the third metacarpal and metatarsal bone in 18 racehorses.

    Science.gov (United States)

    Wright, Ian M; Smith, Matthew R W

    2009-08-01

    To report the technique, observations on fracture configurations and results of treatment by fixation lag screw following the fracture plane determined by an approach to the third metacarpal/metatarsal bone (MC3/MT3) that begins laterally over the metacarpo(metatarso)phalangeal joint and extends dorsally over the diaphysis of the bone. Case series. Thoroughbred horses (n=18) with propagating fractures of the medial condyle of MC3/MT3. Retrospective analysis of case records of horses with fractures of the medial condyle of MC3/MT3 that propagated sagittaly or in a spiral configuration into the diaphysis, repaired surgically under general anesthesia by screw fixation in lag fashion through a lateral approach with periosteal reflection. Fractures were readily identified at surgery, enabling screw fixation in lag fashion following the fracture plane. Fracture configurations varied and could be classified as sagittal and spiral fractures with fractures within each group generally following a similar course. All horses recovered relatively uneventfully from general anesthesia and surgery, and all fractures healed well. Thirteen horses returned to training; 5 subsequently raced. Repair of propagating sagittal and spiral fractures of the medial condyle of MC3/MT3 with diaphyseal involvement, through a lateral approach with periosteal reflection permits stable fixation with minimal complications. In this series there were no catastrophic failures. Fractures of the medial condyle of MC3/MT3 that propagate either sagittaly or in a spiral configuration into the diaphysis can be successfully repaired with screw fixation in lag fashion using a lateral approach with periosteal reflection.

  19. A Scapholunate Ligament-Sparing Technique Utilizing the Medial Femoral Condyle Corticocancellous Free Flap to Reconstruct Scaphoid Nonunions With Proximal Pole Avascular Necrosis.

    Science.gov (United States)

    Kazmers, Nikolas H; Thibaudeau, Stephanie; Levin, L Scott

    2016-09-01

    This article demonstrates a technique for the treatment of scaphoid fracture waist and proximal pole nonunions with avascular necrosis using a free vascularized medial femoral condyle flap. We present our surgical technique and representative case examples in which the scapholunate ligament, a key structure required to preserve carpal kinematics, is spared. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  20. Spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect created in the femoral condyle using a novel double-network hydrogel.

    Science.gov (United States)

    Yokota, Masashi; Yasuda, Kazunori; Kitamura, Nobuto; Arakaki, Kazunobu; Onodera, Shin; Kurokawa, Takayuki; Gong, Jian-Ping

    2011-02-22

    Functional repair of articular osteochondral defects remains a major challenge not only in the field of knee surgery but also in tissue regeneration medicine. The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN) gel at the bottom of the defect. Twenty-five mature rabbits were used in this study. In the bilateral knees of each animal, we created an osteochondral defect having a diameter of 2.4-mm in the medial condyle. Then, in 21 rabbits, we implanted a DN gel plug into a right knee defect so that a vacant space of 1.5-mm depth (in Group I), 2.5-mm depth (in Group II), or 3.5-mm depth (in Group III) was left. In the left knee, we did not apply any treatment to the defect to obtain the control data. All the rabbits were sacrificed at 4 weeks, and the gross and histological evaluations were performed. The remaining 4 rabbits underwent the same treatment as used in Group II, and real-time PCR analysis was performed at 4 weeks. The defect in Group II was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen. The Wayne's gross appearance and histology scores showed that Group II was significantly greater than Group I, III, and Control (p hyaline cartilage regeneration can be induced in vivo in an osteochondral defect created in the femoral condyle by means of implanting the DN gel plug at the bottom of the defect so that an approximately 2-mm deep vacant space was intentionally left in the defect. This fact has prompted us to propose an innovative strategy without cell culture to repair osteochondral lesions in the femoral condyle.

  1. Computed Tomography-Based Occipital Condyle Morphometry in an Indian Population to Assess the Feasibility of Condylar Screws for Occipitocervical Fusion.

    Science.gov (United States)

    Srivastava, Abhishek; Nanda, Geetanjali; Mahajan, Rajat; Nanda, Ankur; Mishra, Nirajana; Karmaran, Srinivasa; Batra, Sahil; Chhabra, Harvinder Singh

    2017-12-01

    A retrospective computed tomography (CT)-based morphometric study of 82 occipital condyles in the Indian population, focusing on critical morphometric dimensions with relation to placing condylar screws. This study focused on determining the feasibility of placing occipital condylar screws in an Indian population using CT anatomical morphometric data. The occipital condylar screw is a novel technique being explored as one of the options in occipitocervical stabilization. Sex and ethnic variations in anatomical structures may restrict the feasibility of this technique in some populations. To the best of our knowledge, there are no CT-based data on an Indian population that assess the feasibility of occipital condylar screws. We measured the dimensions of 82 occipital condyles in 41 adults on coronal, sagittal, and axial reconstructed CT images. The differences were noted between the right and left sides and also between males and females. Statistical analysis was performed using the t -test, with a p -value of occipital condyle shows that condylar screws are anatomically feasible in a large portion of the Indian population. However, because a small number of population may not be suitable for this technique, meticulous study of preoperative anatomy using detailed CT data is advised.

  2. Understanding and Observing Subglacial Friction Using Seismology

    Science.gov (United States)

    Tsai, V. C.

    2017-12-01

    Glaciology began with a focus on understanding basic mechanical processes and producing physical models that could explain the principal observations. Recently, however, more attention has been paid to the wealth of recent observations, with many modeling efforts relying on data assimilation and empirical scalings, rather than being based on first-principles physics. Notably, ice sheet models commonly assume that subglacial friction is characterized by a "slipperiness" coefficient that is determined by inverting surface velocity observations. Predictions are usually then made by assuming these slipperiness coefficients are spatially and temporally fixed. However, this is only valid if slipperiness is an unchanging material property of the bed and, despite decades of work on subglacial friction, it has remained unclear how to best account for such subglacial physics in ice sheet models. Here, we describe how basic seismological concepts and observations can be used to improve our understanding and determination of subglacial friction. First, we discuss how standard models of granular friction can and should be used in basal friction laws for marine ice sheets, where very low effective pressures exist. We show that under realistic West Antarctic Ice Sheet conditions, standard Coulomb friction should apply in a relatively narrow zone near the grounding line and that this should transition abruptly as one moves inland to a different, perhaps Weertman-style, dependence of subglacial stress on velocity. We show that this subglacial friction law predicts significantly different ice sheet behavior even as compared with other friction laws that include effective pressure. Secondly, we explain how seismological observations of water flow noise and basal icequakes constrain subglacial physics in important ways. Seismically observed water flow noise can provide constraints on water pressures and channel sizes and geometry, leading to important data on subglacial friction

  3. Friction characteristics of trocars in laparoscopic surgery.

    Science.gov (United States)

    Alazmani, Ali; Roshan, Rupesh; Jayne, David G; Neville, Anne; Culmer, Peter

    2015-04-01

    This article investigates the friction characteristics of the instrument-trocar interface in laparoscopic surgery for varying linear instrument velocities, trocar seal design and material, and trocar tilt. Furthermore, the effect of applying lubrication at the instrument-trocar seal interface on friction was studied. A friction testing apparatus was designed and built to characterise the resistance force at the instrument-trocar interface as a function of the instrument's linear movement in the 12-mm trocar (at constant velocity) for different design, seal material, and angle of tilt. The resistance force depended on the trocar seal design and material properties, specifically surface roughness, elasticity, hardness, the direction of movement, and the instrument linear velocity, and varied between 0.25 and 8 N. Lubricating the shaft with silicone oil reduced the peak resistance force by 75% for all trocars and eliminated the stick-slip phenomenon evident in non-lubricated cases. The magnitude of fluctuation in resistance force depends on the trocar design and is attributed to stick-slip of the sealing mechanism and is generally higher during retraction in comparison to insertion. Trocars that have an inlet seal made of rubber/polyurethane showed higher resistance forces during retraction. Use of a lubricant significantly reduced frictional effects. Comparisons of the investigated trocars indicate that a low friction port, providing the surgeon with improved haptic feedback, can be designed by improving the tribological properties of the trocar seal interface. © IMechE 2015.

  4. Confinement-Dependent Friction in Peptide Bundles

    Science.gov (United States)

    Erbaş, Aykut; Netz, Roland R.

    2013-01-01

    Friction within globular proteins or between adhering macromolecules crucially determines the kinetics of protein folding, the formation, and the relaxation of self-assembled molecular systems. One fundamental question is how these friction effects depend on the local environment and in particular on the presence of water. In this model study, we use fully atomistic MD simulations with explicit water to obtain friction forces as a single polyglycine peptide chain is pulled out of a bundle of k adhering parallel polyglycine peptide chains. The whole system is periodically replicated along the peptide axes, so a stationary state at prescribed mean sliding velocity V is achieved. The aggregation number is varied between k = 2 (two peptide chains adhering to each other with plenty of water present at the adhesion sites) and k = 7 (one peptide chain pulled out from a close-packed cylindrical array of six neighboring peptide chains with no water inside the bundle). The friction coefficient per hydrogen bond, extrapolated to the viscous limit of vanishing pulling velocity V → 0, exhibits an increase by five orders of magnitude when going from k = 2 to k = 7. This dramatic confinement-induced friction enhancement we argue to be due to a combination of water depletion and increased hydrogen-bond cooperativity. PMID:23528088

  5. Velocity Dependence of Friction of Confined Hydrocarbons

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    2010-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence of the f......We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence...... of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (∼3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  6. Rubber friction: role of the flash temperature

    International Nuclear Information System (INIS)

    Persson, B N J

    2006-01-01

    When a rubber block is sliding on a hard rough substrate, the substrate asperities will exert time-dependent deformations of the rubber surface resulting in viscoelastic energy dissipation in the rubber, which gives a contribution to the sliding friction. Most surfaces of solids have roughness on many different length scales, and when calculating the friction force it is necessary to include the viscoelastic deformations on all length scales. The energy dissipation will result in local heating of the rubber. Since the viscoelastic properties of rubber-like materials are extremely strongly temperature dependent, it is necessary to include the local temperature increase in the analysis. At very low sliding velocity the temperature increase is negligible because of heat diffusion, but already for velocities of order 10 -2 m s -1 the local heating may be very important. Here I study the influence of the local heating on the rubber friction, and I show that in a typical case the temperature increase results in a decrease in rubber friction with increasing sliding velocity for v>0.01 m s -1 . This may result in stick-slip instabilities, and is of crucial importance in many practical applications, e.g. for tyre-road friction and in particular for ABS braking systems

  7. Effect of friction time on the microstructure and mechanic properties of friction welded AISI 1040/Duplex stainless steel

    Directory of Open Access Journals (Sweden)

    İhsan Kırık

    2000-06-01

    Full Text Available In this study, the effect on the characteristic microstructure and mechanic properties of friction time on the couple steels AISI 1040/AISI 2205 stainless steel joining with friction welding method was experimentally investigated. Friction welding experiment were carried out in privately prepared PLC controlled continuous friction welding machine by us. Joints were carried out under 1700 rpm rotation speed, with 30MPa process friction pressure, 60MPa forging pressure, 4 second forging pressure and under 3, 5, 7, 9 and 11 second friction time, respectively. After friction welding, the bonding interface microstructures of the specimens were examined by SEM microscopy and EDS analysis. After weld microhardness and tensile strength of specimens were carried out. The result of applied tests and observations pointed out that the properties of microstructure were changed with friction time increased. The excellent tensile strength of joint observed on 1700 rpm rotation speed and 3 second friction time sample.

  8. Benchmarking of direct and indirect friction tests in micro forming

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Solmer; Calaon, Matteo; Arentoft, M.

    2012-01-01

    The sizeable increase in metal forming friction at micro scale, due to the existence of size effects, constitutes a barrier to the realization of industrial micro forming processes. In the quest for improved frictional conditions in micro scale forming operations, friction tests are applied...... to qualify the tribological performance of the particular forming scenario. In this work the application of a simulative sliding friction test at micro scale is studied. The test setup makes it possible to measure the coefficient of friction as a function of the sliding motion. The results confirm a sizeable...... increase in the coefficient of friction when the work piece size is scaled down. © (2012) Trans Tech Publications....

  9. A molecular dynamics (MD simulation on tire-aggregate friction

    Directory of Open Access Journals (Sweden)

    Fengyan Sun

    2017-07-01

    Full Text Available The friction between tire and road surface is fundamentally depending on the molecular forces. In this paper, the nanoscale 3D contact model is employed to investigate the tire-aggregate friction mechanism. The tire and aggregate micro-structure are both constructed to evaluate the microscopic performance of tire-aggregate friction influence. Simulation results show for a high velocity, the energy dissipation of sliding on crystal structure is small, which results in a small friction coefficient; temperature will have influences on the friction coefficient, and with the increasing of velocity, the effect will gradually reduce. Keywords: Tire, Aggregate, Friction coefficient, Microscopic mechanism, MD simulation

  10. Friction anisotropy-driven domain imaging on exfoliated monolayer graphene.

    Science.gov (United States)

    Choi, Jin Sik; Kim, Jin-Soo; Byun, Ik-Su; Lee, Duk Hyun; Lee, Mi Jung; Park, Bae Ho; Lee, Changgu; Yoon, Duhee; Cheong, Hyeonsik; Lee, Ki Ho; Son, Young-Woo; Park, Jeong Young; Salmeron, Miquel

    2011-07-29

    Graphene produced by exfoliation has not been able to provide an ideal graphene with performance comparable to that predicted by theory, and structural and/or electronic defects have been proposed as one cause of reduced performance. We report the observation of domains on exfoliated monolayer graphene that differ by their friction characteristics, as measured by friction force microscopy. Angle-dependent scanning revealed friction anisotropy with a periodicity of 180° on each friction domain. The friction anisotropy decreased as the applied load increased. We propose that the domains arise from ripple distortions that give rise to anisotropic friction in each domain as a result of the anisotropic puckering of the graphene.

  11. Are there reliable constitutive laws for dynamic friction?

    Science.gov (United States)

    Woodhouse, Jim; Putelat, Thibaut; McKay, Andrew

    2015-09-28

    Structural vibration controlled by interfacial friction is widespread, ranging from friction dampers in gas turbines to the motion of violin strings. To predict, control or prevent such vibration, a constitutive description of frictional interactions is inevitably required. A variety of friction models are discussed to assess their scope and validity, in the light of constraints provided by different experimental observations. Three contrasting case studies are used to illustrate how predicted behaviour can be extremely sensitive to the choice of frictional constitutive model, and to explore possible experimental paths to discriminate between and calibrate dynamic friction models over the full parameter range needed for real applications. © 2015 The Author(s).

  12. Tribo-performance evaluation of ecofriendly brake friction composite materials

    Science.gov (United States)

    Kumar, Naresh; Singh, Tej; Grewal, G. S.

    2018-05-01

    This paper presents the potential of natural fibre in brake friction materials. Natural fibre filled ecofriendly brake friction materials were developed without Kevlar fibre evaluated for tribo-performance on a chase friction testing machine following SAE J 661a standard. Experimental results indicated that natural fibre enhances the fade performance, but depresses the friction and wear performance, whereas Kevlar fibre improves the friction, wear and recovery performance but depresses the fade performance. Also the results revealed that with the increase in natural fibre content, the friction and fade performances enhanced.

  13. Surgical Treatment for Occipital Condyle Fracture, C1 Dislocation, and Cerebellar Contusion with Hemorrhage after Blunt Head Trauma

    Directory of Open Access Journals (Sweden)

    Shigeo Ueda

    2016-01-01

    Full Text Available Occipital condyle fractures (OCFs have been treated as rare traumatic injuries, but the number of reported OCFs has gradually increased because of the popularization of computed tomography (CT and magnetic resonance imaging (MRI. The patient in this report presented with OCFs and C1 dislocation, along with traumatic cerebellar hemorrhage, which led to craniovertebral junction instability. This case was also an extremely rare clinical condition in which the patient presented with traumatic lower cranial nerve palsy secondary to OCFs. When the patient was transferred to our hospital, the occipital bone remained defective extensively due to surgical treatment of cerebellar hemorrhage. For this reason, concurrent cranioplasty was performed with resin in order to fix the occipital bone plate strongly. The resin-made occipital bone was used to secure a titanium plate and screws enabled us to perform posterior fusion of the craniovertebral junction. Although the patient wore a halo vest for 3 months after surgery, lower cranial nerve symptoms, including not only neck pain but also paralysis of the throat and larynx, improved postoperatively. No complications were detected during outpatient follow-up, which continued for 5 years postoperatively.

  14. Diagnostic performance of dental students in identifying mandibular condyle fractures by panoramic radiography and the usefulness of reference images

    International Nuclear Information System (INIS)

    Cho, Bong Hae

    2011-01-01

    The purpose of this study was to evaluate the diagnostic performance of dental students in detection of mandibular condyle fractures and the effectiveness of reference panoramic images. Forty-six undergraduates evaluated 25 panoramic radiographs for condylar fractures and the data were analyzed through receiver operating characteristic (ROC) analysis. After a month, they were divided into two homogeneous groups based on the first results and re-evaluated the images with (group A) or without (group B) reference images. Eight reference images included indications showing either typical condylar fractures or anatomic structures which could be confused with fractures. Paired t-test was used for statistical analysis of the difference between the first and the second evaluations for each group, and student's t-test was used between the two groups in the second evaluation. The intra- and inter-observer agreements were evaluated with Kappa statistics. Intra- and inter-observer agreements were substantial (k=0.66) and moderate (k=0.53), respectively. The area under the ROC curve (Az) in the first evaluation was 0.802. In the second evaluation, it was increased to 0.823 for group A and 0.814 for group B. The difference between the first and second evaluations for group A was statistically significant (p<0.05), however there was no statistically significant difference between the two groups in the second evaluation. Providing reference images to less experienced clinicians would be a good way to improve the diagnostic ability in detecting condylar fracture.

  15. Comparison of Neck Screw and Conventional Fixation Techniques in Mandibular Condyle Fractures Using 3-Dimensional Finite Element Analysis.

    Science.gov (United States)

    Conci, Ricardo Augusto; Tomazi, Flavio Henrique Silveira; Noritomi, Pedro Yoshito; da Silva, Jorge Vicente Lopes; Fritscher, Guilherme Genehr; Heitz, Claiton

    2015-07-01

    To compare the mechanical stress on the mandibular condyle after the reduction and fixation of mandibular condylar fractures using the neck screw and 2 other conventional techniques according to 3-dimensional finite element analysis. A 3-dimensional finite element model of a mandible was created and graphically simulated on a computer screen. The model was fixed with 3 different techniques: a 2.0-mm plate with 4 screws, 2 plates (1 1.5-mm plate and 1 2.0-mm plate) with 4 screws, and a neck screw. Loads were applied that simulated muscular action, with restrictions of the upper movements of the mandible, differentiation of the cortical and medullary bone, and the virtual "folds" of the plates and screws so that they could adjust to the condylar surface. Afterward, the data were exported for graphic visualization of the results and quantitative analysis was performed. The 2-plate technique exhibited better stability in regard to displacement of fractures, deformity of the synthesis materials, and minimum and maximum tension values. The results with the neck screw were satisfactory and were similar to those found when a miniplate was used. Although the study shows that 2 isolated plates yielded better results compared with the other groups using other fixation systems and methods, the neck screw could be an option for condylar fracture reduction. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  16. Open Reduction With K-Wire Stabilization of Fracture Dislocations of the Mandibular Condyle: A Retrospective Review.

    Science.gov (United States)

    Haghighi, Kayvon; Manolakakis, Manolis G; Balog, Connor

    2017-06-01

    The aim of this study was to determine the feasibility of direct transcortical stabilization of fracture dislocations of the mandibular condyle (FDMCs) using narrow-diameter non-threaded Kirschner wire (K-wire). This retrospective review reports on the treatment outcomes for 12 patients (15 fractures) with FDMCs treated with open reduction using transcortical 0.027-inch K-wire stabilization. Postoperative parameters of relevance included infection, facial nerve function, hardware removal, mandibular range of motion, and radiographic determination of fracture union. Three patients had bilateral FDMCs and 9 had unilateral FDMCs (age range at time of injury, 14 to 72 yr; mean age, 32 yr). Postoperative follow-up ranged from 6 weeks to 2 years. Four patients required removal of K-wire hardware for different reasons. K-wires were removed because of infection in 1 patient. Another patient required removal because of migration of the pin into the joint space. One pin was removed electively and another was removed for nonspecific postoperative symptoms that resolved after pin removal. Persistent facial nerve deficit was observed in 1 patient. Open reduction with transcortical K-wire stabilization can achieve satisfactory outcomes for the treatment of FDMC. Further investigation is needed in determining the efficacy of this fixation technique in the management of FDMC. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  17. Direct friction measurement in draw bead testing

    DEFF Research Database (Denmark)

    Olsson, David Dam; Bay, Niels; Andreasen, Jan Lasson

    2005-01-01

    The application of draw beads in sheet metal stamping ensures controlled drawing-in of flange parts. Lubrication conditions in draw beads are severe due to sliding under simultaneous bending. Based on the original draw bead test design by Nine [1] comprehensive studies of friction in draw beads...... have been reported in literature. A major drawback in all these studies is that friction is not directly measured, but requires repeated measurements of the drawing force with and without relative sliding between the draw beads and the sheet material. This implies two tests with a fixed draw bead tool...... and a freely rotating tool respectively, an approach, which inevitably implies large uncertainties due to scatter in the experimental conditions. In order to avoid this problem a new draw bead test is proposed by the authors measuring the friction force acting on the tool radius directly by a build...

  18. Ratchet due to broken friction symmetry

    DEFF Research Database (Denmark)

    Norden, Bengt; Zolotaryuk, Yaroslav; Christiansen, Peter Leth

    2002-01-01

    A ratchet mechanism that occurs due to asymmetric dependence of the friction of a moving system on its velocity or a driving force is reported. For this kind of ratchet, instead of a particle moving in a periodic potential, the dynamics of which have broken space-time symmetry, the system must...... be provided with sonic internal structure realizing such a velocity- or force-friction dependence. For demonstration of a ratchet mechanism of this type, an experimental setup (gadget) that converts longitudinal oscillating or fluctuating motion into a unidirectional rotation has been built and experiments...... with it have been carried out. In this device, an asymmetry of friction dependence on an applied force appears, resulting in rectification of rotary motion, In experiments, our setup is observed to rotate only in one direction, which is in accordance with given theoretical arguments, Despite the setup being...

  19. Simulations of atomic-scale sliding friction

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Jacobsen, Karsten Wedel; Stoltze, Per

    1996-01-01

    Simulation studies of atomic-scale sliding friction have been performed for a number of tip-surface and surface-surface contacts consisting of copper atoms. Both geometrically very simple tip-surface structures and more realistic interface necks formed by simulated annealing have been studied....... Kinetic friction is observed to be caused by atomic-scale Stick and slip which occurs by nucleation and subsequent motion of dislocations preferably between close-packed {111} planes. Stick and slip seems ro occur in different situations. For single crystalline contacts without grain boundaries...... pinning of atoms near the boundary of the interface and is therefore more easily observed for smaller contacts. Depending on crystal orientation and load, frictional wear can also be seen in the simulations. In particular, for the annealed interface-necks which model contacts created by scanning tunneling...

  20. Validation of measured friction by process tests

    DEFF Research Database (Denmark)

    Eriksen, Morten; Henningsen, Poul; Tan, Xincai

    The objective of sub-task 3.3 is to evaluate under actual process conditions the friction formulations determined by simulative testing. As regards task 3.3 the following tests have been used according to the original project plan: 1. standard ring test and 2. double cup extrusion test. The task...... has, however, been extended to include a number of new developed process tests: 3. forward rod extrusion test, 4. special ring test at low normal pressure, 5. spike test (especially developed for warm and hot forging). Validation of the measured friction values in cold forming from sub-task 3.1 has...... been made with forward rod extrusion, and very good agreement was obtained between the measured friction values in simulative testing and process testing....

  1. Mechanisms of friction in diamondlike nanocomposite coatings

    International Nuclear Information System (INIS)

    Scharf, T. W.; Ohlhausen, J. A.; Tallant, D. R.; Prasad, S. V.

    2007-01-01

    Diamondlike nanocomposite (DLN) coatings (C:H:Si:O) processed from siloxane precursors by plasma enhanced chemical vapor deposition are well known for their low friction and wear behaviors. In the current study, we have investigated the fundamental mechanisms of friction and interfacial shear strength in DLN coatings and the roles of contact stress and environment on their tribological behavior. Friction and wear measurements were performed from 0.25 to 0.6 GPa contact pressures in three environments: dry ( 2 containing fragments, whereas those formed in dry nitrogen had hydrogenated and long range ordered carbons with practically no SiO 2 fragments, ultimately resulting in much lower interfacial shear strength and COF

  2. Ratchet device with broken friction symmetry

    DEFF Research Database (Denmark)

    Norden, Bengt; Zolotaryuk, Yaroslav; Christiansen, Peter Leth

    2002-01-01

    An experimental setup (gadget) has been made for demonstration of a ratchet mechanism induced by broken symmetry of a dependence of dry friction on external forcing. This gadget converts longitudinal oscillating or fluctuating motion into a unidirectional rotation, the direction of which is in ac......An experimental setup (gadget) has been made for demonstration of a ratchet mechanism induced by broken symmetry of a dependence of dry friction on external forcing. This gadget converts longitudinal oscillating or fluctuating motion into a unidirectional rotation, the direction of which...... is in accordance with given theoretical arguments. Despite the setup being three dimensional, the ratchet rotary motion is proved to be described by one simple dynamic equation. This kind of motion is a result of the interplay of friction and inertia....

  3. Frictional lubricity enhanced by quantum mechanics.

    Science.gov (United States)

    Zanca, Tommaso; Pellegrini, Franco; Santoro, Giuseppe E; Tosatti, Erio

    2018-04-03

    The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in an important manner the frictional dissipation of a light particle forced to slide in an optical lattice. The density matrix-calculated evolution of the quantum version of the basic Prandtl-Tomlinson model, describing the dragging by an external force of a point particle in a periodic potential, shows that purely classical friction predictions can be very wrong. The strongest quantum effect occurs not for weak but for strong periodic potentials, where barriers are high but energy levels in each well are discrete, and resonant Rabi or Landau-Zener tunneling to states in the nearest well can preempt classical stick-slip with nonnegligible efficiency, depending on the forcing speed. The resulting permeation of otherwise unsurmountable barriers is predicted to cause quantum lubricity, a phenomenon which we expect should be observable in the recently implemented sliding cold ion experiments.

  4. Frictional strength of wet and dry montmorillonite

    Science.gov (United States)

    Morrow, C. A.; Moore, D. E.; Lockner, D. A.

    2017-05-01

    Montmorillonite is a common mineral in fault zones, and its low strength relative to other common gouge minerals is important in many models of fault rheology. However, the coefficient of friction, μ, varies with degree of saturation and is not well constrained in the literature due to the difficulty of establishing fully drained or fully dried states in the laboratory. We measured μ of both saturated and oven-dried montmorillonite at normal stresses up to 700 MPa. Care was taken to shear saturated samples slowly enough to avoid pore fluid overpressure. For saturated samples, μ increased from 0.10 to 0.28 with applied effective normal stress, while for dry samples μ decreased from 0.78 to 0.45. The steady state rate dependence of friction, (a - b), was positive, promoting stable sliding. The wide disparity in reported frictional strengths can be attributed to experimental procedures that promote differing degrees of partial saturation or overpressured pore fluid conditions.

  5. Internal friction in martensitic carbon steels

    International Nuclear Information System (INIS)

    Hoyos, J.J.; Ghilarducci, A.A.; Salva, H.R.; Chaves, C.A.; Velez, J.M.

    2009-01-01

    This paper proposes relationships between the internal friction and the microstructure of two steels containing 0.626 and 0.71 wt.% carbon. The steels were annealed at 1093 K for 5 min, quenched into water and tempered for 10 min at 423, 573 and 723 K. Internal friction was measured by using a forced vibration pendulum, in a temperature range from 100 to 450 K. The internal friction spectrum is decomposed into four peaks: P1 at 215 K, P2 at 235 K, P3 at 260 K and P4 at 380 K for 3 Hz. Peak P1 is attributed to the interactions between dislocations and carbon atoms. Peak P2 is related to the interaction between dislocations and carbide. Peak P3 is related to the generations of kink - pairs along edge dislocations. Peak P4 is attributed to epsilon carbide precipitation.

  6. Friction welded closures of waste canisters

    International Nuclear Information System (INIS)

    Klein, R.F.

    1987-01-01

    Liquid radioactive waste presently stored in underground tanks is to undergo a vitrifying process which will immobilize it into a solid form. This solid waste will be contained in a stainless steel canister. The canister opening requires a positive-seal weld, the properties and thickness of which must be at least equal to those of the canister material. All studies and tests performed in the work discussed in this paper have the inertia friction welding concept to be highly feasible in this application. This paper describes the decision to investigate the inertia friction welding process, the inertia friction welding process itself, and a proposed equipment design concept. This system would provide a positive, reliable, inspectable, and full-thickness seal weld while utilizing easily maintainable equipment. This high-quality weld can be achieved even in highly contaminated hot cell

  7. Friction modelling of preloaded tube contact dynamics

    International Nuclear Information System (INIS)

    Hassan, M.A.; Rogers, R.J.

    2004-01-01

    Many loosely supported components are subjected to flow-induced vibration leading to localized wear. Life prediction depends on robust and accurate modelling of the nonlinear dynamics as the components interact with their supports. The output of such analysis is the component dynamic response and impact forces, including friction forces during stick-slip motions. Such results are used to determine the normal work rates, which are utilized to predict fretting wear damage. Accurate estimates of these parameters are essential. This paper presents simulations of a loosely supported fuel-channel tube subject to turbulence excitation. The effects of tube/support clearance and preload are investigated. Several friction models, including velocity-limited, spring-damper, and force-balance are utilized. A comparison of these models is carried out to investigate their accuracy. The results show good agreement with experimental work rates when a simple iterative procedure to update the friction forces is used. (authors)

  8. Static and dynamic friction of hierarchical surfaces.

    Science.gov (United States)

    Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M

    2016-12-01

    Hierarchical structures are very common in nature, but only recently have they been systematically studied in materials science, in order to understand the specific effects they can have on the mechanical properties of various systems. Structural hierarchy provides a way to tune and optimize macroscopic mechanical properties starting from simple base constituents and new materials are nowadays designed exploiting this possibility. This can be true also in the field of tribology. In this paper we study the effect of hierarchical patterned surfaces on the static and dynamic friction coefficients of an elastic material. Our results are obtained by means of numerical simulations using a one-dimensional spring-block model, which has previously been used to investigate various aspects of friction. Despite the simplicity of the model, we highlight some possible mechanisms that explain how hierarchical structures can significantly modify the friction coefficients of a material, providing a means to achieve tunability.

  9. Friction enhancement in concertina locomotion of snakes

    Science.gov (United States)

    Marvi, Hamidreza; Hu, David L.

    2012-01-01

    Narrow crevices are challenging terrain for most organisms and biomimetic robots. Snakes move through crevices using sequential folding and unfolding of their bodies in the manner of an accordion or concertina. In this combined experimental and theoretical investigation, we elucidate this effective means of moving through channels. We measure the frictional properties of corn snakes, their body kinematics and the transverse forces they apply to channels of varying width and inclination. To climb channels inclined at 60°, we find snakes use a combination of ingenious friction-enhancing techniques, including digging their ventral scales to double their frictional coefficient and pushing channel walls transversely with up to nine times body weight. Theoretical modelling of a one-dimensional n-linked crawler is used to calculate the transverse force factor of safety: we find snakes push up to four times more than required to prevent sliding backwards, presumably trading metabolic energy for an assurance of wall stability. PMID:22728386

  10. Sensitivity to friction for primary explosives.

    Science.gov (United States)

    Matyáš, Robert; Šelešovský, Jakub; Musil, Tomáš

    2012-04-30

    The sensitivity to friction for a selection of primary explosives has been studied using a small BAM friction apparatus. The probit analysis was used for the construction of a sensitivity curve for each primary explosive tested. Two groups of primary explosives were chosen for measurement (a) the most commonly used industrially produced primary explosives (e.g. lead azide, tetrazene, dinol, lead styphnate) and (b) the most produced improvised primary explosives (e.g. triacetone triperoxide, hexamethylenetriperoxide diamine, mercury fulminate, acetylides of heavy metals). A knowledge of friction sensitivity is very important for determining manipulation safety for primary explosives. All the primary explosives tested were carefully characterised (synthesis procedure, shape and size of crystals). The sensitivity curves obtained represent a unique set of data, which cannot be found anywhere else in the available literature. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Friction modelling of preloaded tube contact dynamics

    International Nuclear Information System (INIS)

    Hassan, M.A.; Rogers, R.J.

    2005-01-01

    Many loosely supported components are subjected to flow-induced vibration leading to localized wear. Life prediction depends on robust and accurate modelling of the nonlinear dynamics as the components interact with their supports. The output of such analysis is the component dynamic response and impact forces, including friction forces during stick-slip motions. Such results are used to determine the normal work rates, which are utilized to predict fretting wear damage. Accurate estimates of these parameters are essential. This paper presents simulations of a loosely supported fuel-channel tube subject to turbulence excitation. The effects of tube/support clearance and preload are investigated. Several friction models, including velocity-limited, spring-damper and force-balance are utilized. A comparison of these models is carried out to investigate their accuracy. The results show good agreement with experimental work rates when a simple iterative procedure to update the friction forces is used

  12. Hyperstaticity and loops in frictional granular packings

    Science.gov (United States)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  13. Gas desorption during friction of amorphous carbon films

    International Nuclear Information System (INIS)

    Rusanov, A; Fontaine, J; Martin, J-M; Mogne, T L; Nevshupa, R

    2008-01-01

    Gas desorption induced by friction of solids, i.e. tribodesorption, is one of the numerous physical and chemical phenomena, which arise during friction as result of thermal and structural activation of material in a friction zone. Tribodesorption of carbon oxides, hydrocarbons, and water vapours may lead to significant deterioration of ultra high vacuum conditions in modern technological equipment in electronic, optoelectronic industries. Therefore, knowledge of tribodesorption is crucial for the performance and lifetime of vacuum tribosystems. Diamond-like carbon (DLC) coatings are interesting materials for vacuum tribological systems due to their high wear resistance and low friction. Highly hydrogenated amorphous carbon (a-C:H) films are known to exhibit extremely low friction coefficient under high vacuum or inert environment, known as 'superlubricity' or 'superlow friction'. However, the superlow friction period is not always stable and then tends to spontaneous transition to high friction. It is supposed that hydrogen supply from the bulk to the surface is crucial for establishing and maintaining superlow friction. Thus, tribodesorption can serve also as a new technique to determine the role of gases in superlow friction mechanisms. Desorption of various a-C:H films, deposited by PECVD, ion-beam deposition and deposition using diode system, has been studied by means of ultra-high vacuum tribometer equipped with a mass spectrometer. It was found that in superlow friction period desorption rate was below the detection limit in the 0-85 mass range. However, transition from superlow friction to high friction was accompanied by desorption of various gases, mainly of H 2 and CH 4 . During friction transition, surfaces were heavily damaged. In experiments with DLC films with low hydrogen content tribodesorption was significant during the whole experiment, while low friction was not observed. From estimation of maximum surface temperature during sliding contact it

  14. Effects of antimony trisulfide (Sb2S3) on sliding friction of automotive brake friction materials

    Science.gov (United States)

    Lee, Wan Kyu; Rhee, Tae Hee; Kim, Hyun Seong; Jang, Ho

    2013-09-01

    The effect of antimony trisulfide (Sb2S3) on the tribological properties of automotive brake friction materials was investigated using a Krauss type tribometer and a 1/5 scale dynamometer with a rigid caliper. Results showed that Sb2S3 improved fade resistance by developing transfer films on the disc surface at elevated temperatures. On the other hand, the rubbing surfaces of the friction material exhibited contact plateaus with a broader height distribution when it contained Sb2S3, indicating fewer contact junctions compared to the friction material with graphite. The friction material with Sb2S3 also exhibited a lower stick-slip propensity than the friction material with graphite. The improved fade resistance with Sb2S3 is attributed to its lubricating capability sustained at high temperatures, while the lower stick-slip propensity of the friction material with Sb2S3 is associated with the slight difference between its static and kinetic coefficients of friction and high normal stiffness.

  15. Static frictional resistance with the slide low-friction elastomeric ligature system.

    Science.gov (United States)

    Jones, Steven P; Ben Bihi, Saida

    2009-11-01

    This ex-vivo study compared the static frictional resistance of a low-friction ligation system against a conventional elastomeric module, and studied the effect of storage in a simulated oral environment on the static frictional resistance of both ligation systems. Eighty stainless steel brackets were tested by sliding along straight lengths of 0.018 inch round and 0.019 x 0.025 inch rectangular stainless steel wires ligated with either conventional elastomerics or the Slide system (Leone, Florence, Italy). During the tests the brackets and wires were lubricated with artificial saliva. A specially constructed jig assembly was used to hold the bracket and archwire securely. The jig was clamped in an Instron universal load testing machine. Crosshead speed was controlled via a microcomputer connected to the Instron machine. The static frictional forces at 0 degree bracket/wire angulation were measured for both systems, fresh from the pack and after storage in artificial saliva at 37 degrees C for 24 hours. The results of this investigation demonstrated that the Slide ligatures produced significantly lower static frictional resistance than conventional elastomeric modules in the fresh condition and after 24 hours of storage in a simulated oral environment (p static frictional resistance of conventional elastomeric modules and the Slide system (p = 0.525). The claim by the manufacturer that the Slide system produces lower frictional resistance than conventional elastomeric modules is upheld.

  16. Mechanisms of shock-induced dynamic friction

    International Nuclear Information System (INIS)

    Winter, R E; Ball, G J; Keightley, P T

    2006-01-01

    The mechanism of shock-induced dynamic friction has been explored through an integrated programme of experiments and numerical simulations. A novel experimental technique has been developed for observing the sub-surface deformation in aluminium when sliding against a steel anvil at high velocity and pressure. The experimental observations suggest that slight differences in conditions at the interface between the metals affect frictional behaviour even at the very high-velocity, high-pressure regime studied here. However, a clear finding from the experimental work is the presence of two distinct modes of deformation termed deep and shallow. The deep deformation is observed in a region of the aluminium specimen where the interfacial velocity is relatively low and the shallow deformation is observed in a region where the interfacial velocity is higher. A 1D numerical treatment is presented which predicts the existence of two mechanisms for dynamic friction termed 'asymptotic melting' and 'slide-then-lock'. In both modes there is a warm-up phase in which the interface temperature is increased by frictional heating. For high initial sliding velocity, this is followed by the onset of the asymptotic melting state, in which the temperature is almost constant and melting is approached asymptotically. This mechanism produces low late-time frictional stress and shallow deformation. For lower initial sliding velocity, the warm-up terminates in a violent work hardening event that locks the interface and launches a strong plastic shear wave into the weaker material. This slide-then-lock mechanism is characterized by sustained high frictional stress and deep plastic deformation. These predicted mechanisms offer a plausible and consistent explanation for the abrupt transitions in the depth of sub-surface deformation observed in the experiments. A key conclusion arising from the current work is that the frictional stress does not vary smoothly with pressure or sliding velocity

  17. Decreasing Friction Sensitivity for Primary Explosives

    Science.gov (United States)

    Matyáš, Robert; Šelešovský, Jakub

    2014-04-01

    Primary explosives are a group of explosives that are widely used in various initiating devices. One of their properties is sufficient sensitivity to initiating stimuli. However, their sensitivity often introduces a safety risk during their production and subsequent handling. It is generally known that water can be used to desensitize these compounds. The most commonly used industrial primary explosives (lead azide, lead styphnate, tetrazene, and diazodinitrophenol) were mixed with water in various ratios and the sensitivity to friction was determined for all mixtures. It was found that even a small addition of water (5-10%) considerably lowered the friction sensitivity.

  18. Friction measurements of steel on refractory bricks

    International Nuclear Information System (INIS)

    Eiselstein, L.E.

    1981-08-01

    During startup or shutdown of a pool-type LMFBR, substantial shear stresses may arise between the base of the steel reactor vessel and the refractory brick support base. The magnitude of these stresses, which result from differences in thermal expansion, can be estimated if the friction coefficient is known. This report describes experiments to determine friction coefficients between 2 1/4 Cr-1Mo steel and several refractory materials and to examine effects to contact pressure, temperature, sliding velocity, lubricants, and surface condition

  19. Frictional Coulomb drag in strong magnetic fields

    DEFF Research Database (Denmark)

    Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang

    1997-01-01

    A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is eval......A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21...

  20. Change in Frictional Behavior during Olivine Serpentinization

    Science.gov (United States)

    Xing, T.; Zhu, W.; French, M. E.; Belzer, B.

    2017-12-01

    Hydration of mantle peridotites (serpentinization) is pervasive at plate boundaries. It is widely accepted that serpentinization is intrinsically linked to hydromechanical processes within the sub-seafloor, where the interplay between cracking, fluid supply and chemical reactions is responsible for a spectrum of fault slip, from earthquake swarms at the transform faults, to slow slip events at the subduction zone. Previous studies demonstrate that serpentine minerals can either promote slip or creep depend on many factors that include sliding velocity, temperature, pressure, interstitial fluids, etc. One missing link from the experimental investigation of serpentine to observations of tectonic faults is the extent of alteration necessary for changing the frictional behaviors. We quantify changes in frictional behavior due to serpentinization by conducting experiments after in-situ serpentinization of olivine gouge. In the sample configuration a layer of powder is sandwiched between porous sandstone blocks with 35° saw-cut surface. The starting material of fine-grained (63 120 µm) olivine powder is reacted with deionized water for 72 hours at 150°C before loading starts. Under the conventional triaxial configuration, the sample is stressed until sliding occurs within the gouge. A series of velocity-steps is then performed to measure the response of friction coefficient to variations of sliding velocity from which the rate-and-state parameters are deduced. For comparison, we measured the frictional behavior of unaltered olivine and pure serpentine gouges.Our results confirm that serpentinization causes reduced frictional strength and velocity weakening. In unaltered olivine gouge, an increase in frictional resistance with increasing sliding velocity is observed, whereas the serpentinized olivine and serpentine gouges favor velocity weakening behaviors at the same conditions. Furthermore, we observed that high pore pressures cause velocity weakening in olivine but

  1. Friction coefficient determination by electrical resistance measurements

    Science.gov (United States)

    Tunyagi, A.; Kandrai, K.; Fülöp, Z.; Kapusi, Z.; Simon, A.

    2018-05-01

    A simple and low-cost, DIY-type, Arduino-driven experiment is presented for the study of friction and measurement of the friction coefficient, using a conductive rubber cord as a force sensor. It is proposed for high-school or college/university-level students. We strongly believe that it is worthwhile planning, designing and performing Arduino and compatible sensor-based experiments in physics class in order to ensure a better understanding of phenomena, develop theoretical knowledge and multiple experimental skills.

  2. Measuring Search Frictions Using Japanese Microdata

    DEFF Research Database (Denmark)

    Sasaki, Masaru; Kohara, Miki; Machikita, Tomohiro

    This paper estimates matching functions to measure search frictions in the Japanese labor market and presents determinants of search duration to explain the effect of unemployment benefits on a job seeker’s behavior. We employ administrative micro data that track the job search process of individ......This paper estimates matching functions to measure search frictions in the Japanese labor market and presents determinants of search duration to explain the effect of unemployment benefits on a job seeker’s behavior. We employ administrative micro data that track the job search process...

  3. Power law load dependence of atomic friction

    OpenAIRE

    Fusco, C.; Fasolino, A.

    2004-01-01

    We present a theoretical study of the dynamics of a tip scanning a graphite surface as a function of the applied load. From the analysis of the lateral forces, we extract the friction force and the corrugation of the effective tip-surface interaction potential. We find both the friction force and potential amplitude to have a power-law dependence on applied load with exponent similar to1.6. We interpret these results as characteristic of sharp undeformable tips in contrast to the case of macr...

  4. Friction welding of steel to ceramic

    OpenAIRE

    Rombaut, Pieter; De Waele, Wim; Faes, Koenraad

    2011-01-01

    The goal of this paper is to give a clear summary of the literature review performed during the master thesis on friction welding on dissimilar materials. Of main interest for this work is the welding of steel to a ceramic material such as alumina (Al2O3). Because of the difficulties involved in producing a sound weld for this material combination, not a lot of literature is available on this topic. This paper starts with a discussion on the basics of friction welding and typical problems enc...

  5. Preload, Coefficient of Friction, and Thread Friction in an Implant-Abutment-Screw Complex.

    Science.gov (United States)

    Wentaschek, Stefan; Tomalla, Sven; Schmidtmann, Irene; Lehmann, Karl Martin

    To examine the screw preload, coefficient of friction (COF), and tightening torque needed to overcome the thread friction of an implant-abutment-screw complex. In a customized load frame, 25 new implant-abutment-screw complexes including uncoated titanium alloy screws were torqued and untorqued 10 times each, applying 25 Ncm. Mean preload values decreased significantly from 209.8 N to 129.5 N according to the number of repetitions. The overall COF increased correspondingly. There was no comparable trend for the thread friction component. These results suggest that the application of a used implant-abutment-screw complex may be unfavorable for obtaining optimal screw preload.

  6. Cushing syndrome

    Science.gov (United States)

    Hypercortisolism; Cortisol excess; Glucocorticoid excess - Cushing syndrome ... The most common cause of Cushing syndrome is taking too much ... Cushing syndrome . Prednisone, dexamethasone, and prednisolone ...

  7. LEOPARD syndrome

    Science.gov (United States)

    Multiple lentigines syndrome; Noonan syndrome with multiple lentigines ... Genetics Home Reference -- ghr.nlm.nih.gov/condition/noonan-syndrome-with-multiple-lentigines National Organization for Rare Disorders -- ...

  8. Sliding friction: From microscopic contacts to Amontons’ law

    OpenAIRE

    Weber, B.A.

    2017-01-01

    Most engineers describe sliding friction using the friction coefficient, the ratio of frictional force to normal force. While this proportionality is very simple, its origin is not trivial at all and has been subject of investigation for more than a century. The current consensus is that both frictional and normal force are proportional to the 'real contact area'. Surface roughness prevents surfaces from coming into full contact; the real contact area is simply the fraction of the apparent co...

  9. An empirical model for friction in cold forging

    DEFF Research Database (Denmark)

    Bay, Niels; Eriksen, Morten; Tan, Xincai

    2002-01-01

    With a system of simulative tribology tests for cold forging the friction stress for aluminum, steel and stainless steel provided with typical lubricants for cold forging has been determined for varying normal pressure, surface expansion, sliding length and tool/work piece interface temperature...... of normal pressure and tool/work piece interface temperature. The model is verified by process testing measuring friction at varying reductions in cold forward rod extrusion. KEY WORDS: empirical friction model, cold forging, simulative friction tests....

  10. Simulations of the Static Friction Due to Adsorbed Molecules

    OpenAIRE

    He, Gang; Robbins, Mark O.

    2001-01-01

    The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potenti...

  11. FRICTION - WELDING MACHINE AUTOMATIC CONTROL CIRCUIT DESIGN AND APPLICATION

    OpenAIRE

    Hakan ATEŞ; Ramazan BAYINDIR

    2003-01-01

    In this work, automatic controllability of a laboratory-sized friction-welding machine has been investigated. The laboratory-sized friction-welding machine was composed of motor, brake, rotary and constant samples late pliers, and hydraulic unit. In automatic method, welding parameters such as friction time, friction pressure, forge time and forge pressure can be applied sensitively using time relays and contactors. At the end of the experimental study it's observed that automatic control sys...

  12. 30 CFR 57.19008 - Friction hoist synchronizing mechanisms.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Friction hoist synchronizing mechanisms. 57... MINES Personnel Hoisting Hoists § 57.19008 Friction hoist synchronizing mechanisms. Where creep or slip may alter the effective position of safety devices, friction hoists shall be equipped with...

  13. Friction dependence of shallow granular flows from discrete particle simulations

    NARCIS (Netherlands)

    Thornton, Anthony Richard; Weinhart, Thomas; Luding, Stefan; Bokhove, Onno

    2011-01-01

    A shallow-layer model for granular flows is completed with a closure relation for the macroscopic bed friction or basal roughness obtained from micro-scale discrete particle simulations of steady flows. We systematically vary the bed friction by changing the contact friction coefficient between

  14. 30 CFR 56.19008 - Friction hoist synchronizing mechanisms.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Friction hoist synchronizing mechanisms. 56... Personnel Hoisting Hoists § 56.19008 Friction hoist synchronizing mechanisms. Where creep or slip may alter the effective position of safety devices, friction hoists shall be equipped with synchronizing...

  15. Atomic-scale friction : thermal effects and capillary condensation

    NARCIS (Netherlands)

    Jinesh, Kochupurackal Balakrishna Pillai

    2006-01-01

    This work entitled as "Atomic-scale friction: thermal effects and capillary condensation" is a study on the fundamental aspects of the origin of friction from the atomic-scale. We study two realistic aspects of atomic-scale friction, namely the effect of temperature and the effect of relative

  16. 30 CFR 56.19014 - Friction hoist overtravel protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Friction hoist overtravel protection. 56.19014 Section 56.19014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Hoisting Hoists § 56.19014 Friction hoist overtravel protection. In a friction hoist installation, tapered...

  17. 30 CFR 57.19014 - Friction hoist overtravel protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Friction hoist overtravel protection. 57.19014 Section 57.19014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Hoisting Hoists § 57.19014 Friction hoist overtravel protection. In a friction hoist installation, tapered...

  18. Sliding friction : From microscopic contacts to Amontons’ law

    NARCIS (Netherlands)

    Weber, B.A.

    2017-01-01

    Most engineers describe sliding friction using the friction coefficient, the ratio of frictional force to normal force. While this proportionality is very simple, its origin is not trivial at all and has been subject of investigation for more than a century. The current consensus is that both

  19. Performance evaluation for darcy friction factor formulae using ...

    African Journals Online (AJOL)

    It is concluded that Newton Raphson ; Prandtl and Nikurdse; Zingrang and Sylvester ; Serghide ; Barr; Swamee and Jain; Eck ; Haaland ; Brkic ; Wood and Moody are first choice friction formulae based on the values of model of selection criterion. Keywords: Darcy Friction Factor, Pipe Flow, Statistical Methods, Darcy Friction ...

  20. Observing the Forces Involved in Static Friction under Static Situations

    Science.gov (United States)

    Kaplan, Daniel

    2013-01-01

    Static friction is an important concept in introductory physics. Later in the year students apply their understanding of static friction under more complex conditions of static equilibrium. Traditional lab demonstrations in this case involve exceeding of the maximum level of static friction, resulting in the "onset of motion." (Contains…

  1. A Novel Time-Varying Friction Compensation Method for Servomechanism

    Directory of Open Access Journals (Sweden)

    Bin Feng

    2015-01-01

    Full Text Available Friction is an inevitable nonlinear phenomenon existing in servomechanisms. Friction errors often affect their motion and contour accuracies during the reverse motion. To reduce friction errors, a novel time-varying friction compensation method is proposed to solve the problem that the traditional friction compensation methods hardly deal with. This problem leads to an unsatisfactory friction compensation performance and the motion and contour accuracies cannot be maintained effectively. In this method, a trapezoidal compensation pulse is adopted to compensate for the friction errors. A generalized regression neural network algorithm is used to generate the optimal pulse amplitude function. The optimal pulse duration function and the pulse amplitude function can be established by the pulse characteristic parameter learning and then the optimal friction compensation pulse can be generated. The feasibility of friction compensation method was verified on a high-precision X-Y worktable. The experimental results indicated that the motion and contour accuracies were improved greatly with reduction of the friction errors, in different working conditions. Moreover, the overall friction compensation performance indicators were decreased by more than 54% and this friction compensation method can be implemented easily on most of servomechanisms in industry.

  2. Milled Die Steel Surface Roughness Correlation with Steel Sheet Friction

    DEFF Research Database (Denmark)

    Berglund, J.; Brown, C.A.; Rosén, B.-G.

    2010-01-01

    This work investigates correlations between the surface topography ofmilled steel dies and friction with steel sheet. Several die surfaces were prepared by milling. Friction was measured in bending under tension testing. Linear regression coefficients (R2) between the friction and texture...

  3. Static friction of stainless steel wire rope–rubber contacts.

    NARCIS (Netherlands)

    Loeve, A.J.; Krijger, T.; Mugge, W.; Breedveld, P.; Dodou, D.; Dankelman, J.

    2014-01-01

    Little is known about static friction of stainless-steel wire ropes ('cables') in contact with soft rubbers, an interface of potential importance for rigidifiable medical instruments. Although friction theories imply that the size and profile of the cables affect static friction, there are no

  4. Bioeconomy, Moral Friction and Symbolic Law

    DEFF Research Database (Denmark)

    Hoeyer, Klaus

    2016-01-01

    several competing agendas are at play and to understand the effects, we therefore need to investigate empirically what emerges through this friction between competing governmental ambitions. My discussion is based on studies of tissue exchange in Europe and seeks to integrate theories of symbolic law...

  5. Friction Pull Plug Welding in Aluminum Alloys

    Science.gov (United States)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  6. Friction Force: From Mechanics to Thermodynamics

    Science.gov (United States)

    Ferrari, Christian; Gruber, Christian

    2010-01-01

    We study some mechanical problems in which a friction force is acting on a system. Using the fundamental concepts of state, time evolution and energy conservation, we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws of thermodynamics and then apply them to investigate the time evolution and heat transfer of…

  7. Design of Piston Ring Friction Tester Apparatus

    DEFF Research Database (Denmark)

    Klit, Peder

    2006-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing the frictio......One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing...... the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... available is reflected in the friction absorbed in the bearing. The following properties will be measured: Oil fillm thickness - along liner (axial variation), oil film thickness - along piston ring (circumferential variation), piston tilt, temperature of piston rings and liner, pressure at piston lands...

  8. Modelling and Testing of Friction in Forging

    DEFF Research Database (Denmark)

    Bay, Niels

    2007-01-01

    Knowledge about friction is still limited in forging. The theoretical models applied presently for process analysis are not satisfactory compared to the advanced and detailed studies possible to carry out by plastic FEM analyses and more refined models have to be based on experimental testing...

  9. Friction coefficients of PTFE bearing liner

    Science.gov (United States)

    Daniels, C. M.

    1979-01-01

    Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

  10. Dry friction damping couple at high frequencies

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk; Košina, Jan; Radolfová, Alena

    2014-01-01

    Roč. 8, č. 1 (2014), s. 91-100 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : dry friction * damping * high frequencies Subject RIV: BI - Acoustics http://www.kme.zcu.cz/acm/acm/article/view/239/265

  11. Tribology: Friction, lubrication, and wear technology

    Science.gov (United States)

    Blau, Peter J.

    1993-01-01

    The topics are presented in viewgraph form and include the following: introduction and definitions of terms; friction concepts; lubrication technology concepts; wear technology concepts; and tribological transitions. This document is designed for educators who seek to teach these concepts to their students.

  12. Frictional Torque on a Rotating Disc

    Science.gov (United States)

    Mungan, Carl E.

    2012-01-01

    Resistance to motion often includes a dry frictional term independent of the speed of an object and a fluid drag term varying linearly with speed in the viscous limit. (At higher speeds, quadratic drag can also occur.) Here, measurements are performed for an aluminium disc mounted on bearings that is given an initial twist and allowed to spin…

  13. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

    A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

  14. Sensitivity to friction for primary explosives

    International Nuclear Information System (INIS)

    Matyáš, Robert; Šelešovský, Jakub; Musil, Tomáš

    2012-01-01

    Highlights: ► The friction sensitivity of 14 samples of primary explosives was determined. ► The same apparatus (small scale BAM) and the same method (probit analysis) was used. ► The crystal shapes and sizes were documented with microscopy. ► Almost all samples are less sensitive than lead azide, which is commercially used. ► The organic peroxides (TATP, DADP, HMTD) are not as sensitive as often reported. - Abstract: The sensitivity to friction for a selection of primary explosives has been studied using a small BAM friction apparatus. The probit analysis was used for the construction of a sensitivity curve for each primary explosive tested. Two groups of primary explosives were chosen for measurement (a) the most commonly used industrially produced primary explosives (e.g. lead azide, tetrazene, dinol, lead styphnate) and (b) the most produced improvised primary explosives (e.g. triacetone triperoxide, hexamethylenetriperoxide diamine, mercury fulminate, acetylides of heavy metals). A knowledge of friction sensitivity is very important for determining manipulation safety for primary explosives. All the primary explosives tested were carefully characterised (synthesis procedure, shape and size of crystals). The sensitivity curves obtained represent a unique set of data, which cannot be found anywhere else in the available literature.

  15. Sensitivity to friction for primary explosives

    Energy Technology Data Exchange (ETDEWEB)

    Matyas, Robert, E-mail: robert.matyas@upce.cz [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, Pardubice 532 10 (Czech Republic); Selesovsky, Jakub; Musil, Tomas [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, Pardubice 532 10 (Czech Republic)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer The friction sensitivity of 14 samples of primary explosives was determined. Black-Right-Pointing-Pointer The same apparatus (small scale BAM) and the same method (probit analysis) was used. Black-Right-Pointing-Pointer The crystal shapes and sizes were documented with microscopy. Black-Right-Pointing-Pointer Almost all samples are less sensitive than lead azide, which is commercially used. Black-Right-Pointing-Pointer The organic peroxides (TATP, DADP, HMTD) are not as sensitive as often reported. - Abstract: The sensitivity to friction for a selection of primary explosives has been studied using a small BAM friction apparatus. The probit analysis was used for the construction of a sensitivity curve for each primary explosive tested. Two groups of primary explosives were chosen for measurement (a) the most commonly used industrially produced primary explosives (e.g. lead azide, tetrazene, dinol, lead styphnate) and (b) the most produced improvised primary explosives (e.g. triacetone triperoxide, hexamethylenetriperoxide diamine, mercury fulminate, acetylides of heavy metals). A knowledge of friction sensitivity is very important for determining manipulation safety for primary explosives. All the primary explosives tested were carefully characterised (synthesis procedure, shape and size of crystals). The sensitivity curves obtained represent a unique set of data, which cannot be found anywhere else in the available literature.

  16. Clutches using engineering ceramics as friction material

    Energy Technology Data Exchange (ETDEWEB)

    Albers, A.; Arslan, A.; Mitariu, M. [Universitaet Karlsruhe (T.H.), IPEK - Institut fuer Produktentwicklung, Kaiserstr. 10, 76131 Karlsruhe (Germany)

    2005-03-01

    The experimental and constructive results illustrate that engineering ceramic materials have a high potential in the field of dry running friction systems. According to first estimations, it is possible to build the vehicle clutch 53 % smaller or to transmit up to 180 % higher torque with the same size by an appropriate selection of the system friction pairing and an adequate ceramic design [1, 2]. The friction coefficient characteristic (decreasing friction coefficient above sliding speed) is unfavourable with regard to comfort (self-induced grab oscillations [3]) of the vehicle clutch. Furthermore, it is important to select the test procedure of the experimental analyses to be as close to the system as possible in order to obtain exact information concerning the target system. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [German] Die experimentellen und konstruktiven Ergebnisse haben gezeigt, dass ingenieurkeramische Werkstoffe ein hohes Potenzial im Bereich der trockenlaufenden Friktionssysteme haben. Durch geeignete Wahl der Systemreibpaarung und eine keramikgerechte Konstruktion ist es nach ersten Abschaetzungen moeglich, die Kfz-Kupplung um 53 % kleiner zu bauen bzw. bei gleicher Groesse bis zu 180 % hoehere Drehmomente zu uebertragen [1, 2]. Die Reibungszahlcharakteristik (fallende Reibungszahl ueber Gleitgeschwindigkeit) ist im Hinblick auf Komfort (selbsterregte Rupfschwingungen [3]) fuer die Kraftfahrzeugkupplung unguenstig. Des Weiteren ist es wichtig, die Versuchsfuehrung der experimentellen Untersuchungen so systemnah wie moeglich zu waehlen, um genauere Aussagen auf das Zielsystem zu erhalten. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  17. Measuring Search Frictions Using Japanese Microdata

    DEFF Research Database (Denmark)

    Sasaki, Masaru; Kohara, Miki; Machikita, Tomohiro

    2013-01-01

    This paper estimates individual-level matching functions to measure search frictions in the Japanese labour market and presents the determinants of search duration. We employ administrative microdata that track the job search process of job seekers who left or lost their job in August 2005...

  18. Blount disease in a case of Prader-Willi syndrome: why is it not as prevalent as in obesity without Prader-Willi syndrome?

    Science.gov (United States)

    Dulka, Susan; Choudhary, Arabinda Kumar; Methratta, Sosamma; Fortuna, Kristine

    2013-05-01

    Prader-Willi syndrome (PWS) is a genetic disorder causing multisystem abnormalities with obesity. Obesity is a well established cause of Blount disease. A 7-year-old girl with PWS presented with genu varum of the left knee with deformity of the proximal medial tibial condyle, which was consistent with Blount disease. A lateral physeal stapling and subsequent osteotomy for the left proximal tibia and fibula were performed with improved anatomical alignment. Blount disease has not been reported in the literature in association with PWS despite excessive obesity.

  19. Friction Pull Plug and Material Configuration for Anti-Chatter Friction Pull Plug Weld

    Science.gov (United States)

    Littell, Justin Anderson (Inventor)

    2016-01-01

    A friction pull plug is provided for use in forming a plug weld in a hole in a material. The friction pull plug includes a shank and a series of three frustoconical sections. The relative sizes of the sections assure that a central one of the sections defines the initial contact point between the hole's sides. The angle defined by the central one of the sections reduces or eliminates chatter as the plug is pulled into the hole.

  20. Fanconi syndrome

    Science.gov (United States)

    De Toni-Fanconi syndrome ... Fanconi syndrome can be caused by faulty genes, or it may result later in life due to kidney damage. Sometimes the cause of Fanconi syndrome is unknown. Common causes of Fanconi syndrome in ...