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1.
J Phys Condens Matter ; 35(42)2023 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-37429290

RESUMEN

Linearly polarized soft x-rays provide information about electronic or magnetic anisotropy through absorption into materials or generation of photoelectrons. In order to change the relative angle between linear polarization and sample crystalline axes, either x-ray polarization or the sample needs to be rotated. Due to difficulties of polarization control in the soft x-ray range, a conventional approach was to rotate the sample. However, this method is not compatible, for example, withoperandomeasurements on non-uniform samples where sample size and rotational motion are severely restricted. At BL07LSU of SPring-8, we developed a new method to rotate the linear polarization angle using a segmented cross undulator. We report an application of this linear polarization rotation to resonant photoemission spectroscopy on an magnetic atomic layer Fe2N on Cu(111) to probe the electronic anisotropy of the 3dstates in the vicinity of the Fermi level.

5.
Int J Oral Maxillofac Surg ; 48(9): 1227-1234, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30833093

RESUMEN

The aim of this study was to investigate the probability of facial nerve injury (FNI) in the treatment of condylar neck and subcondylar fractures (CN/SCFs) with percutaneous approaches and to identify factors predicting FNI. The data of 80 patients with 87 CN/SCFs were evaluated retrospectively. The primary outcome was FNI occurrence. The predictor variables were age, sex, aetiology, alcohol consumption, fracture site and pattern (dislocation or not), concomitant fractures, time interval to surgery, surgeon experience, plate type, and the dual classification of percutaneous approaches. The approaches were classified based on whether subcutaneous dissection traversed the marginal mandibular branch (MMB) deeply (deep group: submandibular and retroparotid approaches) or superficially (superficial group: transparotid, transmasseteric anteroparotid (TMAP), and high cervical-TMAP approaches). Twenty-two patients (27.5%) suffered FNI, of whom two in the deep group had permanent paralysis of the MMB. In the multivariate logistic regression model, deeply traversing surgery approaches (odds ratio 12.4, P=0.025) and the presence of a dislocated fracture (odds ratio 6.66, P=0.012) were associated with an increased risk of FNI. These results suggest that percutaneous approaches in the superficial group should be recommended for the treatment of CN/SCFs to reduce the risk of FNI.


Asunto(s)
Traumatismos del Nervio Facial , Fracturas Mandibulares , Nervio Facial , Fijación Interna de Fracturas , Humanos , Cóndilo Mandibular , Estudios Retrospectivos
6.
Accid Anal Prev ; 122: 350-364, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29174855

RESUMEN

This paper presents an enhanced model that considers the specifications of personal space to describe uni- and bi-directional pedestrian movement on stairs. The shape of the personal space of each pedestrian is regarded as an oval shape, which is composed of four arcs, to precisely quantify movements. Specific models that facilitate the simulation of movement include adjustments to individual speeds based on the proximity of other members, conflict avoidance, overtaking, and direction finding. By implementing these parameters in the simulation, basic data concerning these movement behaviours were collected from the experiment, which was carried out at one a Shanghai subway station. Twenty-four young college students participated in this experiment. Numerical simulation results for a stochastic case under those parameters were obtained. The fundamental diagrams and moving behaviours according to different proportions of ascending and descending pedestrians are analysed and discussed. The results indicate that the simulation platform for personal space can serve as a useful tool to evaluate pedestrian movement on stairs.


Asunto(s)
Peatones/psicología , Espacio Personal , Subida de Escaleras , China , Femenino , Humanos , Masculino , Movimiento/fisiología
7.
J Phys Chem B ; 120(47): 12127-12134, 2016 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-27933937

RESUMEN

A simple model of a hydrophobic polymer in water is studied. The model polymer, a chain of Lennard-Jones particles with a fixed bond length, is designed in such a way that it undergoes a coil-to-globule conformational change near room temperature upon heating in liquid water. At low temperatures (≲270 K), the polymer chain under vacuum takes a globular conformation, whereas in water, it adopts an extended form. At higher temperatures (≳320 K), the polymer has a more compact conformation in water than under vacuum. The same polymer chain in a nonpolar solvent is always extended and shows no sign of a coil-to-globule transformation up to 360 K. The heat-induced collapse of the polymer uniquely observed in water is not attributed to the hydrophobic effect on individual monomers, but it is correlated with the temperature dependence of the potential of mean force between two monomers at contact distance.


Asunto(s)
Metano/química , Polímeros/química , Agua/química , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Modelos Moleculares , Conformación Molecular , Transición de Fase , Temperatura , Termodinámica , Vacio
8.
Curr Oncol ; 23(5): e439-e442, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27803603

RESUMEN

BACKGROUND: No potential tumour markers have been validated for prognosis in endometrial cancer. However, carcinoembryonic antigen (cea) is one of the most widely used tumour markers in various types of cancer. Although cea expression in endometrial cancer has been investigated, its prognostic value remains controversial, and no studies have investigated serum cea levels in large case series. In the present study, we investigated diagnostic and prognostic applications of serum cea for endometrial cancer. METHODS: This prospective study was approved by our Institutional Review Board. Between January 2006 and December 2012, serum cea was measured prospectively in 215 patients with endometrial cancer and was subsequently measured during treatment and at scheduled follow-up examinations in patients with elevated baseline serum cea. RESULTS: During the study period, 215 patients (142 stage i, 19 stage ii, 32 stage iii, 22 stage iv) were treated for endometrial cancer. By the time of last follow-up, 52 had relapsed (24.2%), and the median follow-up duration was 45 months (range: 1-95 months). Elevated serum cea was identified in 25 patients (11.6%) and was associated with histologic type (p = 0.04), histologic grade (p = 0.03), and myometrial invasion depth (p = 0.01). Elevated serum cea was not related to clinical stage, lymph node metastasis, distant metastasis, age, menopausal status, or body mass index. Relapse of disease was related to elevated serum cea (p = 0.006). CONCLUSIONS: Serum cea is a potential prognostic indicator for endometrial cancer.

9.
Eur J Gynaecol Oncol ; 37(2): 265-6, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27172760

RESUMEN

Nongestational choriocarcinoma is very rare and carries a poor prognosis in female patients. In this report, the authors present a case of nongestational choriocarcinoma with brain metastasis in a female. A 58-year-old female with intermittent back pain was referred to a private hospital. On examination, a mediastinal tumor and a pancreatic tumor were detected. Endoscopic ultrasound-guided fine needle aspiration biopsy of the tumor was performed for histological evaluation. Pathological diagnosis was difficult because only a small amount of tissue was collected. Head MRI showed multiple metastatic tumors in the brain. The patient was diagnosed with primary mediastinal choriocarcinoma with brain metastasis. She was treated with one course of an etoposide, methotrexate, dactinomycin, cyclophosphamide, and vincristine regimen, but her general condition gradually deteriorated, and she died on day 41. Nongestational choriocarcinoma is drug resistant, whereas gestational choriocarcinoma has better chemotherapeutic sensitivity.


Asunto(s)
Neoplasias Encefálicas/secundario , Coriocarcinoma no Gestacional/secundario , Neoplasias del Mediastino/patología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/tratamiento farmacológico , Coriocarcinoma no Gestacional/diagnóstico , Coriocarcinoma no Gestacional/tratamiento farmacológico , Ciclofosfamida/administración & dosificación , Dactinomicina/administración & dosificación , Etopósido/administración & dosificación , Resultado Fatal , Femenino , Humanos , Neoplasias del Mediastino/diagnóstico , Neoplasias del Mediastino/tratamiento farmacológico , Metotrexato/administración & dosificación , Persona de Mediana Edad , Vincristina/administración & dosificación
10.
Eur J Gynaecol Oncol ; 37(1): 139-41, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27048128

RESUMEN

BACKGROUND: Krukenberg tumors mostly occur after 40 years. Metastatic ovarian tumors in young age are very rare. CASE: A 18-year-old female presented with colon cancer which was accompanied by Krukenberg tumor. The present case was a very rare case of metastatic ovarian tumor in very young age. The present patient presented with abdominal pain. On examination, colon tumor was detected and bilateral ovary were almost normal with only slight swelling. During the operation for colon tumor, biopsy of bilateral ovary was performed for histopathological evaluation. Although there were no specific findings in bilateral ovary, microscopic examination revealed poorly differentiated adenocarcinoma, diffusely invading the ovarian parenchyma. Diagnosis of colon cancer was made postoperatively and ovarian Krukenberg tumor was confirmed. CONCLUSION: In case of suspecting colon cancer even in very young patient with normal ovary, biopsy of ovary should be considered for the diagnosis of Krukenberg tumor.


Asunto(s)
Tumor de Krukenberg/patología , Neoplasias Ováricas/patología , Adolescente , Femenino , Humanos , Queratina-20/análisis , Tumor de Krukenberg/química , Metástasis de la Neoplasia , Neoplasias Ováricas/química , Enfermedades Raras
11.
Mon Not R Astron Soc ; 457(4): 4089-4113, 2016 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-32848283

RESUMEN

We present a statistical analysis of the first four seasons from a "second-generation" microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg2 of the Galactic bulge by the OGLE, MOA, and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for ~1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that 55 - 22 + 34 % of microlensed stars host a snowline planet. Moreover, we find that Neptunes-mass planets are ~ 10 times more common than Jupiter-mass planets. The companion-to-host mass ratio distribution shows a deficit at q ~ 10-2, separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower-mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions.

12.
Eur J Gynaecol Oncol ; 36(2): 168-73, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26050355

RESUMEN

OBJECTIVES: Chemotherapy-induced thrombocytopenia seems to be a relevant problem and the risk or clinical bleeding in patients wim gynecologic malignancy is reported to be higher than other malignancy. In this study, the authors investigated chemotherapy-induced thrombocytopenia recently performed in all patients with gynecologic malignancy. MATERIALS AND METHODS: Between January 2009 and December 2011, the authors examined reported chemotherapy-induced thrombocytopenia using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.0. They analyzed the incidence and clinical features of chemotherapy-induced thrombocytopenia in patients with gynecologic malignancy. RESULTS: During this period they administered over 1,614 infusions (29 regimens) to 291 patients. Chemotherapy-induced thrombocytopenia occurred in 43 (14.8%) patients over 56 (3.5%) chemotherapy cycles. Bleeding occurred in 13 (4.5%) patients over 14 (0.9%) cycles. Platelet transfusions were administered for eight (2.7%) patients over eight (0.5%) cycles. Median platelet count at platelet transfusions was 17,000 /µl. Chemotherapy-induced thrombocytopenia was associated with more than five previous chemotherapy cycles, previous radiotherapy, disseminated disease, distant metastatic disease, poor performance status, and taxane-including regimens. Clinical bleeding was associated with previous radiotherapy, distant metastatic disease, poor performance status, and taxane-including regimens. CONCLUSIONS: Estimating bleeding risk factor such as previous radiotherapy, distant metastatic disease, poor performance status, and taxane-including regimens seem to be important for safe management of chemotherapy-induced thrombocytopenia.


Asunto(s)
Antineoplásicos/efectos adversos , Neoplasias de los Genitales Femeninos/tratamiento farmacológico , Hemorragia/inducido químicamente , Trombocitopenia/inducido químicamente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Persona de Mediana Edad , Transfusión de Plaquetas , Estudios Retrospectivos
13.
Eur J Gynaecol Oncol ; 36(1): 49-53, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25872334

RESUMEN

PURPOSE OF INVESTIGATION: Primary peritoneal carcinoma (PPC) is histologically similar to ovarian serous carcinoma, but its biochemical features remain obscure. The authors investigated and compared clinical findings, treatments, and outcomes of patients with PPS and those with epithelial ovarian cancer (EOC) patients. MATERIALS AND METHODS: The authors retrospectively reviewed data from 14 patients with PPC and 219 patients with EOC treated at the present hospital from January 2005 to December 2012, including demographic data, pathologic findings, treatments, and outcomes. RESULTS: Patients with PPC were significantly older (62.6 ± 8.4 years) than those with EOC (56.3 ± 11.3 years) (p = 0.045). There was no significant difference in serum CA-125 levels. The five-year survival rates did not differ significantly between patients with PPC (61.1%) and those with EOC (60.3%; p = 0.78); nor between patients with PPC and those with Stage III serous EOC (43.8%; p = 0.40). CONCLUSIONS: Treatment strategies for EOC applied to PPC apparently led to similar survival patterns among the two patient groups. Cytoreductive surgery combined with pre/postoperative platinum-containing chemotherapy may be effective for PPC patients.


Asunto(s)
Adenocarcinoma/patología , Antígeno Ca-125/sangre , Neoplasias Glandulares y Epiteliales/patología , Neoplasias Ováricas/patología , Neoplasias Peritoneales/patología , Adenocarcinoma/sangre , Adenocarcinoma/terapia , Adulto , Factores de Edad , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carboplatino/administración & dosificación , Carcinoma Epitelial de Ovario , Quimioterapia Adyuvante , Procedimientos Quirúrgicos de Citorreducción , Femenino , Humanos , Persona de Mediana Edad , Terapia Neoadyuvante , Estadificación de Neoplasias , Neoplasias Glandulares y Epiteliales/sangre , Neoplasias Glandulares y Epiteliales/terapia , Neoplasias Ováricas/sangre , Neoplasias Ováricas/terapia , Paclitaxel/administración & dosificación , Neoplasias Peritoneales/sangre , Neoplasias Peritoneales/terapia , Estudios Retrospectivos , Tasa de Supervivencia
14.
Clin Exp Obstet Gynecol ; 42(6): 819-21, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26753495

RESUMEN

BACKGROUND: Anti-N-methyl D-aspartate (anti-NMDA) receptor encephalitis is often accompanied by ovarian teratoma. Early tumor resection is reported to be effective as a treatment. CASE: A 21-year-old woman presented with anti-NMDA receptor encephalitis which was accompanied by ovarian teratoma. The present case was a very rare case of an early stage of anti-NMDA receptor encephalitis receiving operative treatment before confirming the presence of anti-NMDA receptor antibody. The diagnosis was established postoperatively by identifying anti-NMDA receptor antibody. CONCLUSION: In case of suspecting anti-NMDA receptor encephalitis in a patient with ovarian teratoma, early operative treatment should be considered even before confirming the presence of anti-NMDA receptor antibody.


Asunto(s)
Encefalitis Antirreceptor N-Metil-D-Aspartato/diagnóstico , Neoplasias Ováricas/diagnóstico , Receptores de N-Metil-D-Aspartato/inmunología , Teratoma/diagnóstico , Encefalitis Antirreceptor N-Metil-D-Aspartato/sangre , Encefalitis Antirreceptor N-Metil-D-Aspartato/complicaciones , Diagnóstico Diferencial , Femenino , Humanos , Neoplasias Ováricas/complicaciones , Neoplasias Ováricas/diagnóstico por imagen , Neoplasias Ováricas/cirugía , Teratoma/complicaciones , Teratoma/diagnóstico por imagen , Teratoma/cirugía , Tomografía Computarizada por Rayos X , Adulto Joven
15.
Sarcoma ; 2014: 498682, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25400500

RESUMEN

Uterine smooth muscle tumors (SMTs) are common pelvic tumors in women, and most of them are diagnosed as usual leiomyoma (UL). Exclusion of malignant disease is important in the management of SMTs. However, differentiation of SMTs remains difficult. In this study, we aimed to improve the preoperative diagnosis of SMTs. We examined 21 ULs, 7 atypical leiomyomas (ALs), and 6 leiomyosarcomas (LMSs), all of which were diagnosed by uterine tumor biopsy. Immunohistochemical findings (low-molecular-mass polypeptide 2 (LMP2) and Ki-67) and clinical features (serum lactate dehydrogenase level and menopause) were evaluated. Statistically significant differences in the expression of LMP2 and Ki-67 were observed between UL and AL and between UL and LMS. The combined LMP2 and Ki-67 score was significantly different between UL and AL, between UL and LMS, and between AL and LMS. The combined immunohistochemistry and clinical findings score (total score) was also significantly different between pathological types. The findings of this study suggest that the accuracy of the preoperative diagnosis of SMTs may be improved by using a combination of immunohistochemical and clinical findings.

16.
Eur J Gynaecol Oncol ; 34(3): 265-8, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23967561

RESUMEN

BACKGROUND: Malignant melanoma is an extremely malignant tumor with an unpredictable metastatic profile with variable periods of remission. CASE: A 41-year-old woman presented with recurrent malignant melanoma which had clinical features of an acute state mimicking primary peritoneal cancer. The case was an unusual recurrence of malignant melanoma occurring seven years after diagnosis and treatment of malignant melanoma in the patient's arm. The diagnosis was established postoperatively by immunohistochemistry. CONCLUSION: A variety of imaging methods and pathological methods, including an exploratory laparotomy, may be necessary in cases of patients suspecting primary peritoneal cancer with a previous history of melanoma with possible metastatic dissemination. Urgent diagnosis and treatment of these patients seems to be critical.


Asunto(s)
Diagnóstico Diferencial , Melanoma/patología , Recurrencia Local de Neoplasia/patología , Neoplasias Peritoneales/patología , Adulto , Femenino , Humanos , Melanoma/diagnóstico , Recurrencia Local de Neoplasia/diagnóstico , Neoplasias Peritoneales/diagnóstico
17.
Eur J Gynaecol Oncol ; 33(3): 252-4, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22873092

RESUMEN

PURPOSE OF INVESTIGATION: Chemotherapy-related hypersensitivity reaction seems to be problematic in the safe management of chemotherapy. In this study we investigated chemotherapy-related hypersensitivity reaction in patients with gynecologic malignancy. METHODS: Between January 2009 and December 2010, we examined hypersensitivity reaction (> or = grade2) using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.0. We analyzed the incidence, clinical features, management, and outcome. RESULTS: We administered over 1,057 infusions (24 regimens) to 205 patients. We found a total of four hypersensitivity reactions (> or = grade 2) cases (carboplatin: 2; nedaplatin: 1; docetaxel: 1). Signs and symptoms were varied. In two cases, the same regimen was rechallenged by using anti-allergic drugs. The docetaxel case was successful. The carboplatin case was not successful. CONCLUSION: Chemotherapy-related hypersensitivity reaction (> or = grade2) does not occur frequently. In the case of platinum, especially, carboplatin, re-administering after hypersensitivity reaction should be done carefully though platinum is a key drug in patients with gynecologic malignancies.


Asunto(s)
Antineoplásicos/efectos adversos , Hipersensibilidad a las Drogas/etiología , Neoplasias de los Genitales Femeninos/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Hidrocarburos Aromáticos con Puentes/efectos adversos , Carboplatino/efectos adversos , Femenino , Humanos , Japón , Persona de Mediana Edad , Compuestos Organoplatinos/efectos adversos , Estudios Retrospectivos , Taxoides/efectos adversos , Adulto Joven
18.
Nature ; 481(7380): 167-9, 2012 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-22237108

RESUMEN

Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10 AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10 M(J), where M(J) = 318 M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30 M(⊕)) and super-Earths (5-10 M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception.

19.
AJNR Am J Neuroradiol ; 33(4): 761-6, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22173765

RESUMEN

BACKGROUND AND PURPOSE: ADCs may help distinguish benign from malignant head and neck diseases. We sought to evaluate the effectiveness of ADC for differentiating between carcinomas and lymphomas of the nasopharynx and oropharynx. MATERIALS AND METHODS: We retrospectively compared the ADCs between 24 histologically proved lymphomas and 32 carcinomas, including 8 NPCs and 7 lymphomas of the nasopharynx, and 24 SCCs and 17 lymphomas of the oropharynx. ADCs were determined on tumor-by-tumor (overall ADCs) and pixel-by-pixel (ADC mapping) bases by using 2 b-values (500 and 1000 s/mm(2)). RESULTS: Lymphomas and oropharyngeal SCCs had unique histologic features in terms of keratinization, cell attenuation, stromal areas, and necrosis and had distinctive ADCs (0.503 ± 0.099 × 10(-3) mm(2)/s for lymphomas and 0.842 ± 0.164 × 10(-3) mm(2)/s for SCCs). However, NPCs and lymphomas were similar in terms of these histologic features, exhibiting comparable ADCs (0.567 ± 0.057 × 10(-3) mm(2)/s for NPCs and 0.528 ± 0.094 × 10(-3) mm(2)/s for lymphomas). Poorly and moderately differentiated SCCs with homogeneous T2 signals were indistinguishable from lymphomas on conventional MR images; however, ADCs of these SCC subtypes were significantly larger than those of lymphomas. ADC mapping profiles with respect to percentage of tumor areas of extremely low, intermediate, and high ADC levels were well-correlated with the histologic features of lymphomas, NPCs, and different types of SCCs. CONCLUSIONS: The effectiveness of ADC-based differentiation between lymphomas and carcinomas of the nasopharynx and oropharynx depends on their histologic characteristics.


Asunto(s)
Carcinoma de Células Escamosas/patología , Imagen de Difusión por Resonancia Magnética/métodos , Linfoma/patología , Neoplasias Nasofaríngeas/patología , Neoplasias Orofaríngeas/patología , Anciano , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estadística como Asunto
20.
J Oral Rehabil ; 39(5): 391-8, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22175784

RESUMEN

Titanium or zirconium computer-aided design/computer-aided manufacturing abutments are now widely used for aesthetic implant treatments; however, information regarding microscopic structural differences that may influence the biological and mechanical outcomes of different implant systems is limited. Therefore, the characteristics of different connection systems were investigated. Optical microscopic observation and scanning electron microscopy showed different characteristics of two internal systems, namely the Astra Tech and the Replace Select system, and for different materials. The scanning electron microscopic observation showed for the Astra Tech that the implant-abutment interface seemed to be completely sealed for both titanium and zirconium abutments, both horizontally and sagittally; however, the first implant-abutment contact was below the fixture top, creating a microgap, and fixtures connected with titanium abutments showed significantly larger values (23·56µm±5·44 in width, and 168·78µm±30·39 in depth, P<0·001). For Replace Select, scanning electron microscopy in the sagittal direction showed that the sealing of titanium and zirconium abutments differed. The seal between the implant-titanium and implant-zirconium abutments seemed to be complete at the butt-joint interface; however, the displacement of the abutment in relation to the fixture in the lateral direction was evident for both abutments with no statistical differences (P>0·70), creating an inverted microgap. Thus, microscopy evaluation of two commonly used internal systems connected to titanium or zirconium abutments showed that the implant-abutment interface was perfectly sealed under no-loading conditions. However, an inverted microgap was seen in both systems, which may result in bacterial accumulation as well as alteration of stress distribution at the implant-abutment interface.


Asunto(s)
Implantes Dentales/normas , Materiales Dentales/química , Ensayo de Materiales , Titanio/química , Circonio/química , Diseño Asistido por Computadora , Pilares Dentales , Diseño de Implante Dental-Pilar/métodos , Humanos , Microscopía Electrónica de Rastreo
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