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2.
Eur Heart J Acute Cardiovasc Care ; : 2048872619883619, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31657616

RESUMO

BACKGROUND: The European Society of Cardiology's 0/1-hour algorithm improves the early triage of patients towards "rule-out" or "rule-in" of non-ST-segment elevation myocardial infarction. The HEART score is a risk stratification tool for patients with undifferentiated chest pain. We sought to evaluate the performance of the European Society of Cardiology 0/1-hour algorithm and the HEART score to evaluate chest pain patients in the emergency department. METHODS: In this prospective study, we applied the European Society of Cardiology 0/1-hour algorithm and the HEART score in 1355 consecutive patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome without ST-segment elevation. Patients were followed for non-ST-segment elevation myocardial infarctions and major adverse cardiac events at 30 days: death, non-ST-segment elevation myocardial infarction, or unplanned coronary revascularization. RESULTS: The European Society of Cardiology 0/1-hour algorithm classified 921 (68.0%) patients as "rule-out" and the HEART score classified 686 (50.6%) patients as "low-risk". The 30-day incidence of non-ST-segment elevation myocardial infarctions was 0.32% in the European Society of Cardiology 0/1-hour algorithm "rule-out" patients versus 0.29% in the HEART score "low-risk" patients (p=0.75). The rate of major adverse cardiac events was 7.7% in the European Society of Cardiology 0/1-hour algorithm "rule-out" patients versus 1.1% in the HEART score "low-risk" patients (p<0.001). CONCLUSION: The European Society of Cardiology 0/1-hour algorithm identified more patients with low risk of non-ST-segment elevation myocardial infarctions at 30 days whereas for major adverse cardiac events, the HEART score had a greater capacity to detect low-risk patients.

3.
J Am Coll Cardiol ; 74(4): 483-494, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31345421

RESUMO

BACKGROUND: The European Society of Cardiology (ESC) recommends the 0/1-h algorithm for rapid triage of patients with suspected non-ST-segment elevation myocardial infarction (MI). However, its impact on patient management and safety when routinely applied is unknown. OBJECTIVES: This study sought to determine these important real-world outcome data. METHODS: In a prospective international study enrolling patients presenting with acute chest discomfort to the emergency department (ED), the authors assessed the real-world performance of the ESC 0/1-h algorithm using high-sensitivity cardiac troponin T embedded in routine clinical care and its associated 30-day rates of major adverse cardiac events (MACE) (the composite of cardiovascular death and MI). RESULTS: Among 2,296 patients, non-ST-segment elevation MI prevalence was 9.8%. In median, 1-h blood samples were collected 65 min after the 0-h blood draw. Overall, 94% of patients were managed without protocol violations, and 98% of patients triaged toward rule-out did not require additional cardiac investigations including high-sensitivity cardiac troponin T measurements at later time points or coronary computed tomography angiography in the ED. Median ED stay was 2 h and 30 min. The ESC 0/1-h algorithm triaged 62% of patients toward rule-out, and 71% of all patients underwent outpatient management. Proportion of patients with 30-day MACE were 0.2% (95% confidence interval: 03% to 0.5%) in the rule-out group and 0.1% (95% confidence interval: 0% to 0.2%) in outpatients. Very low MACE rates were confirmed in multiple subgroups, including early presenters. CONCLUSIONS: These real-world data document the excellent applicability, short time to ED discharge, and low rate of 30-day MACE associated with the routine clinical use of the ESC 0/1-h algorithm for the management of patients presenting with acute chest discomfort to the ED.

4.
J Prosthet Dent ; 119(1): 166-174, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28478987

RESUMO

STATEMENT OF PROBLEM: Bond strength (BS) values from in vitro studies are useful when dentists are selecting an adhesive system, but there is no ideal measuring method. PURPOSE: The purpose of this in vitro study was to investigate the influence of the evaluation method in the BS between dentin and composite resin. MATERIAL AND METHODS: Molars with exposed superficial dentin (N=240) were divided into 3 groups according to the test: microtensile (µTBS), microshear (µSBS), and micropush-out (µPBS). Each one was subdivided into 4 groups according to the adhesive system: total etch, 3- and 2-step; and self-etch, 2- and 1-step). For the µPBS test, a conical cavity was prepared and restored with composite resin. An occlusal slice (1.5 mm in thickness) was obtained from each tooth. For the µSBS test, a composite resin cylinder (1 mm in diameter) was built on the dentin surface of each tooth. For the µTBS test, a 2-increment composite resin cylinder was built on the dentin surface, and beams with a sectional area of 0.5 mm2 were obtained. Each subgroup was divided into 2 (n=10) as the specimens were tested after 7 days and 1 year of water storage. The specimens were submitted to load, and the failure recorded in units of megapascals. Original BS values from the µTBS and µSBS tests were normalized for the area from µPBS specimens. Original and normalized results were submitted to a 3-way ANOVA (α=.05). The correlation among mechanical results, stress distribution, and failure pattern was investigated. RESULTS: Significant differences (P<.05) were found among the adhesive systems and methods within both the original and normalized data but not between the storage times (P>.05). Within the 7 days of storage, the original BS values from µTBS were significantly higher (P<.001) than those from µPBS and µSBS. After 1 year, µSBS presented significantly lower results (P<.001). However, after the normalization for area, the BS values of the µTBS and µPBS tests were similar, and both were higher (P<.001) than that of µSBS in both storage times. In the µSBS and µTBS specimens, cohesive and adhesive failures were observed, whereas µPBS presented 100% of adhesive failures. The failure modes were compatible with the stress distribution. CONCLUSIONS: The storage time did not affect the results, but differences were found among the adhesives and methods. For comparisons of bond strength from tests with different bonding areas, the normalization for area seemed essential. The microshear bond test should not be used for bond strength evaluation, and the microtensile test needs improvement to enable reliable results regarding stress concentration and failure mode. The micropush-out test may be considered more reliable than the microtensile in the bond strength investigation, as demonstrated by the uniform stress concentration and adhesive failure pattern.


Assuntos
Resinas Compostas , Adesivos Dentinários , Dentina , Resistência ao Cisalhamento , Resistência à Tração , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Técnicas In Vitro , Teste de Materiais , Dente Molar
5.
Pacing Clin Electrophysiol ; 39(6): 588-91, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27000950

RESUMO

BACKGROUND: High-sensitivity cardiac troponin assays have provided a significant contribution for the early diagnosis of cardiovascular events. However, elevated cardiac troponin levels may occur in other clinical situations as supraventricular tachyarrhythmias with concerns about the mechanism of this elevation. OBJECTIVES AND METHODS: The goal of this study was to describe the performance of high-sensitivity cardiac troponin T (hs-cTnT) assay in patients presenting to the emergency department with a primary diagnosis of supraventricular tachyarrhythmia and to evaluate its relation with cardiovascular events during follow-up. RESULTS: One hundred patients were included; mean age was 64 ± 12 years and 59.8% were men. The most common arrhythmia at admission was atrial fibrillation (68%), followed by atrial flutter (16%) and reentrant tachycardia (16%). The results of the first determination of hs-cTnT were positive (>14 ng/L) in 44.2% of the patients and the second determination was positive in 50.7% of the cases. The variation between the first and the second troponin levels was 1 (0-5) ng/L, and was >7 ng/L in 24.6% of the cases, with a clear trend toward higher troponin values in reentrant tachycardias. Four events were reported at 30 days; in all the cases the patients had presented atrial fibrillation and there were no significant differences in hs-cTnT values. CONCLUSIONS: There are a significant number of patients with supraventricular tachyarrhythmias who present elevated hs-cTnT levels. The association of this elevation with cardiovascular events seems to be very low.


Assuntos
Taquicardia Supraventricular/sangue , Troponina/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade
8.
Cardiol J ; 23(1): 78-83, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26412605

RESUMO

BACKGROUND: The aim of the study was to evaluate the value of high-sensitivity cardiac troponin (hs-cTn) for identifying high-risk patients. METHODS AND RESULTS: One hundred and eighty-seven patients admitted with acute heart failure (HF) (without myocardial infarction) were consecutively included; hs-cTn was measured at admission; the relation between elevated hs-cTn and the clinical outcome during hospitalization and at 90 days was analyzed; 93% (n = 174) had hs-cTn above the maximal normal value (14 ng/L); median hs-cTn was 42 ng/L (IQR 24-81). Patients with ejection fraction (EF) ≤ 45% had higher hs-cTn values (p = 0.0004). Patients with low cardiac output syndrome (LCOS) or shock had higher troponin levels compared with those with less severe clinical presentations (p = 0.004). Patients who required inotropic presented higher troponin values (p = 0.002), troponin values were also higher in those requiring complex therapies (intra-aortic balloon pump, mechanical ventilation or hemodialysis, p = 0.002). At 90-day follow-up, 28 (15.5%) patients died and 27 rehospitalizations occurred (55 events). The risk of events was greater in patients with hs-cTn > 42 ng/L (0.021), low blood pressure at admission (p = 0.002), LCOS or shock (p < 0.0001), EF ≤ 45% (p = 0.005) and inotropic use (p < 0.0001). In multivariate analysis, only inotropic agents requirements was associated independently with a high risk of death or rehospitalizations at 90 days (p = 0.007). CONCLUSIONS: Elevation of hs-cTn is a finding almost constant in patients with decompensated HF. In subjects with higher troponin levels ventricular dysfunction is frequent. The use of hs-cTn for risk stratification at admission helps to identify populations with poor outcome during hospitalization and increased risk of death or rehospitalizations during follow-up who will require rapid implementation of aggressive treatment.


Assuntos
Insuficiência Cardíaca/sangue , Troponina/sangue , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , Argentina/epidemiologia , Biomarcadores/sangue , Feminino , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/terapia , Hospitalização , Humanos , Estimativa de Kaplan-Meier , Masculino , Valor Preditivo dos Testes , Prevalência , Prognóstico , Modelos de Riscos Proporcionais , Medição de Risco , Fatores de Risco , Fatores de Tempo , Regulação para Cima
9.
J Prosthet Dent ; 114(3): 447-55, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26001492

RESUMO

STATEMENT OF PROBLEM: The outcomes from load-to-failure tests may not be applicable to clinical situations. PURPOSE: The purpose of this study was to critically evaluate the efficacy of load-to-failure tests in the investigation of the fracture load and pattern of metal-free crowns. MATERIAL AND METHODS: Four groups were formed from 128 bovine roots restored with metal posts, resin cores, and feldspathic, leucite, or lithium disilicate ceramic systems or polymer crowns. Each group was divided into 4 (n=8) according to the cement: zinc phosphate, self-adhesive resin, autopolymerizing resin, and glass ionomer. Mean fracture loads from compressive tests were submitted to ANOVA and Tukey HSD test. Finite element and fractographic analyses were performed and associated with the fracture load and pattern. RESULTS: Significantly higher fracture load values were obtained for the lithium disilicate ceramic, but finite element and fractographic analyses showed that the cement effect could not be determined. The finite element analysis showed the cement likely affected the fracture pattern, confirmed that stresses in the cements were little affected by the crown materials, and found that the stressed conditions were lowest in the lithium disilicate compared with other crowns for all cement combinations. The stressed conditions in the crowns depended more on the adhesive properties than on the elastic modulus of the cement materials. The level of the stressed condition in the crowns at the occlusal surface was about the same or higher than along their cement interface, consistent with the fractography, which indicated fractures starting at the load point. Higher stress levels in the crowns corresponded with a lower number of catastrophic fractures, and higher stresses in the cements seemed to reduce the number of catastrophic fracture patterns. The highest stressed conditions occurred along the occlusal surface for crown materials with a low elastic modulus or in combination with adhesive cements. CONCLUSIONS: The method used was not appropriate either for investigating the crowns' fracture load and pattern or for stating the role of the cements within the crown-cement-tooth interaction.


Assuntos
Cimentação , Coroas , Cimentos Dentários , Falha de Restauração Dentária , Fraturas dos Dentes , Silicatos de Alumínio , Animais , Bovinos , Cerâmica/síntese química , Cerâmica/química , Porcelana Dentária , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Cimentos de Ionômeros de Vidro , Humanos , Teste de Materiais , Técnica para Retentor Intrarradicular , Cimentos de Resina
10.
Pacing Clin Electrophysiol ; 38(2): 196-200, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25469647

RESUMO

BACKGROUND: Vernakalant is an available drug for the treatment of recent-onset atrial fibrillation, producing conversion between 55% and 87% of the patients treated. In this sense, little is known about the predictors of conversion with this agent. The aim of our study was to analyze the predictors of conversion in our 2-year experience using vernakalant for the treatment of recent-onset atrial fibrillation. METHODS: One hundred twenty-one patients with recent-onset atrial fibrillation without hemodynamic impairment received pharmacological treatment with vernakalant. Clinical variables, history of cardiovascular diseases, and echocardiographic data were recorded. RESULTS: Mean age was 58.1 ± 13.9 years and 13.4% of patients had structural heart disease. Conversion to sinus rhythm was achieved in 84.5% of patients, and 46% required the second dose of vernakalant. After analyzing the predictors of conversion, the presence of structural heart disease was significantly larger in the group without conversion (35.3 vs 9.7%; P = 0.02). The mean ejection fraction in the group with conversion was 61.05 ± 5.7% versus 54.9 ± 8.4% in the group without conversion (P = 0.016). After dichotomizing the variable ejection fraction, patients with ejection fraction <55% had a lower conversion rate (P = 0.001). CONCLUSION: In our study, the absence of any kind of structural heart disease and preserved systolic function were associated with greater conversion rate with vernakalant.


Assuntos
Anisóis/uso terapêutico , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/tratamento farmacológico , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/tratamento farmacológico , Pirrolidinas/uso terapêutico , Antiarrítmicos/uso terapêutico , Fibrilação Atrial/complicações , Feminino , Insuficiência Cardíaca/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , Resultado do Tratamento
11.
Pediatr Pulmonol ; 49(12): 1170-6, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24500941

RESUMO

BACKGROUND: The PIKO-6® is an electronic device that measures forced expiratory volume at seconds 1 (FEV1) and 6 (FEV6) of a forced vital capacity (FVC) maneuver. This device could aid in diagnosing obstructive respiratory diseases. OBJECTIVES: To determine the concordance of FEV1, FEV6, and the FEV1/FEV6 quotient achieved with PIKO-6® versus spirometric values from asthmatic patients, and compare results with measures from healthy children. METHODS: A cross-sectional study with asthmatic and healthy 6-to-14-year-old children, all of whom performed a forced spirometry as well as a PIKO-6® test. RESULTS: The study included 82 subjects (58 asthmatics, 24 healthy children). Except for the functional parameters, the basal characteristics of the two groups were similar. The concordance correlation coefficient (CCC) for FEV1 was 0.938 (P < 0.001), with 95% limits of agreement of -0.591 to 0.512 L, and an average of differences of -0.040 L. For FEV6, CCC was 0.927 (P < 0.001), and the 95% limits of agreement were -0.751 to 0.598 L with an average of differences of -0.077 L. The concordance analysis and the FEV1 and FEV6 associations were better in children with controlled asthma and healthy subjects, as well as in the post-bronchodilator results. CONCLUSIONS: The concordance between PIKO-6® and spirometry was lower in patients with partially controlled or uncontrolled asthma compared to controlled or healthy children. The broad limits of agreement show that the FEV1, FEV6, and FEV1/FEV6 obtained with the PIKO-6® are not interchangeable with spirometry results. Longitudinal evaluations of asthma patients are necessary to assess the utility of PIKO-6®.


Assuntos
Asma/fisiopatologia , Volume Expiratório Forçado/fisiologia , Espirometria/instrumentação , Estudos de Casos e Controles , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Espirometria/métodos , Capacidade Vital/fisiologia
12.
Gen Dent ; 62(1): 74-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24401355

RESUMO

Amelogenesis imperfecta is a hereditary condition that can alter the thickness, color, and shape of tooth enamel. Recent adhesive materials and techniques have provided less invasive treatment options. This case report presents the treatment of a patient whose anterior teeth had color alterations, white spots, pits, and shape defects. Using a more conservative technique, the mandibular and maxillary anterior teeth were restored using veneer direct composite restorations. After 6 years, the restorations demonstrated no deterioration, and no pathology was seen in association with the rehabilitation.


Assuntos
Amelogênese Imperfeita/cirurgia , Restauração Dentária Permanente/métodos , Adolescente , Amelogênese Imperfeita/complicações , Resinas Compostas/uso terapêutico , Facetas Dentárias , Estética Dentária , Feminino , Humanos , Descoloração de Dente/etiologia , Descoloração de Dente/cirurgia
14.
J. bras. neurocir ; 23(4): 332-336, 2013.
Artigo em Português | LILACS | ID: lil-699464

RESUMO

Os paragangliomas, tumores formados por células potencialmente produtoras de catecolaminas, são lesões raras no SNC e ainda mais raras na cauda equina. Menos de 100 casos são descritos na literatura e isto os torna afecções muito pouco pensadas como diagnóstico diferencial de lesões nesta região. O presente relato descreve o caso de um paciente admitido em crise hipertensiva severa secundário a paraganglioma funcionante com localização na cauda equina. Após ressecção cirúrgica, houve completa estabilização do quadro hemodinâmico e melhora do paciente, com alta no 5º PO.


Assuntos
Cauda Equina , Neoplasias , Paraganglioma
15.
J Prosthodont ; 20(6): 447-55, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21843228

RESUMO

PURPOSE: This in vitro study investigated the null hypothesis that metal-free crowns induce fracture loads and mechanical behavior similar to metal ceramic systems and to study the fracture pattern of ceramic crowns under compressive loads using finite element and fractography analyses. MATERIALS AND METHODS: Six groups (n = 8) with crowns from different systems were compared: conventional metal ceramic (Noritake) (CMC); modified metal ceramic (Noritake) (MMC); lithium disilicate-reinforced ceramic (IPS Empress II) (EMP); leucite-reinforced ceramic (Cergogold) (CERG); leucite fluoride-apatite reinforced ceramic (IPS d.Sign) (SIGN); and polymer crowns (Targis) (TARG). Standardized crown preparations were performed on bovine roots containing NiCr metal dowels and resin cores. Crowns were fabricated using the ceramics listed, cemented with dual-cure resin cement, and submitted to compressive loads in a mechanical testing machine at a 0.5-mm/min crosshead speed. Data were submitted to one-way ANOVA and Tukey tests, and fractured specimens were visually inspected under a stereomicroscope (20×) to determine the type of fracture. Maximum principal stress (MPS) distributions were calculated using finite element analysis, and fracture origin and the correlation with the fracture type were determined using fractography. RESULTS: Mean values of fracture resistance (N) for all groups were: CMC: 1383 ± 298 (a); MMC: 1691 ± 236 (a); EMP: 657 ± 153 (b); CERG: 546 ± 149 (bc); SIGN: 443 ± 126 (c); TARG: 749 ± 113 (b). Statistical results showed significant differences among groups (p < 0.05) represented by different lowercase letters. Metal ceramic crowns presented fracture loads significantly higher than the others. Ceramic specimens presented high incidence of fractures involving either the core or the tooth, and all fractures of polymer crown specimens involved the tooth in a catastrophic way. Based on stress and fractographic analyses it was determined that fracture occurred from the occlusal to the cervical direction. CONCLUSIONS: Within the limitations of this study, the results indicated that the use of ceramic and polymer crowns without a core reinforcement should be carefully evaluated before clinical use due to the high incidence of failure with tooth involvement. This mainly occurred for the polymer crown group, although the fracture load was higher than normal occlusal forces. High tensile stress concentrations were found around and between the occlusal loading points. Fractographic analysis indicated fracture originating from the load point and propagating from the occlusal surface toward the cervical area, which is the opposite direction of that observed in clinical situations.


Assuntos
Coroas , Porcelana Dentária/química , Análise de Elementos Finitos , Óxido de Alumínio/química , Silicatos de Alumínio/química , Animais , Apatitas/química , Bis-Fenol A-Glicidil Metacrilato/química , Bovinos , Ligas de Cromo/química , Resinas Compostas/química , Análise do Estresse Dentário , Adesivos Dentinários/química , Cimentos de Ionômeros de Vidro/química , Compostos de Lítio/química , Teste de Materiais , Ligas Metalo-Cerâmicas/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Técnica para Retentor Intrarradicular/instrumentação , Compostos de Potássio/química , Cimentos de Resina/química , Cimento de Silicato/química , Estresse Mecânico , Fraturas dos Dentes/fisiopatologia , Cimento de Fosfato de Zinco/química
16.
Gen Dent ; 58(4): e162-7, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20591764

RESUMO

This study evaluated the water sorption (WS), solubility (SL), and biaxial flexural strength (BFS) of a resin composite based on different polymerization units, storage permeants (distilled water and 75% ethanol), and distances between the light's tip and the composite resin. Using a stainless steel mold, 80 specimens were made and separated in two independent groups, according to the duration of storage (7 days or 60 days). The specimens were photocured using either a QTH or LED light (both used at 600 mW/cm2 for 40 seconds), with the light's tip guide either 0 mm or 2 mm from the surface of the resin. In general, the 75% ethanol produced higher WS and SL values but lower BFS values compared to water. Both distances influenced the WS and SL values, especially when 75% ethanol was used (p < 0.05), although neither distance affected BFS values (p > 0.05). For nearly all groups, the WS, SL, and BFS in different solvents and at different distances for photocuring of the tested resin were not affected by the curing light used.


Assuntos
Bis-Fenol A-Glicidil Metacrilato/efeitos da radiação , Resinas Compostas/efeitos da radiação , Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários/métodos , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cura Luminosa de Adesivos Dentários/instrumentação , Teste de Materiais , Solventes/química , Água/química , Molhabilidade
17.
Dent Mater J ; 28(6): 671-8, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20019417

RESUMO

Finite element analysis (FEA) was used to investigate the influence of different post systems on the stress distribution of weakened teeth under oblique-load application. A maxillary central incisor root obtained from a sound tooth was weakened by partial removal of dentin inside the root canal. Seven two-dimensional numerical models, one from the sound tooth and six from the weakened root restored with composite resin and post systems were created as follows - ST: sound tooth; CPC: cast CuAl post and core; SSP: stainless steel post + composite core; GP: fiberglass + composite core; CP: carbon fiber + composite core; ZP: zirconium dioxide post + composite core; TP: titanium post + composite core. The numerical models were considered to be restored with a leucite-reinforced all-ceramic crown and received a 45 masculine occlusal load (10 N) on the lingual surface.All the materials and structures were considered linear elastic, homogeneous, and isotropic, with the exception of fiberglass and carbon fiber posts which assumed orthotropic behavior. The numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using von Mises and Sy stress criteria. When compared with the sound tooth, FEA revealed differences in stress distribution when post systems were used. Among the restored teeth, the use of CPC, SSP, ZP, and TP resulted in higher stress concentration in the post itself when compared to GP and CP. Therefore, results from the FEA images suggested that the use of non-metallic post systems could result in improved mechanical behavior for the weakened restored teeth.


Assuntos
Resinas Compostas/química , Materiais Dentários/química , Análise de Elementos Finitos , Técnica para Retentor Intrarradicular/instrumentação , Raiz Dentária/fisiopatologia , Dente não Vital/fisiopatologia , Alumínio/química , Silicatos de Alumínio/química , Força de Mordida , Carbono/química , Fibra de Carbono , Simulação por Computador , Cobre/química , Ligas Dentárias/química , Porcelana Dentária/química , Planejamento de Prótese Dentária , Módulo de Elasticidade , Vidro/química , Humanos , Incisivo/fisiopatologia , Teste de Materiais , Modelos Biológicos , Aço Inoxidável/química , Estresse Mecânico , Propriedades de Superfície , Titânio/química , Zircônio/química
18.
Indian J Dent Res ; 20(2): 153-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19553714

RESUMO

BACKGROUND: Post design and material has very important effects on dentinal stress distribution since the post placement can create stresses that lead to root fracture. MATERIALS AND METHODS: In this study we use finite element analysis (FEA) to evaluate stress distribution on endodontically treated maxillary central incisors that have been restored with different prefabricated posts. Six models were generated from the image of anatomical plate: Four metallic posts (ParaPost XH, ParaPost XT, ParaPost XP, and Flexi-Flange) and one fiberglass post (ParaPost Fiber Lux). The sixth model was a control-a sound maxillary central incisor. We used CAD software and exported the models to ANSYS 9.0. All the materials and structures were considered elastic, isotropic, homogeneous, and linear except the fiberglass post which was considered orthotropic. The values for the mechanical properties were obtained by a review of the literature and the model was meshed with 8-node tetrahedral elements. A load of 2N was applied to the lingual surface at an angle of 135 degrees. RESULTS: The stress results were recorded by shear stress and von Mises criteria; it was observed that there was no difference for stress distribution among the titanium posts in the radicular portions and into posts. There was higher stress concentration on the coronary portion with the titanium posts than with the glass fiber post. It seems that the metallic posts' external configuration does not influence the stress distribution. CONCLUSION: Fiber posts show more homogeneous stress distribution than metallic posts. The post material seems to be more relevant for the stress distribution in endodontically treated teeth than the posts' external configuration.


Assuntos
Planejamento de Prótese Dentária , Análise de Elementos Finitos , Incisivo/fisiopatologia , Maxila/fisiopatologia , Técnica para Retentor Intrarradicular/instrumentação , Silicatos de Alumínio/química , Fenômenos Biomecânicos , Resinas Compostas/química , Simulação por Computador , Projeto Auxiliado por Computador , Coroas , Materiais Dentários/química , Porcelana Dentária/química , Dentina/fisiopatologia , Elasticidade , Vidro/química , Humanos , Teste de Materiais , Modelos Biológicos , Compostos de Potássio/química , Software , Estresse Mecânico , Titânio/química , Raiz Dentária/fisiopatologia , Dente não Vital/fisiopatologia
19.
J Prosthodont ; 17(2): 114-119, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17971112

RESUMO

PURPOSE: The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. MATERIALS AND METHODS: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). RESULTS: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 +/- 25.4); G2 (52.7 +/- 20.2); G3 (82.1 +/- 24.9); G4 (40.2 +/- 14.2); G5 (64.5 +/- 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. CONCLUSIONS: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.


Assuntos
Dente Pré-Molar/fisiopatologia , Resinas Compostas/química , Restauração Dentária Permanente , Fraturas dos Dentes/fisiopatologia , Dente não Vital/fisiopatologia , Fenômenos Biomecânicos , Força Compressiva , Simulação por Computador , Preparo da Cavidade Dentária/métodos , Restauração Dentária Permanente/métodos , Análise de Elementos Finitos , Guta-Percha/uso terapêutico , Humanos , Teste de Materiais , Maxila , Modelos Biológicos , Materiais Restauradores do Canal Radicular/uso terapêutico , Obturação do Canal Radicular/métodos , Preparo de Canal Radicular/métodos , Estresse Mecânico , Dente não Vital/terapia
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