Estudo de fatores associados ao lascamento de coroas de zircônia

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Odontologia, Florianópolis, 2011Este estudo teve como objetivo esclarecer o fenômeno de lascamento em próteses a base de zircônia através de testes mecânicos, evidências fractográficas e da mensuração dos estresses residuais na camada de porcelana. Sessenta e quatro copings de zicônia foram fabricados (Cerec3 Inlab, Sirona), sinterizados e jateados com partículas de alumina de 250 µm ou não jateados (n=32). Os copings foram estratificados com duas porcelanas com coeficientes de expansão térmica diferentes (VM9, VITA, CET: avm9=9.1 ppm/°C; LAVA Ceram, 3M ESPE, CET: alava=10.2 ppm/°C) de modo a criar uma incompatibilidade térmica alta ou baixa com a zirconia (YZ Cubes, VITA, CET: azirconia=10.5 ppm/°C) respectivamente. Metade das coroas de cada grupo foram submetidas ao teste de compressão ou ao teste de fadiga cíclica em um simulador de mastigação até a fratura (n=8). Os dados foram tratados seguindo uma distribuição Weibull, onde os parâmetros m, s0 e s5% foram calculados. As superfícies fraturadas das coroas foram avaliadas fractograficamente para determinar padrões discriminativos de estresses residuais dentro das porcelanas e o efeito do jateamento na união entre zircônia e porcelana. Doze coroas adicionais foram fabricadas com as duas porcelanas e resfriadas seguindo um protocolo de resfriamento rápido ou lento (n=3). Fatias de ~1.0 mm de espessura foram cortadas longitudinalmente a partir da região central das coroas (de palatal para vestibular), polidas e transiluminadas por luz polarizada para a mensuração do retardo entre as ondas e obtenção da magnitude e distribuição espacial dos estresses residuais dentro da camada de porcelana. O teste de compressão não indicou diferenças entre os grupos. O teste de fadiga conseguiu discriminar coroas com estresses residuais diferentes, revelando uma resistência característica significativamente maior para coroas estratificadas com Lava Ceram. Uma forte tendência de aumento dos parametros Weibull também foram observados para as coroas que tiveram seus copings jateados. Fraturas do tipo lascamento, similares às encontradas clinicamente, foram observadas apenas no teste de fadiga. As superfícies fraturadas revelaram comportamentos de trinca distintos entre as porcelanas, como consequência de diferentes estados de estresse. A mensuração dos estresses por fotoelastividade obteve sucesso em detectar diferenças de anisotropia ótica entre os grupos. As coroas estratificadas com VM9 apresentaram maior estresse residual que as coroas estratificadas com Lava Ceram, concentrados próximo à interface. A taxa de resfriamento mostrou ter pouca influência na magnitude e distribuição dos estresses. Resultados de fadiga, da análise fractográfica e da birrefringência apresentaram forte correlação.In the swine production, the high nutrient load, coupled with the large volume of wastewater, are the biggest challenges of management activity. Generally, the lack of arable land for disposal of effluent on the ground requires the use of treatment techniques capable of removing high loads of nutrients. There are numerous alternatives for nitrogen removal from wastewater, including anammox process preceded by a system of partial nitritation. The aim of this study was to optimize the operation of anammox reactors with different configurations and perform cargo progression through different operating conditions. Three reactors, called A, B and C, were inoculated and started, in upward flow, temperature controlled at 35 ° C, DO concentration below 0.2 mg L-1, with suspended biomass and used as inoculum biomass with stable anammox activity from a pilot reactor at different concentrations. The starting time of the reactor, inoculated with 1% biomass (v / v) was approximately 100 days, and the reactors B and C, inoculated with 30% biomass (v / v) was approximately 60 days, showing it is possible to start the reactors with low inoculum concentration and higher concentrations significantly reduce the start up time of the system. To prove the veracity of the anammox process in the reactors was monitored the behavior of nitrogen forms, we calculated the stoichiometric coefficients (which were close to those found in literature) and was carried of the FISH analysis with specific probe (AMX 368) (with results positive). Through the kinetic study was determined the specific consumption rates of ammonium and nitrite and nitrate production, which were µN-NH3=47,94mgN-NH3.gSSV-1.d-1; µN-NO2 = 59,39 mgN-NO2 -.gSSV-1.d-1 e µN-NO3 = 14,75 mgN-NO3 -.gSSV-1.d-1. the process was more sensitive to the increased nitrogen concentration that reductions in HRT, the maximum load removed by the reactor A, which operated with increasing concentration was 1.53 KgN.m-3.d-1, to 331 days of operation, being fed 560 mgN.L-1.d-1 and HRT of 6h, and in the reactor C, which operated with reduced HRT was 16.24 KgN.m-3.d-1, to 193 days of operation being fed 200 mgN.L-1.d-1 and HRT of 0.2 h

Limpeza pós-condicionamento e união compósito-cerâmica: avaliação através de uma nova técnica de microtração

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em OdontologiaO objetivo deste estudo foi avaliar a resistência de união à microtração de uma resina composta aderida a duas cerâmicas injetáveis após a realização de diferentes técnicas de limpeza pós-condicionamento para remover os resíduos formados pelo condicionamento com ácido hidrofluorídrico HF à 10%. Trezentos e sessenta espécimes de resina composta (Z250, 3M) foram aderidos à superfície de discos cerâmicos de IPS Empress Esthetic (EE) e IPS Empress 2 (E2) após o condicionamento com HF à 10%, limpeza da superfície, silanização (Scotchbond Ceramic Primer, 3M) e aplicação de um agente adesivo hidrófobo sem carga (Scotchbond Multipurpose Adhesive, 3M). Os espécimes de resina composta foram fabricados utilizando tubos de silicone de 4mm de altura e 0,8mm de luz. Trinta espécimes foram fabricados para técnica de limpeza empregada (n=30): sem limpeza (SL); jato de ar-água por 30 segundos (JAA); condicionamento com ácido fosfórico à 37% por 30 segundos (AF); banho ultrasônico em água destilada por 5 minutos (BU); AF+BU (AFBU) e; aplicação do sistema de silanização auto-condicionante Clearfil Silane Kit (CSK). Através de um método que não utiliza processos mecânicos na produção dos espécimes, os cilindros de resina composta foram submetidos a uma tensão de tração a uma velocidade de 0,5mm/min. Discos cerâmicos suplementares foram fabricados para cada cerâmica e grupo de limpeza e observados no MEV. Análise por espectroscopia de energia dispersiva por raios-x foi realizada para cada grupo e subgrupo para determinar a distribuição química das amostras. O teste ANOVA e o teste de Tukey detectaram diferenças estatísticas entre os subgrupos para E2 (p=0,0325), embora os subgrupos E2JAA, E2AF, E2BU, E2AFBU e E2CSK não tenham apresentado diferenças significativas entre si. Para o grupo EE, os subgrupos EESL e EECSK apresentaram diferenças estatísticas entre os outros grupos e entre si (p<0,05). Testes-t pareados detectaram diferenças estatisticamente significativas entre a cerâmica EE e E2 apenas para os subgrupos SL e CSK. Fotomicrografias do MEV das amostras cerâmicas mostraram que o jato de ar-água é capaz de remover todos os resíduos tanto para EE quanto para E2. O subgrupo CSK não obteve sucesso na dissolução dos resíduos da superfície de ambas as cerâmicas

Fractography of clinically fractured, implant-supported dental computer-aided design and computer-aided manufacturing crowns

Today, a substantial part of the dental crown production uses computer-aided design and computer-aided manufacturing (CAD/CAM) technology. A recent step in restorative dentistry is the replacement of natural tooth structure with pre-polymerized and machined resin-based methacrylic polymers. Recently, a new CAD/CAM composite was launched for the crown indication in the load-bearing area, but the clinical reality forced the manufacturer to withdraw this specific indication. In parallel, a randomized clinical trial of CAD/CAM composite crowns luted on zirconia implant abutments revealed a high incidence of failure within the first year of service. Fractured crowns of this clinical trial were retrieved and submitted to a fractographic examination. The aim of the case series presented in this article was to identify failure reasons for a new type of CAD/CAM composite crown material (Lava Ultimate; 3M Oral Care, St. Paul, Minnesota, USA) via fractographic examinations and analytical assessment of luting surfaces and water absorption behavior. As a result, the debonding of the composite crowns from the zirconia implant abutments was identified as the central reason for failure. The adhesive interface was found the weakest link. A lack of silica at the zirconia surface certainly has compromised the bonding potential of the adhesive system from the beginning. Additionally, the hydrolytic stress released from swelling of the resin-based crown (water absorption) and transfer to the luting interface further added to the interfacial stress and most probably contributed to a great extend to the debonding failure

Replicative Age Induces Mitotic Recombination in the Ribosomal RNA Gene Cluster of Saccharomyces cerevisiae

Somatic mutations contribute to the development of age-associated disease. In earlier work, we found that, at high frequency, aging Saccharomyces cerevisiae diploid cells produce daughters without mitochondrial DNA, leading to loss of respiration competence and increased loss of heterozygosity (LOH) in the nuclear genome. Here we used the recently developed Mother Enrichment Program to ask whether aging cells that maintain the ability to produce respiration-competent daughters also experience increased genomic instability. We discovered that this population exhibits a distinct genomic instability phenotype that primarily affects the repeated ribosomal RNA gene array (rDNA array). As diploid cells passed their median replicative life span, recombination rates between rDNA arrays on homologous chromosomes progressively increased, resulting in mutational events that generated LOH at >300 contiguous open reading frames on the right arm of chromosome XII. We show that, while these recombination events were dependent on the replication fork block protein Fob1, the aging process that underlies this phenotype is Fob1-independent. Furthermore, we provide evidence that this aging process is not driven by mechanisms that modulate rDNA recombination in young cells, including loss of cohesion within the rDNA array or loss of Sir2 function. Instead, we suggest that the age-associated increase in rDNA recombination is a response to increasing DNA replication stress generated in aging cells

Machine learning algorithms performed no better than regression models for prognostication in traumatic brain injury

Objective: We aimed to explore the added value of common machine learning (ML) algorithms for prediction of outcome for moderate and severe traumatic brain injury. Study Design and Setting: We performed logistic regression (LR), lasso regression, and ridge regression with key baseline predictors in the IMPACT-II database (15 studies, n = 11,022). ML algorithms included support vector machines, random forests, gradient boosting machines, and artificial neural networks and were trained using the same predictors. To assess generalizability of predictions, we performed internal, internal-external, and external validation on the recent CENTER-TBI study (patients with Glasgow Coma Scale <13, n = 1,554). Both calibration (calibration slope/intercept) and discrimination (area under the curve) was quantified. Results: In the IMPACT-II database, 3,332/11,022 (30%) died and 5,233(48%) had unfavorable outcome (Glasgow Outcome Scale less than 4). In the CENTER-TBI study, 348/1,554(29%) died and 651(54%) had unfavorable outcome. Discrimination and calibration varied widely between the studies and less so between the studied algorithms. The mean area under the curve was 0.82 for mortality and 0.77 for unfavorable outcomes in the CENTER-TBI study. Conclusion: ML algorithms may not outperform traditional regression approaches in a low-dimensional setting for outcome prediction after moderate or severe traumatic brain injury. Similar to regression-based prediction models, ML algorithms should be rigorously validated to ensure applicability to new populations

Variation in Structure and Process of Care in Traumatic Brain Injury: Provider Profiles of European Neurotrauma Centers Participating in the CENTER-TBI Study.

INTRODUCTION: The strength of evidence underpinning care and treatment recommendations in traumatic brain injury (TBI) is low. Comparative effectiveness research (CER) has been proposed as a framework to provide evidence for optimal care for TBI patients. The first step in CER is to map the existing variation. The aim of current study is to quantify variation in general structural and process characteristics among centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. METHODS: We designed a set of 11 provider profiling questionnaires with 321 questions about various aspects of TBI care, chosen based on literature and expert opinion. After pilot testing, questionnaires were disseminated to 71 centers from 20 countries participating in the CENTER-TBI study. Reliability of questionnaires was estimated by calculating a concordance rate among 5% duplicate questions. RESULTS: All 71 centers completed the questionnaires. Median concordance rate among duplicate questions was 0.85. The majority of centers were academic hospitals (n = 65, 92%), designated as a level I trauma center (n = 48, 68%) and situated in an urban location (n = 70, 99%). The availability of facilities for neuro-trauma care varied across centers; e.g. 40 (57%) had a dedicated neuro-intensive care unit (ICU), 36 (51%) had an in-hospital rehabilitation unit and the organization of the ICU was closed in 64% (n = 45) of the centers. In addition, we found wide variation in processes of care, such as the ICU admission policy and intracranial pressure monitoring policy among centers. CONCLUSION: Even among high-volume, specialized neurotrauma centers there is substantial variation in structures and processes of TBI care. This variation provides an opportunity to study effectiveness of specific aspects of TBI care and to identify best practices with CER approaches

Primary versus early secondary referral to a specialized neurotrauma center in patients with moderate/severe traumatic brain injury: a CENTER TBI study

Funder: ZNS - Hannelore Kohl Stiftung; doi: http://dx.doi.org/10.13039/501100007731Funder: Integra LifeSciences CorporationFunder: OneMindAbstract: Background: Prehospital care for patients with traumatic brain injury (TBI) varies with some emergency medical systems recommending direct transport of patients with moderate to severe TBI to hospitals with specialist neurotrauma care (SNCs). The aim of this study is to assess variation in levels of early secondary referral within European SNCs and to compare the outcomes of directly admitted and secondarily transferred patients. Methods: Patients with moderate and severe TBI (Glasgow Coma Scale < 13) from the prospective European CENTER-TBI study were included in this study. All participating hospitals were specialist neuroscience centers. First, adjusted between-country differences were analysed using random effects logistic regression where early secondary referral was the dependent variable, and a random intercept for country was included. Second, the adjusted effect of early secondary referral on survival to hospital discharge and functional outcome [6 months Glasgow Outcome Scale Extended (GOSE)] was estimated using logistic and ordinal mixed effects models, respectively. Results: A total of 1347 moderate/severe TBI patients from 53 SNCs in 18 European countries were included. Of these 1347 patients, 195 (14.5%) were admitted after early secondary referral. Secondarily referred moderate/severe TBI patients presented more often with a CT abnormality: mass lesion (52% vs. 34%), midline shift (54% vs. 36%) and acute subdural hematoma (77% vs. 65%). After adjusting for case-mix, there was a large European variation in early secondary referral, with a median OR of 1.69 between countries. Early secondary referral was not associated with functional outcome (adjusted OR 1.07, 95% CI 0.78–1.69), nor with survival at discharge (1.05, 0.58–1.90). Conclusions: Across Europe, substantial practice variation exists in the proportion of secondarily referred TBI patients at SNCs that is not explained by case mix. Within SNCs early secondary referral does not seem to impact functional outcome and survival after stabilisation in a non-specialised hospital. Future research should identify which patients with TBI truly benefit from direct transportation

How do 66 European institutional review boards approve one protocol for an international prospective observational study on traumatic brain injury? Experiences from the CENTER-TBI study

Abstract: Background: The European Union (EU) aims to optimize patient protection and efficiency of health-care research by harmonizing procedures across Member States. Nonetheless, further improvements are required to increase multicenter research efficiency. We investigated IRB procedures in a large prospective European multicenter study on traumatic brain injury (TBI), aiming to inform and stimulate initiatives to improve efficiency. Methods: We reviewed relevant documents regarding IRB submission and IRB approval from European neurotrauma centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI). Documents included detailed information on IRB procedures and the duration from IRB submission until approval(s). They were translated and analyzed to determine the level of harmonization of IRB procedures within Europe. Results: From 18 countries, 66 centers provided the requested documents. The primary IRB review was conducted centrally (N = 11, 61%) or locally (N = 7, 39%) and primary IRB approval was obtained after one (N = 8, 44%), two (N = 6, 33%) or three (N = 4, 23%) review rounds with a median duration of respectively 50 and 98 days until primary IRB approval. Additional IRB approval was required in 55% of countries and could increase duration to 535 days. Total duration from submission until required IRB approval was obtained was 114 days (IQR 75–224) and appeared to be shorter after submission to local IRBs compared to central IRBs (50 vs. 138 days, p = 0.0074). Conclusion: We found variation in IRB procedures between and within European countries. There were differences in submission and approval requirements, number of review rounds and total duration. Research collaborations could benefit from the implementation of more uniform legislation and regulation while acknowledging local cultural habits and moral values between countries

Occurrence and timing of withdrawal of life-sustaining measures in traumatic brain injury patients: a CENTER-TBI study

Funder: National Institute for Health Research (UK)Abstract: Background: In patients with severe brain injury, withdrawal of life-sustaining measures (WLSM) is common in intensive care units (ICU). WLSM constitutes a dilemma: instituting WLSM too early could result in death despite the possibility of an acceptable functional outcome, whereas delaying WLSM could unnecessarily burden patients, families, clinicians, and hospital resources. We aimed to describe the occurrence and timing of WLSM, and factors associated with timing of WLSM in European ICUs in patients with traumatic brain injury (TBI). Methods: The CENTER-TBI Study is a prospective multi-center cohort study. For the current study, patients with traumatic brain injury (TBI) admitted to the ICU and aged 16 or older were included. Occurrence and timing of WLSM were documented. For the analyses, we dichotomized timing of WLSM in early (< 72 h after injury) versus later (≥ 72 h after injury) based on recent guideline recommendations. We assessed factors associated with initiating WLSM early versus later, including geographic region, center, patient, injury, and treatment characteristics with univariable and multivariable (mixed effects) logistic regression. Results: A total of 2022 patients aged 16 or older were admitted to the ICU. ICU mortality was 13% (n = 267). Of these, 229 (86%) patients died after WLSM, and were included in the analyses. The occurrence of WLSM varied between regions ranging from 0% in Eastern Europe to 96% in Northern Europe. In 51% of the patients, WLSM was early. Patients in the early WLSM group had a lower maximum therapy intensity level (TIL) score than patients in the later WLSM group (median of 5 versus 10) The strongest independent variables associated with early WLSM were one unreactive pupil (odds ratio (OR) 4.0, 95% confidence interval (CI) 1.3–12.4) or two unreactive pupils (OR 5.8, CI 2.6–13.1) compared to two reactive pupils, and an Injury Severity Score (ISS) if over 41 (OR per point above 41 = 1.1, CI 1.0–1.1). Timing of WLSM was not significantly associated with region or center. Conclusion: WLSM occurs early in half of the patients, mostly in patients with severe TBI affecting brainstem reflexes who were severely injured. We found no regional or center influences in timing of WLSM. Whether WLSM is always appropriate or may contribute to a self-fulfilling prophecy requires further research and argues for reluctance to institute WLSM early in case of any doubt on prognosis

Variation in general supportive and preventive intensive care management of traumatic brain injury: a survey in 66 neurotrauma centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study

Abstract Background General supportive and preventive measures in the intensive care management of traumatic brain injury (TBI) aim to prevent or limit secondary brain injury and optimize recovery. The aim of this survey was to assess and quantify variation in perceptions on intensive care unit (ICU) management of patients with TBI in European neurotrauma centers. Methods We performed a survey as part of the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. We analyzed 23 questions focused on: 1) circulatory and respiratory management; 2) fever control; 3) use of corticosteroids; 4) nutrition and glucose management; and 5) seizure prophylaxis and treatment. Results The survey was completed predominantly by intensivists (n = 33, 50%) and neurosurgeons (n = 23, 35%) from 66 centers (97% response rate). The most common cerebral perfusion pressure (CPP) target was > 60 mmHg (n = 39, 60%) and/or an individualized target (n = 25, 38%). To support CPP, crystalloid fluid loading (n = 60, 91%) was generally preferred over albumin (n = 15, 23%), and vasopressors (n = 63, 96%) over inotropes (n = 29, 44%). The most commonly reported target of partial pressure of carbon dioxide in arterial blood (PaCO2) was 36–40 mmHg (4.8–5.3 kPa) in case of controlled intracranial pressure (ICP) < 20 mmHg (n = 45, 69%) and PaCO2 target of 30–35 mmHg (4–4.7 kPa) in case of raised ICP (n = 40, 62%). Almost all respondents indicated to generally treat fever (n = 65, 98%) with paracetamol (n = 61, 92%) and/or external cooling (n = 49, 74%). Conventional glucose management (n = 43, 66%) was preferred over tight glycemic control (n = 18, 28%). More than half of the respondents indicated to aim for full caloric replacement within 7 days (n = 43, 66%) using enteral nutrition (n = 60, 92%). Indications for and duration of seizure prophylaxis varied, and levetiracetam was mostly reported as the agent of choice for both seizure prophylaxis (n = 32, 49%) and treatment (n = 40, 61%). Conclusions Practice preferences vary substantially regarding general supportive and preventive measures in TBI patients at ICUs of European neurotrauma centers. These results provide an opportunity for future comparative effectiveness research, since a more evidence-based uniformity in good practices in general ICU management could have a major impact on TBI outcome