Comparing different bar materials for mandibular implant-supported overdenture: Finite-element analysis

Aim: This study was conducted aiming to optimize the selection of bar material that can minimize stresses on mandibular bone. Subjects and Methods: One finite-element model was created under ANSYS environment to evaluate the use of different materials as a bar-manufacturing material in mandibular implant-supported overdenture (OD). Model components were created on engineering computer-aided design software and then assembled under the finite-element package. A force of 200 N was unilaterally and vertically applied on the left second premolar area. Results: Within these study conditions, the polyether ether ketone bar produced the lowest Von Mises stress on OD and the maximum value of deformation. Stainless steel bar produced the maximum OD total deformation. Conclusions: Cortical and spongy bones are not sensitive to the bar material. Increasing bar material stiffness increases Von Mises stresses in the bar itself and reduces its total deformation, in what is called overconstrained system.

Combined spontaneous bacterial empyema and peritonitis in cirrhotic patients with ascites and hepatic hydrothorax

Background and study aims: Spontaneous bacterial empyema [SBEM] is an underestimated condition in patients with ascites and hepatic hydrothorax with a high mortality. This study aimed to find whether spontaneous bacterial peritonitis [SBP] is a prerequisite for SBEM

Patients and methods: 3000 HCV-related cirrhotic patients with ascites and hydrothorax were screened for the presence of SBP [ascitic fluid neutrophils >250/mm[3]] and SBEM [positive pleural fluid culture and neutrophils >250/mm[3] or negative pleural fluid culture and neutrophils >500/mm[3] with no evidence of pneumonia/parapneumonic effusion on chest radiograph or CT]

Results: The prevalence of SBEM in cirrhotic patients was 1.2% [36/3000] unlike SBP [1.6%; 48/3000]. SBEM was detected in 51.4% of the patients with hepatic hydrothorax [36/70]. A total of 70 patients had concomitant ascites and hydrothorax, namely SBP [n = 17], SBEM [n = 5], and dual SBP and SBEM [n = 31], whereas 17 patients had sterile concomitant ascites and hydrothorax. Age, sex, liver function, kidney function tests, complete blood count, INR, MELD, MELD-Na, blood chemistry, and culture/sensitivity for ascitic and pleural fluid were statistically not different [p > 0.05] between SBP and dual SBP and SBEM patients. Escherichia coli and Klebsiella pneumoniae were detected in the culture. From univariate analysis, no predictors of dual SBP and SBEM were detected

Conclusion: SBEM is a part of SBP in cirrhotic patients with ascites and hydrothorax

Finite Element Study on Continuous Rotating versus Reciprocating Nickel-Titanium Instruments

Abstract In the present study, GTX and ProTaper as continuous rotating endodontic files were numerically compared with WaveOne reciprocating file using finite element analysis, aiming at having a low cost, accurate/trustworthy comparison as well as finding out the effect of instrument design and manufacturing material on its lifespan. Two 3D finite element models were especially prepared for this comparison. Commercial engineering CAD/CAM package was used to model full detailed flute geometries of the instruments. Multi-linear materials were defined in analysis by using real strain-stress data of NiTi and M-Wire. Non-linear static analysis was performed to simulate the instrument inside root canal at a 45° angle in the apical portion and subjected to 0.3 N.cm torsion. The three simulations in this study showed that M-Wire is slightly more resistant to failure than conventional NiTi. On the other hand, both materials are fairly similar in case of severe locking conditions. For the same instrument geometry, M-Wire instruments may have longer lifespan than the conventional NiTi ones. In case of severe locking conditions both materials will fail similarly. Larger cross sectional area (function of instrument taper) resisted better to failure than the smaller ones, while the cross sectional shape and its cutting angles could affect instrument cutting efficiency.

Resumo As limas rotativas GTX e ProTaper foram comparadas numericamente com as limas reciprocatórias WaveOne pela análise de elementos finitos, com o objetivo de baixar custos, comparação fiel e exata, além de pesquisar o efeito do projeto das limas e de seu material sobre a durabilidade. Dois modelos tridimensionais de análise de elementos finitos foram especialmente elaborados para esta comparação. Utilizou-se um sistema de engenharia CAD/CAM comercial para construir o modelo totalmente detalhado da geometria das estrias das limas. Materiais multi-lineares foram definidos na análise usando dados reais de deformação por estresse de NiTi e M-Wire. Procedeu-se à análise estática não linear para simular a ação do instrumento dentro do canal radicular em ângulo de 45° na região apical, submetido a uma torsão de 0.3 N.cm. As três simulações realizadas no presente estudo demonstraram que o M-Wire é um pouco mais resistente a falhas que o NiTi convencional. Por outro lado, ambos os materiais são bastante similares em condições de travamento severo. No caso da geometria das limas, os instrumentos de M-Wire podem ter vida útil mais longa que os de NiTi convencional. Em condições de travamento severo, ambos os materiais terão falhas similares. Maior área transversal (em função da conicidade do instrumento) resiste melhor a falhas que as áreas transversais menores, ao passo que a geometria da área transversal e seus ângulos de corte podem afetar a eficiência de corte das limas.

Influence of implant-abutment angulations and crown material on stress distribution on central incisor: a 3D FEA

Aim: To investigate the effect of implant-abutment angulation and crown material on stress distribution of central incisors. Finite element method was used to simulate the clinical situation of a maxillary rightcentral incisor restored by two different implant-abutment angulations, 15° and 25°, using two different crown materials (IPS E-Max CAD and zirconia). Methods: Two 3D finite element models were specially prepared for this research simulating the abutment angulations. Commercial engineering CAD/CAM package was used to model crown, implant abutment complex and bone(cortical and spongy) in 3D. Linear static analysis was performed by applying a 178 N oblique load.The obtained results were compared with former experimental results. Results: Implant Von Misesstress level was negligibly changed with increasing abutment angulation. The abutment with higherangulation is mechanically weaker and expected to fail at lower loading in comparison with thesteeper one. Similarly, screw used with abutment angulation of 25° will fail at lower (about one-third)load value the failure load of similar screw used with abutment angulated by 15°. Conclusions: Bone (cortical and spongy) is insensitive to crown material. Increasing abutment angulation from15° to 25°, increases stress on cortical bone by about 20% and reduces it by about 12% onspongy bone. Crown fracture resistance is dramatically reduced by increasing abutment angulation. Zirconia crown showed better performance than E-Max one.

A finite element study on the mechanical behavior of reciprocating endodontic files

To evaluate the mechanical behavior of reciprocating endodontic files, comparing nickel-titanium NiTi and stainless steel 316L St.St. 316L as manufacturing material for such instruments. METHODS: A three-dimensional finite element model was designed for this study. The simplified instrument model geometry was created on commercial CAD/CAM software. Real strain stress curves of St.St. 316L and NiTi were used in the analysis. Non-linear static analysis was performed to simulate the instrument inside root canal at an angle of 45° in the apical portion, and subjected to torsion of 0.3 N.cm. RESULTS: Non-linear NiTi material showed super elasticity and high functionality in such applications. Very high levels of stress appeared in the file at 3 mm from the tip close to yield point. CONCLUSIONS: St. St. 316L is not suitable for manufacturing reciprocating instruments. Modeling of the instrument with equivalent circular cross-sectional area did not affect results quality. Reciprocating instruments have short lifespan, thus manufacturers recommend using one file per tooth. Reciprocating instruments are recommended for less experienced dentist...

Segurança e eficácia dos stents farmacológicos eluidores de biolimus com polímero biodegradável: análise do registro EINSTEIN (Evaluation of Next-generation drug-eluting STEnt IN patients with coronary artery disease) / Safety and efficacy of biolimus-eluting stent with biodegradable polymer: insights from EINSTEIN (Evaluation of Next-generation drug-eluting STEnt IN patients with coronary artery disease) Registry

OBJETIVO: Avaliar a incidência de eventos adversos cardíacos maiores (morte cardíaca, infarto agudo do miocárdio ou necessidade de nova revascularização do vaso-alvo) em 1 ano em pacientes do "mundo real". MÉTODOS: O registro EINSTEIN é um estudo observacional prospectivo, unicêntrico, que incluiu consecutivamente 103 pacientes (152 lesões) tratados com o stent BiomatrixTM, eluidor de biolimus A9 e polímero biodegradável. RESULTADOS: A média das idades foi de 65,0±12,4 anos; o gênero masculino representou 83,5% dos pacientes; e 37,9% deles eram diabéticos. Em 1 ano, eventos adversos cardíacos maiores ocorreram em 11,7% dos pacientes, incluindo 2,9% de morte cardíaca, 4,9% de infarto agudo do miocárdio sem supradesnivelamento do segmento ST e 3,9% de revascularização do vaso-alvo. Trombose de stent esteve presente em apenas 1% (1 paciente) após o seguimento clínico de 1 ano. CONCLUSÃO: O presente registro sugere que os novos stents farmacológicos eluidores de biolimus A9 com polímero biodegradável são seguros e eficazes em pacientes da prática clínica diária, com baixas taxas de eventos adversos cardíacos maiores no longo prazo.

OBJECTIVE: To evaluate the incidence of major adverse cardiac events (cardiac death, or acute myocardial infarct, or target vessel revascularization) at one year in "real world" patients. METHODS: The EINSTEIN registry is an observational, prospective, single center study that consecutively included 103 patients (152 lesions) treated with the BiomatrixTM stent, a biolimus A9-eluting stent with biodegradable polymer. RESULTS: The mean age was 65.0±12.4 years; male gender represented 83.5% of the patients; and 37.9% of them were diabetic. At one-year, major adverse cardiac events occurred in 11.7% of the patients, including 2.9% of cardiac death, 4.9% of with non ST- segment elevation acute myocardial infarction, and 3.9% of target vessel revascularization. Stent thrombosis occurred in only 1% (1 patient) at one-yearfollow-up. CONCLUSION: The present Registry suggests that new generation biolimus A9 drug-eluting stents are safe and effective in a "real world", all-comers patients, showing low rates of major cardiac adverse events on long-term follow-up.

Estradiol in men with severe acne

This study assessed serum concentrations of estradiol, free testosterone, total testosterone, dihydrotestosterone, dehydroepiandrosterone sulfate and sex hormone binding globulin in 18 patients aged 19-27 years with severe acne including three patients with nodulo-cystic acne as well as 20 age matched normal controls. There were no significant differences in serum levels of all these hormones between patients and controls, except for serum E2 level which was significantly higher in patient group. So, hemodynamics of serum androgens in male patients with acne do not differ significantly from that of normal controls. Elevated E2 levels might affect the inflammatory response of acne