Cephalometric and three-dimensional assessment of superior posterior airway space after maxillomandibular advancement

The purpose of this study was to quantify cephalometric and three-dimensional alterations of the posterior airway space of patients who underwent maxillomandibular advancement surgery. 20 patients treated by maxillomandibular advancement were selected. The minimal postoperative period was 6 months. The treated patients underwent cone-beam computed tomography at 3 distinct time intervals, preoperative (T1), immediate postoperative period up to 15 days after surgery (T2), and late postoperative period at least 6 months after surgery. The results showed that the maxillomandibular advancement promoted an increase in the posterior airway space in each patient in all the analyses performed, with a statistically significant difference between T2 and T1, and between T3 and T1, p < 0.05. There was a statistical difference between T2 and T3 in the analysis of area and volume, which means that the airway space became narrower after 6 months compared with the immediate postoperative period. The maxillomandibular advancement procedure allowed great linear area and volume increase in posterior airway space in the immediate and late postoperative periods, but there was partial loss of the increased space after 6 months. The linear analysis of airway space has limited results when compared with analysis of area and volume.

Healing process of dog teeth after post space preparation and exposition of the filling material to the oral environment

Foi propósito deste estudo analisar a influência da infiltração marginal coronária no comportamento dos tecidos periapicais de dentes de cães após obturação de canal e preparo para pino. Quarenta canais de dentes de cães foram instrumentados e obturados pela técnica da condensação lateral com cones de guta percha e os cimentos Roth e Sealer 26. Após preparo para pino, o remanescente da obturação foi protegido ou não com um plug do cimento temporário Lumicon. Após exposição ao meio oral por 90 dias, os animais foram sacrificados e as peças preparadas para análise histomorfológica. A técnica de Brown e Brenn mostrou 70% de casos com infiltração de microrganismos para o cimento Roth e 20% com o Sealer 26. Quando um plug de Lumicon foi empregado ocorreu 30% de casos de infiltração de microrganismos com o cimento Roth e 0,0% com o cimento Sealer 26. Reação inflamatória crônica foi mais freqüentemente observada com o cimento Roth do que com o Sealer 26. Foi concluído que o plug de Lumicon é eficiente no controle da infiltração coronária (p=0.05) e que o Sealer 26 foi mais biocompatível e selou melhor os canais radiculares do que o cimento Roth (p=0.01).

Comparison of space analysis performed on plaster vs. digital dental casts applying Tanaka and Johnston's equation

OBJETIVO: comparar medidas de tamanhos dentários, suas reprodutibilidades e a aplicação da equação de regressão de Tanaka e Johnston na predição do tamanho dos caninos e pré-molares em modelos de gesso e digital. MÉTODOS: trinta modelos de gesso foram escaneados para obtenção dos modelos digitais. As medidas do comprimento mesiodistal dos dentes foram obtidas com paquímetro digital nos modelos de gesso e nos modelos digitais utilizando o software O3d (Widialabs). A somatória do tamanho dos incisivos inferiores foi utilizada para obter os valores de predição do tamanho dos pré-molares e caninos utilizando equação de regressão, e esses valores foram comparados ao tamanho real dos dentes. Os dados foram analisados estatisticamente, aplicando-se aos resultados o teste de correlação de Pearson, a fórmula de Dahlberg, o teste t pareado e a análise de variância (p < 0,05). RESULTADOS: excelente concordância intraexaminador foi observada nas medidas realizadas em ambos os modelos. O erro aleatório não esteve presente nas medidas obtidas com paquímetro, e o erro sistemático foi mais frequente no modelo digital. A previsão de espaço obtida pela aplicação da equação de regressão foi maior que a somatória dos pré-molares e caninos presentes nos modelos de gesso e nos modelos digitais. CONCLUSÃO: apesar da boa reprodutibilidade das medidas realizadas em ambos os modelos, a maioria das medidas dos modelos digitais foram superiores às do modelos de gesso. O espaço previsto foi superestimado em ambos os modelos e significativamente maior nos modelos digitais.

Cephalometric Evaluation of Pharyngeal Airway Space Changes in Class III Patients Undergoing Orthognathic Surgery

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Periapical radiographs overestimate root canal wall thickness during post space preparation

Aim To evaluate differences between anatomic and radiographic measurements of root canal wall thickness (RCWT) after each root canal preparation stage during post placement.Methodology Twenty mandibular premolars with a single canal were decoronated and the roots embedded in resin using a teflon muffle. Roots were sectioned horizontally at a pre-established level and canals were prepared for post placement. Endodontic hand files were used for root canal preparation, followed by Gates Glidden drills and Peeso reamers. Standardized radiographs and photographs at pre-established measurement levels were taken before preparation, after root canal instrumentation, after Gates Glidden preparation and after Peeso enlargement. All images were digitized and RCWT at the mesial and distal walls measured (IMAGETOOL 3.0). Differences between radiographic and anatomic measurements were analysed with paired t-tests. ANOVA was used to compare the percentages of radiographic distortions.Results Regardless of the time-point evaluated, RCWT determined by radiographs were greater than the respective anatomic measurements (P < 0.05). The difference detected at each stage was similar and constant (P > 0.05).Conclusions Throughout preparation for post placement, radiographic images overestimated the RCWT by approximately 25%, regardless of the clinical stage evaluated.

Some experiments with high order compact methods using a computer algebra software - Part I

We consider a procedure for obtaining a compact fourth order method to the steady 2D Navier-Stokes equations in the streamfunction formulation using the computer algebra system Maple. The resulting code is short and from it we obtain the Fortran program for the method. To test the procedure we have solved many cavity-type problems which include one with an analytical solution and the results are compared with results obtained by second order central differences to moderate Reynolds numbers. (c) 2005 Elsevier B.V. All rights reserved.

Some experiments with high order compact methods using a computer algebra software - Part II (non-uniform grid)

We generalize a procedure proposed by Mancera and Hunt [P.F.A. Mancera, R. Hunt, Some experiments with high order compact methods using a computer algebra software-Part 1, Appl. Math. Comput., in press, doi: 10.1016/j.amc.2005.05.015] for obtaining a compact fourth-order method to the steady 2D Navier-Stokes equations in the streamfunction formulation-vorticity using the computer algebra system Maple, which includes conformal mappings and non-uniform grids. To analyse the procedure we have solved a constricted stepped channel problem, where a fine grid is placed near the re-entrant corner by transformation of the independent variables. (c) 2006 Elsevier B.V. All rights reserved.

A study of a numerical solution of the steady two dimensions Navier-Stokes equations in a constricted channel problem by a compact fourth order method

We present a numerical solution for the steady 2D Navier-Stokes equations using a fourth order compact-type method. The geometry of the problem is a constricted symmetric channel, where the boundary can be varied, via a parameter, from a smooth constriction to one possessing a very sharp but smooth corner allowing us to analyse the behaviour of the errors when the solution is smooth or near singular. The set of non-linear equations is solved by the Newton method. Results have been obtained for Reynolds number up to 500. Estimates of the errors incurred have shown that the results are accurate and better than those of the corresponding second order method. (C) 2002 Elsevier B.V. All rights reserved.

Feeding selectivity of ichthyofauna in a tropical stream: space-time variations in trophic plasticity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On turbulent, erratic and other dynamical properties of Zadeh's extensions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Purification, crystallization and preliminary X-ray diffraction analysis of a class P-III metalloproteinase (BmMP-III) from the venom of Bothrops moojeni

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Boundary of the rauzy fractal sets in R x C generated by P(x)=x(4)-x(3)-x(2)-x-1

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Configuration-dependent diffusion can shift the kinetic transition state and barrier height of protein folding

We show that diffusion can play an important role in protein-folding kinetics. We explicitly calculate the diffusion coefficient of protein folding in a lattice model. We found that diffusion typically is configuration- or reaction coordinate-dependent. The diffusion coefficient is found to be decreasing with respect to the progression of folding toward the native state, which is caused by the collapse to a compact state constraining the configurational space for exploration. The configuration- or position-dependent diffusion coefficient has a significant contribution to the kinetics in addition to the thermodynamic free-energy barrier. It effectively changes (increases in this case) the kinetic barrier height as well as the position of the corresponding transition state and therefore modifies the folding kinetic rates as well as the kinetic routes. The resulting folding time, by considering both kinetic diffusion and the thermodynamic folding free-energy profile, thus is slower than the estimation from the thermodynamic free-energy barrier with constant diffusion but is consistent with the results from kinetic simulations. The configuration- or coordinate-dependent diffusion is especially important with respect to fast folding, when there is a small or no free-energy barrier and kinetics is controlled by diffusion. Including the configurational dependence will challenge the transition state theory of protein folding. The classical transition state theory will have to be modified to be consistent. The more detailed folding mechanistic studies involving phi value analysis based on the classical transition state theory also will have to be modified quantitatively.

Determining the shape of the universe using discrete sources

Suppose we have identified three clusters of galaxies as being topological copies of the same object. How does this information constrain the possible models for the shape of our universe? It is shown here that, if our universe has flat spatial sections, these multiple images can be accommodated within any of the six classes of compact orientable three-dimensional flat space forms. Moreover, the discovery of two more triples of multiple images in the neighbourhood of the first one would allow the determination of the topology of the universe, and in most cases the determination of its size.

Momentum-space non-hydrogenic wavefunction of quantum defect theory

We derive a closed-form analytic expression in momentum space for the asymptotic non-hydrogenic wavefunction of the quantum defect theory (QDT) due to Seaton and compare it with a widely used QDT-approximate wavefunction for the Rydberg states Li-3(2s), Mg-24(6s) and Rb-37(5s).