Centric relation registration: intra- and interexaminer agreement after a calibration program Avaliação da reprodutibilidade intra e interexaminador no registro da relação cêntrica, após um programa de calibração

Centric relation (CR) has been considered a maxillomandibular position of choice for some dental and prosthetic procedures. Although regarded as a fully reproducible relation, there is great controversy about its clinical use and recording technique, especially in patients with signs and symptoms of temporomandibular disorders (TMD). This study aimed at evaluating the effectiveness of a training program on intra- and interexaminer agreement when determining the clinical record of the CR position. Forty individuals constituted the sample, divided into symptomatic (TMD) and asymptomatic groups. Three previously calibrated examiners performed the initial assessment and the second evaluation after 30 days in a blind design, using Dawson’s bilateral manipulation technique with and without an anterior stop. The amount of frontal and sagittal deviations in relation to intercuspal position, the presence of pain and discomfort during manipulation, and the first occlusal contact in CR were analyzed. Kendall and Kappa tests with a 5% level of significance were used to determine agreement. Values for both intra- and interexaminer agreement were deemed good. The best results were obtained for frontal deviations and assessment of pain (or absence of it) during manipulation. Sagittal deviations showed the lowest agreement in both examinations. The authors concluded that a calibration program could be effective for intra- and interexaminer agreement when recording centric relation. However, caution is recommended when analyzing some isolated items.<br>Na tentativa de estabelecer uma posição maxilomandibular reprodutível em pacientes sem dentes suportes posteriores ou portadores de oclusão instável, o conceito de relação cêntrica (RC) foi introduzido. Apesar de ser utilizada como uma posição de referência, existe uma considerável divergência de opiniões sobre a sua reprodutibilidade. Este estudo procurou avaliar se os métodos de treinamento profissional são efetivos na análise e obtenção de RC. Para isso utilizou-se uma amostra de 40 indivíduos, divididos em 20 assintomáticos e 20 portadores de disfunções da ATM. Os indivíduos foram avaliados por 3 examinadores, previamente calibrados. Foram realizados 2 exames: inicial e final (30 dias após o inicial), possibilitando dessa forma, análise da concordância interexaminadores, assim como intra- examinadores. Posteriormente, os resultados foram submetidos à análise estatística, utilizando-se os testes de concordância de Kendall e de Kappa. Os resultados foram considerados bons, sendo os melhores obtidos para a análise do desvio frontal e relato de dor (ou ausência) durante a manipulação. Os autores concluíram que os programas de calibração podem ser efetivos para análise da RC. No entanto, cautela é recomendada quando da análise de alguns itens isolados

On the potential for CO₂ mineral storage in continental flood basalts – PHREEQC batch- and 1D diffusion–reaction simulations

<p>Abstract</p> <p>Continental flood basalts (CFB) are considered as potential CO₂ storage sites because of their high reactivity and abundant divalent metal ions that can potentially trap carbon for geological timescales. Moreover, laterally extensive CFB are found in many place in the world within reasonable distances from major CO₂ point emission sources.</p> <p>Based on the mineral and glass composition of the Columbia River Basalt (CRB) we estimated the potential of CFB to store CO₂ in secondary carbonates. We simulated the system using kinetic dependent dissolution of primary basalt-minerals (pyroxene, feldspar and glass) and the local equilibrium assumption for secondary phases (weathering products). The simulations were divided into closed-system batch simulations at a constant CO₂ pressure of 100 bar with sensitivity studies of temperature and reactive surface area, an evaluation of the reactivity of H₂O in scCO₂, and finally 1D reactive diffusion simulations giving reactivity at CO₂ pressures varying from 0 to 100 bar.</p> <p>Although the uncertainty in reactive surface area and corresponding reaction rates are large, we have estimated the potential for CO₂ mineral storage and identified factors that control the maximum extent of carbonation. The simulations showed that formation of carbonates from basalt at 40 C may be limited to the formation of siderite and possibly FeMg carbonates. Calcium was largely consumed by zeolite and oxide instead of forming carbonates. At higher temperatures (60 – 100 C), magnesite is suggested to form together with siderite and ankerite. The maximum potential of CO₂ stored as solid carbonates, if CO₂ is supplied to the reactions unlimited, is shown to depend on the availability of pore space as the hydration and carbonation reactions increase the solid volume and clog the pore space. For systems such as in the scCO₂ phase with limited amount of water, the total carbonation potential is limited by the amount of water present for hydration of basalt.</p