Single-session use of mineral trioxide aggregate as an apical barrier in a case of external root resorption.

External root resorption may occur as a consequence of trauma, orthodontic treatment, bacterial infection or incomplete sealing of the root canal system (bacterial re-infection), and lead to crater formation on the resorbed apex. This would deform the root apex surface, and cause loss of apical constriction. Depending on the extent of the resorptive process, different treatment regimens have been proposed. A 34-year-old male patient presented with an intra-radicular retainer and an inadequate filling on tooth #21, as well as a radiographic image suggesting periapical bone rarefaction. After root canal retreatment, the defect was accessed coronally. The resorption area was chemo-mechanically debrided and since the apical end was very wide, a calcium sulphate matrix was made. Mineral trioxide aggregate (MTA) was used to fill the resorptive defect, and the coronal access was temporarily sealed. After 24 h, the quality of the apical seal was evaluated with the aid of an operating microscope, and then the root canal system was filled. A 12-month follow-up radiograph showed adequate repair of the resorption. Clinically, the tooth was asymptomatic. We concluded that MTA can be successfully used to avoid overextension of the filling material when treating a tooth with external resorption.

Monitoring Saccharomyces cerevisiae populations by mtDNA restriction analysis and other molecular typing methods during spontaneous fermentation for production of the artisanal cachaça

An ecological study on Saccharomyces cerevisiae populations in spontaneous fermentation has been conducted in three vats of a cachaça distillery in Minas Gerais, Brazil. Ninety-seven yeast isolates were collected at the beginning, the middle and at the end of the production period, and were identified by standard methods. Differentiation between the indigenous S. cerevisiae strains isolated was performed by mitochondrial DNA (mtDNA) restriction analysis, RAPD-PCR, and PCR fingerprint using an intron splice primer. Analysis of the mtDNA restriction profiles revealed 12 different patterns, 11 corresponding to indigenous yeasts (I to XI) and one (XII) to a commercial strain of the bakery yeast. Pattern II (53.6 percent of the population) and pattern IV strains were present in all the vats. Pattern IV strain raised from the middle to the end of the period reaching proportions near those of pattern II strain. PCR methods allowed the differentiation of 41 molecular profiles. Both methods showed population fluctuation of S. cerevisiae strains along the period of cachaça production and among different vats of the distillery.

Um estudo ecológico das populações de Saccharomyces cerevisiae em fermentações espontâneas foi conduzido em três dornas de uma destilaria de cachaça em Minas Gerais, Brasil. Noventa e sete isolados foram coletados no início, meio e final do período de produção, e identificados por métodos padrões. A diferenciação entre as linhagens isoladas de S. cerevisiae indígenas foi feita pela analise de restrição do DNA mitocondrial (mtDNA), RAPD-PCR, e PCR por impressão digital do DNA utilizando um iniciador complementar a sítios de processamento de íntron. As análises dos perfis de restrição do mtDNA mostraram a ocorrência de 12 perfis diferentes, sendo 11 correspondentes as leveduras indígenas (I ao XI) e um (XII) a uma linhagem comercial de levedura de panificação. Linhagens com o perfil II (53,6 por cento da população) e o perfil IV estiveram presentes em todas as dornas. A linhagem com perfil IV aumentou do meio para o final do período de fermentação, alcançando proporções próximas a aquelas encontradas para a linhagem com o perfil II. Os métodos baseados em PCR permitiram a diferenciação de 41 perfis moleculares. Ambos os métodos mostraram flutuações populacionais nas linhagens de S. cerevisiae durante o período de produção da cachaça e entre as diferentes dornas da destilaria.