Resumo Introdução Streptococcus mutans (S. mutans) apresentam ampla diversidade genotípica, mas o papel desta variação ainda é pouco compreendido. Objetivo Avaliar a diversidade genotípica de S. mutans em pré-escolares com e sem assistência odontológica precoce e associá-la à experiência de cárie dentária. Material e método Participaram da pesquisa 20 crianças, de cinco anos de idade, com história de assistência odontológica desde o primeiro ano de vida (G1) e 20 crianças sem história de assistência odontológica precoce (G2). A experiência de cárie dentária foi avaliada por meio do índice ceo-d. Amostras de S. mutans foram isoladas a partir da saliva dos participantes e analisadas pela Reação em Cadeia da Polimerase para identificação molecular da espécie. Um total de 339 isolados bacterianos (173 do G1 e 166 do G2) foram genotipados através da Amplificação ao Acaso de DNA Polimórfico, utilizando-se os primers OPA-02 e OPA-13. Resultado Os resultados revelaram 75 diferentes genótipos de S. mutans no G1 e 73 no G2. Além disso, as crianças do G1 e G2 abrigaram em sua cavidade bucal de um a oito e de um a sete genótipos distintos de S. mutans, respectivamente. Foram observadas uma associação estatisticamente significante (P=0.021) e uma moderada correlação (r=0,503) entre a diversidade genotípica de S. mutans e a experiência de cárie somente no G1. Conclusão A partir das limitações do desenho do estudo, os resultados apenas sugerem que as ações realizadas por meio de um atendimento odontológico precoce podem estar contribuindo para o estabelecimento de uma microbiota bucal distinta.

Abstract Introduction Streptococcus mutans (S. mutans) exhibits extensive genotypic diversity, but the role of this variation is poorly understood. Objective To evaluate the genotypic diversity of S. mutans in preschoolers with and without early dental care and to associate it with dental caries experience. Material and method Twenty children, aged five year old, with history of dental care since they were one year old (G1) and 20 children without history of dental care (G2) were included. Their oral health status was assessed by the dmft index. S. mutans samples were isolated from the saliva and analysed by polymerase chain reaction. A total of 339 S. mutans isolates (173 from G1 and 166 from G2) were genotyped by random amplified polymorphic DNA with arbitrary primers OPA-02 and OPA-13. Result The results revealed 75 distinct genotypes of S. mutans in G1 and 73 in G2. Furthermore, G1 and G2 subjects harboured one to eight and one to seven distinct genotypes of S. mutans, respectively. A statistically significant association (P=0.021) and a moderate correlation (r= 0.503) were observed between dental caries experience and genotypic diversity of S. mutans in G1. Conclusion From the limitations of the study design, we just can hypothesize that actions of early dental care carried out by an educative-preventive program can contribute to a distinct oral microbiota.

Ostrich eggshells are a potentially abundant and a high purity and low cost source of calcium to produce β-Tricalcium Phosphate (β-TCP) and Hydroxyapatite (HA), important calcium phosphates used as biomaterials. Here, we use a wet precipitation procedure to synthesize these phosphates using ostrich eggshells as a source of calcium ions. The biphasic precipitated powder, calcined at 800ºC, is a mixture of both Hydroxyapatite and β-Tricalcium Phosphate, also known as the biomaterial Biphasic Calcium Phosphate (BCP). Physico-chemical properties of the final powder product show water and CO32- groups absorbed in the particles surface, 0.1 to 100 µm particles size distribution and 11.70 m2/g of specific surface area.

A comparison between silica by acid leaching of rice husk (RH) and silica obtained from thermal treatment of rice husk ash (RHA) is presented. The best leaching results were obtained using 10% hydrochloric acid followed by washing with water. The alternative method, calcination of RHA at 700 ºC for 6 h followed by grinding for 80 min, was more effective. Silica obtained from RH was about 97% amorphous, had a 17.37 µm mean particle size, and a specific surface area of 296 m²/g. On the other hand, for silica obtained from RHA the values were about 95% amorphous material 0.68 µm, and 81 m²/g.