Microbiological analysis of bacterial sealing of internal conical implants with different taper angles

Abstract The present study evaluated the effect of the taper angle of different internal conical connection implants and cyclic loading on the implant-abutment bacterial seal. A total of 96 implant-abutment sets were divided into eight groups. Four groups of different taper degrees with cyclic mechanical loading of 500,000 cycles per sample, with a 120-N load at 2 Hz before analysis [16DC (16-degree, cycled), 11.5DC (11.5-degree, cycled), 3DC (3- degree, cycled) and 4DC (4- degree, cycled)] were compared to four control groups without cyclic loading [16D (16-degree), 11.5D (11.5-degree), 3D (3-degree), and 4D (4-degree)]. Microbiological analysis was performed by immersing all samples in a suspension containing Escherichia coli and incubating them at 37°C. After 14 days, the presence of bacterial seals was evaluated. Fisher-Freeman-Halton exact tests and binomial tests were performed (5% significance level). The groups showed significant differences in bacterial seal, and mechanical load cycling improved the bacterial seal in the 3DC group. In all other groups, no significant differences in bacterial seal were found between cycled and uncycled samples. To conclude, the internal conical connection with a 3-degree taper angle showed better results than the other connection with different angles when subjected to load cycling. However, none of the angles tested were fully effective in sealing the implant-abutment interface.

Análise comparativa pelo método dos elementos finitos da distribuição de tensões em pilares de próteses fixas implantossuportadas por implantes distais retos e inclinados / Comparative finite element analysis of stress distribution on abutments of fixed dentures supported by vertical and tilted posterior implants

Introdução: o conceito all-on-four preconiza a inclinação dos implantes distais com o objetivo de reduzir o cantiléver distal. Objetivo: avaliar a biomecânica através da análise com elementos finitos tridimensionais, a inclinação dos implantes distais e a utilização de componentes protéticos angulados e retos no tratamento de mandíbulas edêntulas. Métodos: quatro modelos tridimensionais de mandíbula foram criados simulando tecido ósseo cortical e medular. Foram instalados nos modelos quatro implantes paralelos com componentes protéticos retos, dois implantes retos com os dois implantes distais inclinados em 17 ou 30° com componentes protéticos retos ou angulados. Todos os modelos foram carregados axialmente ou obliquamente bilateral, ou unilateralmente em toda a extensão da prótese. Resultados: o uso de implantes retos e os componentes angulados apresentaram maiores concentrações de tensões. A inclinação distal dos implantes favoreceu a distribuição de tensões. Conclusão: o conceito all-on-four com o uso de componentes protéticos retos favorece a biomecânica de reabilitações totais implantossuportadas.