Identifiable range of osseointegration of dental implants through resonance frequency analysis.

This paper aims to determine the identifiable stiffness range of interfacial tissue of dental implants by means of resonance frequency analysis. Two structural models of the Implant-Tissue-Bone system are built and the lowest two resonance frequencies of these two models are analyzed by Finite Element Method in the software Abaqus. The effects of four key parameters, i.e. the geometry, boundary constrain, material property of the bone and the interfacial tissue, to the resonance frequencies are examined in great detail. An intensive parametric study is conducted to reveal quantitative relationships between the resonance frequencies and these parameters. It is found that when the Young's modulus of the interfacial tissue is less than 15MPa, the resonance frequencies are dominantly affected by the interfacial tissue but not the other three parameters. This finding is extremely important to imply that the lowest two resonance frequencies of the Implant-Tissue-Bone system can be accurately determining the osseointegration of dental implants without worrying about all the other factors, as long as the Young's modulus of the interfacial tissue is in the range of 1-15MPa. However, beyond this range the measured resonance frequencies are affected by all these parameters, and need to be properly interpreted.

Actinomadura miaoliensis sp. nov., a thermotolerant polyester-degrading actinomycete.

An actinomycete, strain BC 44T-5(T), with the ability to degrade poly(d-3-hydroxybutyrate) was isolated from a soil sample collected from Miaoli County, Taiwan. The isolate displayed substrate mycelia and short spore chains were borne on the aerial mycelia. Spores were non-motile, round, 1 mum in diameter and spiny. The aerial spore mass was blue. Strain BC 44T-5(T) had meso-diaminopimelic acid as the diagnostic diamino acid of the cell-wall peptidoglycan. Whole-cell sugars of the novel strain were identified as glucose, galactose and madurose. Diphosphatidylglycerol and phosphatidylinositol were detected. The predominant menaquinones were MK-9(H(4)) and MK-9(H(2)). Mycolic acids were not detected. Major cellular fatty acids were iso-C(16 : 0) (14.82 %), C(16 : 0) (14.63 %), C(17 : 0) (13.79 %) and 10-methyl-C(17 : 0) (23.77 %.) The DNA G+C content of strain BC 44T-5(T) was 70.6 mol%. On the basis of phenotypic and genotypic data, it is proposed that strain BC 44T-5(T) (=FIRDI 002(T)=BCRC 16873(T)=LMG 24335(T)) should be classified as the type strain of a novel species of the genus Actinomadura, Actinomadura miaoliensis sp. nov.