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Evaluation of bone stress distribution around thinly hydroxyapatite coated dental implant using finite element analysis

Ozeki K., Fukunaga K., Yaguchi T., Funakubo A., Asaoka T., Fukui Y., Aoki H.

Biocybernetics and Biomedical Engineering

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2007

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Vol. 27, no. 1-2

89-94

EN

Dental implants were coated with hydroxyapatite (HA) by the sputtering technique. The influences of the HA film thickness on the bone stress distribution was investigated using the three-dimensional finite element analysis. In this analysis, force of 100 N axial load was applied on the non-coated, thickly HA coated, and thinly HA coated titanium implants The maximum equivalent bone stresses were 21.5, 8.55 and 6.33 MPa for the non-coated, thickly HA coated, and thinly HA coated cylinder type implants, respectively. The bone stress of the screw type implants was 29.0, 9.20 and 9.03 MPa, respectively. The maximum bone stress of the thinly HA coated implant was lower than in the other implants. Eight types of the implant shape for the thinly HA coated implant were also designed, and the tiered neck type implant showed the lowest maximum bone stress in all the types.

2

Hydroxyapatite coated dental implants by sputtering technique

Ozeki K., Fukui Y., Aoki H.

Biocybernetics and Biomedical Engineering

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2006

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Vol. 26, no. 1

95-101

EN

Hydroxyapatite (HA) was coated onto titanium substrates using radio frequency sputtering, and the coated HA films were crystallized in autocIave at 110°C using the low temperature hydtrothermal method. In pull-out tests, the adhesion strength of the sputtered film to the substrate increased from 1.9 : 0.2 to 5.3 : 1.6 MPa after the hydrothermal treatment. Sputtered films subjected to the hydrothermal treatment and plasma-sprayed coating on titanium columns were implanted in the diaphysis of the femora of six adult dogs, and pull-out tests were carried out after two, four, and 12 weeks. The sputtered film showed a higher bone bonding strength than the plasma-sprayed coating at the same periods. The coated implants were also placed into mandibles for 2,4, 12 and 24 weeks for histological examination. In the histological examination, connective tissue was noted after 2 and 4 weeks around the controls, whereas, in the sputter-coated implant, new bone formation was noted after 2 and 4 weeks, without any connective tissue.

3

Intramolecular ion-channel sensors using gold electrodes immobilized with macrocyclic polyamines for voltammetric detection of adenine nucleotides

Radecka H., Szymańska I., Pietraszkiewicz M., Pietraszkiewicz O., Aoki H., Umezawa Y.

Chemia Analityczna

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2005

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Vol. 50, No. 1

85-102

EN

Here, we report on two types of intramolecular ion-channel sensors using self-assembled monofayers deposited onto gold electrodes for electrochemical detection of adenosine nucleotides. In the first, macrocyclic polyamine molecules with -SH groups were bound directly on the gold surface (covalent modification). In the second, the macrocyclic polyamine molecules with long alkyl chains were adsorbed into the monolayer of 1 -dodecanethiol on the gold surface (embedment modification). These two types of electrodes have been used for the voltammetric ion-channel sensing of adenosine triphosphate (ATP4-, adenosine diphosphate (ADP3-), adenosine monophosphate (AMP2-) and inorganic phosphate.The signals generated due to formation of supramolecular complexes between macrocyclic polyamine hosts and adeninę nucleotide guests at the electrode interface were measured bycyclic voltammetry and Osteryoung square-wave voltammetry with [Ru(NH36]3+ as an elec-troactive marker. The selectivity and sensitivity of the presented sensors were comparedwith those ion selective electrodes (ISEs) incorporated with the same and similar macrocyclic polyamines.

PL

Omówiono dwa typy czujników z wewnątrzcząsteczowymi kanałami jonowymi wykorzystującymi samo-uporządkowane monowarstwy osadzone na złotej elektrodzie, służące do oznaczania nukteotydów adeninowych. W pierwszym typie czujników makrocykliczna poliamina z gmpami-SH jest bezpośrednio związana kowalencyjnie ze ziotąpowierzchnią, w drugim - cząsteczki makrocyklicznej poliaminy z długimi łańcuchami alkilowymi są umocowane adsorbcyjniewmonowarstwie 1-dodekanolioluznajdującegosięnapowierzchni złota. Te dwa typy elektrod stosowano do woltamperometrycznego wykrywania trifosforanu adenozyny, difosforanu adenozyny, monofosforanu adenozyny i fosforanu nieorganicznego. Sygnały, powstające przy powierzchni elektrody wskutek tworzenia się kompleksów supramolekularnych miedzy makrocykliczna poliaminą. - gospodarzem, a nukleotydem adeniny - gościem, były mierzone metodami cyklicznej woltamperometrii i woltampero-metrii prostokątne falowej wg Osteryounga z [Ru(NH36]3++ jako elektroaktywnym markerem. Selektywność i czułość przedstawionych czujników porównano z elektrodami jonoselektywnymi (ISEs) wykorzystującymi te same lub podobne makrocykliczne poliaminy.