치과 임플란트의 임상사용 전후에 전기화학적 안정성 평가
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- Successful implant therapy requires a dynamic equilibrium between biological and mechanical factors. The biological factors are generally considered multifactorial, whereas mechanical factors has been associated with instability of implant fixture, abutment and abutment screw. Interface defects between the implant fixture screw, electrochemical methods. Implant system( abutment screws, abutment screw and abutment after function may be associated with Implant failure.
In this study, evaluation of electrochemical stability of implant system(in vivo and in vitro) has been researched by using abutment and titanium fixture;frialit) were retrieved from patients after clinically used for 5 years. The unused implant systems were prepared for control group. Surfaces of implant systems observed by using FE-SEM and EDS after cross-section of were retrieved implant systems. In order to manufacture implant systems like a clinically used one, type III gold alloy was used for suprastructure of the implant systems. To simulate an oral environment, the samples of clinically used and non-used implant systems as a working electrode were exposed to artificial saliva at 36.5±1oC. In potentiodynamic method, the potentials were controlled at a scan rate of 1.66mV/sec by a potentiostat(EG&G Co, PARSTAT 2273, USA). The electrochemical impedance spectroscopy was performed (10 mHz to 100 kHz) in artificial solution at 36.5±1oC. After electrochemical test, the corrosion morphology of each sample was investigated by FE-SEM and EDS.
Before corrosion test, surface of clinically used implant system showed severely attacked by oral debris at crevice of interface between fixture, abutment and abutment screw. After corrosion test, corrosion potential (-750mV) and pitting potential(+100mV) of clinically used implant system showed lower than those(-300mV and +1000mV) of non used implant system and clinically used implant system exhibited a lower range of passivation, indicating a lesser degree of inherent resistance against chloride ion. From the observation of the sectioned segments with FE-SEM, surface of clinically used implant system showed a greater extent of crevice corrosion at interface between implant fixture, abutment screw and suprastructure. From impedance tests of implant systems, the polarization resistance(Rp: 9.27×103Ω㎠) decreased in the case of clinically used implant system, whereas, Rp(9.66×102 Ω㎠) for clinically non used implant system increased compared to clinically used implant system.
Conclusively the surface attack after corrosion may result in the implant system instability. Also, we recommend the use of implant system without galvanic characteristics and crevice between fixture, abutment screw, and abutment.
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