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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-27 5:18 |
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Conference: Bucharest University Faculty of Physics 2008 Meeting
Section: Polymer Physics
Title:
Hypersensibility of I- degree. Study of the surface phenomena in order to improve biocompatibility of Ni-Cr alloy
Authors:
E. Gatin*, B. Iordache**, Lidia Ciobanu**
Affiliation:
* University of Bucharest, Faculty of Physics
**University of Medicine ‘Carol Davila’ Bucharest, Faculty of Stomatology
E-mail
Keywords:
denture, ceramics, composite, alloy Ni-Cr, polarization, corrosion
Abstract:
After a tooth has been damaged or destroyed, restoration of the missing structure can be achieved with a variety of treatments. Restorations may be realized from a variety of materials, such as: amalgam, gold, porcelain, composite. When a tooth is lost, dentures, bridges of metal alloys, or implants may be used as replacements. Bridges replace smaller spaces of missing teeth and use adjacent teeth to support the restoration. Also, in many cases for restoration, a dentist must obtain resistance and physiognomy in the same time. For this purpose it is used a combination of materials, such as: a metal alloy (or a metal) crown for resistance and then, porcelain (crown) for physiognomy. A large variety of metal alloys is used, such as: nickel-chromium, cobalt-chromium, gold-platinum or silver-platinum. A large interest is for nickel-chromium alloy, because it is well known, its low cost to use it for restoration structures. There were observed side effects for Ni-Cr alloy restorations, such as: corrosion and surface deposits, causing allergy (hyper sensibility of I degree). For this reason, electrochemical processes on Ni-Cr sample surface, on different medium conditions (simple saliva, saliva-yeast, saliva-yeast-bacteria) and sample surface quality as well, have been investigated. Polarization curves, for each case have been evaluated and following parameters have been determined: intensity of corrosion current, polarization resistance and pitting potential. The presence of bacteria, improves the rate of corrosion for Ni-Cr alloy. The defects on alloy surface improve plaque bacteria deposits and the rate of corrosion as well. As a special request, for the improvement of the results, an Impedance Spectroscopy investigation (ESI) must be performed. The purpose of the present investigation is the deep knowledge of surface processes of Ni-Cr alloy restoration works in oral cavity and to establish some directions (of metal treatment) for a better compatibility of metal alloy, to avoid allergy.
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