ABSTRACT
Objective@#To evaluate the influence of different heat treatments on the corrosion behavior of a new Pd-Ag-In-Ga alloy. @*Methods @#The corrosion of a new Pd-Ag-In-Ga alloy was tested according to ISO 10271：2001/cor.1:2005(E). Taken as comparison, a commercial high-palladium alloy (Spartan® Plus) was also employed in the study. For electrochemical corrosion test, the open-circuit potential (Eocp) and potentiodynamic polarization curve were recorded and then the electrochemical parameters, namely corrosion potential (Ecorr) and corrosion current density (Icorr) calculated. The surfaces of the specimens that before and after corrosion test were observed by scanning electron microscopy (SEM). @* Results @#Both of the high-palladium alloys had lower corrosion tendency and higher corrosion resistance by heat treatment in the ISO 10271 electrochemical corrosion test. For both alloys, heat treatment at 500 ℃ was found to be effective in improving the corrosion resistance as the best datas of electrochemical parameters (Eocp, Ecorr, Icorr) were detected among the four temperature groups. However, no evidence showed that there was significant difference in corrosion resistance between the two alloys. Comparison of surface morphology of the specimens before and after electrochemical experiments by SEM demonstrated that all groups of the two alloys were visible of pitting corrosion and crevice corrosion phenomenon that gradually became less with increasing heat treatment temperature. Horizontal comparing among the groups of the two alloys, no apparent differences in the distribution of pitting and crevice corrosion was found. @*Conclusin @#The variation in compositions of high-palladium alloys did not cause significant difference in corrosion behavior due to the identical palladium matrix. The similarity in corrosion behavior among the two high-palladium alloys might be attributed to the predominant palladium content.
ABSTRACT
Objective@#To analyze the stress difference of alveolar bone around the abutment and alveolar ridge of edentulous of three different kinds of root-attachment-supported overdenture under different load conditions, in order to provide a reference for the choice of clinical root attachment. @*Methods @#The occlusal force of overdenture was simulated by electrical resistance strain measurement in vitro. The stress of the alveolar bone, the central part of the mandibular arch and the first molar correspond to the alveolar ridge were measured. The stress difference of 3 kinds of attachment overdenture under different loading conditions were compared and analyzed.@*Results@#Under the same loading condition, all three kinds of overdentures had a certain degree of slip of the denture (magnetic attachment denture) or rotation (3 kinds of attachment dentures). The abutment neck in different parts of the dental arch and alveolar bone, anterior free end edentulous alveolar ridge stress distribution was significantly different. @*Conclusion@# ERA attachment overdenture was the most preferable, followed by the magnetic attachment overdenture. Suitable attachment should be selected based on specific clinical cases.