Effect of particle geometry of alloys on corrosion resistance in copper enriched amalgams

Amalgam restorations often tarnish and corrode in a hostile oral environment. Corrosion of dental amalgam can produce galvanism in a mouth having amalgam restorations. Ion release as a result of corrosion is most important. Amalgams are categorized as high copper amalgam and conventional amalgam. The latter having copper content less than 6%, corrode more and have limited use nowadays. There are many factors that can produce corrosion in amalgam restorations. This study is performed to assess the effect of shape and size of the particles of an alloy on the corrodibility of various high copper amalgams. Samples were prepared using three high copper amalgams having particles of various size and shape. The samples were tested for rate of corrosion using electrochemical corrosion testing apparatus. The data was collected and analyzed applying ANOVA. The results reveal that corrosion resistance of lathecut amalgam was significantly higher than spherical and admixed amalgams. High copper Lathe-cut amalgam has higher corrosion resistance than other amalgams

Amalgam repair: efficacy of spherical-particle amaljcam as repair material

Repair of faulty or broken amalgam restorations is a routine procedure carded out in dental practices. Various factors affect the bond strength of repaired restorations. One of such factors is the type of amalgam alloy used to repair the restoration. This study was conducted to determine which type of alloy produces highest bond-strength. One hundred twenty samples were prepared from conventional, admixed and lathe-cut amalgams [40 samples from each type]. Equal number of these samples was repaired with spherical-particle amalgam, conventional amalgam, admixed amalgam and lathe-cut amalgam using amalgambond [a 4-META dentine adhesive] as a bonding material. Tensile bond-strength of the samples was tested on electro-mechanical testing machine at cross head speed of 10 mm per minute at Pakistan Ordnance factory, Wah Cantonment. To determine the significance of the findings, Anova [one-way] was applied. revealed that spherical amalgam produces highest bond-strength. The p- values <0.05 were cons4dered significant. The samples repaired with spherical amalgam [p-value p<0.0001] show highly significant bond strength