ترمیم با آمالگام

The aim of this research was to evaluate the effect of surface treatment, clinical performance and the condition and position of the dental restoration on the corrosion behavior of dental amalgam. Commercial amalgam namely Oralloy was selected to prepare 21 flat amalgam samples. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of the three clinical procedures carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the inter-proximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was placed on the internal mold surfaces and amalgam paste was compacted in the mold and 14 cylindrical samples were prepared. Electrochemical tests were performed at a temperature of 37±1oC in normal saline in order to determine the corrosion behavior of dental amalgam samples. Tafel extrapolation and linear polarization methods determined corrosion potential and corrosion current densities. The mean value and standard deviations of the results were calculated. The mean values were statistically compared by ANOVA and Duncan methods at 95% level of confidence. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam(P<0.05). The carved group showed more corrosion resistance in comparison with the sample near the matrix band (P<0.05) as an index of the proximal surfaces of the dental restorations. Even a simple clinical performance could effect on the corrosion resistance of dental amalgam. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance.

Amalgam restorations often tarnish and corrode in the oral environment. The degree of tarnish and the resulting discoloration appear to be dependent on the parameters such as oral environment, oral hygiene, and the particular alloy employed and clinical procedures. The aim of this research was to evaluate and compare the effect of clinical procedures such as carving, carving-burnishing and carving-burnishing-polishing on the tarnish and corrosion behavior of four brand dental amalgams. Method & Materials: Four different type of commercial amalgam alloy powders with different powders with various particles shape (lathe cut, spherical, spheroids) namely Sybraloy (Sy), Cinalux (CL), Oralloy (Or) and cinaalloy (Ca) were studied. A special mold was used to prepare the samples of each type of commercial amalgams. Twenty-one samples of each type of amalgams were prepared. After trituration and condensation, the samples of each type of amalgams were divided into three groups and each group was finished by using one of three procedures carving, carving-burnishing, carving-burnishing-polishing. Electrochemical potentiodynamic tests were performed at a temperature of 37±1 °C in order to determine and compare the corrosion behavior of dental amalgams, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current densities values of three different groups of each type of commercial amalgam (P<0.05). The polished group of each type of commercial amalgams possesses the lowest corrosion current density and the carved group shows the highest corrosion current density (the lowest corrosion resistance). This trend was not affected by the brand and chemical composition of commercial amalgams. The polished Sybraloy amalgam possesses the highest corrosion resistance between four types of polished amalgams and the polished Cinaaloy amalgam showed the lowest corrosion resistance. The similar trend was observed in carved group and carved-burnished group of four types of amalgams. It was concluded that the clinical operations and procedures could influence the tarnish and corrosion behavior of high copper dental amalgams. Polishing procedure increases the corrosion resistance of high copper dental amalgams and is more effective on the corrosion behavior of dental amalgams, which are less corrosion resistant in compare with the dental amalgams that are more corrosion resistant.

Statement of Problem: Microleakage presents the major cause for restorations failure in the oral cavity resulting in postoperative sensitivity, pulp irritation and secondary caries formation. The aim of this study was to compare two dentinal adhesive systems of fifth generation and copalite varnish in reducing microleakage of amalgam restorations in primary teeth. In this in-vitro study, 100 class V amalgam restorations were prepared on the buccal or lingual surfaces of primary molar and canine teeth. Samples were randomly divided into four groups (25 samples each). No liner was used for the first group and the second group restorations were lined with copalite varnish. Two dentin adhesives, called Syntac C and Single Bond, were used for the third and fourth groups, respectively. At the next stage, the samples were immersed in 5% fuschin solution for 24 hours, then sectioned buccolingually, and examined under a stereomicroscope for microleakage evaluation. There was a significant difference between four groups statistically (PO.000I), Comparing four groups, the first and fourth ones, demonstrated the most and the least microleakage, respectively. The present study showed that new dentinal adhesive systems caused microleakage reduction in amalgam restorations of primary teeth.