| Objective:Dentition defects were the common diseases. Because of the development of living standard of the people, casting frame-type denture has become the main method of removable partial denture when they suffer from such diseases. Owing to the superior mechanical properties, advancement in Casting Technology and low price, Co-Cr alloy has been widely used in prosthodontics. Oral cavity is the beginning of the digestive tract, with air, food and drinking directly into it, and these factors make it a complex ecological environment, and such factors affect the release of metal ions from the metal restoration. The role of microorganisms, changes of temperature in oral environment, mechanical action (mastication and brushing), eating habits, oral sanitation etc., also influence the release of metal ion. Among them, the corrosion of alloy by metabolic products of microorganisms is a key factor, and consequently the metal ion released may result in various adverse effects. Dental plaque biofilm which adhere to the restoration can cause caries and periodontal tissue inflammation by the microbe-derived metabolic product. Domestic and foreign scholars have explored some ways of modifying alloy surface properties in recent years, such as coating titanium nitride films, coating organic gold paste and gold-plating, and got satisfactory results. By reason of the proven technique, simple operation procedure needed, good esthetic effects, superior corrosion-resistance and low price, gold-plating treatment has been widely used.So far, gold-plated treatment is used mostly for the porcelain-fused-to-metal crown, while less for casting frame-type denture, moreover, experimental research mostly focuses on the change of surface corrosion resistance by gold-plated technology, but seldom on the influence of microorganism adhesion to restorations surface. This experiment provide a basis for application of gold-plated treatment, by comparing the amount of bacteria attached on the surface of experimental group which was electroplated with gold coating treatment and control group non-coated in simulation of oral environment.Methods:1. Co-Cr alloy was processed for20specimens, and randomly divided into two groups:experimental group which was electroplated with gold coating treatment and control group non-coated. Streptococcus mutans was cultured with the2groups of specimens for24h. The amount of bacteria attached on the surface of the samples was measured by the method of clone forming unit (CFU).2. Co-Cr alloy was processed for30specimens, and divided into three groups by processing mode. Then all the specimens were electroplated with gold coating treatment. Streptococcus mutans was cultured with the3groups of specimens for24h. The amount of bacteria attached on the surface of the samples was measured by the method of clone forming unit (CFU).Results:1. The amount of bacteria attached on the surface of experimental group was reduced to the control group (P<0.05).2. There is significant difference between the amount of bacteria attached on the surface of three groups (P<0.05), and groups are significantly different each other.Conclusion:1. The gold-plated layer of Co-Cr alloy surface may reduce streptococcus mutans adhesion.2. The surface roughness of the specimens before being electroplated with gold coating treatment is important for the adhesion of bacteria. |
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