The Study On The Surface Roughness And The Adhesion Of Streptococcus Mutans Of Dental Resin And Composite Materials

Statement of problem:The surface roughness of three types of resins and a type of composite (self-curing denture acrylic,room temperature curing denture base resin,heat-curing denture base resin,light curing microfilled composite resin) used usually after respective surface finish in clinical observation and the subsequent contamination by Streptococcus mutans.Purpose:This study is to measure the surface roughness of the samples after the respective surface finish and the retention of Streptococcus mutans.Material and methods:Ten specimens of each material were fabricated according tothemanufactures' directions and divided into four groups according to the material. Every sample group adopts respective clinical and commonly used surface treatment method grinding and polishing. Initial roughness measurements (Ra measured in μm) were made by use of a profilometer. Then put every sample in cultivation liquid of the streptococcus mutans. After shake cultivating for 48 hours under 37 degrees Centigrade conditions and training the fungus liquid diluted on the stereotyped culture of agar-agar for 36 hours,carry on colony forming units(CFU). Resuit: The following are results of each group: 1.47±0.47 μm,51±17CFU;3.53±0.94μm,91±27CFU; 1.24±0.42μm,23±7; 0.16±0.10 μm,14±5.The result of the forth group is the minimal.The differences between materials were statistically significant. And correlation to analyse of the count of CFU and Ra value of the same type ofmaterial showed positive correlation.Conclusion: Under the limitation condition of this experiment, draw the following conclusion: At the clinic, among four type of resin and composite resin commonly used, heating curing denture base resin can obtain better surface properties.The processing methods and the surface treatment methods adopted contributed to this concision.For homogeneous material under the same surface treating condition,Ra values and the bacterium retenting have positive correlation.The surface roughness has certain influence on the ability of seizing the bacterium of material surface.