[Adhesion of different bacterium to the surface of restorative materials in vitro]

Mutans(Ua), porphynomonas(Pg),actinomyces Naeslundii(An) are the 3 bacteria that may cause the clonal formation, gingivitis and periodontitis. The aim of this study was to observe adhesion on the surface of the dental restorative materials and enamel, and to analyze the sequence of these adhesions and offer now the options for the prevention of their occurrence.

The specimen made of PFM and Co-Cr alloy were polished step by step. Then, along with the enamel.they were put into the liquid BHI culture medium containing Ua, Pg and An. After 6 hours, 12 hours and 24 hours, the adhesive microbial amount in the culture medium were determined by counting formation unit.F test was used to analyze the results with SPSS6.0 software package.

Pg was found neither on the surface of specimen, nor in the liquid BHI culture medium; The surface roughness (Ra) of PFM and enamel was bigger than that of Co-Cr alloy, but the number of adherent bacterium on them was smaller; The value of Ua/An was almost the same among the 3 groups within 6 hours. Twelve hours later, the maximal increment of An was seen in the group of Co-Cr alloy and the minimal increment in the group of enamel while 24 hours later, the largest number of Ua/An was seen in the group Co-Cr alloy. There were no change in the groups of PFM and enamel during 12 and 24 hours.

Pg is inhibited when these bacteria are cultivated together. To prevent the adhesion of Ua, the first 6 hours is the critical period for Co-Cr alloy, and the first 12 hours for PFM.To avoid the adhesion of An, the key period is the first 24 hours for Co-Cr alloy and the first 12 hours for PFM. Given the result of the analysis, we prefer PFM to Co-CR alloy. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No. 08DZ2271100) and Shanghai Leading Academic Discipline Project (Grant No. T0202).