The Preliminary Study On Growth And Biofilm Formation Ability Of Streptococcus Mutans

Dental caries is one of the common oral infectious diseases. Streptococcus mutans is the principle cariogenic bacterial,which could adhere on the surface of the teeth, produce acid, survive acid environment and finally cause dental caries. By the study on growth character and biofilm structure of Streptococcus mutans, the pathogenesis of dental caries could be studied well. Recent years, with the development of science and technology, study on biofilm is further. Compared with SEM, CLSM not only keep the primitive structure of biofilm, but also does three dimensional reconstruction taking horizontal and vertical sections. Structure and character of biofilm could be studied from different perspectives. However, the samples need be stained or ?uorescently marked, which would prolong the test time. That reporter gene technology was used to study the advantages of bacterial morphology would be reflected. Fluorescent protein is transferred into bacterial and give off light, which makes people observe bacterial instantly and directly. In this study, the comparison of growth and biofilms formation ability of Streptococcus mutans were made between wild-type streptococcus mutans (UA140) and streptococcus mutans using fluorescent protein report (UA140-mrfp). They were similar. Afterwards, biofilm formation ability of UA140-mrfp on composite resin and glass-ionomer surface was studied combining reporter gene with Confocal Laser Scanning Microscopy.The study will provide a basis on selecting clinical restorative materials.1. The comparision of growth ability between wild-type streptococcus mutans and streptococcus mutans using ?uorescent protein reportResuscitate UA140, UA140-mrfp, dilute the same OD and cultivate in the 37℃Anaerobic Incubator. Take samples at 0,1.5,3,4,6,8,10,12,16,20,24h and measure OD600. Growth curve was similar. It is suggested that they had the same growth condition.2. The comparision of biofilm formation ability between wild-type streptococcus mutans and streptococcus mutans using ?uorescent protein reportBiofilm of UA140 and UA140-mrfp formed in 96 well plates. The samples were taken at 4h, 8h, 12h, 24h, stained by crystal violet and decoloured by absolute alcohol. Their OD575 were measured by spectrophotometry. The differences in the amount of biofilm between UA140 and UA140-mrfp were not statistically significant (p>0.05).Biofilm of UA140 and UA140-mrfp formed on coverslip. The samples were taken at 4h, 8h, 12h, 24h and Washed, fixed, dehydrated, dried and observed by SEM. The shape of their biofilm was similar at different time. They both Scattered and had a small amount of cross-linking at early stage. Each colony fused and overlapped to form a network structure at later stage. The shape of bacterial didn't alter at high magnification. 3. The research of biofilm formation ability of streptococcus mutans using ?uorescent protein report on different material surface.Biofilm of UA140-mrfp formed on the surface of composite resin and glass-ionomer pieces in identical size. The samples were taken respectively at 4h, 8h, 12h, 24h and washed, mounted. The surfaces of selected samples were observed using CLSM, meanwhile taken vertical (xz) sections to measure biofilm thickness and architecture on different appositions. The quantity and thickness of biofilm on glass ionomer was less than composite. It is suggested that the ability of biofilm formation by UA140-mrfp on the surface of glass-ionomer was lower than composite resin.