The Interaction Between Oral Bacterial Species In Biofilm Formation And Their Adhesion On Different Materials

Caries is one of the most common chronic bacterial infectious diseases,which will progress to pulpitis and periapical periodontitis and even affect the overall health if not treated in time.It is recognized that oral plaque is one of the most important pathogenic factor of caries.As a cariogenic bacteria,Streptococcus mutans(Sm)plays an important role in the pathogenesis of caries.Streptococcus sanguis(Ss)is the biggest number of resident bacterial,who attaches earliest to teeth and is dominant in early formation of oral plaque.Porphyromonas gingivalis(Pg)is a Gram-negative bacterium associated with chronic periodontitis.Pg's colonization to teeth relies on supragingival plaque such as oral streptococcus.Such pleomorphic adhesion is related to its pilli.However,when Pg adheres to oral streptococcus,proliferation of subgingival plaque will be suppressed by supragingival plaque.So it's important to study and clarify the interaction of different oral plaques.Recent years have witnessed a great breakthrough in dental materials.In addition to the traditional glass ionomer cement(GIC)?zinc phosphate cement?composite resin,dental infiltration resin-Icon began to be used in the minimal invasive treatment of caries involving proximal,buccal and labial surface.Soon afterwards,bioceramic materials are applied to root canal treatment.It is highly concerned that whether all these dental materials have an antibacterial activity and how to choose a proper material.In this study,a biofilm model of main strains was established.The inhibitory effect of Sm and Ss on Pg and their effects on biofilm were observed by scanning electron microscopy and fluorescence microscopy.And by simulating the initial state of oral biofilm formation,Pg was found to be able to adhere to various dental materials and supragingival plaque can suppress subgingival plaque formation,which can further compare the adhesion ability of oral bacterial to different dental materials.Common bacteria of supragingival plaque—Sm and Actinomyces viscosus(Av)as well as subgingival plaque?Pg and Enterococcus faecalis(Ef)were chosen to do the research.The adhesion of different bacteria to different material and the formation of biofilm were observed at different times.Thus different adhesion effects between oral materials and root canal filling materials on supragingival and subgingival plaque were revealed.After establishing a biofilm model in vivo,DNA extraction,Miseq sequencing,biological analysis were used to analyze the types and abundance of bacteria in different materials.Pg was inhibited when Sm and Ss was 1.5×108 CFU/ml respectively.The inhibition was more obvious when Sm and Ss was 3×108 CFU/ml respectively.Both supernatants of Ss/Sm can inhibit the formation of the biofilm of Pg,and it was more obvious when the supernatant of Ss was used.A large number of Pg could adhere to the surface of composite resin and AH-Plus,while Pg adhered to the surface of MTA,GIC,Icon,iRoot-SP,BP,FS much less.Sm adhering to resins and zinc phosphate cements is most while GIC and Icon is less.Av adhering to resins and zinc phosphate cements is most while GIC and Icon is less.Pg adhering to AH-Plus is most while MTA is least.Ef adhering to AH-Plus is most while MTA is least.Biological study of model in vivo has found that GIC and Icon shows a better performance of preventing secondary caries than resins and zinc phosphate cememts.In this study,scanning electron microscopy and fluorescence microscopy were used to observe the mutual inhibitory effects of oral bacteria in the biofilm,which laid a foundation for the mechanism of interaction of Sm,Ss and Pg;The new materials in the oral cavity in recent years:Icon,MTA,iRoot were used in the experiment,which can help us choose the best materials in the clinical practise;Combination of experiments in vivo and in vitro can help us to compare the adhesion ability of different bacteria to different material;The introduction of a new plaque biofilm mouth model in situ can help us to lay the foundation for the formation of biofilm models in vivo.