A multispecies subgingival biofilm model from periodontitis and peri-implantitis patients

Objectives: To compare the growth of multispecies biofilm derived from periodontitis and peri-implantitis donors on 2 types of surfaces (titanium, Ti and glass, G). Additionally we aimed to study the treatment of biofilms grown on Ti with chlorhexidine (CHX) and an oxygenating agent Ardox –X^® (AX).
Methods: Subgingival plaque samples were collected from pockets (PPD≥6mm) of 3 patients diagnosed with periodontitis (P) and 3 patients diagnosed with peri-implantitis (PI). An active attachment biofilm model and specific medium (Thompson) supplemented with 30% serum was used. Ti and G discs were used as substratum (triplicate per group, total 4 groups). After 2 weeks of growth, biofilms were treated for 10 min with either water (W, control), CHX or AX and harvested. DNA of dead cells was blocked for amplification by propidium monoazide (PMA) treatment. Composition was analyzed using 16S RNA gene amplicon pyrosequencing. Similarities between the biofilms were assessed by non-metric Multidimensional scaling (n-MDS) using Bray Curtis (BC) similarity index. Inoculum source, surface type and treatment were compared.
Results: Biofilms consisted of genus Peptostreptococcus (P=16%,PI=2%), Streptococcus (P=21%,PI=56%), Parvimonas (P=27%,PI=17%), Peptoniphilus (P=10%,PI=1%), Anaeroglobus (P=1%,PI=3%); Prevotella (P=2%,PI=1%); Filifactor (P=3%,PI= 0%), Veillonella (P=1%,PI=5 %) among other 80 genera.
The n-MDS showed a clear clustering by inoculum source. P and PI derived biofilms were significantly different in composition (p<0.001) and were donor-associated (p<0.0001). No difference was found between biofilms grown on Ti or G (p=0.319). Similarity distances (BC) (range 0.6-0.8) and the Shannon diversity index (range 0.8-2.2) revealed no differences between the two substrata.
Exposure to CHX or AX did not result in significant changes in microbial composition compared to the control (p=0.06).
Conclusions: The growth of complex multispecies biofilms derived from periodontitis and peri-implantitis pockets was donor-associated and was not affected by the surface type. Single exposure to CHX or AX did not significantly affect the biofilm composition.