The Influence of Hydroxyapatite, Titanium, and Yttria-Stabilized Zirconia Oxide on Diversity of Bacterial Cultures Grown from Human Dental Biofilm Specimens in an In Vitro Model

Background: Titanium (TI) and yttria stabilized-zirconia oxide (YSZ) are dental materials commonly utilized at the soft-tissue interface surrounding dental implants. The influence of these surfaces on bacterial adhesion and biofilm development may affect clinical performance and patient susceptibility to inflammatory peri-implant disease. The purpose of this study was to evaluate the influence of the substrate material on biofilm diversity. Methods: Biofilms were cultured on TI, YSZ, and hydroxyapatite (HA) surfaces (control) using plaque specimens obtained from three human donors. Duplicate cultures grew for one, two, three, six or nine days. Biofilm diversity was then analyzed using 16S rRNA sequencing. The Shannon Diversity Index (SDI) was calculated for each experimental group. Microbial profiles were intercompared in a pairwise fashion to establish dissimilarity scores, which were recorded in a distance dissimilarity matrix. Results: A total of 16 taxa were identified, and relative abundances of the predominant phyla and genera did not appear statistically different across experimental groups. Biofilms grown on HA surfaces exhibited significantly higher alpha diversity compared with those formed on TI or YSZ (p<0.0001), although biofilms cultured on TI and YSG surfaces exhibited comparable diversity. Statistically significant differences in beta diversity associated with substrate (p=0.012) and growth period (p=0.001) were detected. Conclusions: Under the conditions described, biofilms grown on TI or YSZ appeared significantly less complex than those formed on HA. Transmucosal implant abutment surface characteristics represent one modifiable factor potentially influencing risk of peri-implant disease. Among risk of peri-implant disease. Among multiple considerations in abutment design, biofilm diversity performance may represent a clinically relevant benchmark.