Metagenomic Characterization of the Developing Implant Sulcus

Objectives: Dental endosseous implants are nowadays an increasingly popular option of treatment, when it comes to replacing missing teeth. Until recently, very little was known about the composition of the complex microbiome present in the peri-implant sulcus, and the scientific evidence concerning a sequence of implant microbial colonization is virtually inexistent. Objective : To characterize the dynamics of microbial colonization around dental implants, using a metagenomic approach to examine the functional changes in this community.
Methods: 5 adult partially edentulous nonsmokers receiving a two-staged single implant were selected. Patients were excluded if they were pregnant, presented active periodontal disease or had received antibiotic therapy in the last 3 months. Samples were harvested from the peri-implant sulcus immediately after uncovery, and at 1, 7, 21, 42 and 84 days following uncovery. Genomic DNA was isolated, sheared, size selected and sequenced using the Illumina 300bp paired end chemistry. Sequences were filtered, and functionally annotated using the MG-RAST pipeline. Functional profiles were compared over time using multivariate ANOVA.
Results: PCoA of UniFrac distances revealed distinct clustering of functional groups at Day 1, Days 7 and 21 and Day 84. However, there was no such clustering evident at the phylogenetic level. Day 42 (6 weeks) demonstrated the greatest enrichment of functional capabilities within the biofilm, with acquisition of genes responsible for invasion and intracellular resistance, lipoic acid metabolism, DNA recombination and spore DNA protection. Further functional maturation was evident on Day 84, with acquisition of genes responsible for coenzyme 420, social motility and non-flagellar swimming.
Conclusions: Implant colonization was characterized by phylogenetically distinct species that shared similar functionalities. The greatest functional potential was evident in 6-week biofilms, with further maturation at 12 weeks.