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Prof. Georgios N. Belibasakis believes that identifying the microbial traits of peri-implantitis could help design effective antimicrobial strategies for preventing the onset of the disease. (Image: Stefan Zimmerman)

Interview: How identifying microbial traits of peri-implantitis could help fight the disease

By Iveta Ramonaite, Dental Tribune International
January 26, 2021

Periodontitis and peri-implantitis are both inflammatory conditions that affect gingival tissue. However, owing to the anatomical differences between teeth and implants, the two diseases require distinct treatments. In a recent interview, Dental Tribune International spoke with Dr Georgios N. Belibasakis, professor of clinical oral infection biology and head of the Division of Oral Diseases at Karolinska Institutet in Stockholm in Sweden, on the topic. Belibasakis has recently co-authored a study on the microbial pathogenesis of peri-implantitis and believes that a deeper understanding of the issue could help develop improved strategies for prevention, diagnosis and treatment.

Prof. Belibasakis, what prompted you to conduct the study, and why is it necessary to research the microbial pathogenesis of peri-implantitis?
I have been involved in the field of peri-implant research for more than a decade now. During this time, I participated in specialised peri-implantitis diagnosis and treatment planning groups and published original research and scientific overview articles in the field. Last year, the editor of a section called Critical Reviews in Oral Biology and Medicine in the Journal of Dental Research invited me to write an updated review on the topic of the microbiology of peri-implantitis. I gladly agreed to carry out this task together with my postdoctoral fellow, Dr Daniel Manoil, who is also a dentist and oral microbiologist.

“To date, we largely use the same means to cure peri-implantitis as we do for periodontitis”

One can say that, despite the vast amount of research performed in the pathobiology of peri-implantitis, we still have very little knowledge that can be considered sufficiently groundbreaking to enter routine clinical application. To date, we largely use the same means to cure peri-implantitis as we do for periodontitis. Hence, identifying the microbiological traits and pathological characteristics of this type of oral infection, as well as its differences to periodontitis, may help us diagnose it more efficiently and treat it with more specialised protocols in the future.

According to your findings, what kind of changes occur in dental implants in terms of microbial diversity when transitioning from peri-implant health to peri-implant mucositis and then, finally, to peri-implantitis?
Compiling data from the latest studies based on the 16S ribosomal RNA gene sequencing technique, we observed that microbial diversity gradually increased during this transition from peri-implant health to disease. More specifically, it appeared that most of this increase in diversity occurs during the development of peri-implant mucositis, an early stage in which the peri-implant inflammation is limited to the submucosa, whereas changes that accompanied further deterioration towards peri-implantitis persisted but occurred in a subtler pattern. Of course, the clinical change from peri-implant mucositis to peri-implantitis is a severe one. That is why it is surprising that the microbiological changes are not as drastic.

The increased microbial diversity of submucosal biofilms during the transition from health to peri-implant mucositis and then to peri-implantitis. (Image: Journal of Dental Research. First published in Belibasakis GN and Manoil D, J Dent Res 2021; 100(1): 21-28. Reproduced with permission from SAGE in agreement with the Creative Commons CC-BY license)

Have you noticed any compositional shifts within the peri-implant bacterial communities?
It appeared so, yes. Healthy peri-implant sites displayed bacterial communities harbouring high abundances of oral and periodontal commensals, resembling microbial communities commonly detected in healthy gingival sulci, albeit with lower diversity. Inflammatory peri-implant transitions were characterised microbiologically by gradual depletion of these commensals, along with an enrichment of classical periodonto-pathogens such as representatives of the red complex (Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia) and less well-known and newly emerging pathogens such as Fretibacterium fastidiosum, Anaeroglobus geminatus or species of Mogibacterium. It is also important to mention that a few bacterial taxa, such as Staphylococcus, appeared to be distinctive of the peri-implant niche, at least compared with the periodontal one.

What was to you personally the most striking finding from your research?
Two aspects. The first of them is the non-unitary nature of the oral cavity and its impact on microbial communities. Indeed, despite the evident homologies between a peri-implant sulcus and a gingival sulcus, the rather slight variations in their anatomo-histology suffice to generate an ecologically distinct peri-implant niche. It becomes increasingly evident that, compared with natural teeth, this implant-centred niche may dictate the “selection” of a differentially abundant microbiota.

The second aspect is more methodological. One of the purposes of our work was to provide a comprehensive display of microbial outputs stemming from next-generation sequencing studies. We were rather surprised to observe that the vast majority of such studies relied on 16S rRNA-based sequencing approaches. These have permitted a quantum leap in terms of mapping the diversity of peri-implant communities in both health and disease. Yet, current approaches limit the taxonomic resolution between the genus and the species levels, at best. We anticipate that future studies that manage to reassemble metagenomes via shotgun sequencing or can dig deeper into differentially transcribed genes will bring to light more finite differences between peri-implant diseases. Currently, these remain concealed at the strain level, or within basic functional profiles.

“One cardinal principle of any healthcare profession is a thorough understanding of the aetiology of the disease, and even more so in peri-implant infections”

How could the data gained in your study help improve the long-term retention of implants?
Well, we believe that one cardinal principle of any healthcare profession is a thorough understanding of the aetiology of the disease, and even more so in peri-implant infections. Since the progression rate of peri-implantitis is considerably faster than periodontitis, a clear picture of its microbial traits may disclose possible microbial biomarkers and help prevent the onset of peri-implant inflammation. Ultimately, identifying notable and unique microbial traits in peri-implantitis will help design and select appropriate antimicrobial strategies to target the disease.

Editorial note: The study, titled “Microbial community-driven etiopathogenesis of peri-implantitis”, was published in the January 2021 issue of the Journal of Dental Research.

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