Oral microbial profile variation during canine ligature-induced peri-implantitis development

Experimental models for peri-implant diseases: a narrative review

OBJECTIVES

Peri-implant diseases, being the most common implant-related complications, significantly impact the normal functioning and longevity of implants. Experimental models play a crucial role in discovering potential therapeutic approaches and elucidating the mechanisms of disease progression in peri-implant diseases. This narrative review comprehensively examines animal models and common modeling methods employed in peri-implant disease research and innovatively summarizes the in vitro models of peri-implant diseases.

MATERIALS AND METHODS

Articles published between 2015 and 2023 were retrieved from PubMed/Medline, Web of Science, and Embase. All studies focusing on experimental models of peri-implant diseases were included and carefully evaluated.

RESULTS

Various experimental models of peri-implantitis have different applications and advantages. The dog model is currently the most widely utilized animal model in peri-implant disease research, while rodent models have unique advantages in gene knockout and systemic disease induction. In vitro models of peri-implant diseases are also continuously evolving to meet different experimental purposes.

CONCLUSIONS

The utilization of experimental models helps simplify experiments, save time and resources, and promote advances in peri-implant disease research. Animal models have been proven valuable in the early stages of drug development, while technological advancements have brought about more predictive and relevant in vitro models.

CLINICAL RELEVANCE

This review provides clear and comprehensive model selection strategies for researchers in the field of peri-implant diseases, thereby enhancing understanding of disease pathogenesis and providing possibilities for developing new treatment strategies.

Sustained Release of Salicylic Acid for Halting Peri-Implantitis Progression in Healthy and Hyperglycemic Systemic Conditions: A Gottingen Minipig Model

To develop a peri-implantitis model in a Gottingen minipig and evaluate the effect of local application of salicylic acid poly(anhydride-ester) (SAPAE) on peri-implantitis progression in healthy, metabolic syndrome (MS), and type-2 diabetes mellitus (T2DM) subjects. Eighteen animals were allocated to three groups: (i) control, (ii) MS (diet for obesity induction), and (iii) T2DM (diet plus streptozotocin for T2DM induction). Maxillary and mandible premolars and first molar were extracted. After 3 months of healing, four implants per side were placed in both jaws of each animal. After 2 months, peri-implantitis was induced by plaque formation using silk ligatures. SAPAE polymer was mixed with mineral oil (3.75 mg/μL) and topically applied biweekly for up to 60 days to halt peri-implantitis progression. Periodontal probing was used to assess pocket depth over time, followed by histomorphologic analysis of harvested samples. The adopted protocol resulted in the onset of peri-implantitis, with healthy minipigs taking twice as long to reach the same level of probing depth relative to MS and T2DM subjects (∼3.0 mm), irrespective of jaw. In a qualitative analysis, SAPAE therapy revealed decreased levels of inflammation in the normoglycemic, MS, and T2DM groups. SAPAE application around implants significantly reduced the progression of peri-implantitis after ∼15 days of therapy, with ∼30% lower probing depth for all systemic conditions and similar rates of probing depth increase per week between the control and SAPAE groups. MS and T2DM conditions presented a faster progression of the peri-implant pocket depth. SAPAE treatment reduced peri-implantitis progression in healthy, MS, and T2DM groups.

Multi-omics analysis of oral bacterial biofilm on titanium oxide nanostructure modified implant surface: In vivo sequencing-based pilot study in beagle dogs

Peri-implantitis, the major cause of implant failure, is an inflammatory destructive disease due to the dysbiotic polymicrobial communities at the peri-implant sites. Therefore, it is highly warranted to develop the implant materials with antimicrobial properties and investigate their effects on oral microbiota. However, most of the relevant studies were performed in vitro, and insufficient to provide the comprehensive assessment of the antimicrobial capacity of the implant materials in vivo. Herein, we introduce an innovative approach to evaluate the in vivo antibacterial properties of the most commonly used implant materials, titanium with different nanostructured surfaces, and investigate their antibacterial mechanism via the next-generation sequencing (NGS) technology. We firstly prepared the titanium implants with three different surfaces, i) mechanical polishing (MP), ii) TiO₂ nanotubes (NT) and iii) nanophase calcium phosphate embedded to TiO₂ nanotubes (NTN), and then characterized them using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), confocal laser scanning microscopy (CLSM) and surface hydrophilicity analysis. Afterwards, the implants were placed in the beagle dogs’ mouths to replace the pre-extracted premolar and molar teeth for eight weeks through implant surgery. The supra- and sub-mucosal plaques were collected and subjected to 16S rRNA gene/RNA sequencing and data analysis. It was found that the nanostructured surfaces in NT and NTN groups showed significantly increased roughness and decreased water contact angles compared to the MP group, while the XPS data further confirmed the successful modifications of TiO₂ nanotubes and the subsequent deposition of nanophase calcium phosphate. Notably, the nanostructured surfaces in NT and NTN groups had limited impact on the diversity and community structure of oral microbiota according to the 16S rRNA sequencing results, and the nanostructures in NTN group could down-regulate the genes associated with localization and locomotion based on Gene Ontology (GO) terms enrichment analysis. Moreover, the differentially expressed genes (DEGs) were associated with microbial metabolism, protein synthesis and bacterial invasion of epithelial cells. Taken together, this study provides a new strategy to evaluate the antibacterial properties of the biomedical materials in vivo via the high-throughput sequencing and bioinformatic approaches, revealing the differences of the composition and functional gene expressions in the supra- and sub-mucosal microbiome.

Oral Osteomicrobiology: The Role of Oral Microbiota in Alveolar Bone Homeostasis

Osteomicrobiology is a new research field in which the aim is to explore the role of microbiota in bone homeostasis. The alveolar bone is that part of the maxilla and mandible that supports the teeth. It is now evident that naturally occurring alveolar bone loss is considerably stunted in germ-free mice compared with specific-pathogen-free mice. Recently, the roles of oral microbiota in modulating host defense systems and alveolar bone homeostasis have attracted increasing attention. Moreover, the mechanistic understanding of oral microbiota in mediating alveolar bone remodeling processes is undergoing rapid progress due to the advancement in technology. In this review, to provide insight into the role of oral microbiota in alveolar bone homeostasis, we introduced the term “oral osteomicrobiology.” We discussed regulation of alveolar bone development and bone loss by oral microbiota under physiological and pathological conditions. We also focused on the signaling pathways involved in oral osteomicrobiology and discussed the bridging role of osteoimmunity and influencing factors in this process. Finally, the critical techniques for osteomicrobiological investigations were introduced.

Preparation and characterization of antibacterial and anti-inflammatory hyaluronic acid-chitosan-dexamethasone hydrogels for peri-implantitis repair

Numerous treatment methods for peri-implantitis have been widely used including oral cleaning, traditional metal scraping means, or local antibiotic application. However, to continuously release antibacterial and anti-inflammatory drug in location in situ for effective peri-implantitis repair is still challenging. Herein, an anti-inflammatory drug dexamethasone (DE)-incorporated hyaluronic acid (HA)-chitosan (CT) composite hydrogels system was developed to repair peri-implantitis. The physicochemical characterization and biocompatibility of the hydrogel were evaluated in vitro. The in vivo hydrogels degradation and peri-implantitis repair were assessed in mice. The results showed that the prepared multifunctional hydrogels achieved sustained release, with an equilibrium swelling of 18, and promoted the growth against NIH-3T3 fibroblast cells. The in vitro antibacterial tests showed HA-CT-DE hydrogels can inhibit methicillin-resistant Staphylococcus aureus and Escherichia coli. It down-regulated the expression levels of inflammation factor IL-1β, IL-6 and, TNF-α in peri-implantitis. The prepared HA-CT-DE composite hydrogels with integrated function is promising for the treatment of peri-implantitis.

The temporal shift of peri-implant microbiota during the biofilm formation and maturation in a canine model

OBJECTIVES

Although the mature peri-implant biofilm composition is well studied, there is very little information on the succession of in vivo dental implant colonization. The aim of this study was to characterize the temporal changes and diversity of peri-implant supra-mucosal and sub-mucosal microbiota during the process of the plaque maturation.

MATERIALS AND METHODS

Dental implants (n = 25) were placed in the mandible of 3 beagle dogs. Illumina MiSeq sequencing of the hypervariable V3-V4 region of the 16S rRNA gene amplicons was used to characterize the supra/sub-mucosal microbiota in the peri-implant niches at 1day (T1), 7days (T2), 14days (T3), 21days (T4) and 28days (T5) after Phase Ⅱ surgery of the healing abutment placement. QIIME, Mothur, LEfSe and R-package were used for downstream analysis.

RESULTS

A total of 1184 operational taxonomic units (OTUs), assigned into 22 phyla, 264 genera and 339 species were identified. In supra-mucosal niches, the alpha parameters of shannon, sobs and chao1 displayed significant differences between T1 and other time-points. However, in sub-mucosal niches, only sobs, chao1, and ace indexes displayed significant differences between T1 and T3, and T1 and T5. Beta-diversity showed statistically significant difference between T1 and T2, T3, T4, T5 within both sub-mucosal and supra-mucosal plaque. The phyla Bacteroidetes, Proteobacteria and Firmicutes were the most dominant phyla of both sub-mucosal and supra-mucosal niches at all time-points and Firmicutes increased during the maturation of peri-implant plaque. At the genus level, Neisseria decreased significantly after T1 suggesting the establishment of an anaerobic microenvironment. A decrease of Porphyromonas during the formation of sub-mucosal microbial community was also detected. Co-occurrence network analysis exhibited a more complicated co-occurrence relationship of bacterial species in the sub-mucosal niches. Fusobacterium nucleatum, Filifactor villosus, and some other species may play a crucial role in biofilm maturation.

CONCLUSIONS

The present results suggested that the development of peri-implant biofilm followed a similar pattern to dental plaque formation. Sub-mucosal biofilm may go through a more complicated procedure of maturation than supra-mucosal biofilm.

Exploring Gut Microbiota in Patients with Colorectal Disease Based on 16S rRNA Gene Amplicon and Shallow Metagenomic Sequencing

The gastrointestinal tract, the largest human microbial reservoir, is highly dynamic. The gut microbes play essential roles in causing colorectal diseases. In the present study, we explored potential keystone taxa during the development of colorectal diseases in central China. Fecal samples of some patients were collected and were allocated to the adenoma (Group A), colorectal cancer (Group C), and hemorrhoid (Group H) groups. The 16S rRNA amplicon and shallow metagenomic sequencing (SMS) strategies were used to recover the gut microbiota. Microbial diversities obtained from 16S rRNA amplicon and SMS data were similar. Group C had the highest diversity, although no significant difference in diversity was observed among the groups. The most dominant phyla in the gut microbiota of patients with colorectal diseases were Bacteroidetes, Firmicutes, and Proteobacteria, accounting for >95% of microbes in the samples. The most abundant genera in the samples were Bacteroides, Prevotella, and Escherichia/Shigella, and further species-level and network analyses identified certain potential keystone taxa in each group. Some of the dominant species, such as Prevotella copri, Bacteroides dorei, and Bacteroides vulgatus, could be responsible for causing colorectal diseases. The SMS data recovered diverse antibiotic resistance genes of tetracycline, macrolide, and beta-lactam, which could be a result of antibiotic overuse. This study explored the gut microbiota of patients with three different types of colorectal diseases, and the microbial diversity results obtained from 16S rRNA amplicon sequencing and SMS data were found to be similar. However, the findings of this study are based on a limited sample size, which warrants further large-scale studies. The recovery of gut microbiota profiles in patients with colorectal diseases could be beneficial for future diagnosis and treatment with modulation of the gut microbiota. Moreover, SMS data can provide accurate species- and gene-level information, and it is economical. It can therefore be widely applied in future clinical metagenomic studies.

Changes in the microcirculation in periodontal tissue due to experimental peri-implantitis

OBJECTIVES

Peri-implantitis causes dislodgement of dental implants due to inflammation in the peri-implant tissue. The microcirculation in the periodontal tissue undergoes morphological and physiological changes due to inflammation. The immune mechanism of peri-implantitis differs from that of periodontitis. In this study, we examined the changes in the microcirculation in the peri-implant tissue with experimentally induced inflammation, using morphological and physiological techniques.

METHODS

Six beagle dogs were used in the experiment. After extracting both mandibular premolars, three titanium screw implants were inserted on each side of the mandibular jaw. Dental floss was placed on the right side for 90 days in the study group but not in the control group. Microvascular resin cast models were created, and morphological changes were observed using scanning electron microscopy. Periodontal blood flow was measured using laser Doppler flowmetry.

RESULTS

Ninety days after induction of inflammation, bone resorption was observed around the implant body. Osseointegration was impaired, and a gap at the implant-bone interface was observed. The resin cast models showed that inflamed gingival blood vessels had invaded the bone marrow through the resorbed apical margin of the alveolar bone. Analysis of the physiological data obtained using laser Doppler flowmetry showed a significant increase in blood flow around the implants with experimentally induced inflammation.

CONCLUSIONS

Significant morphological and physiological changes occur in the gingival microcirculation of peri-implant tissue due to inflammation. Evaluating the vasculature and blood flow in the tissue surrounding the site of peri-implantitis may be helpful for pathologic analysis in clinical settings.