Rat peri-implant soft tissue specifically expressed CXCL2 on titanium implant during wound healing

Subgingival titanium wire implantation induces weak inflammatory responses but does not promote substantial T cell activation

Titanium is a biocompatible material commonly used for dental treatments. However, the detailed mechanism underlying the weak biological activity of titanium has not been elucidated. We investigated both the inflammatory responses and T cell activation induced by solid titanium in the gingiva in mice. Both titanium and nickel wire implantation promoted neutrophil infiltration into the gingiva on day 2. Nickel, but not titanium, wire implantation enhanced proinflammatory cytokine expression and dendritic cell activity in gingival tissue by day 2. Nickel wire implantation enhanced the activity of T cells in draining lymph nodes on day 5. Moreover, T cell and neutrophil infiltration and elevated proinflammatory cytokine expression in the gingival tissue were still observed on day 5. However, no such augmented biological responses were observed after titanium wire implantation. These findings suggest that, unlike nickel, solid titanium does not induce sufficient inflammatory responses leading to T cell activation in gingival tissue.

The Characteristics of Microbiome and Cytokines in Healthy Implants and Peri-Implantitis of the Same Individuals

AIM

To characterize the profile of submucosal microbiome and cytokine levels in peri-implant crevicular fluid (PICF) from clinically healthy implants and peri-implantitis in the same individuals.

MATERIAL AND METHODS

A total of 170 patients were screened and, finally, 14 patients with at least one healthy implant and one peri-implantitis implant were included. Submucosal microbiota and cytokines from 28 implants were analyzed using 16S rRNA gene sequencing and multifactor assays, respectively. Correlations of clinical indexes and microbiota or cytokines were analyzed using Spearman's correlation coefficient. A random forest classification model was constructed.

RESULTS

Peri-implantitis sites harbored higher microbial diversity, as well as more Gram-negative bacteria and anaerobic bacteria, compared with healthy implants sites. The genera of Peptostreptococcaceae XIG-1, Treponema, Porphyromonas, and Lachnospiraceae G-8, as well as the cytokines of IL-17A, IL-6, IL-15, G-CSF, RANTES, and IL-1β were significantly higher in peri-implantitis than healthy implants. Furthermore, these genera and cytokines had positive relationships with clinical parameters, including probing depth (PD), bleeding on probing (BOP), and marginal bone loss (MBL). The classification model picked out the top 15 biomarkers, such as IL-17A, IL-6, IL-15, VEGF, IL-1β, Peptostreptococcaceae XIG-1, Haemophilus, and Treponema, and obtained an area under the curve (AUC) of 0.85.

CONCLUSIONS

There are more pathogenic bacteria and inflammatory cytokines in peri-implantitis sites, and biomarkers could facilitate the diagnosis of peri-implantitis.