Mutanolysin-Digested Peptidoglycan of Lactobacillus reuteri Promotes the Inhibition of Porphyromonas gingivalis Lipopolysaccharide-Induced Inflammatory Responses through the Regulation of Signaling Cascades via TLR4 Suppression.

Periodontitis is an oral infectious disease caused by various pathogenic bacteria, such as Porphyromonas gingivalis. Although probiotics and their cellular components have demonstrated positive effects on periodontitis, the beneficial impact of peptidoglycan (PGN) from probiotic Lactobacillus remains unclear. Therefore, our study sought to investigate the inhibitory effect of PGN isolated from L. reuteri (LrPGN) on P. gingivalis-induced inflammatory responses. Pretreatment with LrPGN significantly inhibited the production of interleukin (IL)-1ß, IL-6, and CCL20 in RAW 264.7 cells induced by P. gingivalis lipopolysaccharide (LPS). LrPGN reduced the phosphorylation of PI3K/Akt and MAPKs, as well as NF-κB activation, which were induced by P. gingivalis LPS. Furthermore, LrPGN dose-dependently reduced the expression of Toll-like receptor 4 (TLR4), indicating that LrPGN inhibits periodontal inflammation by regulating cellular signaling cascades through TLR4 suppression. Notably, LrPGN exhibited stronger inhibition of P. gingivalis LPS-induced production of inflammatory mediators compared to insoluble LrPGN and proteinase K-treated LrPGN. Moreover, MDP, a minimal bioactive PGN motif, also dose-dependently inhibited P. gingivalis LPS-induced inflammatory mediators, suggesting that MDP-like molecules present in the LrPGN structure may play a crucial role in the inhibition of inflammatory responses. Collectively, these findings suggest that LrPGN can mitigate periodontal inflammation and could be a useful agent for the prevention and treatment of periodontitis.

Reliability of 2 implant stability measuring methods in assessment of various periimplant bone loss: an in vitro study with the Periotest and Osstell Mentor.

PURPOSE: The aim of this in vitro study was to evaluate reliability of the Periotest and Osstell Mentor in assessment of periimplant vertical and circular bone loss. MATERIALS AND METHODS: Sixteen dental implants were embedded into acrylic resin blocks. The portion of resin around the implant neck was successively removed to mimic periimplant vertical and circular bone loss. Measurement values of 2 devices were compared by assessing the change of Periotest value (PTV) and Implant Stability Quotient (ISQ) values, by calculating correlation analysis and by means of regression analysis referring to increasing bone loss. RESULTS: Both devices were able to discriminate differences of circular bone loss. However, PTVs were not noticeably changed in buccal, buccal-mesial, and buccal-mesial-distal bone loss. The differences in buccal and buccal-mesial bone loss were not discriminated by Osstell Mentor. As the range of bone loss was increased, there was a noticeable correlation of the PTV and ISQ values. CONCLUSIONS: The results of this study suggest that both diagnostic devices for implant stability are useful in detecting the circular bone loss. However, the clinical reliability of both devices for detecting the partial vertical bone loss is low.