Macrophages contribute to periodontal wound healing mainly in the tissue proliferation stage.

OBJECTIVE: The aim of this study was to determine the preliminary role of macrophages in different stages of periodontal healing. BACKGROUND: Macrophages are promising target cells for periodontal regeneration. However, the stage at which they play a more important role during periodontal repair has not been elucidated till date. METHODS: First, the dynamic changes in M1 and M2 macrophages were analyzed in a rat periodontal-defect model at Days 1, 3, 5, 7, 14, 21, and 28 post-surgery. Macrophages were then depleted after 1, 6, and 14 days of surgery, and the healing results were evaluated via micro-computed tomography and histopathological detection. Finally, the effects of M1 and M2 macrophages on the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs) were verified in vitro. RESULTS: During natural periodontal healing, the number of M1 macrophages increased the most during the early stage of healing (3 days post-operation), and subsequently, it decreased rapidly. The number of M2 macrophages was at its peak during the middle and late stages of tissue healing (5-21 days post-surgery). Interestingly, the highest number of M2 macrophages was observed at 5-14 days post-operation in the alveolar bone, while it was observed at 21 days post-operation in the cementum area. On the first and 14th day post-operation, the clearance of macrophages had no significant effect on tissue healing; however, on the sixth day post-operation, macrophage depletion significantly inhibited tissue regeneration (p < .05). In vitro studies showed that M2 macrophages, rather than M1 macrophages, could significantly promote the proliferation of MSCs (p < .01). CONCLUSION: It is better to intervene in tissue proliferation phase when a M2 macrophage regulation-based periodontal regenerative therapy is planned in the future.

The Clinical Efficacy of Subgingival Debridement by Ultrasonic Instrumentation Compared With Subgingival Air Polishing During Periodontal Maintenance: A Systematic Review.

OBJECTIVE: The objective of this review was to evaluate the effect of subgingival debridement by ultrasonic debridement (UD) in comparison with subgingival air polishing (SubGAP) during periodontal maintenance. METHODS: A systematic search of electronic databases was conducted to identify publications from January 01, 2000, to December 21, 2018. Publication selection, data extraction, and risk of bias assessment were performed by two reviewers independently. The addressed problem-intervention-comparison-outcomes question was "For patients in the periodontal maintenance phase, is SubGAP more likely to result in better clinical outcomes than UD?" RESULTS: From a total of 435 articles identified, 6 studies were included. Although none of them was evaluated to have a low risk of bias, overall, the main reason was that blinding of personnel was almost impossible to achieve for the study design. Owing to the heterogeneity, the data from included studies could not be synthesized. Most of the included studies suggested no statistical difference in pocket-depth reduction, except for one which showed UD was superior to SubGAP. In terms of clinical attachment loss and gingival regression, no treatment was indicated to have more benefits than the other based on the present evidence. SubGAP had a preferable comfort level compared with UD, as reported. It must be noted that none of included studies' follow-up time was more than 1 year. CONCLUSION: The clinical efficacy of SubGAP compared with that of UD for periodontal maintenance remains inconclusive on account of limited evidence. To date, neither SubGAP nor UD showed superior clinical effect when compared. High-quality, well-designed clinical studies are still needed to ascertain the long-term clinical stability.

Brandt's vole (Lasiopodomys brandtii) affects the dominant position of three gramineous species by altering defense traits and interspecific competition.

Rodents can cause considerable changes in plant community composition. However, relationships between shifts in species dominance and plant functional traits caused by rodents have seldom been investigated, especially for belowground functional traits. In this study, a set of enclosures was constructed to analyze the effects of 10 years of Brandt's voles' activities on the defense strategies and dominant position changes of three gramineous plants (Leymus chinensis, Stipa krylovii, and Cleistogenes squarrosa) in Inner Mongolia. Here, we measured the dominance, biomass, and fourteen functional traits of three plants. The effects of Brandt's voles on dominance, biomass, and functional traits were analyzed, and then we explored the effect of functional traits on plant dominance by using the structural equation model. Results showed that long-term feeding by Brandt's voles resulted in a significant decrease in the dominance of L. chinensis and S. krylovii, whereas C. squarrosa was positively affected. The belowground biomass of L. chinensis and S. krylovii was higher in the vole treatment, which showed that they were increasing their escape characteristics. The leaf thickness of L. chinensis and the leaf C:N ratio of S. krylovii significantly increased, while the specific leaf area of C. squarrosa significantly decreased. All three gramineous showed increased resistance traits in response to Brandt's voles, which positively affected their dominance. Tolerance-related traits of S. krylovii significantly increased, with the increasing growth rate of root length contributing to enhancing its dominance. We highlight that selective feeding by rodents led to the selection of different defense strategies by three gramineous plants, and that changes in biomass allocation and functional traits in the different species affected plant dominance, driving changes in the plant communities.