Accuracy of an autonomous dental implant robotic system in partial edentulism: A pilot clinical study.

OBJECTIVES: Robots are increasingly being used for surgical procedures in various specialties. However, information about the accuracy of robot-assisted dental implant surgery is lacking. This pilot clinical study aimed to investigate the accuracy of an autonomous dental implant robotic (ADIR) system in partially edentulous cases. MATERIAL AND METHODS: The ADIR system was used to place a total of 20 implants in 13 participants. Implant deviation from the planned positions was assessed to determine accuracy. The entry, apex, and angular deviations were described as means ± standard deviation. A two-sample t test was used to compare implant deviation between the flap and flapless groups and between maxillary and mandibular implants (α = .05). RESULTS: The entry, apex, and angular deviations were 0.65 ± 0.32 mm, 0.66 ± 0.34 mm, and 1.52 ± 1.01°, respectively, with no statistically significant difference between the flap and flapless approaches (P > .05). No adverse events were encountered in any of the participants. CONCLUSIONS: DIR accuracy in this clinical series was comparable to that reported for static and dynamic computer-assisted implant surgery. Robotic computer-assisted implant surgery may be useful for dental implant placement, potentially improving the quality and safety of the procedure. CLINICAL RELEVANCE: The findings of this study showed that the ADIR system could be useful for dental implant surgery.

Association between periodontitis and hypertension: cross-sectional survey from the Fourth National Oral Health Survey of China (2015-2016).

OBJECTIVES: To evaluate the association between periodontitis severity and hypertension based on Chinese epidemiological data. DESIGN: This cross-sectional survey enrolled adults from the Fourth National Oral Health Survey of China (2015-2016). SETTING: The data were obtained from the Fourth National Oral Health Survey of China (2015-2016). PARTICIPANTS: The study included individuals aged 35-44 years (n=4409), 55-64 years (n=4568) and 65-74 years (n=4218). PRIMARY AND SECONDARY OUTCOME MEASURES: Periodontal status, defined on the basis of the 2017 classification scheme, and periodontal parameters (eg, bleeding on probing (BOP)) were compared between individuals with hypertension and individuals with normotension. Smoothed scatterplots were constructed to demonstrate the associations of periodontal parameters and periodontal status with hypertension. RESULTS: Severe periodontitis (stages III and IV) was present in 41.4% of individuals with hypertension and 28.0% of individuals with normotension, respectively (p<0.001). The prevalence of severe periodontitis was higher in individuals with hypertension than that in individuals with normotension among participants aged 35-44 years (18.0% vs 10.1%, p<0.001) and 55-64 years (40.2% vs 36.7%, p=0.035), but not in participants aged 65-74 years (46.4% vs 45.1%, p=0.429). Therefore, the difference in periodontal status between individuals with hypertension and individuals with normotension decreased with age. There were higher prevalences of BOP, probing depth (PD) ≥4 mm and PD ≥6 mm in individuals with hypertension than in individuals with normotension (52.1% vs 49.2%, 19.6% vs 14.7% and 1.8% vs 1.1%, respectively). Periodontitis severity and the proportion of teeth with PD ≥4 or ≥6 mm were positively associated with hypertension. CONCLUSION: Periodontitis is associated with hypertension in Chinese adults. Hypertension prevalence increased with periodontitis severity, particularly among young participants. Accordingly, it is necessary to improve the education, awareness of periodontal treatment and preventive management among individuals at risk of hypertension, particularly in the younger population.

The tendency of anemia of inflammation in periodontal diseases.

Anemia of inflammation (AI) is associated with inflammatory diseases, and inflammation-induced iron metabolism disorder is the major pathogenic factor. Earlier studies have reported a tendency of AI in periodontitis patients, but the explicit relationship and possible pathological mechanisms remain unclear. Here, the analyses of both periodontitis patients and a mouse model of ligature-induced experimental periodontitis showed that periodontitis was associated with lower levels of hemoglobin and hematocrit with evidence of systemic inflammation (increased white blood cell levels) and evidence of iron restriction (low serum iron along with a high serum hepcidin and ferritin levels), in accordance with the current diagnosis criteria for AI. Moreover, periodontal therapy improved the anemia status and iron metabolism disorders. Furthermore, the increased level of hepcidin and significant correlation between hepcidin and key indicators of iron metabolism emphasized the pivotal role of hepcidin in the pathogenesis of periodontitis-related AI. Administration of the signal transducer and activator of transcription 3 (STAT3) inhibitors Stattic suggested that the IL-6-STAT3-hepcidin signaling pathway participated in this regulatory process. Together, these findings demonstrated that periodontitis should be considered an inflammatory disease that contributes to the development of AI; furthermore, IL-6-STAT3-hepcidin signaling pathway plays a key regulatory role in the pathogenesis of periodontitis-related AI. Our study will provide new insights into the systemic effects of periodontitis, while meaningfully expanding the spectrum of inflammatory diseases that contribute to AI.

Modified Suture Technique for Stabilization of Connective Tissue Graft in Immediate Implant Placement and Provisionalization: A Short Technical Report.

Immediate implant placement and provisionalization with subepithelial connective tissue graft is considered the reference therapy for achieving a good esthetic outcome, especially in cases with a thin periodontal phenotype. Positioning sutures are usually required to maintain graft stability. This article describes the use of a modified suture technique involving vertical/horizontal double-parallel mattress sutures in immediate implant placement to achieve stable passive fixation of the graft in the appropriate position and to provide a more equal distribution of tension in the wound. A novel, simplified, reproducible technique is described in two cases of immediate implant placement and provisionalization with subepithelial connective tissue grafting and double-parallel mattress sutures.

Classification of premolars sagittal root position and angulation for immediate implant placement: a cone beam computed tomography study.

OBJECTIVES: Sagittal root position (SRP) and buccal plate thickness are important considerations in implant treatment planning. The objective of this study was to classify the relationship of the SRP and angulation to the osseous housing to assist treatment plan making for immediate implant placement in the premolar region. STUDY DESIGN: We classified the SRP and angulations of the maxillary and mandibular premolars and measured the buccal plate thickness of 150 patients using cone beam computed tomography to support clinical decision making. RESULTS: Regarding SRP types, 41.67%, 51.83%, 3.67%, and 2.83% of maxillary premolars and 84.33%, 15%, 0%, and 0.67% of mandibular premolars were classified as types B, M, L, and N, respectively. In terms of angulation, 20.83%, 46%, 32.17%, and 1% of maxillary premolars and 2%, 5.33%, 36.67%, and 56% of mandibular premolars were grouped into classes 1, 2, 3, and 4, respectively. The buccal bone thickness at most locations in premolar regions was <1 mm. CONCLUSIONS: The classification of SRP and angulation will assist in treatment plan making for immediate implant placement in the premolar region.

Clinical solutions for natural abutments with preexisting defected crown margin in the aesthetic area.

Crown replacement has remained one of the difficult methods for installing fixed prosthesis but is often performed because of aesthetic factors and invasion of biological width. This article focuses on the clinical scenario in which preexisting crown margin has defects. Given that clinical decisions regarding restoration management and perio-dontal tissues have to be made with caution, a decision tree of the decision making process for natural abutments in aesthetic area with preexisting defected crown margin is presented. The re-establishment of a new crown margin is the key to the success of a new restoration, and the new margin should be located at the proper esthetic position and right biological position. It should have fine, smooth, and continuous morphology.

Preliminary study on the involvement of platelets in mouse experimental periodontitis.

Background/purpose: Although some studies have taken an interest in the participation of platelets in periodontitis, so far, we know very little about the roles of platelets in periodontitis. The objective of this study is to explore the involvement of platelets in the development of experimental periodontitis in mice. Materials and methods: Twenty C57BL/6 male mice were used for this study. Experimental periodontitis models of mice were constructed by ligating for 1, 3, 7, and 14 days, respectively. Morphological changes in the alveolar bone were assessed by micro-computed tomography (Micro-CT). The gingival crevicular fluid samples of ligation sites were collected and stained by immunocytochemistry. Immunohistochemistry was used to detect platelets infiltration in gingival tissues of mice. Results: The results of Micro-CT showed that with the extension of ligation time, alveolar bone resorption increased, suggesting that the experimental periodontitis models were established. Immunochemical staining showed that there were almost no platelets in the gingival crevicular fluid of mice ligated for 1 and 3 days. And at 7 and 14 days of ligation, a large number of platelets were present in the gingival crevicular fluid and formed complexes with neutrophils. And with the extension of ligation time, the extent of platelet infiltration increased in mice gingival tissues. Conclusion: Platelets were infiltrated increasedly in the gingival sulcus and gingival tissues following the experimental time, and may participate in the development of mouse experimental periodontitis.

A Digital Way for Fabricating a Resin-Bonded Fixed Partial Denture Combined with Periodontal Splint in the Mandibular Anterior Region.

Teeth loosening are caused by insufficient supporting tissue, inflammation of periodontal tissue, or occlusal trauma, which is one of the main clinical symptoms of periodontitis. A digital technique for fabricating resin-bonded splinting fixed partial dentures (S-FPDs) is presented. It restores the missing mandible anterior teeth and splints the adjacent periodontally mobile teeth of the patient at the same time. The S-FPDs is designed and fabricated by computer-aided design and computer-aided manufacturing (CAD/CAM) technology with flexible PMMA material. The workflow is straightforward, convenient, and accurate. Meanwhile, the restoration can meet the esthetic requirements and help with the stability of adjacent loosening natural teeth spontaneously. It could be considered a medium-term provisional restorative treatment option, but further controlled investigations still be needed.

Interactions of periodontal pathogens with platelets in the gingival crevicular fluid of patients with periodontitis.

AIM: To explore the immunological defensive effects of platelets on periodontal pathogens in the gingival crevicular fluid (GCF). MATERIALS AND METHODS: GCF samples were collected from 20 patients with periodontitis and 10 healthy controls. Platelets in the GCF were detected by immunocytochemistry and immunofluorescence. Isolated platelets from healthy volunteers were co-cultured with Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn). The interactions between platelets and periodontal pathogens were observed by transmission and scanning electron microscopy. The isolated platelets plus neutrophils were co-cultured with Pg or Fn, and the formation of neutrophil extracellular traps (NETs) was evaluated by staining with Sytox Green. RESULTS: The platelet level in the GCF was higher in patients with periodontitis than in healthy controls. Platelets interacted with bacteria and neutrophils in the GCF. In vitro, platelets recruited and engulfed periodontal pathogens. In response to periodontal pathogens, neutrophils released web chromatin, and platelets promoted the formation of intensive NETs. CONCLUSIONS: Platelets, migrating to the gingival sulcus, may exert direct antibacterial effects or assist neutrophils.

Comparison of Implant Placement Accuracy in Healed and Fresh Extraction Sockets between Static and Dynamic Computer-Assisted Implant Surgery Navigation Systems: A Model-Based Evaluation.

The aim of this model-base study was to compare the accuracy of implant placement between static and dynamic computer-assisted implant surgery (CAIS) systems in a fresh extraction socket and healed ridge. A randomized in vitro study was conducted. Twenty 3D-printed maxillary models and 80 implants were used. One experienced researcher placed the implants using either the static navigation or dynamic navigation system. Accuracy was measured by overlaying the real position in the postoperative CBCT on the virtual presurgical placement of the implant in a CBCT image. Descriptive and bivariate analyses of the data were performed. In the fresh sockets, the mean deviation was 1.24 ± 0.26 mm (entry point), 1.69 ± 0.34 mm (apical point), and 3.44 ± 1.06° (angle discrepancy) in the static CAIS group, and 0.60 ± 0.29 mm, 0.78 ± 0.33 mm, and 2.47 ± 1.09° in the dynamic CIAS group, respectively. In the healed ridge, the mean deviation was 1.09 ± 0.17 mm and 1.40 ± 0.30 mm, and 2.12 ± 1.11° in the static CAIS group, and 0.80 ± 0.29 mm, 0.98 ± 0.37 mm, and 1.69 ± 0.76° in the dynamic CIAS group, respectively. Compared with the static CAIS system, the dynamic CAIS system resulted in significantly lower entry and apical errors in both fresh sockets and healed ridges. Differences in bone morphology therefore seem to have little effect on accuracy in the dynamic CAIS group.

Effectiveness of acellular dermal matrix graft with a coronally advanced flap for the treatment of Miller Class I/II single gingival recession with thin gingival phenotype: study protocol for a split-mouth randomised controlled trial.

INTRODUCTION: Gingival recession is one of the most common mucogingival deformities requiring surgical correction. The American Academy of Periodontology Regeneration Workshop recommended connective tissue graft (CTG) combined with coronally advanced flap (CAF) for the treatment of Miller Class I and II single-tooth gingival recession. The disadvantages of harvesting autogenous tissue include postoperative bleeding, pain and discomfort at the donor site, restricted tissue supply, increased morbidity and prolonged operative times. Acellular dermal matrix (ADM) contains undamaged collagen and elastin matrices that can be used as a substitute for CTG during root coverage procedures. However, the use of ADM is still controversial. The objective of this split-mouth; randomised, controlled, clinical study is to evaluate the long-term effects of ADM graft (ADMG) combined with CAF on root coverage, aesthetics and patient satisfaction for the treatment of single gingival recession with thin gingival phenotype. METHODS AND ANALYSIS: Forty participants with bilateral Miller Class I/II gingival recession will be randomised to receive an ADMG on one side and CTG on the contralateral side, combined with CAF. Gingival recession depth, gingival recession width and keratinised tissue width will be measured at baseline, 2 weeks and 1, 3, 6, 12 and 24 months. Mean root coverage, complete root coverage, root coverage aesthetic score, colour change (∆E) and patient satisfaction will be assessed during follow-up visits. ETHICS AND DISSEMINATION: The present study has received approval from the Ethics Committee of Peking University School and Hospital of Stomatology (PKUSSIRB-202054029). Data of this study will be registered with the International Clinical Trials Registry Platform. Additionally, we will disseminate the results through scientific journal. TRIAL REGISTRATION NUMBER: ChiCTR2000033230.

Digital workflow for prosthetically driven implant navigation surgery in a fully edentulous patient: a case report.

BACKGROUND: Dynamic navigation has important potential advantages over the static approach for fully edentulous patients. To the best of the authors' knowledge, this is the first published case report describing the use of a dynamic implant navigation technique for a fully edentulous patient. CASE REPORT: A 55-year-old female presented for the replacement of missing teeth. Treatment with an implant-supported fixed dental prosthesis was proposed. A digital navigation implant surgery/immediate provisionalization protocol was used. An acrylic resin denture was fabricated as a radiographic guide. Digital data were obtained through the double scan technique, and a prosthetically driven 3D implant positioning was designed. Four titanium mini screws were inserted into the mandible for registration. The first implant was inserted in a freehand manner and attached to a patient tracker. After calibration and registration, the navigation system was set up. The other five implants were inserted using the navigation system. The procedure followed for the maxilla was similar. After surgery, a loading procedure was performed within 24 h. RESULTS: Following implant placement, a postoperative CBCT scan was performed. The results showed that all implants were placed precisely, in accordance with the treatment plan. CONCLUSION: From the results obtained it appears that a fully digital workflow for prosthetically driven implant navigation surgery is suitable for the treatment of fully edentulous patients requiring an implant-supported fixed restoration. High-level evidence is needed to determine the accuracy and precision of this workflow.

Pro-inflammatory cytokine interleukin-6-induced hepcidin, a key mediator of periodontitis-related anemia of inflammation.

OBJECTIVES: To investigate whether anemia of inflammation (AI) occurs in periodontitis patients and to further explore underlying pathogenesis of periodontitis-related AI by an experimental periodontitis model. BACKGROUND: Previous studies have reported periodontitis patients could show a tendency toward AI. However, the relationship between periodontitis and AI remains unclear, and the related pathological mechanisms have not been identified. MATERIALS AND METHODS: Periodontal clinical parameters, inflammatory markers, and anemia-related indicators were compared between 98 aggressive periodontitis (AgP) patients and 103 healthy subjects. An experimental periodontitis model was induced by ligature placement in mice. The changes in mice inflammatory markers, anemia indicators, hepcidin mRNA expression, and serum hepcidin concentrations were measured. Human and mouse liver cells were treated with interleukin-6 (IL-6) for analyzing the changes in hepcidin expression based on mRNA and protein levels. RESULTS: AgP patients exhibited higher white blood cell counts, IL-6, and C-reactive protein. Adjusted linear regression analyses showed correlations between AgP and decreased hemoglobin (HGB) and hematocrit (HCT). The ligature-induced periodontitis caused systemic inflammation and elevated IL-6 levels. Lower red blood cell counts, HGB, and HCT were detected, whereas the levels of hepcidin mRNA expression and serum hepcidin concentrations increased. The treatment of hepatocytes with IL-6 induced both hepcidin mRNA expression and hepcidin secretion. CONCLUSIONS: Systemic inflammation induced by periodontitis leads to an increased risk for AI. IL-6-induced hepcidin could play a central mediator role and act as a key pathologic mechanism. Our results demonstrate periodontitis may be considered as an additional inflammatory disease contributing to the development of AI.

Evaluation of a dynamic navigation system for training students in dental implant placement.

OBJECTIVE: Computer-guided simulation systems may offer a novel training approach in many surgical fields. This study aimed to compare dental students' learning progress in dental implants placement between a dynamic navigation system and a traditional training method using a simulation model. METHODS: Senior dental students with no implant placement experience were randomly assigned to implant placement training using a dynamic navigation system or a traditional freehand protocol. After training, 3-dimensional (3D) deviation at implant platform, 3D deviation at implant apex, and deviation of implant axis between the planned and placed implant positions were measured using superimposed cone beam computed tomography scans. RESULTS: Six students were trained in this study. Students showed significantly greater improvement in implant placement after training using the dynamic navigation system than after using the traditional freehand protocol. Overall deviation of implant axis (P < 0.001) and 3D apex deviation (P = 0.014) improved with training using the dynamic navigation system, but differences in 3D platform deviation (P = 0.513) were not statistically significant. CONCLUSIONS: A dynamic navigation system may be a useful teaching tool in the early development of clinical skills in implant placement for the novice practitioners. Novice practitioners exhibited significant improvement in angulation deviation across implant placement attempts with dynamic navigation system training.

Platelets as inflammatory mediators in a murine model of periodontitis.

AIM: To investigate the role of platelets during the development of ligature-induced experimental periodontitis in mice. MATERIALS AND METHODS: Experimental periodontitis was induced by placement of sterilized 5-0 cotton ligatures around the maxillary and mandibular second molars of C57BL/6 wild-type mice. Flow cytometry was used to analyse platelet activation and platelet-leucocyte aggregate formation, and histologic analysis was used to evaluate inflammation and localization of platelets and leucocytes in periodontal tissues during the development of experimental periodontitis and in experimental periodontitis with and without antiplatelet drug treatment. RESULTS: Experimental periodontitis induced platelet activation and platelet-leucocyte interaction. Platelets and leucocytes gradually infiltrated in inflammatory gingival tissues during the development of experimental periodontitis. The inhibition of platelet activation via drug therapy led to significant inhibition of leucocyte migration and marked reduction in periodontal inflammation. CONCLUSION: This study revealed that platelets are critical for inflammation and tissue injury in periodontitis and serve as mediators of inflammation in periodontal tissue.

Clinical evaluation of ultrasonic subgingival debridement versus ultrasonic subgingival scaling combined with manual root planing in the treatment of periodontitis: study protocol for a randomized controlled trial.

BACKGROUND: Periodontal diseases are regarded as the most common diseases of mankind. The prevalence rate of periodontal disease assumes a clear growth tendency, increasing by 57.3% from 1990 to 2010. Thereby, effective periodontal therapy is still a long-term task and a difficult problem. The goals of periodontal therapy are to eliminate the infectious and inflammatory processes of periodontal diseases. Root planing, in order to eliminate the "infected cementum," has been an important step in the treatment of periodontitis since the 1970s. However, along with the understanding of the effects of endotoxin on the root surface, the necessity of manual root planing has been gradually queried. Ultrasonic instruments, which are more recent innovations, would not remove the cementum excessively, and are also more time-saving and labor-saving compared to using hand instruments. Hence, an increasing number of dentists prefer to do scaling with ultrasonic instruments only. However, the necessity of root planing remains emphasized in the international mainstream views of periodontal mechanical treatment. Therefore, this study is devoted to compare the clinical effect of ultrasonic subgingival debridement and ultrasonic subgingival scaling combined with manual root planing, which takes the implementation of root planing as the only variable and is more in line with the current clinical situation, thus hoping to provide some valuable reference to dentists. METHODS/DESIGN: Forty adult patients who fit the inclusion criteria are being recruited from the Peking University Hospital of Stomatology (Beijing, China). By means of randomization tables, one quadrant of the upper and lower teeth is the test group and the other is the control group. Test group: ultrasonic subgingival scaling combined with manual root planing. CONTROL GROUP: ultrasonic subgingival debridement. In a 24-week follow-up period, plaque index, probing depth, clinical attachment loss, bleeding index, furcation involvement, mobility, and patient-reported outcome (Visual Analog Scale for pain and sensitivity) will be observed and documented. DISCUSSION: This study evaluates the effectiveness of ultrasonic subgingival scaling combined with manual root planing and ultrasonic subgingival debridement alone in the nonsurgical treatment of periodontitis with a split-mouth design after 1, 3 and 6 months. The result of the trial should potentially contribute to an advanced treatment strategy for periodontitis with an ideal clinical outcome. TRIAL REGISTRATION: International Clinical Trials Registry Platform (ICTRP), ID: ChiCTR1800017122. Registered on 12 July 2018.

Up-regulated ferritin in periodontitis promotes inflammatory cytokine expression in human periodontal ligament cells through transferrin receptor via ERK/P38 MAPK pathways.

OBJECTIVE: Ferritin, an iron-binding protein, is ubiquitous and highly conserved; it plays a crucial role in inflammation, which is the main symptom of periodontitis. Full-length cDNA library analyses have demonstrated abundant expression of ferritin in human periodontal ligament. The aims of the present study were to explore how ferritin is regulated by local inflammation, and to investigate its functions and mechanisms of action in the process of periodontitis. METHODS: Human gingival tissues were collected from periodontitis patients and healthy individuals. Experimental periodontitis was induced by ligature of second molars in mice. The expression of ferritin light polypeptide (FTL) and ferritin heavy polypeptide (FTH) were assessed by immunohistochemistry. Meanwhile, after stimulating human periodontal ligament cells (HPDLCs) with P. gingivalis-lipopolysaccharide (LPS), interleukin (IL)-6, and tumor necrosis factor-α (TNF-α), the expression of FTH and FTL were measured. Then, IL-6 and IL-8 were measured after incubation with different concentrations of apoferritin (iron-free ferritin) and several intracellular signaling pathway inhibitors, or after knockdown of the transferrin receptor. RESULTS: Both FTH and FTL were substantially higher in inflamed periodontal tissues than in healthy tissues. The location of the elevated expression correlated well with the extent of inflammatory infiltration. Moreover, expression of FTH and FTL were enhanced after stimulation with P. gingivalis-LPS, IL-6, TNF-α. Apoferritin induced the production of IL-6 and IL-8 in a dose-dependent manner partly through binding to the transferrin receptor and activating ERK/P38 signaling pathways in HPDLCs. CONCLUSIONS: Ferritin is up-regulated by inflammation and exhibits cytokine-like activity in HPDLCs inducing a signaling cascade that promotes expression of pro-inflammatory cytokines associated with periodontitis.

Population-Genomic Insights into Variation in Prevotella intermedia and Prevotella nigrescens Isolates and Its Association with Periodontal Disease.

High-throughput sequencing has helped to reveal the close relationship between Prevotella and periodontal disease, but the roles of subspecies diversity and genomic variation within this genus in periodontal diseases still need to be investigated. We performed a comparative genome analysis of 48 Prevotella intermedia and Prevotella nigrescens isolates that from the same cohort of subjects to identify the main drivers of their pathogenicity and adaptation to different environments. The comparisons were done between two species and between disease and health based on pooled sequences. The results showed that both P. intermedia and P. nigrescens have highly dynamic genomes and can take up various exogenous factors through horizontal gene transfer. The major differences between disease-derived and health-derived samples of P. intermedia and P. nigrescens were factors related to genome modification and recombination, indicating that the Prevotella isolates from disease sites may be more capable of genomic reconstruction. We also identified genetic elements specific to each sample, and found that disease groups had more unique virulence factors related to capsule and lipopolysaccharide synthesis, secretion systems, proteinases, and toxins, suggesting that strains from disease sites may have more specific virulence, particularly for P. intermedia. The differentially represented pathways between samples from disease and health were related to energy metabolism, carbohydrate and lipid metabolism, and amino acid metabolism, consistent with data from the whole subgingival microbiome in periodontal disease and health. Disease-derived samples had gained or lost several metabolic genes compared to healthy-derived samples, which could be linked with the difference in virulence performance between diseased and healthy sample groups. Our findings suggest that P. intermedia and P. nigrescens may serve as "crucial substances" in subgingival plaque, which may reflect changes in microbial and environmental dynamics in subgingival microbial ecosystems. This provides insight into the potential of P. intermedia and P. nigrescens as new predictive biomarkers and targets for effective interventions in periodontal disease.

The role of platelets in inflammatory immune responses in generalized aggressive periodontitis.

AIM: To investigate the relationship between inflammatory markers and platelet size in generalized aggressive periodontitis (GAgP). MATERIAL AND METHODS: Periodontal, inflammatory and platelet indices were compared between 59 GAgP patients and 59 healthy subjects. Gingival biopsies from five patients and five healthy subjects were examined by immunohistochemistry and electron microscopy. Changes in patient periodontal and platelet indices were re-evaluated at 3 months after periodontal therapy. RESULTS: Platelet size was decreased significantly in GAgP patients compared to healthy subjects (p ≤ 0.003). Weak negative correlations between platelet size and periodontal parameters were found in GAgP patients (p ≤ 0.025). Platelet aggregates and adhesion to the endothelium or leucocytes were found in venules and connective tissues of gingival biopsies from GAgP patients. Mean platelet volume (MPV) and platelet large cell ratio increased after periodontal therapy in GAgP patients (p ≤ 0.038). The increase in MPV was related to the decrease in bleeding index in GAgP patients after periodontal therapy (p < 0.001; r = 0.357). CONCLUSION: Platelet size was reduced in GAgP patients compared to healthy controls, possibly due to the consumption of large platelets at sites of periodontal inflammation. Platelets may be involved in host responses to periodontal infection in GAgP.

Platelet activation and platelet-leukocyte interaction in generalized aggressive periodontitis.

Generalized aggressive periodontitis (GAgP) is an inflammatory disease of host response to bacterial challenge. To explore the role of platelets in host-microbial interactions in patients with periodontitis, 124 patients with GAgP and 57 healthy subjects were enrolled. Reliable indicators of subclinical platelet functional status, platelet count (PLT), platelet large cell ratio (PLCR), and mean platelet volume (MPV), were significantly lower in the GAgP group than in the control group and were negatively correlated with clinical periodontal parameters. The levels of important cytosolic protein in neutrophils, calprotectin (S100A8/A9) in plasma, and gingival crevicular fluid (GCF) were significantly higher in patients with GAgP compared with healthy subjects. Moreover, the GCF calprotectin level was negatively correlated with PLCR and MPV values. To explore the possible mechanisms of changes in platelet indices in periodontitis, flow cytometry analysis was performed, and patients with GAgP were found to have a higher status of platelet activation compared with healthy controls. Porphyromonas gingivalis (P. gingivalis) and recombinant human S100A8/A9 (rhS100A8/A9) induced platelet activation and facilitated platelet-leukocyte aggregate formation in whole blood of healthy subjects. In response to P. gingivalis and rhS100A8/A9, platelets from patients with GAgP increased activation and increased formation of platelet-leukocyte aggregates compared with those from healthy subjects. Platelet aggregates and platelets attached to leukocytes were found on gingival tissues from patients with GAgP, suggesting that decreased platelet size and count in the circulation might be related to consumption of large, activated platelets at inflamed gingiva. Platelets may have a previously unrecognized role in host response to periodontal infection.