Evaluation of bleeding on probing and gingival crevicular fluid enzyme activity for detection of periodontally active sites during supportive periodontal therapy

Neutrophils in Inflammatory Bone Diseases

PURPOSE OF REVIEW

In this review, we summarize the current evidence that suggests that neutrophils play a key role in facilitating damage to local bone structures.

RECENT FINDINGS

Neutrophil infiltration is a hallmark of inflammatory bone diseases such as rheumatoid arthritis (RA) and periodontitis disease (PD). Both of these human diseases are marked by an imbalance in bone homeostasis, favoring the degradation of local bone which ultimately leads to erosions. Osteoclasts, a multinucleated resident bone cell, are responsible for facilitating the turnover of bone and the bone damage observed in these diseases. The involvement of neutrophils and neutrophil extracellular trap formation have recently been implicated in exacerbating osteoclast function through direct and indirect mechanisms. We highlight a recent finding that NET proteins such as histones and elastase can generate non-canonical, inflammatory osteoclasts, and this process is mediated by post-translational modifications such as citrullination and carbamylation, both of which act as autoantigens in RA. It appears that NETs, autoantibodies, modified proteins, cytokines, and osteoclasts all ultimately contribute to local and permanent bone damage in RA and PD. However, more studies are needed to fully understand the role of neutrophils in inflammatory bone diseases.

The efficacy of air polishing devices in supportive periodontal therapy: Clinical, microbiological and patient-centred outcomes. A systematic review

OBJECTIVES

The aim of this review was to compare air polishing devices with conventional periodontal therapy (hand instrumentation and/or ultrasonic debridement), in terms of their clinical, microbiological and patient-related outcomes in patients undergoing periodontal maintenance therapy.

METHODS

An online database search was performed to identify randomized controlled trials (RCTs) published between January 1987 and March 2021. Selection, data extraction and assessment risk of individual bias were conducted by two independent reviewers. The PICO method was employed to formulate the question: "In patients undergoing periodontal maintenance therapy/supportive periodontal therapy, do air polishing systems result in better clinical, microbiological and patient related outcomes than ultrasonic instrumentation or hand instrumentation?" Primary outcomes were bleeding on probing, gingival index and/or bleeding index. Secondary outcomes were probing depth, clinical attachment level, plaque index, microbiological counts and/or patient tolerance. The risk of bias was evaluated and the systematic review protocol was registered in PROSPERO.

RESULTS

The electronic search yielded 501 references of which 14 were included in this review. A meta-analysis was not performed due to great heterogeneity within the studies. Air polishing devices and conventional periodontal therapy presented identical results in the 14 studies analysed; however, air polishing devices presented better antimicrobial behaviour and better patient-related outcomes.

CONCLUSIONS

Both air polishing devices and conventional techniques demonstrated no difference in terms of clinical efficacy; however, air polishing devices seem to present improved antimicrobial results. In addition, they are also a safer, faster and more comfortable option for patients undergoing supportive periodontal therapy.

Cathepsin K degrades osteoprotegerin to promote osteoclastogenesis in vitro

Osteoblasts produce the receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin, the inducer and the suppressor of osteoclast differentiation and activation. We previously proposed that the degradation of osteoprotegerin by lysine-specific gingipain of Porphyromonas gingivalis and neutrophil elastase is one of the mechanisms of bone resorption associated with infection and inflammation. In the present study, we found that cathepsin K (CTSK) also degraded osteoprotegerin in an acidic milieu and the buffer with a pH of 7.4. The 37 k fragment of osteoprotegerin produced by the reaction with CTSK was further degraded into low molecular weight fragments, including a 13 k fragment, depending on the reaction time. The N-terminal amino acid sequence of the 37 k fragment matched that of the intact osteoprotegerin, indicating that CTSK preferentially hydrolyzes the death domain-like region of osteoprotegerin, not its RANKL-binding region. The 13 k fragment of osteoprotegerin was the C-terminal 13 k portion within the RANKL-binding region of the 37 k fragment. Finally, CTSK restored RANKL-dependent osteoclast differentiation that was suppressed by the addition of osteoprotegerin. Collectively, CTSK is a possible positive regulator of osteoclastogenesis.

In situ gel drug delivery system for periodontitis: an insight review

Background

Periodontitis is a microbial disease that leads to inflammation in the tooth-supporting tissues of the oral cavity that is common among the elderly. It is initiated by oral inflammation induced by bacterial dysbiosis. Choosing an appropriate antimicrobial agent with the right course of drug administration is the key to successful periodontal therapy. In recent times, with more biomarkers and the development of new technologies, several point-of-care testing (POCT) platforms have been developed for the diagnosis and monitoring of periodontitis. This review focuses on oral microbiology and the pathogenesis of periodontitis as well as recent insights into the in situ gel system for periodontitis.

Design

An exhaustive search was conducted in the following scientific databases Science Direct, Springer, Pub Med, and Google Scholar to review all relevant literatures. This is a comprehensive narrative review of the literature, summarizing the perspectives of the authors.

Results

Novel in situ forming gel is introduced at the site that shows a promising potential to overcome one of the main practical obstacles associated with the treatment of local periodontitis: partial adhesion to the surrounding tissue, causing in the accidental expulsion of at least parts of the implants from patient’s pockets. This results in a large residence time of the system at the site of action and uncertainty of the final exposure to the drug.

Conclusion

From the reviewed literature, it is concluded that experimental evidence suggests that the in situ gel-forming systems can be useful in treating several common diseases of the oral cavity. Future research should focus on clinical studies to be performed for the in situ gel to make a significant contribution to periodontitis.

Graphical abstract

Effects of Initial Periodontal Therapy on Heat Shock Protein 70 Levels in Gingival Crevicular Fluid from Periodontitis Patients

Periodontitis is an inflammatory disease of periodontium which is caused by periodontopathic bacteria. Moreover, various cytokines such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6 are expressed in the inflamed periodontium. Heat shock proteins (HSPs) protect cells from abnormal conditions including inflammation, microbial infection and diseases. The 70-kDa HSPs (HSP70s) are major HSPs that express in the inflamed tissues. In this study, an enzyme-linked immunosorbent assay was applied to measure the levels of HSP70 in gingival crevicular fluid (GCF) from two periodontal pockets in each of 10 patients with Stage III, Grade B periodontitis. Sites with probing pocket depth (PPD) of ≤3 mm were named the healthy control (HC) sites, and sites with PPD of ≥5 mm were named the diseased sites. HSP70 levels in GCF were expressed higher at diseased sites than at HC sites, and decreased after initial periodontal therapy at diseased sites. These results suggest the association of HSP70 with the stage of periodontitis.

Usefulness of hemoglobin examination in gingival crevicular fluid during supportive periodontal therapy to diagnose the pre-symptomatic state in periodontal disease

Objectives

The absence of bleeding on probing (BOP) is a good predictor of disease stability. This study investigated whether detection of hemoglobin (Hb) in gingival crevicular fluid (GCF) indicates minute signs of periodontal disease, even in BOP (−) cases.

Materials and methods

GCF was collected from gingival sulci of 152 sound maxillary and mandibular teeth from 76 patients who had entered supportive periodontal therapy (SPT) using the split-mouth design. As clinical parameters, plaque index, GCF amount, gingival index, probing depth (PD), clinical attachment level, BOP, and alveolar bone resorption ratio were then recorded. As biochemical parameters, Hb amount, alkaline phosphatase (ALP) activity, and protein amount in GCF were measured. Periodontal conditions of diseased sites (PD ≥ 4 mm, BOP (+)) and healthy sites (PD ≤ 4 mm, BOP (−)) were further classified into two groups using the Hb cutoff value determined by PD and BOP and analyzed.

Results

Despite being healthy, ALP activity and protein amount in sulci of the group with Hb level greater than the cutoff value were significantly higher than those in the group with Hb level less than the cutoff value (P < 0.01).

Conclusions

This study indicates that Hb examination is a promising candidate marker of pre-symptomatic periodontal disease because Hb presence in GCF suggests slight tissue damage, even in healthy sites defined as BOP (−).

Clinical relevance

Hb examination of GCF is a powerful diagnostic tool for pre-symptomatic diagnosis of periodontal disease.

Anti-heat shock protein 70 levels in gingival crevicular fluid of Japanese patients with chronic periodontitis

Periodontitis is an inflammatory disease involving complex tripartite cross-interactions among bacterial, host and environment factors. Heat shock proteins (Hsps) are a protein family produced in response to stress conditions. Hsps protect cells under adverse circumstances such as infection, inflammation and disease. One of the causes of periodontal disease is thought to be an imbalance in the expression of Hsps and anti-Hsp antibodies. Hsps are classified according to their molecular weight, and one of the major ones is Hsp70. In the present study, enzyme-linked immunosorbent assay was used to measure the levels of anti-Hsp70 antibody in gingival crevicular fluid (GCF) from two gingival sulci in each of nine patients with chronic periodontitis (CP): one healthy control (HC) site with a probing pocket depth (PPD) of ≤3 mm and one CP site with a PPD of >5 mm. Anti-Hsp70 antibody levels in GCF were higher at HC sites than at CP sites. Moreover, the anti-Hsp70 antibody levels were found to increase after initial periodontal therapy at both HC and CP sites. These results suggest an association of anti-Hsp70 antibody with periodontitis.

Possible involvement of elastase in enhanced osteoclast differentiation by neutrophils through degradation of osteoprotegerin

Neutrophils are one of the most abundant leukocytes in the sites of lesion of inflammatory diseases such as periodontitis and rheumatoid arthritis. These diseases are accompanied by bone loss, which worsens the quality of life of the patients. However, the role of neutrophils in the inflammatory bone loss has not been fully investigated. In the present study, we found that human neutrophils enhanced osteoclast differentiation from mouse bone marrow cells co-cultured with mouse osteoblasts in the presence of active vitamin D₃. The enhanced osteoclast differentiation was significantly suppressed by elastatinal, a synthetic inhibitor of neutrophil elastase. Also, we found that human neutrophils degraded human recombinant osteoprotegerin (OPG), a decoy receptor for nuclear factor κB (RANK) ligand (RANKL), the essential osteoclast differentiation-inducing factor, expressed by osteoblasts. Degradation of OPG by neutrophils was suppressed by human α₁-protease inhibitor, the major endogenous inhibitor of neutrophil elastase. Recombinant human neutrophil elastase degraded human OPG in its death domain-like region. These results indicated that the degradation of OPG by elastase contributed at least in part to the enhanced osteoclast differentiation by neutrophils. There is a possibility that neutrophils play an important role in inflammatory bone loss.

Association of chairside salivary aMMP-8 findings with periodontal risk assessment parameters in patients receiving supportive periodontal therapy

Purpose

The aim of this retrospective cross-sectional study was to evaluate whether salivary findings of active matrix-metalloproteinase 8 (aMMP-8) chairside (point of care; POC) tests were associated with periodontal risk assessment parameters in patients receiving supportive periodontal therapy (SPT).

Methods

A total of 125 patients receiving regular SPT were included, and their records were examined. The following inclusion criteria were used: a diagnosis of chronic periodontitis, at least 1 non-surgical periodontal treatment (scaling and root planning) with following regular SPT (minimum once a year), at least 6 remaining teeth, and clinical and aMMP-8 findings that were obtained at the same appointment. In addition to anamnestic factors (e.g., smoking and diabetes), oral hygiene indices (modified sulcus bleeding index [mSBI] and approximal plaque index), periodontal probing depth simultaneously with bleeding on probing, and dental findings (number of decayed, missing, and filled teeth) were recorded. Salivary aMMP-8 levels were tested using a commercial POC test system (Periomarker, Hager & Werken, Duisburg, Germany). Statistical analysis was performed using the t-test, Mann-Whitney U test, Fisher's exact test, and χ² test, as appropriate (P<0.05).

Results

Only the mSBI was significantly associated with positive salivary aMMP-8 findings (aMMP-8 positive: 27.8%±20.9% vs. aMMP-8 negative: 18.0%±14.5%; P=0.017). No significant associations were found between aMMP-8 and smoking, diabetes, periodontal parameters, or parameters related to the maintenance interval (P>0.05).

Conclusions

Salivary aMMP-8 chairside findings were not associated with common parameters used for periodontal risk assessment in patients receiving SPT. The diagnostic benefit of POC salivary aMMP-8 testing in risk assessment and maintenance interval adjustment during SPT remains unclear.

Correlation Between Gingival Crevicular Fluid Hemoglobin Content and Periodontal Clinical Parameters

BACKGROUND

Probing depth (PD) and bleeding on probing (BOP) are essential clinical parameters used for periodontal diagnosis. This study investigated whether detection of hemoglobin (Hb) in gingival crevicular fluid (GCF), along with PD and BOP, would improve diagnostic accuracy.

METHODS

After plaque index (PI) was measured, GCF was collected from the gingival sulci of 401 anterior teeth in the maxilla and mandible from 184 patients who had entered periodontal maintenance therapy. Clinical parameters (gingival index [GI], PD, clinical attachment level [CAL], and BOP) were recorded. Hb values in GCF were assessed by immunochromatography. Moreover, cutoff values for PI, GI, and CAL based on the degree of PD and amount of GCF were created and analyzed.

RESULTS

Hb was detected in 64.8% of GCF samples in 105 BOP-negative (-) sites in the periodontally stable group out of 107 sites that were less than all cutoff values. There were 71 BOP(-) sites in the periodontal-management-required group out of 122 sites that were more than all cutoff values, although no improvement in periodontal disease was observed. Hb was detected in 88.7% of GCF samples from these 71 BOP(-) sites.

CONCLUSIONS

Hb was observed in more than 60% of GCF samples in BOP(-) gingival sulci in both periodontally stable and periodontal-management-required groups. These results suggest inspection of Hb derived from microbleeding in gingival sulci may serve as an index for preclinical diagnosis.

Synthesis, characterization and evaluation of tinidazole-loaded mPEG-PDLLA (10/90) in situ gel forming system for periodontitis treatment

Traditional in situ gel forming systems are potential applications for parenteral administration but always accompanied with burst release. To overcome this limitation, the tinidazole (TNZ)-loaded in situ gel forming system using a diblock copolymer, monomethoxy poly(ethylene glycol)-block-poly(d,l-lactide) (mPEG-PDLLA), was designed. The formulation of the mPEG-PDLLA-based TNZ in situ gel forming system contained 5% (w/w) TNZ, 0.4% glycerol, 5 ml N-methyl pyrrolidone (NMP) and 35% (w/w) mPEG-PDLLA. The in situ gel forming system showed sustained TNZ release over 192 h with low burst effect (around 7% in the first 8 h) in the in vitro release study. Additionally, in vivo studies were performed on rabbits with ligature-induced periodontitis, and the concentration of TNZ in the gingival crevicular fluid (GCF) as well as the pharmacokinetic parameters was calculated and the pharmacological effect of TNZ-loaded in situ gel forming (mPEG-PDLLA)-based system was found effective. Finally, histological studies revealed that the gel was a safe formulation with low irritation. The desirable drug release kinetics combined with the excellent in vivo characteristics highlight the potential of the gel in the treatment of periodontitis. Therefore, these results confirmed that the TNZ-loaded in situ gel forming mPEG-PDLLA-based system could reduce burst release of TNZ and act as a sustained-release and injectable drug depot for periodontitis treatment.