The effect of metronidazole on the presence of P. gingivalis and T. forsythia at 3 and 12 months after different periodontal treatment strategies evaluated in a randomized, clinical trial

Metronidazole may display anti-inflammatory features in periodontitis treatment: A scoping review

AIM

Metronidazole (MTZ) is an antimicrobial agent used to treat anaerobic infections. It has been hypothesized that MTZ may also have anti-inflammatory properties, but the evidence is limited and has not been previously reviewed. Thus, this scoping review aimed to answer the following question: "What is the evidence supporting anti-inflammatory properties of metronidazole that are not mediated by its antimicrobial effects?"

METHODS

A scoping review was conducted according to the PRISMA-ScR statement. Five databases were searched up to January 2023 for studies evaluating the anti-inflammatory properties of MTZ used as monotherapy for treating infectious and inflammatory diseases.

RESULTS

A total of 719 records were identified, and 27 studies (21 in vivo and 6 in vitro) were included. The studies reported experimental evidence of MTZ anti-inflammatory effects on (1) innate immunity (barrier permeability, leukocyte adhesion, immune cell populations), (2) acquired immunity (lymphocyte proliferation, T-cell function, cytokine profile), and (3) wound healing/resolution of inflammation.

CONCLUSION

Taken together, this scoping review supported a potential anti-inflammatory effect of MTZ in periodontitis treatment. We recommend that future clinical studies should be conducted to evaluate specific MTZ anti-inflammatory pathways in the treatment of periodontitis.

Periodontal microbiology and microbial etiology of periodontal diseases: Historical concepts and contemporary perspectives

This narrative review summarizes the collective knowledge on periodontal microbiology, through a historical timeline that highlights the European contribution in the global field. The etiological concepts on periodontal disease culminate to the ecological plaque hypothesis and its dysbiosis-centered interpretation. Reference is made to anerobic microbiology and to the discovery of select periodontal pathogens and their virulence factors, as well as to biofilms. The evolution of contemporary molecular methods and high-throughput platforms is highlighted in appreciating the breadth and depth of the periodontal microbiome. Finally clinical microbiology is brought into perspective with the contribution of different microbial species in periodontal diagnosis, the combination of microbial and host biomarkers for this purpose, and the use of antimicrobials in the treatment of the disease.

Full-mouth treatment modalities (within 24 hours) for periodontitis in adults

BACKGROUND

Periodontitis is a highly prevalent, chronic inflammation that causes damage to the soft tissues and bones supporting the teeth. Conventional treatment is quadrant scaling and root planing (the second step of periodontal therapy), which comprises scaling and root planing of teeth in one quadrant of the mouth at a time, with the four different sessions separated by at least one week. Alternative protocols for anti-infective periodontal therapy have been introduced to help enhance treatment outcomes: full-mouth scaling (subgingival instrumentation of all quadrants within 24 hours), or full-mouth disinfection (subgingival instrumentation of all quadrants in 24 hours plus adjunctive antiseptic). We use the older term 'scaling and root planing' (SRP) interchangeably with the newer term 'subgingival instrumentation' in this iteration of the review, which updates one originally published in 2008 and first updated in 2015.

OBJECTIVES

To evaluate the clinical effects of full-mouth scaling or full-mouth disinfection (within 24 hours) for the treatment of periodontitis compared to conventional quadrant subgingival instrumentation (over a series of visits at least one week apart) and to evaluate whether there was a difference in clinical effects between full-mouth disinfection and full-mouth scaling.

SEARCH METHODS

An information specialist searched five databases up to 17 June 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) lasting at least three months that evaluated full-mouth scaling and root planing within 24 hours, with or without adjunctive use of an antiseptic, compared to conventional quadrant SRP (control). Participants had a clinical diagnosis of (chronic) periodontitis according to the International Classification of Periodontal Diseases from 1999. A new periodontitis classification was launched in 2018; however, we used the 1999 classification for inclusion or exclusion of studies, as most studies used it. We excluded studies of people with systemic disorders, taking antibiotics or with the older diagnosis of 'aggressive periodontitis'.

DATA COLLECTION AND ANALYSIS

Several review authors independently conducted data extraction and risk of bias assessment (based on randomisation method, allocation concealment, examiner blinding and completeness of follow-up). Our primary outcomes were tooth loss and change in probing pocket depth (PPD); secondary outcomes were change in probing attachment (i.e. clinical attachment level (CAL)), bleeding on probing (BOP), adverse events and pocket closure (the number/proportion of sites with PPD of 4 mm or less after treatment). We followed Cochrane's methodological guidelines for data extraction and analysis.

MAIN RESULTS

We included 20 RCTs, with 944 participants, in this updated review. No studies assessed the primary outcome tooth loss. Thirteen trials compared full-mouth scaling and root planing within 24 hours without the use of antiseptic (FMS) versus control, 13 trials compared full-mouth scaling and root planing within 24 hours with adjunctive use of an antiseptic (FMD) versus control, and six trials compared FMS with FMD. Of the 13 trials comparing FMS versus control, we assessed three at high risk of bias, six at low risk of bias and four at unclear risk of bias. We assessed our certainty about the evidence as low or very low for the outcomes in this comparison. There was no evidence for a benefit for FMS over control for change in PPD, gain in CAL or reduction in BOP at six to eight months (PPD: mean difference (MD) 0.03 mm, 95% confidence interval (CI) -0.14 to 0.20; 5 trials, 148 participants; CAL: MD 0.10 mm, 95% CI -0.05 to 0.26; 5 trials, 148 participants; BOP: MD 2.64%, 95% CI -8.81 to 14.09; 3 trials, 80 participants). There was evidence of heterogeneity for BOP (I² = 50%), but none for PPD and CAL. Of the 13 trials comparing FMD versus control, we judged four at high risk of bias, one at low risk of bias and eight at unclear risk of bias. At six to eight months, there was no evidence for a benefit for FMD over control for change in PPD or CAL (PPD: MD 0.11 mm, 95% CI -0.04 to 0.27; 6 trials, 224 participants; low-certainty evidence; CAL: 0.07 mm, 95% CI -0.11 to 0.24; 6 trials, 224 participants; low-certainty evidence). The analyses found no evidence of a benefit for FMD over control for BOP (very low-certainty evidence). There was no evidence of heterogeneity for PPD or CAL, but considerable evidence of heterogeneity for BOP, attributed to one study. There were no consistent differences in these outcomes between intervention and control (low- to very low-certainty evidence). Of the six trials comparing FMS and FMD, we judged two trials at high risk of bias, one at low risk of bias and three as unclear. At six to eight months, there was no evidence of a benefit of FMD over FMS for change in PPD or gain in CAL (PPD: MD -0.11 mm, 95% CI -0.30 to 0.07; P = 0.22; 4 trials, 112 participants; low-certainty evidence; CAL: MD -0.05 mm, 95% CI -0.23 to -0.13; P = 0.58; 4 trials, 112 participants; low-certainty evidence). There was no evidence of a difference between FMS and FMD for BOP at any time point (P = 0.98; 2 trials, 22 participants; low- to very low-certainty evidence). There was evidence of heterogeneity for BOP (I² = 52%), but not for PPD or CAL. Thirteen studies predefined adverse events as an outcome; three reported an event after FMD or FMS. The most important harm identified was an increase in body temperature. We assessed the certainty of the evidence for most comparisons and outcomes as low because of design limitations leading to risk of bias, and the small number of trials and participants, leading to imprecision in the effect estimates.

AUTHORS' CONCLUSIONS

The inclusion of nine new RCTs in this updated review has not changed the conclusions of the previous version of the review. There is still no clear evidence that FMS or FMD approaches provide additional clinical benefit compared to conventional mechanical treatment for adult periodontitis. In practice, the decision to select one approach to non-surgical periodontal therapy over another should include patient preference and the convenience of the treatment schedule.

Influence of Anti-Infective Periodontal Therapy on Subgingival Microbiota Evaluated by Chair-Side Test Compared to qPCR—A Clinical Follow-Up Study

A chair-side test (CST) for five periodontal pathogens (Aggregatibacter actinomycetemcomitans, A.a.; Porphyromonas gingivalis, P.g.; Prevotella intermedia, P.i.; Treponema denticola, T.d.; Tannerella forsythia, T.f.) was compared with qPCR in a previous clinical study on 100 periodontitis patients at first diagnosis (T0). Following non-surgical treatment alone (SRP) or in combination with systemic or local antibiotics, 74 patients (57.4 ± 13.5 years) were again tested at the same sites from 14 to 24 months after T0. Bacterial elimination (%; compared to T0) was determined for each single species and compared between both test systems. In all patients, all five pathogens could not be fully eliminated regardless of therapy or test method. Tested with CST, the mean elimination ranged from 90% for SRP + Amoxicillin/Metronidazole to 59.13% for SRP only. The corresponding qPCR values were 30% and 29.6%. Only A.a. was eradicated in 100% by SRP + Amoxicillin/Metronidazole tested by CST, and it was 80% when qPCR was the test method. CST agreed with qPCR in 98.7% in the detection of A.a., and 74.3%, 78.4%, 73.0%, and 48.7% for P.g., P.i., T.d., and T.f., respectively. Neither conventional treatment nor the additional use of antibiotics—even with the correct indication—could completely eradicate the tested pathogens or prevent pocket reinfection.

Antibiotics in the Treatment of Periodontitis: A Systematic Review of the Literature

Introduction

Systemic antibiotics present one of the alternative adjunctive therapies in nonsurgical periodontal treatment (NSPT). Different protocols have been proposed, but their indication and effectiveness are still controversial. The aim of this study is to assess the effectiveness of the addition of antibiotics after nonsurgical debridement during initial therapy and compare different antimicrobial prescription protocols.

Materials and Methods

An electronic search was performed through MEDLINE and EBSCOhost databases using the appropriate MeSH words. The target studies have to be published during the last five years. Data from the selected studies were extracted and analyzed. Study selection was done based on inclusion and exclusion criteria.

Results

Seven randomized clinical trials were included in our review. Their data were extracted using a grid established for this purpose. Collectively, different protocols have been proposed and almost all of them yield superior clinical and microbiological results compared to the placebo group.

Conclusion

The overall findings of this review show a positive effect of the use of antibiotics as an adjunctive to NSPT, regardless of the antimicrobial agents used in our included studies. Sites with PD > 6 mm may benefit most from the adjunctive use of antibiotics in NSPT. This trial is registered with Clinicaltrials.gov identifiers: NCT02829983 (Bechara Andere et al., 2016); NCT02839421 (Ardila et al., 2020); NCT02735395 (Borges et al., 2017); NCT02359721 (Suryaprasanna et al., 2018); and NCT01318928 (Hans, 2015).

Comparative In Vitro Resistance of Human Periodontal Bacterial Pathogens to Tinidazole and Four Other Antibiotics

The in vitro resistance of selected red/orange complex periodontal pathogens to tinidazole was compared with four other antibiotics. Subgingival biofilm samples from 88 adults with severe periodontitis were anaerobically incubated on enriched Brucella blood agar with and without supplementation with tinidazole (16 mg/L), metronidazole (16 mg/L), amoxicillin (8 mg/L), doxycycline (4 mg/L), or clindamycin (4 mg/L). Growth of Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Fusobacterium nucleatum, Streptococcus constellatus, or Campylobacter rectus on antibiotic-supplemented plates indicated their in vitro antibiotic resistance. Tinidazole inhibited all test species, except P. intermedia/nigrescens, P. micra, and S. constellatus in 3.8%, 10.2%, and 88.9% of species-positive patients, respectively. Significantly fewer patients yielded tinidazole-resistant test species, and had significantly lower subgingival proportions of tinidazole-resistant organisms, than patients with amoxicillin, doxycycline, or clindamycin-resistant species, but not those with metronidazole-resistant strains. Joint in vitro species resistance to tinidazole and amoxicillin, or metronidazole and amoxicillin, was rare. Tinidazole performed in vitro similar to metronidazole, and markedly better than amoxicillin, doxycycline, or clindamycin, against fresh clinical isolates of red/orange complex periodontal pathogens. As a result of its similar antimicrobial spectrum, and more convenient once-a-day oral dosing, tinidazole should be considered in place of metronidazole for systemic periodontitis drug therapy.

What is the Proper Sample Size for Studies of Periodontal Treatment?

Small sample sizes are a common problem in biomedical research, and the periodontal literature is no exception. It is a problem leading to not only reduced statistical power but also an inappropriate statistical inference of a treatment effect. Using statistical methods with an insufficient sample size may give rise to an increased chance of falsely detecting treatment efficacy. This article provides some guidelines to cope with the small sample size problem. The authors discuss adequate sample sizes in several statistical tests and then suggest alternative statistical methods that are valid with a small sample size.

Methodological issues in the quantification of subgingival microorganisms using the checkerboard technique

The reproducibility and reliability of quantitative microbiological assessments using the DNA-DNA hybridization "checkerboard method" (CKB) were assessed. The data originated from 180 chronic periodontitis patients, who were enrolled in a clinical trial and sampled at baseline, and 3 and 12m post-therapy. The samples were divided into two portions allowing evaluation of reproducibility. In total, 531 samples were analyzed in a first run, using standard bacterial preparations of cells and 513 samples were accessible for analysis in the second, using standards based on purified DNA from the species. The microbial probe panel consisted of periodontitis marker bacteria as well as non-oral microorganisms. Three different ways of quantifying and presenting data; the visual scoring method, VSM, the standard curve method, SCM, and the percent method, PM, were compared. The second set of analyses based on the use of standard preparations of pure DNA was shown to be more consistent than the first set using standards based on cells, while the effect of storage time per se up to 2.5y seemed to be marginal. The best reproducibility was found for Tannerella forsythia, irrespective of quantification technique (Spearman's rho=0.587, Pearson's r≥0.540). The percent method (PM) based on percent of High Standard (10(6) cells) was more reliable than SCM based on a linear calibration of the High Standard and a Low Standard (10(5) cells). It was concluded that the reproducibility of the CBK method varied between different bacteria. High quality and pure specific DNA whole genomic probes and standards may have a stronger impact on the precision of the data than storage time and conditions.