Microbiological changes associated with four different periodontal therapies for the treatment of chronic periodontitis

Community dynamics of subgingival microbiome in periodontitis and targets for microbiome modulation therapy

The microbial aetiology for periodontitis has been widely studied and deciphered for more than a century. The evolving and changing concepts about periodontal microbiology can be attributed to continuously developing laboratory techniques. The current sequencing platforms have not only expanded the catalog of periodontal pathogens but have also facilitated the understanding of functional interactions of the ecological framework. However, the translation of this new knowledge to advance periodontal therapeutics is minimal. We contend that novel clinical interventions directed beyond conventional therapies need to be emphasized. A clear understanding of the structural and functional dynamics of subgingival microbiota is a pre-requisite for developing any microbiome-based interventions for applications in periodontal health care. In this review, we discuss the 16 s-rRNA gene sequencing-based knowledge of the subgingival microbial community structure, its interactions and functions, and our perspective on the potential to engineer it for periodontal therapeutics. Harnessing this next-generation sequencing-based knowledge, microbiome modulation therapies are poised to change microbiome therapeutics' face.

Newly identified pathogens in periodontitis: evidence from an association and an elimination study

We assessed the level of evidence for the presence of new periodontal pathogens by (i) comparing the occurrence of non-classical periodontal taxa between healthy vs. periodontitis patients (Association study); (ii) assessing the modifications in the prevalence and levels of these species after treatments (Elimination study). In the Association study, we compared the prevalence and levels of 39 novel bacterial species between periodontally healthy and periodontitis patients. In the Elimination study, we analyzed samples from periodontitis patients assigned to receive scaling and root planing alone or with metronidazole+ amoxicillin TID/ 14 days. Levels of 79 bacterial species (39 novel and 40 classic) were assessed at baseline, 3 and 12 months post-therapy. All samples were analyzed using Checkerboard DNA-DNA hybridization. Out of the 39 novel species evaluated, eight were categorized as having strong and four as having moderate association with periodontitis. Our findings suggest strong evidence supporting Lancefieldella rimae, Cronobacter sakazakii, Pluralibacter gergoviae, Enterococcus faecalis, Eubacterium limosum, Filifactor alocis, Haemophilus influenzae, and Staphylococcus warneri, and moderate evidence supporting Escherichia coli, Fusobacterium necrophorum, Spiroplasma ixodetis, and Staphylococcus aureus as periodontal pathogens. These findings contribute to a better understanding of the etiology of periodontitis and may guide future diagnostic and interventional studies.

Periodontal treatment and microbiome-targeted therapy in management of periodontitis-related nonalcoholic fatty liver disease with oral and gut dysbiosis

A growing body of evidence from multiple areas proposes that periodontal disease, accompanied by oral inflammation and pathological changes in the microbiome, induces gut dysbiosis and is involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). A subgroup of NAFLD patients have a severely progressive form, namely nonalcoholic steatohepatitis (NASH), which is characterized by histological findings that include inflammatory cell infiltration and fibrosis. NASH has a high risk of further progression to cirrhosis and hepatocellular carcinoma. The oral microbiota may serve as an endogenous reservoir for gut microbiota, and transport of oral bacteria through the gastro-intestinal tract can set up a gut microbiome dysbiosis. Gut dysbiosis increases the production of potential hepatotoxins, including lipopolysaccharide, ethanol, and other volatile organic compounds such as acetone, phenol and cyclopentane. Moreover, gut dysbiosis increases intestinal permeability by disrupting tight junctions in the intestinal wall, leading to enhanced translocation of these hepatotoxins and enteric bacteria into the liver through the portal circulation. In particular, many animal studies support that oral administration of Porphyromonas gingivalis, a typical periodontopathic bacterium, induces disturbances in glycolipid metabolism and inflammation in the liver with gut dysbiosis. NAFLD, also known as the hepatic phenotype of metabolic syndrome, is strongly associated with metabolic complications, such as obesity and diabetes. Periodontal disease also has a bidirectional relationship with metabolic syndrome, and both diseases may induce oral and gut microbiome dysbiosis with insulin resistance and systemic chronic inflammation cooperatively. In this review, we will describe the link between periodontal disease and NAFLD with a focus on basic, epidemiological, and clinical studies, and discuss potential mechanisms linking the two diseases and possible therapeutic approaches focused on the microbiome. In conclusion, it is presumed that the pathogenesis of NAFLD involves a complex crosstalk between periodontal disease, gut microbiota, and metabolic syndrome. Thus, the conventional periodontal treatment and novel microbiome-targeted therapies that include probiotics, prebiotics and bacteriocins would hold great promise for preventing the onset and progression of NAFLD and subsequent complications in patients with periodontal disease.

Sodium Hypochlorite and Diode Laser in Non-Surgical Treatment of Periodontitis: Clinical and Bacteriological Study with Real Time Polymerase Chain Reaction (PCR)

Increasing the disinfection during non-surgical treatment of periodontitis is primordial. This study assesses the effectiveness of sodium hypochlorite and a 980 nm diode laser in non-surgical treatment of periodontitis. Thirty sites of localized periodontitis with a probing pocket depth (PPD) of ≥ 6 mm were included. Fifteen underwent scaling root planing (SRP group) and 15 underwent SRP + 0.5% NaOCl and a 980 nm diode laser (study group). A biological molecular test and real time polymerase chain reaction (RT-PCR) were performed before (T0) and after intervention (T1). Total bacterial count and counts of Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Prevotella intermedia, Peptostreptococcus micros, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Eubacterium nodatum, Capnocytophaga gingivalis were assessed. Plaque index (PI), bleeding on probing (BOP), gingival recession (GR), PPD and clinical attachment loss (CAL) were evaluated at T0, and 3 and 6 months after. Study group showed a statistically significant reduction of TBC (5.66 × 10⁸ CFU/mL) compared to SRP (6.2 × 10⁹ CFU/mL). Both groups showed a statistically significant reduction of Treponema denticola, Tannerella forsythia, Prevotella intermedia, Peptostrep. (micromonas) micros and Fusobacterium nucleatum; however, a significant reduction of Eubacterium nodatum and Capnocytophaga gingivalis was observed in the study group. At T6, both groups had a statistically significant reduction of PI, BOP, GR, PD and CAL. The study group showed more GR compared to SRP and a significant reduction of PD (4.03 mm ± 0.49) compared to SRP (5.28 mm ± 0.67). This study reveals that NaOCl and a diode laser are effective as an adjunctive to the non-surgical treatment of periodontitis.

Metronidazole enhances killing of Porphyromonas gingivalis by human PMNs

Background and objectives

Periodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.

Materials and methods

Flow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.

Results

We demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/ml) displayed enhanced killing of P. gingivalis compared to untreated PMNs. At concentrations achieved physiologically in the periodontal pocket, MTZ induced PMN surface expression of two activation markers (CD66 and CD63). MTZ did not alter P. gingivalis-induced NETosis, but suppressed P. gingivalis-induced ROS production and phagocytosis.

Conclusion

MTZ displays a positive interaction with PMNs to potentiate PMN mediated killing of P. gingivalis and may therefore contribute to its beneficial effects in the treatment of periodontitis initiated by P. gingivalis infections including those refractory to conventional treatment.

Influence of Manual and Ultrasonic Scaling on Surface Roughness of Four Different Base Materials Used to Elevate Proximal Dentin-Cementum Gingival Margins: An In Vitro Study

AIM

To evaluate and compare the effects of both manual and ultrasonic scaling on surface roughness of four different base materials, used for elevating dentin/cementum gingival margins of proximal cavities.

METHODS AND MATERIALS

Eighty human upper molars with compound Class II mesial cavities, with gingival margins 1 mm below the cemento-enamel junction (CEJ), were divided into four different groups according to the type of the base material used; resin-modified glass ionomer (RMGI), glass hybrid (HV-GIC), flowable bulk-fill resin composite (Bulk Flow) and bioactive ionic resin (Activa). This was followed by completing the restorations with the same resin composite. All materials were used according to the manufacturers' instructions. All groups were further subdivided into two subgroups according to the scaling technique: manual (hand) or ultrasonic. All restorative and scaling procedures were performed after fixation of specimens with acrylic beside neighboring teeth to simulate natural contact. The mean surface roughness (Ra, μm) of all specimens was measured quantitatively and qualitatively by a three-dimensional (3D) surface analyzer system at two stages; (1) after thermal cycling for 5000 cycles without scaling and (2) after scaling. Data were statistically analyzed using analysis of variance (ANOVA), Tukey post hoc tests, and paired sample t-tests (at α=0.05).

RESULTS

For baseline readings, the Bulk Flow group had the lowest Ra values, while HV-GIC group had the highest. RMGI and Activa groups had no statistical significant difference between their Ra values (p>0.05). For post scaling readings, hand scaling had significantly lower Ra values than ultrasonic scaling in all the material groups (p<0.05), except in the Bulk Flow group, where both scaling methods were not significantly different from each other (p>0.05).

CONCLUSION

Bulk Flow had the smoothest surfaces when cured against a matrix band compared with the other tested base materials. When hand and ultrasonic scaling methods were compared, the latter technique had more detrimental effect on the surface texture of the four tested base materials.

Adjunctive efficacy of systemic metronidazole in the surgical treatment of periodontitis: a double-blind parallel randomized clinical trial

OBJECTIVES

The purpose of this study was to evaluate the clinical and microbiological impact of adjunctive metronidazole to periodontal surgery.

MATERIALS AND METHODS

Systemically healthy patients, with stages III-IV, grades B-C periodontitis, were randomly assigned to receive metronidazole or placebo adjunctive to periodontal surgery, after subgingival instrumentation. Clinical variables were recorded at the initial visit, 6 weeks after subgingival instrumentation, and 3, 6, and 12 months after surgery. Microbiological samples were taken at initial and final visits and analyzed by quantitative polymerase chain reaction.

RESULTS

Our results showed no statistically significant differences in the reduction of probing depth between the initial and final (1 year) visits in the two treatment groups. Additionally, no statistically significant differences were observed between study groups when comparing the post-subgingival instrumentation and final visits. However, 3 months after surgery, probing depth (mean difference, MD = 0.31 mm, 95% confidence interval, CI [0.13; 0.49]; p = 0.001) and clinical attachment level (MD = 0.64 mm, 95% CI [0.02; 1.27]; p = 0.044) were significantly lower in the test group.

CONCLUSIONS

The adjunctive use of systemic metronidazole to periodontal surgery has a limited clinical and microbiological impact in the present study, and therefore, its use is not recommended.

CLINICAL RELEVANCE

There are no studies that have evaluated the clinical and microbiological impact of the adjunctive use of systemic metronidazole to periodontal surgery (step 3 of periodontal therapy). The results of the present study do not support the adjunctive use of systemic metronidazole to periodontal surgery.

Bacterial resistance to minocycline after adjunctive minocycline microspheres during periodontal maintenance: A randomized clinical trial

BACKGROUND

Despite widespread use, the impact of minocycline hydrochloride microspheres on the shifts of oral bacterial species resistant to minocycline remains unknown. This study aimed at examining the percentage and taxonomy of minocycline-resistant isolates in saliva and subgingival plaque samples before and after minocycline microspheres application in periodontitis patients during maintenance.

METHODS

Patients received supra- and sub-gingival debridement with (test) or without (control) minocycline microspheres application to sites with probing depth >4 mm and were clinically monitored at baseline, 1, 3, and 6 months. Samples were collected at baseline, 1 and 6 months and analyzed via cultivation with or without 4 μg/mL minocycline. Percentage of resistant strains was determined by colony counting and taxonomy by checkerboard DNA-DNA hybridization. Significant clinical changes were sought with the Mann-Whitney test and differences in percentage of resistant isolates with the Friedman and Mann-Whitney tests.

RESULTS

Groups showed similar clinical improvements. Mean percentage of resistant isolates rose at 1 month and decreased at 6 months in saliva and plaque samples in test group (P <0.05) but remained unchanged in control group. Percentage of resistant isolates of Gemella morbillorum and Eubacterium saburreum increased significantly at 6 months in both groups. Antibiotic resistance by Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Porphyromonas gingivalis was either absent or infrequent.

CONCLUSION

Minocycline microspheres result in transient selection of minocycline resistant species in saliva and subgingival plaque samples.

Dental Plaque Microbial Resistomes of Periodontal Health and Disease and Their Changes after Scaling and Root Planing Therapy

The human oral microbial community has been considered a reservoir of antibiotic resistance. Currently, the effects of periodontitis and the scaling and root planing (SRP) treatment on the performance of antibiotic-resistant genes (ARGs) and metal-resistant genes (MRGs) in the dental plaque microbiota are not well characterized. To explore this issue, we selected 48 healthy-state (HS), 40 periodontitis-state (PS; before treatment), and 24 resolved-state (RS; after SRP treatment) metagenomic data of dental plaque samples from the Sequence Read Archive (SRA) database. NetShift analysis identified Fretibacterium fastidiosum, Tannerella forsythia, and Campylobacter rectus as key drivers during dental plaque microbiota alteration in the progression of periodontitis. Periodontitis and SRP treatment resulted in an increase in the number of ARGs and MRGs in dental plaque and significantly altered the composition of ARG and MRG profiles. Bacitracin, beta-lactam, macrolide-lincosamide-streptogramin (MLS), tetracycline, and multidrug resistance genes were the main classes of ARGs with high relative abundance, whereas multimetal, iron, chromium, and copper resistance genes were the primary types of MRGs in dental plaque microbiota. The cooccurrence of ARGs, MRGs, and mobile genetic elements (MGEs) indicated that a coselection phenomenon exists in the resistomes of dental plaque microbiota. Overall, our data provide new insights into the standing of the distribution of ARGs and MRGs in oral microbiota of periodontitis patients, and it was possible to contribute to the understanding of the complicated correlations among microorganisms, resistomes, and MGEs. IMPORTANCE The emergence and development of resistance to antibiotics in periodontal pathogens have affected the success rate of treatment for periodontitis. The development of new antibacterial strategies is urgently needed to help control and treat periodontal disease, and dental plaque microbiome studies offer a promising new angle of attack. In this study, we investigated the dental plaque microbiota and resistomes in periodontal health and disease states and their changes after SRP therapy. This is the first analysis of the profile of the microbial community and antibiotic and metal resistance genes in dental plaque by the metagenomic approach, to the best of our knowledge. Monitoring the profile of these resistomes has huge potential to provide reference levels for proper antibiotics use and the development of new antimicrobial strategies in periodontitis therapy and thereby improve actual efficacy of the treatment regimens.

Application value of combination therapy of periodontal curettage and root planing on moderate-to-severe chronic periodontitis in patients with type 2 diabetes

Background

Our study attempted to observe the value of periodontal curettage combined with root planing on moderate-to-severe chronic periodontitis in patients with type 2 diabetes.

Methods

There involved 72 patients with type 2 diabetes mellitus complicated with moderate-to-severe chronic periodontitis who were diagnosed and treated in our hospital from January 2019 to December 2019. The patients enrolled were randomly divided into four groups using a computer-generated table: root planing and periodontal curettage combined group (n = 18), root planning group (n = 18), periodontal curettage group (n = 18) and cleansing group (n = 18). Blood glucose, plaque index (PI), gingival index (GI), probing depth (PD), attachment loss (AL), serum levels of inflammatory factors (Tumor Necrosis Factor Alpha [TNF- α] and hypersensitive C-reactive protein [hs-CRP]) were observed before and after treatment. The collecting dates were analyzed by the chi-square χ 2 test, repeated measurement analysis of variance, or t-test according to different data types and research objectives.

Results

Before treatment, there was no significant difference in PI, GI, PD and AL among the four groups (P> 0.05), while after 3-month treatment, the levels of PI, GI, PD and AL in the combined group were lower than those in the root planing group, periodontal curettage group and cleansing group, with both root planing group and periodontal curettage group significantly lower than cleansing group (P< 0.05). The fasting blood glucose, 2-h postprandial blood glucose and glycosylated hemoglobin in the combined group, root planing group, periodontal curettage group and cleansing group were significantly lower than those before treatment (P < 0.05). Before treatment, there was no significant difference in TNF- α and hs-CRP among the four groups (P> 0.05), but the levels of TNF- α and hs-CRP in the four groups decreased significantly after 3-month treatment (P< 0.05). The levels of TNF- α and hs-CRP in the combined group were lower than those in the root planing group, periodontal curettage group and cleansing group, and those in the root planing group and periodontal curettage group were significantly lower than those in the cleansing group (P< 0.05).

Conclusion

The combination therapy of periodontal curettage and root planing exerted beneficial effects on moderate-to-severe chronic periodontitis in patients with type 2 diabetes mellitus, which holds the potential to maintain the level of blood glucose and improve the quality of life of the patients.

Dysbiosis From a Microbial and Host Perspective Relative to Oral Health and Disease

The significance of microbiology and immunology with regard to caries and periodontal disease gained substantial clinical or research consideration in the mid 1960's. This enhanced emphasis related to several simple but elegant experiments illustrating the relevance of bacteria to oral infections. Since that point, the understanding of oral diseases has become increasingly sophisticated and many of the original hypotheses related to disease causality have either been abandoned or amplified. The COVID pandemic has reminded us of the importance of history relative to infectious diseases and in the words of Churchill "those who fail to learn from history are condemned to repeat it." This review is designed to present an overview of broad general directions of research over the last 60 years in oral microbiology and immunology, reviewing significant contributions, indicating emerging foci of interest, and proposing future directions based on technical advances and new understandings. Our goal is to review this rich history (standard microbiology and immunology) and point to potential directions in the future (omics) that can lead to a better understanding of disease. Over the years, research scientists have moved from a position of downplaying the role of bacteria in oral disease to one implicating bacteria as true pathogens that cause disease. More recently it has been proposed that bacteria form the ecological first line of defense against "foreign" invaders and also serve to train the immune system as an acquired host defensive stimulus. While early immunological research was focused on immunological exposure as a modulator of disease, the "hygiene hypothesis," and now the "old friends hypothesis" suggest that the immune response could be trained by bacteria for long-term health. Advanced "omics" technologies are currently being used to address changes that occur in the host and the microbiome in oral disease. The "omics" methodologies have shaped the detection of quantifiable biomarkers to define human physiology and pathologies. In summary, this review will emphasize the role that commensals and pathobionts play in their interaction with the immune status of the host, with a prediction that current "omic" technologies will allow researchers to better understand disease in the future.

Screening and Assessment of Antimicrobial Susceptibility of Periodontopathic Bacteria in Peruvian Patients with Periodontitis: A Pilot Study

Background

Severe periodontal disease is highly prevalent worldwide, affecting 20% of the population between the ages of 35 and 44 years. The etiological epidemiology in Peru is scarce, even though some studies describe a prevalence of 48.5% of periodontal disease in the general population. Periodontitis is one of the most prevalent oral diseases associated with site-specific changes in the oral microbiota and it has been associated with a socioeconomic state. This study aimed to determine the etiology and resistance profile of bacteria identified in a group of Peruvian patients with periodontal disease.

Methods

Six subgingival plaque samples were collected from eight patients with severe periodontitis. Bacterial identification was carried out by an initial culture, PCR amplification, and subsequently DNA sequencing. We evaluated the antibiotic susceptibility by the disk diffusion method.

Results

Variable diversity in oral microbiota was identified in each one of the eight patients. The bacterial genus most frequently found was Streptococcus spp. (15/48, 31.3%) followed by Rothia spp. (11/48, 22.9%), Actinomyces spp. (9/48, 18.8%), and Eikenella spp. (4/48, 8.3%). The most common species found was Rothia dentocariosa (8/48, 16.7%). The antimicrobial susceptibility assay varied according to the species tested; however, among all the isolates evaluated, Actinomyces naeslundii was resistant to penicillin and tetracycline; Eikenella corrodens was resistant to dicloxacillin; and Rothia dentocariosa was resistant to amoxicillin + clavulanic acid and metronidazole but also susceptible to trimethoprim-sulfamethoxazole.

Conclusions

The most prevalent periodontal bacterium found in this study was Rothia dentocariosa. Specific antimicrobial therapy is required to improve the treatment outcomes of patients with periodontal disease and avoid antibiotic resistance.

Did Omics change periodontal therapy?

The starting point for defining effective treatment protocols is a clear understanding of the etiology and pathogenesis of a condition. In periodontal diseases, this understanding has been hindered by a number of factors, such as the difficulty in differentiating primary pathogens from nonpathogens in complex biofilm structures. The introduction of DNA sequencing technologies, including taxonomic and functional analyses, has allowed the oral microbiome to be investigated in much greater breadth and depth. This article aims to compile the results of studies, using next-generation sequencing techniques to evaluate the periodontal microbiome, in an attempt to determine how far the knowledge provided by these studies has brought us in terms of influencing the way we treat periodontitis. The taxonomic data provided, to date, by published association and elimination studies using next-generation sequencing confirm previous knowledge on the role of classic periodontal pathogens in the pathobiology of disease and include new species/genera. Conversely, species and genera already considered as host-compatible and others less explored were associated with periodontal health as their levels were elevated in healthy individuals and increased after therapy. Functional and transcriptomic analyses also demonstrated that periodontal biofilms are taxonomically diverse, functionally congruent, and highly cooperative. Very few interventional studies to date have examined the effects of treatment on the periodontal microbiome, and such studies are heterogeneous in terms of design, sample size, sampling method, treatment provided, and duration of follow-up. Hence, it is still difficult to draw meaningful conclusions from them. Thus, although OMICS knowledge has not yet changed the way we treat patients in daily practice, the information provided by these studies opens new avenues for future research in this field. As new pathogens and beneficial species become identified, future randomized clinical trials could monitor these species/genera more comprehensively. In addition, the metatranscriptomic data, although still embryonic, suggest that the interplay between the host and the oral microbiome may be our best opportunity to implement personalized periodontal treatments. Therapeutic schemes targeting particular bacterial protein products in subjects with specific genetic profiles, for example, may be the futuristic view of enhanced periodontal therapy.

Probiotic strains of Lactobacillus brevis and Lactobacillus plantarum as adjunct to non-surgical periodontal therapy: 3-month results of a randomized controlled clinical trial

OBJECTIVES

To determine if periodontitis patients benefit from treatment with Lactobacillus brevis and Lactobacillus plantarum strains, applied into periodontal pockets as gel and thereafter taken as lozenges, as an adjunct to scaling and root planing (SRP).

MATERIALS AND METHODS

In a double-blind, randomized, placebo-controlled trial, 40 patients received scaling and root planing (SRP) in two sessions within 7 days. Patients then received either probiotic gel and lozenges (n = 20) or placebo (n = 20). The primary outcome variable was the number of diseased sites (DS: PD > 4 mm + BOP) at the 3-month re-evaluation. The effects of gender, age, probiotic therapy, presence of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans, smoking, tooth being a molar and interdental location were evaluated using a multivariate multilevel logistic regression model.

RESULTS

The number of DS after 3 months was similar in the test (Me = 8, IQR = 5-11) and control (Me = 5, IQR = 1-10) groups. Both groups showed substantial but equivalent improvements in periodontal parameters. The logistic regression showed higher odds for the healing of gingival bleeding (OR = 2.12, p = 0.048) and lower odds for the healing of DS (OR = 0.51; p < 0.001) in the probiotic group.

CONCLUSIONS

Patients with periodontitis benefit from adjunctive use of probiotics containing L. brevis and L. plantarum in terms of reduction of gingival bleeding. However, adjunctive probiotics increase the number of persisting diseased sites with PD > 4 mm and BOP.

CLINICAL RELEVANCE

The adjunctive use of probiotics containing L. brevis and L. plantarum strains in treating chronic periodontitis results in a higher number of residual diseased sites when compared with SRP + placebo; its use is therefore unfounded.

Distinct Profiles of Specialized Pro-resolving Lipid Mediators and Corresponding Receptor Gene Expression in Periodontal Inflammation

Polyunsaturated fatty acid-derived specialized pro-resolving lipid mediators (SPMs) play an important role in modulating inflammation. The aim of the study was to compare profiles of SPMs, SPM related lipid mediators and SPM receptor gene expression in gingiva of subjects with periodontitis to healthy controls. A total of 28 subjects were included; 13 periodontally healthy and 15 periodontitis before or after non-surgical periodontal therapy. Gingival tissues were collected from two representative posterior teeth prior to and 8 weeks after scaling and root planning; only once in the healthy group. Lipid mediator-SPM metabololipidomics was performed to identify metabolites in gingiva. qRT-PCR was performed to assess relative gene expression (2^−ΔΔCT) of known SPM receptors. Intergroup comparisons were made using Wilcoxon tests. Thirty-six omega-6 or omega-3 fatty acid-derived lipid mediators and seven receptor genes were identified in gingiva. Profiles of lipid mediators and receptor gene expression were significantly different between the three groups. Levels of six lipid mediators, 5-HETE, 15-HETE, 15(S)-HEPE, 4-HDHA, 7-HDHA, and 17-HDHA in periodontitis before treatment were significantly higher than in periodontitis after treatment. The expression of BLT1 in the healthy group was significantly higher than periodontitis subjects before and after treatment. The expression of GPR18 in periodontitis before treatment was significantly higher than in periodontitis after treatment while the expression of GPR32 in periodontitis before treatment was significantly lower than in periodontitis after treatment. Elevated levels of SPM biosynthetic pathway markers in periodontitis subjects before treatment indicated inflammation induced pro-resolution activity in gingiva, but receptors for these molecules were deficient in periodontitis pre-treatment suggesting that failure of resolution of inflammation contributes to excess, chronic inflammation in periodontitis.

Microbial biogeography and ecology of the mouth and implications for periodontal diseases

In humans, the composition of microbial communities differs among body sites and between habitats within a single site. Patterns of variation in the distribution of organisms across time and space are referred to as "biogeography." The human oral cavity is a critical observatory for exploring microbial biogeography because it is spatially structured, easily accessible, and its microbiota has been linked to the promotion of both health and disease. The biogeographic features of microbial communities residing in spatially distinct, but ecologically similar, environments on the human body, including the subgingival crevice, have not yet been adequately explored. The purpose of this paper is twofold. First, we seek to provide the dental community with a primer on biogeographic theory, highlighting its relevance to the study of the human oral cavity. We summarize what is known about the biogeographic variation of dental caries and periodontitis and postulate that disease occurrence reflects spatial patterning in the composition and structure of oral microbial communities. Second, we present a number of methods that investigators can use to test specific hypotheses using biogeographic theory. To anchor our discussion, we apply each method to a case study and examine the spatial variation of the human subgingival microbiota in 2 individuals. Our case study suggests that the composition of subgingival communities may conform to an anterior-to-posterior gradient within the oral cavity. The gradient appears to be structured by both deterministic and nondeterministic processes, although additional work is needed to confirm these findings. A better understanding of biogeographic patterns and processes will lead to improved efficacy of dental interventions targeting the oral microbiota.

Relationship between herpesviruses and periodontal disease progression

AIM

To investigate the role of Epstein-Barr virus (EBV), cytomegalovirus (CMV), and anaerobic bacteria in the progression of periodontitis.

METHODS

Eighty-one adults with generalized moderate to severe periodontitis were randomly assigned to: oral hygiene or scaling and root planning ± placebo or polyunsaturated fatty acids fish oil. Subgingival plaque samples collected from three healthy and three disease sites at weeks 0, 16, and 28 and from sites demonstrating disease progression were analysed for EBV, CMV, P. gingivalis (Pg), T. forsythia (Tf), and T. denticola (Td) DNA using quantitative polymerase chain reaction.

RESULTS

Cytomegalovirus was detected in 0.3% (4/1454) sites. EBV was present in 12.2% of healthy sites (89/728) and 27.6% disease sites (201/726; p < .0001), but was in low copy number. Disease progression occurred in 28.4% of participants (23/81) and developed predominantly at sites identified as diseased (75/78; 96.2%). CMV and EBV were not associated with disease progression (p = .13) regardless of treatment. In contrast, disease sites were associated with higher levels of Pg, Td, Tf, and total bacteria, and sites that exhibited disease progression were associated with an abundance of Td and Tf (p < .04).

CONCLUSION

Disease progression was associated with Gram-negative anaerobic bacteria; not EBV or CMV.

Effects of timing of adjunctive systemic antibiotics on the clinical outcome of periodontal therapy: A systematic review

Background

Many systematic reviews and meta-analysis have indicated beneficial effects of adjunctive systemic antibiotics in periodontal therapy in specific situations. However, some essential issues such as the ideal time of their administration during periodontal therapy remain unanswered. This systematic review aimed to determine at which phase of periodontal treatment would adjunctive systemic antibiotics lead to the best clinical outcomes, during the active phase or in the reevaluation phase.

Material and Methods

Searches in the databases Medline, Scopus and Cochrane Library were conducted. The randomized clinical trials and retrospective cohort studies comparing the clinical benefits of adjunctive systemic antibiotic administration in the active phase of periodontal treatment versus their administration in the reevaluation phase were included. The primary outcomes assessed were differences in clinical changes in periodontal pocket depth and clinical attachment loss at all post-treatment phases.

Results

Of the 6209 records identified, two randomized clinical trials and two retrospective cohort studies were eligible according to inclusion criteria. Two studies suggested there were greater clinical benefits when systemic antibiotics were prescribed during the active phase of periodontal therapy than in the reevaluation phase while two other studies showed no significant difference in clinical outcomes at 6 months between these two different timing of administration.

Conclusions

The evidence available and evaluated in this systematic review is of heterogeneous quality and limited by the restricted number of studies and their dissimilarities in their study design and outcome reporting. Despite insufficient evidence to determine the ideal time to the adjunctive systemic antibiotic administration in the periodontal therapy, it seems that prescription of systemic antibiotic at the active phase of periodontal therapy leads to better clinical outcomes.

Key words:Active phase; periodontal therapy, periodontitis, reevaluation, systemic antibiotics, timing.

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.

Inhibitory effects of azithromycin on the adherence ability of Porphyromonas gingivalis

BACKGROUND

Porphyromonas gingivalis is a major pathogen and has a high detection rate in periodontal disease. Fimbriae and hemagglutinin are expressed by P. gingivalis, and these play an important role in the adherence of the bacteria to periodontal tissue and biofilm formation. The aim of this study was to investigate the effects of sub-minimal inhibitory concentrations (sub-MICs) of azithromycin on the adherence of P. gingivalis, focusing on the inhibition of fimbriae expression and hemagglutinin activity.

METHODS

P. gingivalis ATCC 33277 were incubated anaerobically with sub-MICs of azithromycin at 37°C by gentle shaking for 18 hours. The bacterial cells were harvested, washed twice with phosphate-buffered saline (PBS), and the proteins analyzed by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. Adherence assay and hemagglutinin activity tests were done with the same culture.

RESULTS

The results of SDS-PAGE indicated that the sub-MICs of azithromycin inhibited 41-kDa fimbrial protein expression and hemagglutinin activities. The disappearance of 41-kDa fimbrial protein expression and long fimbriae in 0.4 µg/mL, 0.2 µg/mL, and 0.1 µg/mL of azithromycin was confirmed by western blotting and transmission electron microscopy. The adherence of P. gingivalis to human gingival epithelial cells was reduced by sub-MICs of azithromycin compared with the adherence levels without antibiotic.

CONCLUSIONS

These results suggest that sub-MICs of azithromycin may reduce the adherence of P. gingivalis to host cells, by inhibiting production of fimbriae and hemagglutinin activities. Therefore, azithromycin can be used as a biofilm treatment of periodontal disease caused by P. gingivalis.

Comparing the Antimicrobial In Vitro Efficacy of Amoxicillin/Metronidazole against Azithromycin-A Systematic Review

On account of its proven clinical efficacy, the combination of systemically administered amoxicillin and metronidazole is frequently adjuncted to non-operative periodontal therapy and well documented. Potential drawbacks of this regimen, e.g., side effects and problems with the compliance, led to an ongoing search for alternatives. Azithromycin, an antibiotic extensively used in general medicine, has recently found its niche in periodontal therapy as well. This systematic review aimed to analyze the in vitro antimicrobial efficacy of amoxicillin plus metronidazole versus azithromycin. For this purpose, a systematic literature search was performed, and studies published up to 29 March 2018 referenced in Medline, Embase, Cochrane, and Biosis were independently screened by two authors. An additional hand search was performed and studies focusing on the evaluation of in vitro antimicrobial efficacy of amoxicillin + metronidazole or azithromycin on bacteria from the subgingival biofilm were included. English and German language research reports were considered. From 71 identified articles, only three articles were eligible for inclusion. These studies showed heterogeneity in terms of analytical methods and strains explored. However, all studies used multispecies biofilm models for analysis of the antimicrobial activity. Unanimously, studies reported on more pronounced antimicrobial effects when applying the combination of amoxicillin + metronidazole, compared to azithromycin. Based on the few studies available, the combination of amoxicillin + metronidazole seemed to display higher antimicrobial efficacy in vitro than azithromycin.

Randomized clinical trial of the effects of azithromycin use in the treatment of peri-implantitis

BACKGROUND

The aim of this clinical trial was to establish a proof of concept that the adjunctive use of systemic azithromycin (AZM) in conjunction with mechanical debridement has an increased benefit in reducing soft tissue inflammation in the treatment of peri-implantitis.

METHODS

In a randomized, double-blind, clinical trial, the treatment group (nine patients) received AZM as well as mechanical debridement in a single course of treatment, whereas the control group (eight patients) received a placebo and mechanical debridement. The primary outcome variables studied were bleeding on probing, suppuration, pocket probing depth and gingival recession. The secondary variables studied were gingival index, plaque index, microbiological and interleukin-1β status. The observation period was 6 months.

RESULTS

Over the 6 months' observation period, the treatment patients showed a consistently greater reduction of gingival inflammation and an improvement in soft tissue healing than the control patients.

CONCLUSIONS

The adjunctive use of a single course of systemic azithromycin can assist in the control of peri-implant mucositis in the treatment of peri-implantitis.

The effect of metronidazole plus amoxicillin or metronidazole plus penicillin V on periodontal pathogens in an in vitro biofilm model

A combination of metronidazole (MET) and amoxicillin (AMX) is commonly used as adjunct to mechanical therapy of periodontal disease. The use of broad spectrum antibiotics such as AMX may contribute to development of antibiotic resistance. The aim was to evaluate the in vitro effect of replacing AMX with penicillin V (PV) in combination with MET on a biofilm model. A biofilm model consisting of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Fusobacterium nucleatum was developed. The biofilms were exposed to AMX + MET and PV + MET in two different concentrations. Bacterial viability in biofilms following antibiotic exposure was assessed by viable counts and by confocal microscopy. No live colonies of P. gingivalis nor F. nucleatum were retrieved from biofilms exposed to AMX + MET or PV + MET. The amount of A. actinomycetemcomitans was 4-5 logs reduced following antibiotic treatment; no statistical significance was achieved between AMX + MET or PV + MET treated biofilms. Replacement of AMX with PV at the same concentration, in combination with MET, resulted in similar effect on bacterial viability in this in vitro model. The option of using PV + MET instead of AMX + MET deserves further investigation, as this may contribute to reduce the risk of antibiotic resistance development.

Clarithromycin as an Adjunct to One-Stage Full-Mouth Ultrasonic Periodontal Debridement in Generalized Aggressive Periodontitis: A Randomized Controlled Clinical Trial

BACKGROUND

The aim of the present study is to evaluate the periodontal clinical and microbiologic responses and possible adverse effects of clarithromycin (CLM) combined with periodontal mechanical therapy in the treatment of patients with generalized aggressive periodontitis.

METHODS

Forty patients were selected and randomly assigned into one of two groups: 1) CLM (n = 20): one-stage full-mouth ultrasonic debridement (FMUD) associated with CLM (500 mg, every 12 hours for 3 days); and 2) placebo (n = 20): FMUD associated with placebo pills. Clinical and microbiologic parameters were evaluated at baseline and 3 and 6 months postoperatively.

RESULTS

Both treatments presented statistically significant clinical and microbiologic improvements. However, the CLM group presented lower means of probing depth for pockets ≥7 mm at 6 months (4.0 ± 1.7 mm) compared with the placebo group (4.7 ± 1.3 mm) (P = 0.04). In addition, the CLM group also presented greater reduction of Porphyromonas gingivalis (Pg) DNA counts at 6 months (P = 0.0001).

CONCLUSION

Results from this study suggest both treatments are effective; however, adjunct use of CLM to FMUD leads to better reduction of deep pockets and Pg at 6 months compared with FMUD alone.

Effect of azithromycin on a red complex polymicrobial biofilm

Azithromycin has recently gained popularity for the treatment of periodontal disease, despite sparse literature supporting efficiency in treating periodontal bacterial biofilms. The aim of this study was to evaluate the effect of azithromycin on biofilms comprised of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia in comparison to an amoxicillin and metronidazole combination. P. gingivalis W50, T. denticola ATCC35405, and T. forsythia ATCC43037 grown under anaerobic conditions at 37°C were aliquoted into 96-well flat-bottom plates in different combinations with addition of azithromycin or amoxicillin + metronidazole at various concentrations. For the biofilm assay, the plates were incubated at 37°C anaerobically for 48 h, after which the biofilms were stained with crystal violet and measured for absorbance at AU₆₂₀. In this model, polymicrobial biofilms of P. gingivalis + T. denticola, P. gingivalis + T. forsythia, and T. denticola + T. forsythia were cultured. Combination of all three bacteria enhanced biofilm biomass. Azithromycin demonstrated a minimal biofilm inhibitory concentration (MBIC) of 10.6 mg/L, while the amoxicillin + metronidazole combination was more effective in inhibiting biofilm formation with a MBIC of 1.63 mg/L. Polymicrobial biofilm formation was demonstrated by combination of all three red complex bacteria. Azithromycin was ineffective in preventing biofilm formation within a clinically achievable concentration, whereas the combination of amoxicillin and metronidazole was more effective for this purpose.

Antimicrobial and Immunomodulatory Surface-Functionalized Electrospun Membranes for Bone Regeneration

Guided bone regeneration (GBR) is a surgical procedure utilizing occlusive membranes for providing space maintenance and enabling selective repopulation of the damaged area. While this technique is effective in regenerating bone, bacterial infiltration occurs frequently and can compromise the regenerative outcome. In this study, the authors describe the development and characterization of a GBR membrane made of medical grade polycaprolactone (mPCL) electrospun fibers with antibacterial and immunomodulatory properties. This is achieved by the immobilization of the antibiotic azithromycin into the membrane via a solvent evaporation technique leading to a sustained release of the drug over 14 d. In vitro testing shows that this controlled release of azithromycin is proficient at inhibiting the growth of Staphylococcus aureus for 14 d. Implantation of azithromycin loaded mPCL membrane in a rodent calvarial defect induces macrophage polarization toward the M2 phenotype after one week and results in significantly more bone regeneration eight weeks post-surgery. The results suggest that this antibacterial membrane should be effective at preventing infection and also impacts on the macrophage polarization enhancing bone regeneration. The drug loading technique developed in this study is simple, effective with a strong potential for clinical translation and can be applied to different types of scaffolds and implants for applications in craniofacial and orthopedics applications.

Systemic antibiotics in the treatment of periodontitis

Despite the fact that several clinical studies have shown additional benefits when certain systemic antibiotics are used as adjuncts to periodontal treatment, clear guidelines for the use of these agents in the clinical practice are not yet available. Basic questions concerning the use of systemic antibiotics to treat periodontitis remain unanswered, such as: which drug(s) should be used; which patients would most benefit from treatment; which are the most effective protocols (i.e. doses and durations); and in which phase of the mechanical therapy should the drug(s) be administered? Although not all of those questions have been directly addressed by controlled randomized clinical trials, recent concepts related to the ecology of periodontal diseases, as well as the major advances in laboratory and clinical research methods that have occurred in the past decade, have significantly broadened our knowledge in this field. This article endeavored to provide a 'state of the art' overview on the use of systemic antibiotics in the treatment of periodontitis, based on the most recent literature on the topic as well as on a compilation of data from studies conducted at the Center of Clinical Trials at Guarulhos University (São Paulo, Brazil) from 2002 to 2012.

Herpes Simplex Virus Type 1 and Other Pathogens are Key Causative Factors in Sporadic Alzheimer's Disease

This review focuses on research in epidemiology, neuropathology, molecular biology, and genetics regarding the hypothesis that pathogens interact with susceptibility genes and are causative in sporadic Alzheimer's disease (AD). Sporadic AD is a complex multifactorial neurodegenerative disease with evidence indicating coexisting multi-pathogen and inflammatory etiologies. There are significant associations between AD and various pathogens, including Herpes simplex virus type 1 (HSV-1), Cytomegalovirus, and other Herpesviridae, Chlamydophila pneumoniae, spirochetes, Helicobacter pylori, and various periodontal pathogens. These pathogens are able to evade destruction by the host immune system, leading to persistent infection. Bacterial and viral DNA and RNA and bacterial ligands increase the expression of pro-inflammatory molecules and activate the innate and adaptive immune systems. Evidence demonstrates that pathogens directly and indirectly induce AD pathology, including amyloid-β (Aβ) accumulation, phosphorylation of tau protein, neuronal injury, and apoptosis. Chronic brain infection with HSV-1, Chlamydophila pneumoniae, and spirochetes results in complex processes that interact to cause a vicious cycle of uncontrolled neuroinflammation and neurodegeneration. Infections such as Cytomegalovirus, Helicobacter pylori, and periodontal pathogens induce production of systemic pro-inflammatory cytokines that may cross the blood-brain barrier to promote neurodegeneration. Pathogen-induced inflammation and central nervous system accumulation of Aβ damages the blood-brain barrier, which contributes to the pathophysiology of AD. Apolipoprotein E4 (ApoE4) enhances brain infiltration by pathogens including HSV-1 and Chlamydophila pneumoniae. ApoE4 is also associated with an increased pro-inflammatory response by the immune system. Potential antimicrobial treatments for AD are discussed, including the rationale for antiviral and antibiotic clinical trials.

Relative effectiveness of azithromycin in killing intracellular Porphyromonas gingivalis

Invasive infections by Porphyromonas gingivalis are associated with persistent periodontal attachment loss and can be difficult to eliminate by scaling and root planing. Azithromycin (AZM) inhibits P. gingivalis and is actively accumulated by most human cells. We used an in vitro infection model to compare the effectiveness of AZM in killing intracellular P. gingivalis to the combined regimen of amoxicillin (AMX) and metronidazole (MET). Transport of [3H]-AZM by human gingival fibroblasts was characterized. Monolayers of Smulow-Glickman gingival epithelial cells or gingival fibroblasts were infected with P. gingivalis (strain 33277 or W83). After extracellular bacteria were eliminated with teicoplanin, infected cells were treated with therapeutic concentrations of AZM, AMX, or AMX + MET. Viable intracellular bacteria were released by cell lysis and plated on blood agar for enumeration. Antimicrobial activity against planktonic P. gingivalis was also evaluated. While survival of intraepithelial P. gingivalis 33277 was not significantly different after treatment with the three regimens, survival in infected fibroblasts was significantly lower after AZM treatment (65.9 ± 5.5%) compared with AMX (92.2 ± 3.5%) or AMX + MET (79.8 ± 5.2%, P < 0.01). Carnitine, a competitive inhibitor of AZM transport, reduced killing by AZM by ~55% (P < 0.05). Survival of intrafibroblast P. gingivalis W83 was also significantly lower after AZM treatment compared with the other regimens (P < 0.05). At therapeutic concentrations, AZM was significantly more active against intracellular P. gingivalis than against planktonic P. gingivalis (P < 0.0083). Gingival epithelial cells and fibroblasts possess a transport system that accumulates AZM and enhances elimination of intracellular P. gingivalis. Compared with the combination of AMX and MET, AZM was equally effective against intraepithelial P. gingivalis 33277 and significantly more effective against both strains of P. gingivalis from infected gingival fibroblasts. The results suggest that AZM could be a reasonable alternative to the regimen of AMX and MET for periodontal patients who should not take these agents due to known side effects or compliance issues.

Azithromycin enhances phagocytic killing of Aggregatibacter actinomycetemcomitans Y4 by human neutrophils

BACKGROUND

Aggregatibacter actinomycetemcomitans resists killing by neutrophils and is inhibited by azithromycin (AZM) and amoxicillin (AMX). AZM actively concentrates inside host cells, whereas AMX enters by diffusion. The present study is conducted to determine whether AZM is more effective than AMX at enhancing phagocytic killing of A. actinomycetemcomitans by neutrophils.

METHODS

Killing assays were conducted in the presence of either 2 μg/mL AZM or 16 μg/mL AMX (equipotent against A. actinomycetemcomitans). Neutrophils were loaded by incubation with the appropriate antibiotic. Opsonized A. actinomycetemcomitans strain Y4 was incubated with the indicated antibiotic alone, with loaded neutrophils and antibiotic, or with control neutrophils (without antibiotic) at multiplicities of infection (MOIs) of 30 and 90 bacteria per neutrophil.

RESULTS

Neutrophil incubation with 2 μg/mL AZM yielded an intracellular concentration of 10 μg/mL. At an MOI of 30, neutrophils loaded with AZM failed to kill significantly more bacteria than control neutrophils during the 60- and 90-minute assay periods. At an MOI of 90, neutrophils loaded with AZM killed significantly more bacteria than either AZM alone or control neutrophils during 60- and 90-minute incubations (P < 0.05), and killed significantly more bacteria after 90 minutes than the sum of the killing produced by AZM alone or neutrophils alone. Neutrophils incubated with AMX under identical conditions also killed significantly more bacteria than either AMX alone or control neutrophils, but there was no evidence of synergism between AMX and neutrophils.

CONCLUSIONS

Neutrophils possess a concentrative transport system for AZM that may enhance killing of A. actinomycetemcomitans. Its effects are most pronounced when neutrophils are greatly outnumbered by bacteria.

Clinical effect of azithromycin as an adjunct to non-surgical treatment of chronic periodontitis: a meta-analysis of randomized controlled clinical trials

The results of recent published studies focusing on the effect of azithromycin as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis are inconsistent. We conducted a meta-analysis of randomized controlled clinical trials to examine the effect of azithromycin combined with SRP on periodontal clinical parameters as compared to SRP alone. An electronic search was carried out on Pubmed, Embase and the Cochrane Central Register of Controlled Trials from their earliest records through December 28, 2014 to identify studies that met pre-stated inclusion criteria. Reference lists of retrieved articles were also reviewed. Data were extracted independently by two authors. Either a fixed- or random-effects model was used to calculate the overall effect sizes of azithromycin on probing depth, attachment level (AL) and bleeding on probing (BOP). Heterogeneity was evaluated using the Q test and I(2) statistic. Publication bias was evaluated by Begg's test and Egger's test. A total of 14 trials were included in the meta-analysis. Compared with SRP alone, locally delivered azithromycin plus SRP statistically significantly reduced probing depth by 0.99 mm (95% CI 0.42-1.57) and increased AL by 1.12 mm (95% CI 0.31-1.92). In addition, systemically administered azithromycin plus SRP statistically significantly reduced probing depth by 0.21 mm (95% CI 0.12-0.29), BOP by 4.50% (95% CI 1.45-7.56) and increased AL by 0.23 mm (95% CI 0.07-0.39). Sensitivity analysis yielded similar results. No evidence of publication bias was observed. The additional benefit of systemic azithromycin was shown at the initially deep probing depth sites, but not at shallow or moderate sites. The overall effect sizes of systemic azithromycin showed a tendency to decrease with time, and meta-regression analysis suggested a negative relation between the length of follow-up and net change in probing depth (r = -0.05, p = 0.02). This meta-analysis provides further evidence that azithromycin used as an adjunct to SRP significantly improves the efficacy of non-surgical periodontal therapy on reducing probing depth, BOP and improving AL, particularly at the initially deep probing depth sites.

Full mouth periodontal debridement with or without adjunctive metronidazole gel in smoking patients with chronic periodontitis: A pilot study

BACKGROUND AND OBJECTIVE

The evidence of effectiveness of metronidazole (Mtz) as an adjunct therapy to periodontal procedure in the treatment of patients with chronic periodontitis is not conclusive. The aim of this study was to compare the effect of Mtz (delivered locally as a gel or systemically as a tablet) as an adjunctive therapy with full mouth periodontal debridement (1 h of ultrasonic calculus/plaque removal) in smokers with chronic periodontitis.

MATERIAL AND METHODS

This pilot study involved 30 smokers with at least six teeth with a clinical attachment loss of ≥ 5 mm and probing pocket depth (PPD) of ≥ 5 mm. They were randomly assigned into one of three groups (n = 10): (i) 3 g daily of placebo gel applied topically (using a dental tray with the gel overnight) + periodontal debridement; (ii) 3 g daily of a 15% Mtz benzoate gel applied topically (using a dental tray with the gel overnight) + periodontal debridement; and (iii) a daily single dose of 750 mg Mtz (Flagyl(®)) + periodontal debridement. Clinical parameters (visible plaque index, gingival bleeding index [GBI], relative attachment level and PPD) and quantitative analysis (by real-time polymerase chain reaction) of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia were assessed at baseline and at 1, 3 and 6 mo after periodontal debridement.

RESULTS

There was no statistically significant difference in the average GBI and visible plaque index values at baseline between the groups (p ≥ 0.05). There was no significant difference between groups in all parameters evaluated (p ≥ 0.05). Significant reductions in GBI at 3 and 6 mo were observed in all groups (p < 0.05). Significant reductions in both PPD and relative attachment level at 1, 3 and 6 mo were observed in all groups (p < 0.05). Significant reductions in bacterial levels at 7 and 30 d were observed in all groups (p < 0.05).

CONCLUSION

Adjunctive use of Mtz (gel or tablet) to periodontal debridement had similar clinical and microbiological improvement compared to treatment with placebo + periodontal debridement in smokers with chronic periodontitis up to 6 mo post-treatment. Further studies are necessary to confirm the clinical relevance of these findings.

Microbiologic Observations After Four Treatment Strategies Among Patients With Periodontitis Maintaining a High Standard of Oral Hygiene: Secondary Analysis of a Randomized Controlled Clinical Trial

BACKGROUND

The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), with or without adjunctive metronidazole, when treating chronic destructive periodontitis remains equivocal, as does the long-term association between clinical and microbiologic outcomes after such strategies. The aim of this study is to examine the relationship between clinical and microbiologic outcomes of four different treatment strategies for chronic destructive periodontitis among patients who maintain excellent oral hygiene and low gingival bleeding scores.

METHODS

One hundred eighty-four patients with periodontitis and capable of maintaining a high standard of oral hygiene were randomly allocated to one of four treatment groups: 1) FDIS + metronidazole; 2) FDIS + placebo; 3) SRP + metronidazole; and 4) SRP + placebo. Recordings of plaque, bleeding on probing, probing depth (PD), and clinical attachment level were carried out in four sites per tooth at baseline, 3 and 12 months after treatment. Before treatment, pooled subgingival samples were obtained from the five deepest pockets, which were sampled again 3 and 12 months after treatment. Microbiologic assessments of eight putative periodontal pathogens were performed using the checkerboard DNA-DNA hybridization method.

RESULTS

Levels of bacterial species were already relatively low at baseline. The only microbial factor statistically significantly associated with the clinical outcomes of treatment after 12 months was the association between reductions of Tannerella forsythia and being free from PD ≥5 mm.

CONCLUSION

In this clinical trial, the only microbial factor associated with the clinical outcomes after 12 months was a statistically significant association between the reductions of T. forsythia and being free from PD ≥5 mm.

Changes in antimicrobial susceptibility profile and prevalence of quinolone low-sensitive strains in subgingival plaque from acute periodontal lesions after systemic administration of sitafloxacin

This study aimed to assess changes in antimicrobial susceptibilities of subgingival bacteria in acute periodontal lesions following systemic administration of a new-generation fluoroquinolone, sitafloxacin and to monitor the occurrence and fate of quinolone low-sensitive strains. Patients with acute phase of chronic periodontitis were subjected to microbiological assessment of their subgingival plaque samples at baseline (A1). Sitafloxacin was then administered systemically (100 mg/day for 5 days). The microbiological examinations were repeated one week after administration (A2). Susceptibilities of clinical isolates from acute sites to various antimicrobials were determined using broth and agar dilution methods. At A2, subgingival bacteria with low sensitivity to levofloxacin were identified in four patients, and they were subjected to a follow-up microbiological examination at on the average 12 months after sitafloxacin administration (A3). The patients received initial and supportive periodontal therapy during the period A2 to A3. From the examined subgingival sites, 8 and 19 clinical isolates were obtained at A2 and A3, respectively. Some Streptococcus strains isolated at A2 were found to be resistant to levofloxacin (MIC 16-64 μg/ml), azithromycin (MIC 2->128 μg/ml) or clarithromycin (MIC 1->32 μg/ml). At A3, isolated streptococci were highly susceptible to levofloxacin (MIC 0.5-2 μg/ml), while those resistant to azithromycin or clarithromycin were still isolated. It is suggested that the presence of the quinolone low-sensitive strains in initially acute lesions after sitafloxacin administration was transient, and they do not persist in the subgingival milieu during the periodontal therapy.

An estimate of pocket closure and avoided needs of surgery after scaling and root planing with systemic antibiotics: a systematic review

BACKGROUND

Relevant benefits of adjunctive medication of antibiotica after conventional root surface debridement in terms of enhanced pocket depth (PD) reduction have been shown. However, means and standard deviations of enhanced reductions are difficult to translate into clinical relevant treatment outcomes such as pocket resolution or avoidance of additional surgical interventions. Accordingly, the aim of this systematic review was to calculate odds ratios for relevant cut-off values of PD after mechanical periodontal treatment with and without antibiotics, specifically the combination of amoxicilline and metronidazol, from published studies. As clinical relevant cut-off values "pocket closure" for PD ≤ 3mm and "avoidance of surgical intervention" for PD ≤ 5 mm were determined.

METHODS

The databases PubMed, Embase and Central were searched for randomized clinical studies assessing the beneficial effect of the combination of amoxicillin and metronidazole after non-surgical mechanical debridement. Titles, abstracts and finally full texts were scrutinized for possible inclusion by two independent investigators. Quality and heterogeneity of the studies were assessed and the study designs were examined. From published means and standard deviations for PD after therapy, odds ratios for the clinically relevant cut-off values were calculated using a specific statistical approach.

RESULTS

Meta-analyses were performed for the time points 3 and 6 month after mechanical therapy. Generally, a pronounced chance for pocket closure from 3 to 6 months of healing was shown. The administration of antibiotics resulted in a 3.55 and 4.43 fold higher probability of pocket closure after 3 and 6 months as compared to mechanical therapy alone. However, as the estimated risk for residual pockets > 5 mm was 0 for both groups, no odds ratio could be calculated for persistent needs for surgery. Generally, studies showed a moderate to high quality and large heterogeneity regarding treatment protocol, dose of antibiotic medication and maintenance.

CONCLUSION

With the performed statistical approach, a clear benefit in terms of an enhanced chance for pocket closure by co-administration of the combination of amoxicillin and metronidazole as an adjunct to non-surgical mechanical periodontal therapy has been shown. However, data calculation failed to show a benefit regarding the possible avoidance of surgical interventions.

Metronidazole alone or with amoxicillin as adjuncts to non-surgical treatment of chronic periodontitis: a secondary analysis of microbiological results from a randomized clinical trial

AIM

To evaluate the changes occurring in the subgingival microbial profile of subjects with generalized chronic periodontitis (ChP) treated by scaling and root planing (SRP) alone or with metronidazole (MTZ) or MTZ + amoxicillin(AMX). A secondary aim was to examine a possible added effect of chlorhexidine(CHX) to these therapies.

METHODS

One hundred and eighteen subjects were randomly assigned to receive SRP-only or with MTZ [400 mg/thrice a day (TID)] or MTZ + AMX (500 mg/TID) for 14 days. Half of the subjects in each group rinsed with 0.12% CHX twice a day (BID) for 2 months. Nine subgingival plaque samples/subject were analysed by checkerboard DNA–DNA hybridization for 40 bacterial species at baseline, 3, 6 and 12 months post-therapy.

RESULTS

At 12 months, the antibiotic-treated groups harboured lower mean counts and proportions of key periodontal pathogens than the SRP group (p < 0.05). These benefits were observed at initially deep and shallow sites. Initial reductions in periodontal pathogens obtained with SRP partially rebound after 12 months. CHX rinsing enhanced the microbiological effects of the MTZ + AMX treatment in shallow sites.

CONCLUSION

The adjunctive use of MTZ and MTZ + AMX results in a greater reduction in the levels of periodontal pathogens in generalized ChP subjects compared to SRP alone.

Lessons learned and unlearned in periodontal microbiology

Periodontal diseases are initiated by bacterial species living in polymicrobial biofilms at or below the gingival margin and progress largely as a result of the inflammation elicited by specific subgingival species. In the past few decades, efforts to understand the periodontal microbiota have led to an exponential increase in information about biofilms associated with periodontal health and disease. In fact, the oral microbiota is one of the best-characterized microbiomes that colonize the human body. Despite this increased knowledge, one has to ask if our fundamental concepts of the etiology and pathogenesis of periodontal diseases have really changed. In this article we will review how our comprehension of the structure and function of the subgingival microbiota has evolved over the years in search of lessons learned and unlearned in periodontal microbiology. More specifically, this review focuses on: (i) how the data obtained through molecular techniques have impacted our knowledge of the etiology of periodontal infections; (ii) the potential role of viruses in the etiopathogenesis of periodontal diseases; (iii) how concepts of microbial ecology have expanded our understanding of host-microbe interactions that might lead to periodontal diseases; (iv) the role of inflammation in the pathogenesis of periodontal diseases; and (v) the impact of these evolving concepts on therapeutic and preventive strategies to periodontal infections. We will conclude by reviewing how novel systems-biology approaches promise to unravel new details of the pathogenesis of periodontal diseases and hopefully lead to a better understanding of their mechanisms.

Concentrations of metronidazole in human plasma and saliva after tablet or gel administration

OBJECTIVES

The aim of this study was to determine the pharmacokinetic profile of metronidazole (Mtz) tablet and to compare Mtz gel and tablet concentrations in both blood plasma and saliva.

METHODS

In this randomized cross-over study with a 1-week washout period, 13 volunteers randomly received one (a single oral dose of 750 mg Mtz (Flagyl®--tablet) and 2) 3 g of 15% Mtz benzoate gel (applied by using a dental tray). The HPLC with ultraviolet detection was used to quantify plasma and saliva concentrations of Mtz. The pharmacokinetic parameters (PPs) areas under the curves from 0 to 48 h (AUC0-48) and from 0 to infinity (AUC0-∞), the maximum plasma concentration (C(max)), the time to C(max), volume of distribution and renal clearance were determined for Mtz tablet.

KEY FINDINGS

Considering the Mtz tablet, plasma showed higher Mtz concentration from 6 to 24 h after drug administration and the highest values concerning AUC0-48 h and AUC0-∞ than those obtained in saliva (P < 0.05). No significant differences were observed between plasma and saliva concentrations for Mtz gel.

CONCLUSIONS

The study showed that some PPs were higher in plasma (P < 0.05) than in saliva concerning Mtz tablet. Gel formulation had similar Mtz bioavailability in plasma and saliva resulting in systemic absorption.

Multilevel analysis of bacterial counts from chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

To follow changes (over 2 years) in subgingival bacterial counts of five microbial complexes including health-related Actinomyces spp. in deeper pockets (≥5 mm) after periodontal treatments.

METHODS

EIGHT DIFFERENT TREATMENTS WERE STUDIED: (1) scaling+root planing (SRP); (2) periodontal surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+locally delivered tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately following SRP. Subgingival plaque was collected mesiobuccally from each tooth, except third molars, from 176 subjects, completing the study, at baseline, 3, 6, 12, 18, and 24 months post-treatment and analysed for 40 different bacteria using checkerboard hybridization. A negative binomial (NB) generalized estimating equation (NB GEE) model was used to analyze count data and a logistic GEE was used for proportions.

RESULTS

We observed short-term beneficial changes in the composition of the red complex of up to 3 months by treating subjects with AMOX+MET+TET. Similar short-term improvements with the same treatment were observed for Tannerella forsythia and Treponema denticola of the red complex. SURG had also short-term beneficial effect on Porphyromonas gingivalis. No periodontal treatments applied to severely affected sites promoted the growth of Actinomyces. Smoking elevated counts of both the red and orange complex while bleeding on probing (BOP) and gingival redness were also predictors of more red complex counts. Comparatively similar findings were obtained by analyzing counts and by analyzing proportions.

CONCLUSIONS

Although short-term reductions in the counts of the red complex were observed in sites that were treated with AMOX+MET+TET, long-term significant effects were not observed with any of the eight treatments. Poor oral hygiene in patients with severe chronic periodontitis diminished the beneficial effects of treatment.

Azithromycin suppresses human osteoclast formation and activity in vitro

Azithromycin is an antibiotic with anti-inflammatory properties used as an adjunct to treat periodontitis, a common inflammatory mediated condition featuring pathologic alveolar bone resorption. This study aimed to determine the effect of azithromycin on human osteoclast formation and resorptive activity in vitro. Osteoclasts were generated from peripheral blood mononuclear cells stimulated with macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappa B (RANK) ligand. The effects of azithromycin at concentrations ranging from 0.5 to 40 µg/ml were tested. Osteoclast formation and activity, acidification, actin ring formation and expression of mRNA, and protein encoding for key osteoclast genes were assessed. The results demonstrated that azithromycin reduced osteoclast resorptive activity at all concentrations tested with osteoclast formation being significantly reduced at the higher concentrations (20 and 40 µg/ml). mRNA and protein expression of key osteoclast transcription factor Nuclear Factor of Activated T cells (NFATc1) was significantly reduced by azithromycin at later stages of osteoclast development (day 17). Azithromycin also reduced tumor necrosis factor receptor associated factor-6 (TRAF6) mRNA expression at day 14, and cathepsin K mRNA expression at days 14 and 17. Integrin β3 and MMP-9 mRNA expression was reduced by azithromycin at day 17 in osteoclasts cultured on dentine. The osteoclast proton pump did not appear to be affected by azithromycin, however formation of the actin ring cytoskeleton was inhibited. This study demonstrates that azithromycin inhibits human osteoclast function in vitro, which may account for at least some of the beneficial clinical effects observed with azithromycin treatment in periodontitis.