Classifying periodontal diseases--a long-standing dilemma

Clinical Features, Etiopathogenesis, and Therapeutic Approaches of Acute Gingival Lesions: A Narrative Review

A bacterial infection is typically the source of gingivitis, a non-destructive condition that produces gum inflammation. Unlike chronic lesions, which have well-defined features and a gradual onset, acute lesions are unpleasant. Usually, the first symptoms are bleeding, swollen, and red gums. If gingivitis is not treated, it can lead to periodontitis, a more serious condition where the gums separate from the teeth. It seems that gingival disease-induced inflammation is a necessary condition for the breakdown of connective tissue attachment apical to the cementoenamel junction (CEJ). This may result in damage to the bone and soft tissue that support the teeth, leading to loosening and unstable teeth, and if the infection worsens, eventual tooth loss may occur. While one of the most prevalent inflammatory diseases in humans is plaque-induced gingivitis, there are several less common but frequently very significant non-plaque-induced gingival illnesses. Maintaining regular dental hygiene can help prevent gingivitis and make it reversible. Non-plaque-induced gingival lesions might be pathologic alterations restricted to gingival tissues, but they are also frequent signs of systemic disorders. Diagnosing patients with these lesions and creating treatment regimens for them must be the aim of the therapy.

Performance of ChatGPT in classifying periodontitis according to the 2018 classification of periodontal diseases

OBJECTIVES

This study assessed the ability of ChatGPT, an artificial intelligence(AI) language model, to determine the stage, grade, and extent of periodontitis based on the 2018 classification.

MATERIALS AND METHODS

This study used baseline digital data of 200 untreated periodontitis patients to compare standardized reference diagnoses (RDs) with ChatGPT findings and determine the best criteria for assessing stage and grade. RDs were provided by four experts who examined each case. Standardized texts containing the relevant information for each situation were constructed to query ChatGPT. RDs were compared to ChatGPT's responses. Variables influencing the responses of ChatGPT were evaluated.

RESULTS

ChatGPT successfully identified the periodontitis stage, grade, and extent in 59.5%, 50.5%, and 84.0% of cases, respectively. Cohen's kappa values for stage, grade and extent were respectively 0.447, 0.284, and 0.652. A multiple correspondence analysis showed high variance between ChatGPT's staging and the variables affecting the stage (64.08%) and low variance between ChatGPT's grading and the variables affecting the grade (42.71%).

CONCLUSIONS

The present performance of ChatGPT in the classification of periodontitis exhibited a reasonable level. However, it is expected that additional improvements would increase its effectiveness and broaden its range of functionalities (NCT05926999).

CLINICAL RELEVANCE

Despite ChatGPT's current limitations in accurately classifying periodontitis, it is important to note that the model has not been specifically trained for this task. However, it is expected that with additional improvements, the effectiveness and capabilities of ChatGPT might be enhanced.

Periodontitis in young individuals: Important factors for disease progression

AIM

To investigate the progression of periodontitis in young individuals and identify factors that contribute to progression rate and whether periodontitis stage and grade have an impact on disease progression.

MATERIALS AND METHODS

This retrospective cohort study was based on patients younger than 36 years at two periodontal clinics between 2003 and 2009. At least 10 years later, a clinical and radiographic examination was performed on 215 patients. The marginal bone loss between baseline and follow-up for the tooth with the most severe bone loss at follow-up was estimated by radiographic measurements. Linear regression analysis was used to investigate the influence of potential risk indicators on periodontitis progression.

RESULTS

Most patients (83%) were classified as periodontitis stage III at baseline. At follow-up, 70% of these patients remained in stage III. The frequency of patients with grade C decreased from 79% to 17% at follow-up. The median (Q25%; Q75%) of the longitudinal marginal bone loss was 0.5 mm (0.0; 2.0). High bleeding on probing (BOP) index at baseline, smoking and interruption of periodontal treatment were found to significantly increase longitudinal bone loss.

CONCLUSIONS

High levels of BOP at baseline, smoking and interruption of periodontal treatment increased the risk of marginal bone loss. The stage and grade at baseline had no significant impact on disease progression.

Effects of Flapless Laser Corticotomy in Upper and Lower Canine Retraction: A Split-mouth, Randomized Controlled Trial

Aim One of the major difficulties in orthodontic treatment is the lengthy course of therapy, particularly in situations involving extractions. Hence, various methods for accelerating tooth movement rate had been devised. Flapless corticotomy is one of those methods. This study aimed to evaluate the effects of flapless laser corticotomy (FLC) compared to the conventional retraction (CR) method on the rate of canine retraction. Methods A split-mouth, randomized controlled trial included 56 canines from 14 patients (12 females and two males) with a mean age of 20.4 ± 2.5 years, who were complaining of bimaxillary protrusion requiring extraction of four premolars. All canines were randomly assigned to four groups (maxillary FLC, maxillary control CR, mandibular FLC, and mandibular control CR). Randomization was performed by creating two equal, random computer-generated lists with a 1:1 allocation ratio-one list for the right side and one for the left. The allocation concealment was achieved using opaque sealed envelopes until the time of intervention. FLC was applied on the experimental sides before canine retraction by drilling six holes penetrating 3 mm into the bone on the mesial and distal sides of the canines. Subsequently, all canines were retracted employing closed coil springs to deliver a force of 150 g using indirect anchorage from temporary anchorage devices (TADs). All canines were assessed at T0 (before retraction), T1 (one month after retraction), T2 (two months), and T3 (three months) using three-dimensional (3D) digital models. Additionally, canine rotation, molar anchorage loss assessed using 3D digital models, root resorption assessed using cone beam computed tomography (CBCT), probing depth, plaque, gingival indices, and pulp vitality were all evaluated as secondary outcomes. It was possible to blind only the outcome analysis expert (single-blinded). Results The measurements of canine retraction during the follow-up period from T0 to T3 were 2.46 ± 0.80 mm and 2.55 ± 0.79 mm in maxillary FLC and control groups, respectively, and 2.44 ± 0.96 mm and 2.31 ± 0.95 mm in mandibular FLC and control groups, respectively. The results demonstrated a statistically non-significant difference in the distance of canine retraction between the FLC and control groups at all time points. Moreover, no differences were observed between groups in canine rotation, molar anchorage loss, root resorption, probing depth, plaque, gingival indices, and pulp vitality (p > 0.05). Conclusion In the FLC procedure performed in this study, the rate of upper and lower canine retraction could not be accelerated and no significant differences were observed between FLC and control groups in canine rotation, molar anchorage loss, root resorption, periodontal condition, and pulp vitality.

Prevalence, extent, and severity of periodontitis among Australian older adults: Comparison of two generations

BACKGROUND

Chronic periodontitis is highly prevalent among older adults. The study aimed to compare periodontal disease among Australian older adults in two generations. We hypothesized that the prevalence and severity of periodontitis would decrease from the previous generation to the recent generation.

METHODS

Data were obtained from the South Australian Dental Longitudinal Study (SADLS) in 1991 to 1992 (SADLS I) and 2013 to 2014 (SADLS II); population-based longitudinal surveys of Australian older adults aged ≥60 years. American Academy of Periodontology, the US Centers for Disease Control and Prevention (AAP/CDC), and the 2018 European Federation of Periodontology (EFP/AAP) classification case definitions were used to define and calculate prevalence of chronic periodontitis. Multivariable log-Poisson regression models were used to identify risk indicators for severe periodontitis after adjusting for other covariates.

RESULTS

There were a total of 801 and 355 participants that underwent a periodontal exam in SADLS I and II, respectively. The prevalence of severe periodontitis was higher in the recent generation (88% and 56%) than the previous generation (75% and 46.7%) under the CDC/AAP and EFP/AAP case definitions, respectively. The mean number of missing teeth was lower in the recent generation (6) than the previous generation (13). The prevalence ratio of severe periodontitis was around two times higher in the younger age group, men, those not born in Australia, and current smokers across both generations.

CONCLUSIONS

Our findings indicated that the recent generation of older adults has higher prevalence and severity of chronic periodontitis than the previous generation. Our findings indicated that aging, being male, born overseas, low household income, no dental insurance, and being a current smoker are significant risk factors associated with severe periodontitis among older Australians.

The adjunctive effect of probiotics to nonsurgical treatment of chronic periodontitis: A randomized controlled clinical trial

Background:

Probiotics catch more attention as adjunctive periodontal therapy. This study was conducted to assess the benefit of locally delivered Lactobacillus reuteri (L. reuteri) probiotic as an adjunctive to scaling and root planing (SRP) in the treatment of chronic periodontitis clinically and microbiologically.

Materials and Methods:

Bacterial cultures and clinical evaluation were recorded in 20 sites of chronic periodontitis in 12 patients and followed up at 3 and 6 months from the start of intervention using clinical attachment level, probing pocket depth, plaque index (PI), bleeding on probing, and microbiologically for Porphyromonas gingivalis (P. gingivalis) load. Patients meeting the inclusion criteria were scheduled within 1 week for two sessions of SRP. After SRP, oral hygiene measures were reassured, and sites were divided randomly into two groups 10 sites each. Group I received SRP only, while Group II received SRP and subgingival delivery of 1 ml of probiotic L. reuteri suspension at baseline and 1, 2, and 4 weeks using a blunt syringe. A periodontal pack was applied after the placement of the drug.

Results:

We found noticeable variation between the two groups in all evaluation aspects at 3 and 6-month follow-up periods except PI at 6 months in which there was no significant difference between both groups.

Conclusions:

The results proved the antimicrobial benefit of L. reuteri probiotic as a promising adjunctive therapy in improving periodontal parameters. However, further long-term studies with large sample size are needed to evaluate the extent of the added value of L. reuteri suspension.

Subgingival Microbiota and Cytokines Profile Changes in Patients with Periodontitis: A Pilot Study Comparing Healthy and Diseased Sites in the Same Oral Cavities

Periodontitis is a common condition characterized by an exacerbated pro-inflammatory response, which leads to tissue destruction and, ultimately, alveolar bone loss. In this pilot study, we assess the microbiota composition and cytokine profile changes in patients with stage III/IV, grade B/C periodontitis, specifically by comparing healthy and diseased sites in the same oral cavity. Overall, we found that microbiota architecture was significantly disrupted between diseased and healthy sites, and that the clustering was driven, in part, by the increased relative abundances of Synergistetes in diseased sites, as well as the increased abundances of Firmicutes in healthy sites. We also observed that diseased sites were enriched in Synergistetes, TM7, SR1, Spirochaetes, Bacteroidetes and Fusobacteria, and depleted in Firmicutes, Proteobacteria, Tenericutes and Actinobacteria compared to healthy sites. We found that Interleukin-1b, Interleukin-4, Interleukin-10, and Interleukin-17A were significantly overexpressed in diseased sites, whereas Interleukin-6 and TNF-alpha do not differ significantly between healthy and diseased sites. Here, we observed concomitant changes in the subgingival plaque microbiota and cytokines profile, suggesting that this combined alteration could contribute to the pathobiology of periodontitis.

The Influence of Diet on Oxidative Stress and Inflammation Induced by Bacterial Biofilms in the Human Oral Cavity

The article is a concise compendium of knowledge on the etiology of pathogenic microorganisms of all complexes causing oral diseases. The influence of particular components of the diet and the role of oxidative stress in periodontal diseases were described. The study investigated the bacteriostatic effect of the diet of adults in in vivo and in vitro tests on the formation of bacterial biofilms living in the subgingival plaque, causing diseases called periodontitis. If left untreated, periodontitis can damage the gums and alveolar bones. Anaerobic bacteria, called periopathogens or periodontopathogens, play a key role in the etiopathogenesis of periodontitis. The most important periopathogens of the oral microbiota are bacteria of all complexes, including the red complex. The obtained results suggest the possibility of using a specific diet in the prevention and treatment of periodontal diseases-already treated as a disease of civilization. The quoted article is an innovative compilation of knowledge on this subject and it can be a valuable source of knowledge for professional hygienists, dentists, peridontologists, dentistry students and anyone who cares about proper oral hygiene. The obtained results suggest the possibility of using this type of diet in the prophylaxis of the oral cavity in order to avoid periodontitis.

Periodontal diseases in the Australian adult population

Periodontal diseases are some of the major oral diseases and conditions in adults.

OBJECTIVE

The study aimed to present the population patterns of periodontal diseases and trends of periodontitis in the Australian adult population.

METHODS

Data collected in the recent National Study of Adult Oral Health (NSAOH) 2017-18 were used to present the current population patterns of periodontal diseases. Periodontal assessment was carried out at three sites per tooth for all present teeth, excluding third molars. Prevalence of gingivitis, periodontal pocket depth of 4+ mm, gingival recession of 2+ mm, and clinical attachment loss of 4+ mm were calculated and reported. The US CDC/AAP case definition was used to define cases of moderate to severe periodontitis. NSAOH 2017-18 data were combined with data collected in NSAOH 2004-06 using similar methods to describe age- and cohort-related trends of periodontitis.

RESULTS

The prevalence of periodontal diseases and conditions were relatively high in the Australian adult population. Some three in every ten Australian adults had moderate to severe periodontitis. There was a tendency of higher prevalence of periodontitis in NSAOH 2017-18 than in NSAOH 2004-06 among people of the same age.

CONCLUSION

Periodontal diseases and conditions remain a significant problem in the Australian adult population.

Immunohistochemical evaluation of CD117 in mast cell of aggressive periodontitis

Context:

Aggressive periodontitis is a type of inflammatory response in periodontal tissues that is differentiated from chronic by its earlier onset, its high rate of progression, subgingival microbial composition, the difference in the host's immune response, and family history of the disease. Mast cells live in tissues and contribute to the various allergic and inflammatory conditions, including periodontal diseases, through the release of cytokines, chemokines, and proteolytic enzymes. CD117, the receptor of the stem cell factor expressed by the mast cells, is the hallmark of mast cell development. This study aimed to determine the expression level of CD117 in the mast cells of aggressive periodontitis using immunohistochemistry.

Aims:

This study aimed to determine the expression level of CD117 in the mast cells of aggressive periodontitis using immunohistochemistry.

Subjects and Methods:

The study was conducted on tissue samples from 15 patients with aggressive periodontitis and 15 patients with healthy gingival tissue. Samples were stained for CD117 markers using immunohistochemistry. After the microscopic examination of samples, all data were entered into SPSS 20 and analyzed.

Statistical Analysis Used:

Statistical data were analyzed using Kolmogorov–Smirnov test and independent t-test.

Results:

According to the results, the mean expression levels of CD117 in the aggressive periodontitis and normal gingival groups were 19.08 ± 6.9 and 18.2 ± 8.1, respectively, which were not statistically significant (P = 0.75). The Kolmogorov–Smirnov test verified the normality of distribution of CD117 expression level. Given the normal distribution of the scores, the independent t-test was used to compare the CD117 expression level in the two study groups.

Conclusions:

There was no significant difference in the level of CD117 expression between the control and aggressive periodontitis groups.

Antimicrobial activity of honey in periodontal disease: a systematic review

BACKGROUND

Honey has shown positive antimicrobial and anti-inflammatory actions in several dermatological studies; however, it is unclear if it could be effective in the treatment of periodontal disease.

OBJECTIVES

To answer the question: Does honey have antimicrobial activity against periodontopathogens?

METHODS

Six electronic databases were screened from initiation to 31 January 2019 for randomized clinical trials (RCTs) and controlled in vitro studies exploring the antimicrobial effect of honey against periodontopathogens. Honey's botanical origin, periopathogens that showed microbial susceptibility to honey, MICs, microbial growth conditions, control product and clinical follow-up were the main investigated outcomes. The risk of bias (RoB) of included RCTs was assessed using the Cochrane Collaboration RoB tool. The RoB of in vitro studies was evaluated based on the Sarkis-Onofre judgement model adapted to the context of honey.

RESULTS

A total of 1448 publications were found as search results in the screened databases. Sixteen eligible papers were included based on predetermined inclusion criteria. Retained studies included 5 RCTs and 11 in vitro controlled trials. Manuka and multifloral honeys were the most studied varieties. The tested honeys showed a significant antimicrobial action, with different MICs, against eight periopathogens. Four of the five RCTs showed a high RoB, while 4 of the 11 retained in vitro studies showed a medium RoB.

CONCLUSIONS

Honey showed a significant antimicrobial activity against all targeted periopathogens. Additional experiments are required to explore the entire antimicrobial spectrum of honey towards all pathogens involved in periodontal disease.

Osmunda japonica Extract Suppresses Pro-Inflammatory Cytokines by Downregulating NF-κB Activation in Periodontal Ligament Fibroblasts Infected with Oral Pathogenic Bacteria

Periodontal diseases are caused by bacterial infection and may progress to chronic dental disease; severe inflammation may result in bone loss. Therefore, it is necessary to prevent bacterial infection or control inflammation. Periodontal ligament fibroblasts (PDLFs) are responsible for the maintenance of tissue integrity and immune and inflammatory events in periodontal diseases. The formation of bacterial complexes by Fusobacterium nucleatum and Porphyromonas gingivalis is crucial in the pathogenesis of periodontal disease. F. nucleatum is a facultative anaerobic species, considered to be a key mediator of dental plaque maturation and aggregation of other oral bacteria. P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting virulence factors. In this study, we investigated whether Osmunda japonica extract exerted anti-inflammatory effects in primary PDLFs stimulated by oral pathogens. PDLFs were stimulated with F. nucleatum or P. gingivalis. We showed that pro-inflammatory cytokine (IL-6 and IL-8) expression was induced by LPS or bacterial infection but decreased by treatment with O. japonica extract following bacterial infection. We found that the activation of NF-κB, a transcription factor for pro-inflammatory cytokines, was modulated by O. japonica extract. Thus, O. japonica extract has immunomodulatory activity that can be harnessed to control inflammation.

Expression of mast cell in aggressive periodontitis

BACKGROUND

Aggressive periodontitis is a progressive disease that can cause tooth loss within a short period of time. Mast cells are found in tissues with various allergic and inflammatory conditions including periodontal disease through the release of cytokines, chemokines, and proteolytic enzymes. Given the findings of some studies on the related role of mast cells, this study was conducted to determine the number of mast cells in aggressive periodontitis.

METHODS

This study was conducted on 30 participants divided into two groups visiting the Faculty of Dentistry of University of Medical Sciences. A total of 15 participants with aggressive periodontitis and 15 healthy participants were investigated. For counting mast cells, toluidine blue staining was used. The percentage of mast cells and demographic factors were evaluated in the two groups and the results were analyzed in SPSS using descriptive statistics and independent t-tests. A P value <0.05 was considered significant.

RESULTS

The mean percentage of mast cells in the aggressive periodontitis group was 27.1±8.9 which was significantly higher than that of the healthy group, i.e. 12.6±5.1 (P<0.001).

CONCLUSIONS

In general, the results of the study showed that the percentage of mast cells in the aggressive periodontitis group was more than two times higher than that of the healthy group, which is indicative of an increase in the number of mast cells in aggressive periodontitis disease.

Periodontitis phenotypes and clinical response patterns to non-surgical periodontal therapy: reflections on the new periodontitis classification

We aimed to identify response patterns to non-surgical periodontal therapy and to investigate whether the new classification system for periodontitis reflects response to treatment after 1 yr. At baseline, data on sociodemographic status, smoking, and diabetes were obtained from participants with periodontal disease. Clinical periodontal data and subgingival plaque were also collected. Participants underwent non-surgical periodontal therapy, and after 3 and 12 months, clinical data were reassessed. Factor analyses, group-based-trajectory modeling, and mixed-effects regression models were used for data analysis. Factor analysis of the baseline periodontal parameters revealed two different periodontitis dimensions: 'moderate' and 'severe'. Two response patterns for each of these periodontitis dimensions were identified. Periodontal therapy had a beneficial effect on both 'moderate' and 'severe' periodontitis; however, individuals with higher levels of disease at baseline experienced greater treatment effect. Regarding the new classification system, while the staging component distinguished different levels of 'moderate' and 'severe' periodontitis before and after treatment, the grading component did not. This study shows the beneficial effect of non-surgical periodontal therapy on both 'moderate' and 'severe' periodontitis. However, the benefit was limited among individuals with low levels of disease. The new classification system did not adequately reflect the periodontal response to therapy in this patient group.

Is nutritional intervention an improvement factor in the management of periodontitis? A systematic review

AIMS

This systematic review aimed to evaluate the effect of nutritional intervention in the management of periodontitis.

METHODS

This study was registered on the Prospective International Registry of Systematic Reviews-PROSPERO, under the registration number CRD42017076674. The database searching was performed on: Pubmed, Scopus, Web of Science, Clinical Trials and Lilacs. The OpenGrey and Google Scholar were also assessed for searching the grey literature. The PICO framework was carried out, in which the participants (P) were humans with periodontitis receiving conventional periodontal therapy simultaneously with dietary supplements (I), compared (C) with those managed with conventional therapy only, having as an outcome (O) the influence-or not influence-of nutritional intervention in the management of periodontitis. After the searching, duplicates were removed and articles were first assessed by title and abstract, following the inclusion and exclusion criteria; then, the full text of the remaining articles were reviewed. All steps within the review process were performed independently by two reviewers and checked by a third-party disagreement evaluator. For quality/risk of bias assessment of the study selection, The Cochrane Collaboration's tool for randomized studies and Robins-TOOL for non-randomized studies (ROBINS-I) were performed. The Grading of recommendations, assessment, development and evaluation (GRADE) was used for assessing the level of evidence.

RESULTS

A total of 2574 citations were recorded, but only four were considered eligible. The included studies reported different nutritional interventions such as fruit concentrate, vegetables and fruit juice powders, multivitamins, fish oil, and a customized dietary advice. The three studies using nutritional supplements showed improvements in at least one clinical parameter of periodontitis -reduction of probing depths, attachment gain, crevicular fluid decreased, reduced bleeding values on probing-after 2-6 months. Although, only two articles presented a moderate risk of bias, a very low level of evidence was found among the four studies taken together.

CONCLUSIONS

Despite the results suggested that nutritional intervention is beneficial for periodontal therapy, the evidence in general, is inconsistent and imprecise. More interventional studies with longer periods of follow-up and the assessment of a specific nutritional intervention must be conducted.

Isolation of Naturally Induced T-regulatory Cells in Gingival Tissues of Healthy Human Subjects and Subjects with Gingivitis and Chronic Periodontitis

Background: The immune mechanism depends on CD4+ T cells for its regular function, and altered T cell function leads to microbial disease progression.

Aim: The present study aimed to determine the role of naturally induced T-regulatory (nTreg) cells (CD4+ CD25+ Fox P3+) in periodontal disease pathogenesis.

Materials and methods: A total of 30 patients attending the out-patient clinic of the Department of Periodontology and Implantology, Faculty of Dental Sciences, Sri Ramachandra University (SRU), Chennai, India were recruited for the study. They were categorized in three groups as healthy individuals, individuals with chronic gingivitis, and individuals with chronic periodontitis gingival tissues. nTreg (CD4+ CD25+ Fox P3+) cells were isolated using flow cytometry. Different conjugated, isolated cells were then gated in the order of CD4+, CD25+, and Fox P3+ cells.

Results: The results of our study showed an increase in the proportions of Treg cells in individuals with chronic periodontitis compared to individuals with gingivitis and healthy individuals.

Conclusion: Further elucidation of cellular and molecular processes underlying Treg cells will help unravel the complexity behind periodontal disease pathogenesis besides paving the way in developing newer treatment strategies.

Complement-Dependent Mechanisms and Interventions in Periodontal Disease

Periodontitis is a prevalent inflammatory disease that leads to the destruction of the tooth-supporting tissues. Current therapies are not effective for all patients and this oral disease continues to be a significant public health and economic burden. Central to periodontal disease pathogenesis is a reciprocally reinforced interplay between microbial dysbiosis and destructive inflammation, suggesting the potential relevance of host-modulation therapies. This review summarizes and discusses clinical observations and pre-clinical intervention studies that collectively suggest that complement is hyperactivated in periodontitis and that its inhibition provides a therapeutic benefit. Specifically, interception of the complement cascade at its central component, C3, using a locally administered small peptidic compound (Cp40/AMY-101) protected non-human primates from induced or naturally occurring periodontitis. These studies indicate that C3-targeted intervention merits investigation as an adjunctive treatment of periodontal disease in humans.

Rotary Instrument in Non-Surgical Treatment of Chronic Periodontal Disease: Clinic Randomized Study

Objective:

The aim of this study is to compare the efficacy of rotary instruments vs hand scalers in non-surgical periodontal therapy, studying the variation of periodontal health indexes.

Materials and Methods:

Forty patients (age between 30 and 70 years) with advanced chronic periodontitis, that were recruited for the study, were divided into two groups; control group and test group. Control patients were treated with hand scalers while test group patients were treated with rotary instruments. Periodontal indexes were evaluated at baseline and after 3 months.

Results:

Nonsignificant differences were found at 12 weeks follow up for all the parameters between test and control groups.

Conclusions:

Within their limits, the results indicate that different instruments can be effective in removing calculus and endotoxins. This requisite is mandatory for a proper periodontal healing.

The reasons for clinicians to use diamond-coated instruments are related to a faster procedure, and the clinical evidence of a smooth root surface. The clinicians’ ability remains one of the most important variables that could affect periodontal therapy.

At least three phenotypes exist among periodontitis patients

AIM

To identify phenotypes of periodontitis patients by the use of an unsupervised modelling technique (clustering), based on pre-treatment radiographic and microbiological characteristics.

MATERIALS AND METHODS

This retrospective study included data from 392 untreated periodontitis patients. Co-regularized spectral clustering algorithm was used to cluster the patients. The resulting clusters were subsequently characterized based on their demographics, radiographic bone loss patterns and microbial data.

RESULTS

The vast majority of patients fitted into one of the three main clusters (accuracy 90%). Cluster A (n = 18) was characterized by high prevalence and high proportions of Aggregatibacter actinomycetemcomitans, a trend for a more localized pattern of alveolar bone loss and young individuals. Clusters B (n = 200) and C (n = 135) differed clearly in disease severity patterns and smoking habits, but not in microbiological characteristics.

CONCLUSION

On the basis of alveolar bone loss patterns and microbiological data, untreated periodontitis patients can be clustered into at least three phenotypes. These results should be validated in other cohorts, and the clinical utility needs to be explored on the basis of periodontal treatment outcomes and/or disease progression.

Anti-Inflammatory Effect of Melittin on Porphyromonas Gingivalis LPS-Stimulated Human Keratinocytes

Periodontitis is a chronic inflammatory disease that contributes to the destruction of the gingiva. Porphyromonas gingivalis (P. gingivalis) can cause periodontitis via its pathogenic lipopolysaccharides (LPS). Melittin, a major component of bee venom, is known to have anti-inflammatory and antibacterial effects. However, the role of melittin in the inflammatory response has not been elucidated in periodontitis-like human keratinocytes. Therefore, we investigated the anti-inflammatory effects of melittin on a P. gingivalis LPS (PgLPS)-treated HaCaT human keratinocyte cell line. The cytotoxicity of melittin was measured using a human keratinocyte cell line, HaCaT, and a Cell Counting Kit-8. The effect of melittin on PgLPS-induced inflammation was determined with Western blot, real-time quantitative PCT, and immunofluorescence. PgLPS increased the expression of toll-like receptor (TLR) 4 and proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, and interferon-γ (IFN-γ). Moreover, PgLPS induced activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), extracellular signal-regulated kinase (ERK), and protein kinase B/Akt. Melittin also inhibited the expression of proinflammatory cytokines by suppressing the activation of the NF-κB signaling pathway, ERK, and Akt. Melittin attenuates the PgLPS-induced inflammatory response and could therefore be applied in the treatment of periodontitis for anti-inflammatory effects.

On the discovery of cementum

Though cementum of the tooth root is critical for periodontal structure and tooth attachment and function, this tissue was not discovered and characterized on human teeth until a full century later than enamel and dentin. Early observations from the seventeenth to the nineteenth centuries by Marcello Malpighi, Antonie van Leeuwenhoek, Robert Blake, Jacques Tenon and Georges Cuvier founded a confusing and conflicting nomenclature that obscured the nature of cementum, often conflating it with bone. Advances in microscopy and histological procedures yielded the first detailed descriptions of human cementum in the 1830s by Jan Purkinje and Anders Retzius, who identified for the first time acellular and cellular types of cementum, and the resident cementocytes embedded in the latter. Comparative anatomy studies by Richard Owen and others over the latter half of the nineteenth century identified coronal and radicular cementum varieties across the Reptilia and Mammalia. The functional importance of cementum was not appreciated until detailed anatomical studies of the periodontium were performed by G.V. Black and others in the late nineteenth and early twentieth centuries. These early studies on cementum laid the foundation for more advanced understanding of cementum ultrastructure, composition, development, physiology, disease, genetics, repair and regeneration throughout the twentieth and into the twenty-first century.

Novel Mutations in the Cathepsin C Gene in Patients with Pre-pubertal Aggressive Periodontitis and Papillon-Lefèvre Syndrome

Aggressive periodontitis (AP) in pre-pubertal children is often associated with genetic disorders like Papillon-Lefèvre syndrome (PLS). PLS is caused by mutations in the cathepsin C ( CTSC) gene. We report a novel CTSC mutation (c.566-572del) in an otherwise healthy AP child and two novel compound heterozygous mutations (c.947T>G, c.1268G>C) in a PLS patient. We conclude that at least a subset of pre-pubertal AP is due to CTSC mutations and therefore may be an allelic variant of PLS.

Lactobacillus rhamnosus could inhibit Porphyromonas gingivalis derived CXCL8 attenuation

An increasing body of evidence suggests that the use of probiotic bacteria is a promising intervention approach for the treatment of inflammatory diseases with a polymicrobial etiology. P. gingivalis has been noted to have a different way of interacting with the innate immune response of the host compared to other pathogenic bacteria, which is a recognized feature that inhibits CXCL8 expression.

Bee Venom Inhibits Porphyromonas gingivalis Lipopolysaccharides-Induced Pro-Inflammatory Cytokines through Suppression of NF-κB and AP-1 Signaling Pathways

Periodontitis is a chronic inflammatory disease that leads to destruction of tooth supporting tissues. Porphyromonas gingivalis (P. gingivalis), especially its lipopolysaccharides (LPS), is one of major pathogens that cause periodontitis. Bee venom (BV) has been widely used as a traditional medicine for various diseases. Previous studies have demonstrated the anti-inflammatory, anti-bacterial effects of BV. However, a direct role and cellular mechanism of BV on periodontitis-like human keratinocytes have not been explored. Therefore, we investigated the anti-inflammatory mechanism of BV against P. gingivalis LPS (PgLPS)-induced HaCaT human keratinocyte cell line. The anti-inflammatory effect of BV was demonstrated by various molecular biological methods. The results showed that PgLPS increased the expression of Toll-like receptor (TLR)-4 and pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, and interferon (IFN)-γ. In addition, PgLPS induced activation of the signaling pathways of inflammatory cytokines-related transcription factors, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP-1). BV effectively inhibited those pro-inflammatory cytokines through suppression of NF-κB and AP-1 signaling pathways. These results suggest that administration of BV attenuates PgLPS-induced inflammatory responses. Furthermore, BV may be a useful treatment to anti-inflammatory therapy for periodontitis.

From orphan drugs to adopted therapies: Advancing C3-targeted intervention to the clinical stage

Complement dysregulation is increasingly recognized as an important pathogenic driver in a number of clinical disorders. Complement-triggered pathways intertwine with key inflammatory and tissue destructive processes that can either increase the risk of disease or exacerbate pathology in acute or chronic conditions. The launch of the first complement-targeted drugs in the clinic has undeniably stirred the field of complement therapeutic design, providing new insights into complement's contribution to disease pathogenesis and also helping to leverage a more personalized, comprehensive approach to patient management. In this regard, a rapidly expanding toolbox of complement therapeutics is being developed to address unmet clinical needs in several immune-mediated and inflammatory diseases. Elegant approaches employing both surface-directed and fluid-phase inhibitors have exploited diverse components of the complement cascade as putative points of therapeutic intervention. Targeting C3, the central hub of the system, has proven to be a promising strategy for developing biologics as well as small-molecule inhibitors with clinical potential. Complement modulation at the level of C3 has recently shown promise in preclinical primate models, opening up new avenues for therapeutic intervention in both acute and chronic indications fueled by uncontrolled C3 turnover. This review highlights recent developments in the field of complement therapeutics, focusing on C3-directed inhibitors and alternative pathway (AP) regulator-based approaches. Translational perspectives and considerations are discussed, particularly with regard to the structure-guided drug optimization and clinical advancement of a new generation of C3-targeted peptidic inhibitors.

Complement inhibition in pre-clinical models of periodontitis and prospects for clinical application

Periodontitis is a dysbiotic inflammatory disease leading to the destruction of the tooth-supporting tissues. Current therapies are not always effective and this prevalent oral disease continues to be a significant health and economic burden. Early clinical studies have associated periodontitis with elevated complement activity. Consistently, subsequent genetic and pharmacological studies in rodents have implicated the central complement component C3 and downstream signaling pathways in periodontal host-microbe interactions that promote dysbiosis and inflammatory bone loss. This review discusses these mechanistic advances and moreover focuses on the compstatin family of C3 inhibitors as a novel approach to treat periodontitis. In this regard, local application of the current lead analog Cp40 was recently shown to block both inducible and naturally occurring periodontitis in non-human primates. These promising results from non-human primate studies and the parallel development of Cp40 for clinical use highlight the feasibility for developing an adjunctive, C3-targeted therapy for human periodontitis.

Inhibition of pre-existing natural periodontitis in non-human primates by a locally administered peptide inhibitor of complement C3

AIM

Human periodontitis is associated with overactivation of complement, which is triggered by different mechanisms converging on C3, the central hub of the system. We assessed whether the C3 inhibitor Cp40 inhibits naturally occurring periodontitis in non-human primates (NHPs).

MATERIALS AND METHODS

Non-human primates with chronic periodontitis were intra-gingivally injected with Cp40 either once (5 animals) or three times (10 animals) weekly for 6 weeks followed by a 6-week follow-up period. Clinical periodontal examinations and collection of gingival crevicular fluid and biopsies of gingiva and bone were performed at baseline and during the study. A one-way repeated-measures anova was used for data analysis.

RESULTS

Whether administered once or three times weekly, Cp40 caused a significant reduction in clinical indices that measure periodontal inflammation (gingival index and bleeding on probing), tissue destruction (probing pocket depth and clinical attachment level) or tooth mobility. These clinical changes were associated with significantly reduced levels of pro-inflammatory mediators and decreased numbers of osteoclasts in bone biopsies. The protective effects of Cp40 persisted, albeit at reduced efficacy, for at least 6 weeks following drug discontinuation.

CONCLUSION

Cp40 inhibits pre-existing chronic periodontal inflammation and osteoclastogenesis in NHPs, suggesting a novel adjunctive anti-inflammatory therapy for treating human periodontitis.

Acute periodontal lesions

This review provides updates on acute conditions affecting the periodontal tissues, including abscesses in the periodontium, necrotizing periodontal diseases and other acute conditions that cause gingival lesions with acute presentation, such as infectious processes not associated with oral bacterial biofilms, mucocutaneous disorders and traumatic and allergic lesions. A periodontal abscess is clinically important because it is a relatively frequent dental emergency, it can compromise the periodontal prognosis of the affected tooth and bacteria within the abscess can spread and cause infections in other body sites. Different types of abscesses have been identified, mainly classified by their etiology, and there are clear differences between those affecting a pre-existing periodontal pocket and those affecting healthy sites. Therapy for this acute condition consists of drainage and tissue debridement, while an evaluation of the need for systemic antimicrobial therapy will be made for each case, based on local and systemic factors. The definitive treatment of the pre-existing condition should be accomplished after the acute phase is controlled. Necrotizing periodontal diseases present three typical clinical features: papilla necrosis, gingival bleeding and pain. Although the prevalence of these diseases is not high, their importance is clear because they represent the most severe conditions associated with the dental biofilm, with very rapid tissue destruction. In addition to bacteria, the etiology of necrotizing periodontal disease includes numerous factors that alter the host response and predispose to these diseases, namely HIV infection, malnutrition, stress or tobacco smoking. The treatment consists of superficial debridement, careful mechanical oral hygiene, rinsing with chlorhexidine and daily re-evaluation. Systemic antimicrobials may be used adjunctively in severe cases or in nonresponding conditions, being the first option metronidazole. Once the acute disease is under control, definitive treatment should be provided, including appropriate therapy for the pre-existing gingivitis or periodontitis. Among other acute conditions affecting the periodontal tissues, but not caused by the microorganisms present in oral biofilms, infectious diseases, mucocutaneous diseases and traumatic or allergic lesions can be listed. In most cases, the gingival involvement is not severe; however, these conditions are common and may prompt an emergency dental visit. These conditions may have the appearance of an erythematous lesion, which is sometimes erosive. Erosive lesions may be the direct result of trauma or a consequence of the breaking of vesicles and bullae. A proper differential diagnosis is important for adequate management of the case.

Periodontal disease classifications revisited

An American Academy of Periodontology Task Force has recently published a report on the Update to the 1999 Classification of Periodontal Diseases and Conditions, which is a focused update outlining changes to be included in a comprehensive update planned for 2017. We discuss the proposed changes, and their rationales, and conclude that the periodontal classification carousel will continue to spin until it is realized that the only way forward is a profound reconsideration of what we hope to achieve with classifications.

Toll-Like Receptor 9-Mediated Inflammation Triggers Alveolar Bone Loss in Experimental Murine Periodontitis

Chronic periodontitis is a local inflammatory disease induced by a dysbiotic microbiota and leading to destruction of the tooth-supporting structures. Microbial nucleic acids are abundantly present in the periodontium, derived through release after phagocytic uptake of microbes and/or from biofilm-associated extracellular DNA. Binding of microbial DNA to its cognate receptors, such as Toll-like receptor 9 (TLR9), can trigger inflammation. In this study, we utilized TLR9 knockout (TLR9(-/-)) mice and wild-type (WT) controls in a murine model of Porphyromonas gingivalis-induced periodontitis and report the first in vivo evidence that TLR9 signaling mediates the induction of periodontal bone loss. P. gingivalis-infected WT mice exhibited significantly increased bone loss compared to that in sham-infected WT mice or P. gingivalis-infected TLR9(-/-) mice, which were resistant to bone loss. Consistent with this, the expression levels of interleukin 6 (IL-6), tumor necrosis factor (TNF), and receptor-activator of nuclear factor kappa B ligand (RANKL) were significantly elevated in the gingival tissues of the infected WT mice but not in infected TLR9(-/-) mice compared to their levels in controls. Ex vivo studies using splenocytes and bone marrow-derived macrophages revealed significantly diminished cytokine production in TLR9(-/-) cells relative to the cytokine production in WT cells in response to P. gingivalis, thereby implicating TLR9 in inflammatory responses to this organism. Intriguingly, compared to the cytokine production in WT cells, TLR9(-/-) cells exhibited significantly decreased proinflammatory cytokine production upon challenge with lipopolysaccharide (LPS) (TLR4 agonist) or Pam3Cys (TLR2 agonist), suggesting possible cross talk between TLR9, TLR4, and TLR2. Collectively, our results provide the first proof-of-concept evidence implicating TLR9-triggered inflammation in periodontal disease pathogenesis, thereby identifying a new potential therapeutic target to control periodontal inflammation.

Complement Involvement in Periodontitis: Molecular Mechanisms and Rational Therapeutic Approaches

The complement system is a network of interacting fluid-phase and cell surface-associated molecules that trigger, amplify, and regulate immune and inflammatory signaling pathways. Dysregulation of this finely balanced network can destabilize host-microbe homeostasis and cause inflammatory tissue damage. Evidence from clinical and animal model-based studies suggests that complement is implicated in the pathogenesis of periodontitis, a polymicrobial community-induced chronic inflammatory disease that destroys the tooth-supporting tissues. This review discusses molecular mechanisms of complement involvement in the dysbiotic transformation of the periodontal microbiome and the resulting destructive inflammation, culminating in loss of periodontal bone support. These mechanistic studies have additionally identified potential therapeutic targets. In this regard, interventional studies in preclinical models have provided proof-of-concept for using complement inhibitors for the treatment of human periodontitis.

On putative periodontal pathogens: an epidemiological perspective

The current understanding on the role of microbiology on periodontitis causation is reviewed. An appraisal of the literature reveals several issues that have limited the attempts to investigate candidate periodontal pathogens as causes of periodontitis and confirms that only limited epidemiological evidence is available. Several aspects of the contemporary understanding on causal inference are discussed with examples for periodontitis.

The inflammophilic character of the periodontitis-associated microbiota

In periodontitis, dysbiotic microbial communities exhibit synergistic interactions for enhanced protection from host defenses, nutrient acquisition, and persistence in an inflammatory environment. This review discusses evidence that periodontitis-associated communities are 'inflammo-philic' (=loving or attracted to inflammation) in that they have evolved to not only endure inflammation but also to take advantage of it. In this regard, inflammation can drive the selection and enrichment of these pathogenic communities by providing a source of nutrients in the form of tissue breakdown products (e.g. degraded collagen peptides and heme-containing compounds). In contrast, those species that cannot benefit from the altered ecological conditions of the inflammatory environment, or for which host inflammation is detrimental, are likely to be outcompeted. Consistent with the concept that inflammation fosters the growth of dysbiotic microbial communities, the bacterial biomass of human periodontitis-associated biofilms was shown to increase with increasing periodontal inflammation. Conversely, anti-inflammatory treatments in animal models of periodontitis were shown to diminish the periodontal bacterial load, in addition to protecting from bone loss. The selective flourishing of inflammophilic bacteria can perpetuate inflammatory tissue destruction by setting off a 'vicious cycle' for disease progression, in which dysbiosis and inflammation reinforce each other. Therefore, the control of inflammation appears to be central to the treatment of periodontitis, as it is likely to control both dysbiosis and disease progression.

Genetic and intervention studies implicating complement C3 as a major target for the treatment of periodontitis

Chronic periodontitis is induced by a dysbiotic microbiota and leads to inflammatory destruction of tooth-supporting connective tissue and bone. The third component of complement, C3, is a point of convergence of distinct complement activation mechanisms, but its involvement in periodontitis was not previously addressed. We investigated this question using two animal species models, namely, C3-deficient or wild-type mice and nonhuman primates (NHPs) locally treated with a potent C3 inhibitor (the compstatin analog Cp40) or an inactive peptide control. In mice, C3 was required for maximal periodontal inflammation and bone loss, and for the sustenance of the dysbiotic microbiota. The effect of C3 on the microbiota was therefore different from that reported for the C5a receptor, which is required for the initial induction of dysbiosis. C3-dependent bone loss was demonstrated in distinct models, including Porphyromonas gingivalis-induced periodontitis, ligature-induced periodontitis, and aging-associated periodontitis. Importantly, local treatment of NHPs with Cp40 inhibited ligature-induced periodontal inflammation and bone loss, which correlated with lower gingival crevicular fluid levels of proinflammatory mediators (e.g., IL-17 and RANKL) and decreased osteoclastogenesis in bone biopsy specimens, as compared with control treatment. To our knowledge, this is the first time, for any disease, that complement inhibition in NHPs was shown to inhibit inflammatory processes that lead to osteoclastogenesis and bone loss. These data strongly support the feasibility of C3-targeted intervention for the treatment of human periodontitis.

Design concepts of a removable partial dental prosthesis with implant-supported abutments

A clinical report is presented that describes the restoration of a severe anterior maxillary ridge defect and pneumatized sinuses with a rotation-path partial removable dental prosthesis and implant-supported abutments. Other treatment options were considered and rejected based on patient preferences and limitations, which included avoiding invasive surgeries. The principles of integrating fixed and removable prosthesis design were applied. However, the clasp design was modified to take into account the direct bone-to-implant contact of the abutments. An esthetic and functional outcome was obtained without any overly invasive surgery.

Salivary and crevicular fluid interleukins in gingivitis

INTRODUCTION

Gingivitis is a frequent inflammatory process of the gum tissue that is mainly caused by the accumulation of plaque. The immune response against inflammatory processes is regulated in part by cytokines.

AIMS

Given that a continuous inflammation exists in gingivitis, it would be logical to assume that the interleukins will be altered locally in those patients. Therefore, the aim of this review was to check whether there is evidence that the interleukins can be used as diagnostic markers of inflammation levels in patients with gingivitis.

MATERIALS AND METHODS

A bibliographical search was undertaken using the key words interleukin and gingivitis in Pubmed, Cochrane, Scopus and Embase. Only those articles published over the last 10 years that were systematic reviews, case-controls or cohort studies in which interleukins in saliva and/or crevicular fluid was investigated in patients with gingivitis were selected.

RESULTS

Finally 15 articles were selected, all of them being case-control studies. The interleukins analyzed in the reviewed articles were: IL-1β, IL-8, IL-18, IL-11, IL-12, TNFα, IL-4, IL-17, IL-1α and IL-6. The most commonly studied interleukin is IL-1β and most authors agree that it is higher in the saliva and/or crevicular fluid of patients with gingivitis. Therefore, it could be used as a diagnostic marker of the degree of inflammation in gingivitis. Moreover, as far as the other interleukins studied are concerned, there is no clear consensus among the authors.

CONCLUSION

There is sufficient evidence to suggest that IL-1β in saliva and/or crevicular fluid can be used as a marker of the degree of inflammation in gingivitis. Key words:Interleukins, gingivitis, saliva, crevicular fluid.

Periodontology: past, present, perspectives

Periodontitis is an infectious disease that affects the tooth-supporting tissues and exhibits a wide range of clinical, microbiological and immunological manifestations. The disease is associated with and is probably caused by a multifaceted dynamic interaction of specific infectious agents, host immune responses, harmful environmental exposure and genetic susceptibility factors. This volume of Periodontology 2000 covers key subdisciplines of periodontology, ranging from etiopathogeny to therapy, with emphasis on diagnosis, classification, epidemiology, risk factors, microbiology, immunology, systemic complications, anti-infective therapy, reparative treatment, self-care and affordability issues. Learned and unlearned concepts of periodontitis over the past 50 years have shaped our current understanding of the etiology of the disease and of clinical practice.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Topical treatment with probiotic Lactobacillus brevis CD2 inhibits experimental periodontal inflammation and bone loss

BACKGROUND AND OBJECTIVE

An increasing body of evidence suggests that the use of probiotic bacteria is a promising intervention approach for the treatment of inflammatory diseases with a polymicrobial etiology. The objective of this study was to determine whether Lactobacillus brevis CD2 could inhibit periodontal inflammation and bone loss in experimental periodontitis.

MATERIAL AND METHODS

Periodontitis was induced by placing a silk ligature around the second maxillary molar of mice treated with L. brevis CD2 (8 × 10(5)  CFU in 1 mm(2) lyopatch) or placebo, which were placed between the gingiva and the buccal mucosa near the ligated teeth. The mice were killed after 5 d and bone loss was measured morphometrically, gingival expression of proinflammatory cytokines was determined by quantitative real-time polymerase chain reaction, and CFU counts of periodontitis-associated bacteria were determined after aerobic and anaerobic culture. To determine the role of arginine deiminase released by L. brevis CD2, soluble extracts with or without formamidine (arginine deiminase inhibitor) were tested in in vitro cellular activation assays.

RESULTS

Mice topically treated with L. brevis CD2 displayed significantly decreased bone loss and lower expression of tumor necrosis factor, and interleukin-1β, -6 and -17A as compared to placebo-treated mice. Moreover, L. brevis CD2-treated mice displayed lower counts of anaerobic bacteria but higher counts of aerobic bacteria than placebo-treated mice. In in vitro assays, the anti-inflammatory effects of soluble L. brevis CD2 extracts were heavily dependent on the presence of functional arginine deiminase, an enzyme that can inhibit nitric oxide synthesis.

CONCLUSION

These data provide proof-of-concept that the probiotic L. brevis CD2 can inhibit periodontitis through modulatory effects on the host response and the periodontal microbiota.

Role of complement in host-microbe homeostasis of the periodontium

Complement plays a key role in immunity and inflammation through direct effects on immune cells or via crosstalk and regulation of other host signaling pathways. Deregulation of these finely balanced complement activities can link infection to inflammatory tissue damage. Periodontitis is a polymicrobial community-induced chronic inflammatory disease that can destroy the tooth-supporting tissues. In this review, we summarize and discuss evidence that complement is involved in the dysbiotic transformation of the periodontal microbiota and in the inflammatory process that leads to the destruction of periodontal bone. Recent insights into the mechanisms of complement involvement in periodontitis have additionally provided likely targets for therapeutic intervention against this oral disease.

Complement-targeted therapeutics in periodontitis

Periodontitis is a prevalent oral chronic inflammatory disease which, in severe forms, may exert a major impact on systemic health. Clinical and histological observations, as well as experimental animal studies, suggest involvement of the complement system in periodontitis. However, the precise roles of the various complement components and pathways in periodontitis have only recently started to be elucidated. In this chapter, we review recent progress in the field and discuss the potential of complement-targeted therapeutics in the treatment of periodontitis.

Local complement-targeted intervention in periodontitis: proof-of-concept using a C5a receptor (CD88) antagonist

When excessively activated or deregulated, complement becomes a major link between infection and inflammatory pathology including periodontitis. This oral inflammatory disease is associated with a dysbiotic microbiota, leads to the destruction of bone and other tooth-supporting structures, and exerts an adverse impact on systemic health. We have previously shown that mice deficient either in complement C5a receptor (C5aR; CD88) or TLR2 are highly and similarly resistant to periodontitis, suggesting that a cross-talk between the two receptors may be involved in the disease process. In this paper, we show that C5aR and TLR2 indeed synergize for maximal inflammatory responses in the periodontal tissue and uncover a novel pharmacological target to abrogate periodontitis. Using two different mouse models of periodontitis, we show that local treatments with a C5aR antagonist inhibited periodontal inflammation through downregulation of TNF, IL-1β, IL-6, and IL-17 and further protected against bone loss, regardless of the presence of TLR2. These findings not only reveal a crucial cooperation between C5aR and TLR2 in periodontal inflammation but also provide proof-of-concept for local targeting of C5aR as a powerful candidate for the treatment of human periodontitis.

Melatonin levels in periodontal health and disease

BACKGROUND AND OBJECTIVE

The aim of this study was to measure melatonin levels in the gingival crevicular fluid and saliva of subjects with healthy periodontal tissues, plaque-induced gingival inflammation, chronic periodontitis and aggressive periodontitis.

MATERIAL AND METHODS

A total of 70 subjects were examined and assigned to four groups: healthy periodontium (10 subjects); plaque-induced gingival inflammation (20 subjects); chronic periodontitis (20 subjects); and aggressive periodontitis (20 subjects). Gingival crevicular fluid and saliva samples were collected from each subject and analyzed using ELISAs.

RESULTS

The melatonin levels in both gingival crevicular fluid and saliva were lower in patients with chronic periodontitis (10.4 and 12.8 pg/mL, respectively) and aggressive periodontitis (8.4 and 8.8 pg/mL, respectively) than in patients with gingivitis (13.9 and 17.6 pg/mL, respectively) and in healthy subjects (16.6 and 22.9 pg/mL, respectively). The mean melatonin levels in both gingival crevicular fluid and saliva were statistically significantly higher in healthy patients compared with patients with chronic periodontitis and aggressive periodontitis; however, there was no significant difference in the plaque-induced gingival inflammation between the study groups.

CONCLUSIONS

The melatonin levels in gingival crevicular fluid and saliva are decreased in diseased periodontal tissues, especially periodontitis. The melatonin level was lowest in the aggressive periodontitis group.

"What is there in a name?": A literature review on chronic and aggressive periodontitis

The objective of this review is to bring the reader up-to-date on the current understanding of chronic and aggressive forms of periodontitis and the implications for diagnosis and treatment of these diseases. The only difference between chronic periodontitis and aggressive periodontitis with regard to tissue destruction appear to be perhaps the magnitude, sequelae, and control of the response. While there may be some differences in the cellular infiltrate between these two diseases, the molecular mediators and pathologic processes are generally the same.

Expression of peptidylarginine deiminase-2 and -4, citrullinated proteins and anti-citrullinated protein antibodies in human gingiva

BACKGROUND AND OBJECTIVE

The presence of citrullinated proteins, and peptidylarginine deiminase types -2 (PAD-2) and -4 (PAD-4) in periodontal tissues, determine the presence of anti-cyclic citrullinated protein antibodies (anti-CCP) in gingival crevicular fluid (GCF) and compare the expression of these proteins between inflamed and non-inflamed sites.

MATERIAL AND METHODS

Tissue sections were stained using antibodies against citrullinated proteins, PAD-2 and PAD-4. RT-PCR was performed to investigate PAD-2 and PAD-4 mRNA in inflamed and non-inflamed gingival tissues. Anti-CCP antibodies in gingival crevicular fluid were detected by ELISA.

RESULTS

Citrullinated proteins, PAD-2 and PAD-4 were detected in gingiva. There was a correlation between inflammation and expression of these proteins. mRNAs for PAD-2 and PAD-4 were detected in both inflamed and non-inflamed gingival tissues. Antibodies to CCP were found mostly in the GCF of individuals with periodontitis.

CONCLUSION

PAD-2 and PAD-4 (protein and mRNA) as well as citrullinated proteins are present in inflamed gingiva, and anti-CCP antibodies can be detected in the GCF of some patients. Tissue expression of citrullinated proteins and PAD increased with the severity of inflammation. The presence of anti-CCP antibodies in GCF was almost exclusive to a subset of patients with periodontitis. Increased expression of these proteins in inflamed gingiva lends support to the notion that periodontal inflammation contributes to the inflammatory burden in a similar way to rheumatoid arthritis.