Effect of smoking and periodontal treatment on the subgingival microflora

Characteristics of the Salivary Microbiota in Periodontal Diseases and Potential Roles of Individual Bacterial Species To Predict the Severity of Periodontal Disease

The purposes of this study were to examine the compositional changes in the salivary microbiota according to the severity of periodontal disease and to verify whether the distribution of specific bacterial species in saliva can distinguish the severity of disease. Saliva samples were collected from 8 periodontally healthy controls, 16 patients with gingivitis, 19 patients with moderate periodontitis, and 29 patients with severe periodontitis. The V3 and V4 regions of the 16S rRNA gene in the samples were sequenced, and the levels of 9 bacterial species showing significant differences among the groups by sequencing analysis were identified using quantitative real-time PCR (qPCR). The predictive performance of each bacterial species in distinguishing the severity of disease was evaluated using a receiver operating characteristic curve. Twenty-nine species, including Porphyromonas gingivalis, increased as the severity of disease increased, whereas 6 species, including Rothia denticola, decreased. The relative abundances of P. gingivalis, Tannerella forsythia, Filifactor alocis, and Prevotella intermedia determined by qPCR were significantly different among the groups. The three bacterial species P. gingivalis, T. forsythia, and F. alocis were positively correlated with the sum of the full-mouth probing depth and were moderately accurate at distinguishing the severity of periodontal disease. In conclusion, the salivary microbiota showed gradual compositional changes according to the severity of periodontitis, and the levels of P. gingivalis, T. forsythia, and F. alocis in mouth rinse saliva had the ability to distinguish the severity of periodontal disease. IMPORTANCE Periodontal disease is one of the most widespread medical conditions and the leading cause of tooth loss, imposing high economic costs and an increasing burden worldwide as life expectancy increases. Changes in the subgingival bacterial community during the progression of periodontal disease can affect the entire oral ecosystem, and bacteria in saliva can reflect the degree of bacterial imbalance in the oral cavity. This study explored whether the specific bacterial species in saliva can distinguish the severity of periodontal disease by analyzing the salivary microbiota and suggested P. gingivalis, T. forsythia, and F. alocis as biomarkers for distinguishing the severity of periodontal disease in saliva.

Porphyromonas gingivalis, the most influential pathogen in red-complex bacteria: A cross-sectional study on the relationship between bacterial count and clinical periodontal status in Japan

BACKGROUND

Porphyromonas gingivalis is a key pathogen in microbiota associated with periodontitis. The purpose of the present study was to assess the association between salivary counts of red-complex bacteria and clinical periodontal status in a Japanese population.

METHODS

A total of 977 subjects who visited a general dental clinic in Japan from 2003 to 2006 were enrolled in the study. Stimulated saliva was obtained, and the amounts of major periodontal bacteria were measured using real-time polymerase chain reaction. Probing pocket depth (PPD), bleeding on probing (BOP), and each subject's average proximal bone crest level (BCL) on dental radiographs were measured.

RESULTS

The number of P. gingivalis strongly associated with percentage of 4 mm or more PPD sites, BOP positive percentage, and 1.5 mm or more BCL sites. The detection of P. gingivalis with Treponema denticola and/or Tannerella forsythia showed a high rate of three positive clinical parameters, whereas the only P. gingivalis detected group and those without P. gingivalis had a low rate of three positive clinical parameters.

CONCLUSION

Among red-complex bacteria, the amount of P. gingivalis showed the strongest association with the severity of periodontal condition, and co-occurrence of P. gingivalis with T. denticola and/or T. forsythia showed heightened progression of periodontitis.

Quantification of pathogenic bacteria in the subgingival oral biofilm samples collected from cigarette-smokers, individuals using electronic nicotine delivery systems and non-smokers with and without periodontitis

OBJECTIVE

The aim of the present study was to quantify pathogenic bacteria isolated from the subgingival oral-biofilm samples collected from cigarette-smokers and ENDS-users with periodontitis, when compared to non-smokers with and without periodontitis.

METHODS

Demographic data was collected using a questionnaire. Periodontal parameters (plaque [PI] and gingival [GI] indices, clinical attachment loss [CAL], probing depth [PD] and marginal bone loss [MBL]) were measured. Subgingival oral bio-film samples were collected and assessed for periodontopathogenic bacteria (Aggregatibacter actinomycetemcomitans [A. actinomycetemcomitans], Prevotella intermedia [P. intermedia], Porphyromonas gingivalis [P. gingivalis], Tannerella forsythia [T. forsythia] and Treponema denticola [T. denticola]). Group-comparisons were performed; and P < 0.01 were considered statistically significant.

RESULTS

All cigarette-smokers, ENDS-users and non-smokers with periodontitis had Grade-B periodontitis. The CFU/mL of A. actinomycetemcomitans (P < 0.001) and P. gingivalis (P < 0.001) were significantly higher among cigarette-smokers (P < 0.01) and ENDS-users (P < 0.01) than non-smokers with periodontitis. The CFU/mL of T. denticola were significantly higher among cigarette-smokers (P < 0.001), ENDS-users (P < 0.001) and non-smokers with periodontitis (P < 0.001) compared with non-smokers without periodontitis. There was no statistically significant difference in the CFU/mL of P. intermedia and T. denticola among cigarette-smokers, ENDS-users and non-smokers with periodontitis.

CONCLUSION

Counts of periodontopathogenic bacteria in the subgingival oral-biofilm are comparable among cigarette-smokers and individuals using ENDS.

The Impact of Smoking on Subgingival Microflora: From Periodontal Health to Disease

Periodontal disease is one of the most common diseases of the oral cavity affecting up to 90% of the worldwide population. Smoking has been identified as a major risk factor in the development and progression of periodontal disease. It is essential to assess the influence of smoking on subgingival microflora that is the principal etiological factor of the disease to clarify the contribution of smoking to periodontal disease. Therefore, this article reviews the current research findings regarding the impact of smoking on subgingival microflora and discusses several potential mechanisms. Cultivation-based and targeted molecular approaches yield controversial results in determining the presence or absence of smoking-induced differences in the prevalence or levels of certain periodontal pathogens, such as the “red complex.” However, substantial changes in the subgingival microflora of smokers, regardless of their periodontal condition (clinical health, gingivitis, or periodontitis), have been demonstrated in recent microbiome studies. Available literature suggests that smoking facilitates early acquisition and colonization of periodontal pathogens, resulting in an “at-risk-for-harm” subgingival microbial community in the healthy periodontium. In periodontal diseases, the subgingival microflora in smokers is characterized by a pathogen-enriched community with lower resilience compared to that in non-smokers, which increases the difficulty of treatment. Biological changes in key pathogens, such as Porphyromonas gingivalis, together with the ineffective host immune response for clearance, might contribute to alterations in the subgingival microflora in smokers. Nonetheless, further studies are necessary to provide solid evidence for the underlying mechanisms.

Smoking or poor oral hygiene do not predispose to peritonsillar abscesses via changes in oral flora

Aim: The purpose of this prospective study was to determine if there is a difference in number and distribution of salivary bacteria between patients with tonsillar infection and healthy volunteers. Background: The etiology of peritonsillar abscess (PTA) is unclear. Smoking, periodontal disease, and infection of minor salivary glands have been suggested as predisposing factors for PTA. Material and methods: Patients with acute tonsillitis (AT) (n = 54), peritonsillitis (PT) (n = 36), PTA (n = 58), and healthy volunteers (n = 52) were prospectively recruited and evaluated. Saliva bacteria were analyzed with flow cytometry. Patients and their treating physicians completed a questionnaire about patients' current disease, smoking habits, alcohol consumption, and oral health. Results: There were no differences in the total number of saliva bacteria between patients with acute throat infection and healthy volunteers (p = .104) or between AT, PT, and PTA patients (p = .273). Smoking habits, alcohol consumption, oral hygiene, or prior antibiotics had no effect on total amount of salivary bacteria in patients with acute throat infection. Conclusions: The effects of smoking on salivary bacteria do not seem to be the mechanism that promotes development of PTA in smokers.

A cross-sectional study on the periodontal status and prevalence of red complex periodontal pathogens in a Japanese population

This large-scale study cross-sectionally examined the periodontal status and prevalence of "red complex" bacteria (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) in Japanese adults. A total of 977 participants were enrolled in the study. Probing depth (PD), bleeding on probing (BOP), and bone crest level (BCL) were recorded, and the presence of red complex bacteria in the saliva was examined using polymerase chain reaction. The mean BCL value and the percentage of sites with a PD ≥4 mm or the presence of BOP were significantly higher in older participants. The detection rates of P. gingivalis, T. denticola, and T. forsythia were 46.3%, 76.4%, and 61.1%, respectively. The P. gingivalis detection rate significantly increased with age, while those of T. denticola and T. forsythia were comparably high for all age groups. A close correlation between P. gingivalis and the percentage of sites with PD ≥4 mm was indicated by nonlinear canonical correlation analysis. Current smokers exhibited a more advanced disease condition and a significantly higher P. gingivalis detection rate than non-smokers. In conclusion, periodontal condition worsens with age, and P. gingivalis appears to be the red complex bacterium most closely associated with periodontitis.

Personalized periodontal treatment for the tobacco- and alcohol-using patient

The use of various forms of tobacco is one of the most important preventable risk factors for the incidence and progression of periodontal disease. Tobacco use negatively affects treatment outcomes for both periodontal diseases and conditions, and for dental implants. Tobacco-cessation programs can mitigate these adverse dental treatment outcomes and may be the most effective component of a personalized periodontal treatment approach. In addition, heavy alcohol consumption may exacerbate the adverse effects of tobacco use. In this review, the microbiology, host/inflammatory responses and genetic characteristics of the tobacco-using patient are presented as a framework to aid the practitioner in developing personalized treatment strategies for these patients. These personalized approaches can be used for patients who use a variety of tobacco products, including cigarettes, cigars, pipes, smokeless tobacco products, e-cigarettes and other tobacco forms, as well as patients who consume large amounts of alcohol. In addition, principles for developing personalized tobacco-cessation programs, using both traditional and newer motivational and pharmacological approaches, are presented.

16S rRNA Long-Read Sequencing of the Granulation Tissue from Nonsmokers and Smokers-Severe Chronic Periodontitis Patients

Smoking has been associated with increased risk of periodontitis. The aim of the present study was to compare the periodontal disease severity among smokers and nonsmokers which may help in better understanding of predisposition to this chronic inflammation mediated diseases. We selected deep-seated infected granulation tissue removed during periodontal flap surgery procedures for identification and differential abundance of residential bacterial species among smokers and nonsmokers through long-read sequencing technology targeting full-length 16S rRNA gene. A total of 8 phyla were identified among which Firmicutes and Bacteroidetes were most dominating. Differential abundance analysis of OTUs through PICRUST showed significant (p>0.05) abundance of Phyla-Fusobacteria (Streptobacillus moniliformis); Phyla-Firmicutes (Streptococcus equi), and Phyla Proteobacteria (Enhydrobacter aerosaccus) in nonsmokers compared to smokers. The differential abundance of oral metagenomes in smokers showed significant enrichment of host genes modulating pathways involving primary immunodeficiency, citrate cycle, streptomycin biosynthesis, vitamin B6 metabolism, butanoate metabolism, glycine, serine, and threonine metabolism pathways. While thiamine metabolism, amino acid metabolism, homologous recombination, epithelial cell signaling, aminoacyl-tRNA biosynthesis, phosphonate/phosphinate metabolism, polycyclic aromatic hydrocarbon degradation, synthesis and degradation of ketone bodies, translation factors, Ascorbate and aldarate metabolism, and DNA replication pathways were significantly enriched in nonsmokers, modulation of these pathways in oral cavities due to differential enrichment of metagenomes in smokers may lead to an increased susceptibility to infections and/or higher formation of DNA adducts, which may increase the risk of carcinogenesis.

One year results of a randomized controlled clinical study evaluating the effects of non-surgical periodontal therapy of chronic periodontitis in conjunction with three or seven days systemic administration of amoxicillin/metronidazole

BACKGROUND

To evaluate the clinical outcomes 12 months after systemic administration of amoxicillin (AMX) and metronidazole (MET) adjunctive to subgingival debridement (SD) in patients with severe chronic periodontitis (sChP).

MATERIAL AND METHODS

102 patients with sChP were treated randomly as follows: SD within 2 consecutive days and placebo for 7 days (group A), SD+AMX+MET (both 500mg x3 times daily TID) for 3 days (group B), SD+AMX+MET (both 500mg x 3 TID) for 7 days (group C). At baseline, at 3-, 6-, and 12-months post-treatment probing pocket depth (PD), clinical attachment level (CAL), furcation involvement, bleeding on probing (BOP), full-mouth plaque score (FMPS) were determined. The reduction in the number of sites with PD≥6mm was defined as main outcome variable.

RESULTS

75 patients completed the study. At 12 months, all three treatment groups showed statistically significant improvements (p<0.001) of mean PD, CAL, BOP and number of sites with PD≥6mm compared to baseline. Mean residual PD were statistically significantly lower and CAL gain statistically significantly greater in the two antibiotic groups as compared to placebo. While PD reductions (p = 0.012) and CAL gain (p = 0.017) were statistically significantly higher in group C compared to group A, only the 3-day AB group showed statistically significantly fewer sites with PD≥6mm at 12 m (p = 0.003). The reduction in the number of sites with PD≥6 mm (primary outcome) showed no statistical significant differences between the 3 treatment groups. However, in both antibiotic groups significantly more patients compared to the placebo group reached a low risk for disease progression at 12 months (≤4 sites with PD≥5mm).

CONCLUSION

At 12 months, both adjunctive antibiotic protocols resulted in statistically significantly greater clinical improvements compared to placebo.

Antibiotics/antimicrobials: systemic and local administration in the therapy of mild to moderately advanced periodontitis

This review gives an update of the current scientific evidence on the efficacy of the adjunctive use of systemic and local antibiotics/antimicrobials in the treatment of periodontitis. In particular, it addresses whether their use can improve the results of nonsurgical mechanical therapy in mild-to-moderate forms of the disease. Large numbers of randomized clinical trials and systematic reviews with meta-analyses have clearly established that adjunctive systemic antibiotics, combined with mechanical debridement, offer clinical improvements additional to those obtained with scaling and root planing alone. These effects are more pronounced in aggressive periodontitis and in initially deep pockets, whereas more limited additional improvements, of 0.3 mm for additional pocket reduction and 0.2 mm for additional clinical attachment gain, have been documented for moderately deep sites (4-6 mm) in patients with chronic periodontitis. The marginal clinical benefit in patients with moderate disease has to be balanced against possible side effects. Notably, it has to be realized that an increasing number of warnings have been articulated against the unrestricted use of antibiotics in treating periodontal diseases because of the emerging global public health issue of bacterial resistance. The effects of the adjunctive local administration of antimicrobials have also been very well documented in several systematic reviews. Overall, in persistent or recurrent localized deep sites, the application of antimicrobials by sustained-delivery devices may offer a benefit of an additional 0.4 mm in pocket depth reduction and 0.3 mm in clinical attachment level gain. In conclusion, the slight additional benefits of adjunctive antimicrobials, which were shown for moderate forms of periodontitis, have to be balanced against their side effects and therefore their prescription should be limited as much as possible.

Subgingival dysbiosis in smoker and non‑smoker patients with chronic periodontitis

Periodontitis is one of the most common oral inflammatory diseases, and results in connective tissue degradation and gradual tooth loss. It manifests with formation of periodontal pockets, in which anaerobic and Gram‑negative bacteria proliferate rapidly. Consequently, alteration of the subgingival microbiota is considered the primary etiologic agent of periodontitis. Previous studies have reported that smokers are at increased risk of periodontal disease, in both prevalence and severity, indicating that smoking is a risk factor for the onset and progression of the pathology. In the present study, 16S rRNA sequencing was employed to assess the subgingival microbiota in 6 smoker patients with chronic periodontitis, 6 non‑smoker patients with chronic periodontitis and 8 healthy controls. The results demonstrated significant alterations in the microbial structure of periodontitis patients. High relative abundance of Parvimonans, Desulfubulbus, Paludibacter, Haemophilus, and Sphaerochaeta genera characterized subgingival microbiota of periodontitis patients, both smokers and non‑smokers. Due to the high precision and sensitivity of the 16S rRNA sequencing method, analysis for low‑abundant genera (including Pedobacter, Granulicatella, Paracoccus, Atopobium, Bifidobacterium, Coprococcus, Oridobacteriu, Peptococcus, Oscillospira and Akkermansia) was feasible, and revealed novel phylotypes associated with periodontitis. Of note, a major microbial community alteration was evident in smoker patients, suggesting an association between smoking and severity of subgingival dysbiosis. The present study confirmed that chronic periodontitis is a polymicrobial disease where changes in the equilibrium of subgingival microbiota contribute to severity of pathology.

Smoking and inflammation: evidence for a synergistic role in chronic disease

Tobacco smoking is the most important preventable risk factor for periodontitis; however, the underlying biological mechanisms responsible for the detrimental effects of smoking on periodontal health remain largely unclear. It is also well established that smoking has a negative impact on several inflammatory diseases, including rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease. The aim of this paper was to review smoking-related changes in local and systemic host responses with a focus on cellular and molecular effects that could explain a hyperinflammatory response leading to periodontal destruction. Biological mechanisms that may be common to periodontal disease and other chronic inflammatory diseases were also explored, together with gene-smoking interactions. An epidemiologic perspective on the burden of smoking on periodontal health and the potential for smoking cessation is also presented. Tobacco smoking seems to induce changes ranging from decreased leukocyte chemotaxis to decreased production of immunoglobulins. Smoking also seems to cause a stronger inflammatory reaction with an increased release of potentially tissue-destructive substances (e.g. reactive oxygen species, collagenase, serine proteases and proinflammatory cytokines). These findings support a hypothesis that periodontitis is a hyperinflammatory condition rather than a hypo-inflammatory condition.

Should Antibiotics Be Prescribed to Treat Chronic Periodontitis?

Although scaling and root planing is a cost-effective approach for initial treatment of chronic periodontitis, it fails to eliminate subgingival pathogens and halt progressive attachment loss in some patients. Adjunctive use of systemic antibiotics immediately after completion of scaling and root planing can enhance the degree of clinical attachment gain and probing depth reduction provided by nonsurgical periodontal treatment. This article discusses the rationale for prescribing adjunctive antibiotics, reviews the evidence for their effectiveness, and outlines practical issues that should be considered before prescribing antibiotics to treat chronic periodontitis.

Cigarette smoke condensate inhibits collagen gel contraction and prostaglandin E2 production in human gingival fibroblasts

BACKGROUND

Granulation tissue remodeling and myofibroblastic differentiation are critically important events during wound healing. Tobacco smoking has a detrimental effect in gingival tissue repair. However, studies evaluating the effects of cigarette smoke on these events are lacking.

MATERIAL AND METHODS

We used gingival fibroblasts cultured within free-floating and restrained collagen gels to simulate the initial and final steps of the granulation tissue phase during tissue repair. Collagen gel contraction was stimulated with serum or transforming growth factor-β1. Cigarette smoke condensate (CSC) was used to evaluate the effects of tobacco smoke on gel contraction. Protein levels of alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor were evaluated through Western blot. Prostaglandin E(2) (PGE(2)) levels were determined through ELISA. Actin organization was evaluated through confocal microscopy.

RESULTS

CSC reduced collagen gel contraction induced by serum and transforming growth factor-β1 in restrained collagen gels. CSC also altered the development of actin stress fibers in fibroblasts cultured within restrained collagen gels. PGE(2) levels were strongly diminished by CSC in three-dimensional cell cultures. However, other proteins involved in granulation tissue remodeling and myofibroblastic differentiation such as alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor, were unmodified by CSC.

CONCLUSIONS

CSC may alter the capacity of gingival fibroblasts to remodel and contract a collagen matrix. Inhibition of PGE(2) production and alterations of actin stress fibers in these cells may impair proper tissue maturation during wound healing in smokers.

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.

Subgingival bacterial recolonization after scaling and root planing in smokers with chronic periodontitis

BACKGROUND

The aim of this study was to compare subgingival bacterial recolonization patterns after scaling and root planing in current smokers and non-smokers.

METHODS

15 smokers and 15 non-smokers with chronic periodontitis received scaling and root planing in six visits lasting one hour each, over a period of 21 days. Clinical monitoring was performed at baseline and 180 days, and microbiological monitoring was performed at baseline, immediately after scaling and root planing (Day 0) and at 42, 63 and 180 days post-therapy. Subgingival plaque samples were analysed by checkerboard DNA-DNA hybridization.

RESULTS

An improvement in clinical condition was observed for smokers and non-smokers; however, non-smokers showed a greater reduction in mean clinical attachment level in intermediate sites in comparison with smokers (p < 0.05). At Day 0, there was a significant reduction in the mean counts of the three pathogens from the red complex, Eubacterium nodatum and Parvimonas micra only in non-smokers (p < 0.05). There was a significant increase in the proportion of host-compatible species in non-smokers and smokers from baseline to 180 days post-therapy (p < 0.05). However, a significant decrease in the pathogenic species was observed only in non-smokers.

CONCLUSIONS

Smokers were more susceptible to the re-establishment of a pathogenic subgingival biofilm than non-smokers.

Subgingival microbiota in health compared to periodontitis and the influence of smoking

The etiology of periodontitis has traditionally been associated to a consortium of three bacterial species—the so-called “red-complex” of periodontal disease—which has been the target for most diagnostic and therapeutic strategies. However, other species have also been found to correlate with disease severity. In addition, the influence of smoking on periodontal microbiota is poorly understood. In the current manuscript, the composition of the subgingival microbiota in healthy individuals vs. patients with chronic periodontitis has been investigated using 16S pyrosequencing and the influence of smoking on periodontal composition has been examined. Subgingival bacterial communities were sampled from 82 patients: 22 non-smoking healthy controls, 28 non-smoking periodontal patients, and 32 smoking periodontal patients. Bacterial diversity was higher in periodontal patients than in healthy subjects, which could be interpreted as the consequence of a nutritionally richer environment or a reduced immune competence. Periodontal patients showed a significantly higher prevalence/relative abundance of “established” periopathogens but also other taxa whose role is not well-established and that should be targets for future research. These include Anaeroglobus, Bulleidia, Desulfobulbus, Filifactor, Mogibacterium, Phocaeicola, Schwartzia or TM7. The microbial community of smoking-associated periodontitis is less diverse and distinct from that of non-smokers, indicating that smoking has an influence on periodontal ecology. Interestingly, the high sequencing coverage allowed the detection at low proportions of periodontal pathogens in all healthy individuals, indicating that chronic periodontitis cannot be strictly considered an infectious disease but the outcome of a polymicrobial dysbiosis, where changes in the proportions of microbial consortia trigger the inflammatory and tissue-degradation responses of the host.

Subgingival microbiome in smokers and non-smokers in Korean chronic periodontitis patients

Smoking is a major environmental factor associated with periodontal diseases. However, we still have a very limited understanding of the relationship between smoking and subgingival microflora in the global population. Here, we investigated the composition of subgingival bacterial communities from the pooled plaque samples of smokers and non-smokers, 134 samples in each group, in Korean patients with moderate chronic periodontitis using 16S rRNA gene-based pyrosequencing. A total of 17,927 reads were analyzed and classified into 12 phyla, 126 genera, and 394 species. Differences in bacterial communities between smokers and non-smokers were examined at all phylogenetic levels. The genera Fusobacterium, Fretibacterium, Streptococcus, Veillonella, Corynebacterium, TM7, and Filifactor were abundant in smokers. On the other hand, Prevotella, Campylobacter, Aggregatibacter, Veillonellaceae GQ422718, Haemophilus, and Prevotellaceae were less abundant in smokers. Among species-level taxa occupying > 1% of whole subgingival microbiome of smokers, higher abundance (≥ 2.0-fold compared to non-smokers) of seven species or operational taxonomic units (OTUs) was found: Fusobacterium nucleatum, Neisseria sicca, Neisseria oralis, Corynebacterium matruchotii, Veillonella dispar, Filifactor alocis, and Fretibacterium AY349371. On the other hand, lower abundance of 11 species or OTUs was found in smokers: Neisseria elongata, six Prevotella species or OTUs, Fusobacterium canifelinum, Aggregatibacter AM420165, Selenomonas OTU, and Veillonellaceae GU470897. Species richness and evenness were similar between the groups whereas diversity was greater in smokers than non-smokers. Collectively, the results of the present study indicate that differences exist in the subgingival bacterial community between smoker and non-smoker patients with chronic moderate periodontitis in Korea, suggesting that cigarette smoking considerably affects subgingival bacterial ecology.

Changes in water sorption and solubility of dental adhesive systems after cigarette smoke

Aim. To evaluate the effect of cigarette smoke on water sorption and solubility of four adhesive systems. Materials and Methods. Sixteen disks of each adhesive system were prepared (Adper Scotchbond Multipurpose Adhesive (SA); Adper Scotchbond Multipurpose Adhesive System (Adhesive + Primer) (SAP); Adper Single Bond Plus (SB); Adper Easy One (EO)). Specimens were desiccated until a constant mass was obtained and divided into two groups (n = 8). One-half of the specimens were immersed in deionized water, while the other half were also immersed, but with daily exposure to tobacco smoke. After 21 days, disks were measured again and stored in desiccators until constant mass was achieved. Data were calculated according to ISO specifications and statistically analyzed. Results. The tobacco smoke only significantly affected the water sorption and solubility of EO. There were significant differences in both analyses among materials tested. The SB exhibited the highest water sorption, followed by EO, which demonstrated significantly higher solubility values than SB. The SA and SAP showed low water sorption and solubility, and there were no significant differences between the two. Conclusion. Regardless of smoke exposure, both simplified adhesive systems presented an inferior performance that could be related to the complex mixture of components in such versions.

Subgingival microbiome in smokers and non-smokers in periodontitis: an exploratory study using traditional targeted techniques and a next-generation sequencing

AIM

To compare the results of two targeted techniques to an open-ended technique in periodontitis patients, differentiated on the basis of smoking habit.

MATERIALS & METHODS

Thirty periodontitis patients (15 smokers and 15 non-smokers) provided subgingival plaque samples for 16S rRNA gene amplicon sequencing, culturing and quantitative polymerase chain reaction (qPCR).

RESULTS

No differences were found in the composition of the subgingival microbiome between smokers and non-smokers with culture and qPCR. With pyrosequencing, operational taxonomic units (OTUs) classified to genera Fusobacterium, Prevotella and Selenomonas were more abundant in smokers, while OTUs belonging to the genera Peptococcus and Capnocytophaga were more abundant in non-smokers. Principal coordinate analysis identified two clusters; one was composed mainly of smokers (80%) and revealed significantly lower taxonomic diversity, higher attachment loss and higher proportion of the genera Fusobacterium, Paludibacter and Desulfobubus.

CONCLUSION

In periodontitis, there is a difference in the composition of the subgingival microbiome between smokers and non-smokers, as revealed by pyrosequencing. This difference was not identified by the targeted techniques. Low taxonomic diversity was associated with higher disease severity, especially in smokers. This supports the hypothesis of the ecological microbial-host interaction in the severity of periodontal disease.

Microbiological basis for periodontal therapy

The search for the etiologic agents of periodontal diseases started in the Golden Era of medical bacteriology, when the etiologic agents of many bacterial infections were isolated and characterized. After the initial enthusiasm in establishing the infectious nature and the true agents of periodontal diseases, this concept was virtually ignored for the next four decades. Until the early 1970s treatment regimens based on the non-specific plaque hypothesis were directed towards a non-specific reduction in plaque amount. Later, the specific plaque hypothesis established the role of some microorganisms such as A. actinomycetemcomitans, P. gingivalis, T. forsythensis, T. denticola, P. intermedia and F. nucleatum in different forms of periodontal diseases. It was recently suggested that these suspected periodontal pathogens seem to not act alone and interactions between species, especially the balance between pathogenic and beneficial species affect both progression of disease and response of tissues to periodontal therapy. Nowadays it is well established that one of the goals of therapy is to control such periodontal pathogens. Among the most commonly used therapies to treat periodontal infections are scaling and root planing (SRP), supragingival plaque control and periodontal surgeries. Many studies confirmed the reduction of "red complex" species by SRP, and apically repositioned flap can lead to an additional beneficial effect in the subgingival microbiota by decreasing levels of "red" and "orange complexes" species. Furthermore, the level of plaque control maintained by the patients has been considered a crucial step in preventing recurrence of destructive periodontitis.

Effects of cigarette smoke and nicotine on cell viability, migration and myofibroblastic differentiation

BACKGROUND AND OBJECTIVE

Several studies have analysed the role of nicotine as a prominent agent affecting wound repair in smokers. However, tobacco smoke contains several components that may alter gingival wound healing. The present study aimed to analyse the roles of cigarette smoke condensate (CSC) and nicotine on cell viability, cell migration/invasion and myofibroblastic differentiation using primary cultures of human gingival fibroblasts.

MATERIAL AND METHODS

To compare the effects of CSC and nicotine, gingival fibroblasts were stimulated with CSC (0.4–500 lg/mL) and the corresponding nicotine concentrations (0.025–32 lg/mL) present in research cigarettes (1R3F). Cell viability was evaluated through the MTS assay. Cell migration and invasion were assessed through scratch wound assays, collagen nested matrices and trans well migration. a-Smooth muscle actin production was evaluated by western blotting.

RESULTS

Cigarette smoke condensate at 50 lg/mL induced a moderate increase in cell viability, whereas the corresponding nicotine concentration (3.2 lg/mL) did not produce this response. Cigarette smoke condensate at 250 lg/mL, but not nicotine at 16 lg/mL (the corresponding nicotine concentration), induced cell death. Both nicotine and CSC stimulated cell migration (50 lg/mL CSC; 3.2 lg/mL nicotine). At 150 lg/mL, CSC inhibited cell migration; however, the corresponding concentration of nicotine (9.6 lg/mL), did not have this effect. Although both nicotine and CSC inhibited a-smooth muscle actin production, only the latter induced a statistically significant effect on this response.

CONCLUSION

Cigarette smoke condensate may stimulate cell survival and migration at low concentrations and inhibit these cell responses at higher levels of exposure. Moreover, CSC may interfere in myofibroblastic differentiation.These results show that cigarette smoke, but not nicotine, may significantly alter cell viability, cell migration and myofibroblastic differentiation in gingival mesenchymal cells.

Er:YAG laser in the treatment of periodontal sites with recurring chronic inflammation: a 12-month randomized, controlled clinical trial

AIM

The objective of this randomized, controlled clinical trial was to compare the clinical and microbiological effects of pocket debridement using erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser with conventional debridement in maintenance patients.

MATERIAL & METHODS

Fifteen patients, all smokers, having at least four teeth with residual probing depth (PD) ≥ 5 mm were recruited. Two pockets in two jaw quadrants were randomly assigned to subgingival debridement using an Er:YAG laser (test) or ultrasonic scaler/curette (control) at 3-month intervals. Relative attachment level (RAL), PD, bleeding on probing and dental plaque were recorded at baseline and at 6 and 12 months. Microbiological subgingival samples were taken at the same time points and analysed using a checkerboard DNA-DNA hybridization technique.

RESULTS

A significant decrease in PD took place in both treatments from baseline to 12 months (p < 0.01). In the control, the mean initial PD decreased from 5.4 to 4.0 mm at 12 months. For the test, a similar decrease occurred. No significant between-treatment differences were shown at any time point. The mean RAL showed no overall significant inter- or intra-treatment differences (p > 0.05). No significant between-treatment differences were observed in subgingival microbiological composition or total pathogens.

CONCLUSION

The results failed to support that an Er:YAG laser may be superior to conventional debridement in the treatment of smokers with recurring chronic inflammation. This appears to be the first time that repeated Er-YAG laser instrumentation has been compared with mechanical instrumentation of periodontal sites with recurring chronic inflammation over a clinically relevant time period.

Periodontal status in smokers and nonsmokers: a clinical, microbiological, and histopathological study

A case-control study was done to assess the influence of smoking on clinical, microbiological, and histopathological parameters. Methods. Two hundred dentate male patients (100 smokers and 100 nonsmokers) ranging between 25 and 50 years were enrolled in the study. Periodontal parameters were recorded. Plaque samples were collected for microbial analysis for BANA test. Gingival biopsies were obtained from selected site for assessing histopathological changes. Results. Both groups showed almost similar plaque levels (P=0.258), but smokers had reduced gingival (0.62 ± 0.31) and bleeding indices (28.53 ± 17.52) and an increased calculus index (1.62 ± 0.36). Smokers had an increased probing depth of 4-7 mm (P=0.009) and overall increased CAL. No difference in microbiota was found between the two groups. Histopathologically smokers showed a decreased blood vessel density (8.84 ± 0.96) and inflammatory cells (52.00 ± 9.79). Conclusions. It is quite possible that many of the pathogenic mechanisms involved in tissue degradation in periodontitis in smokers could be quite different from those in nonsmokers.

Effects of nicotine on the growth and protein expression of Porphyromonas gingivalis

Tobacco smoking is considered one of the most significant environmental risk factors for destructive periodontal disease. The effect of smoking on periodontopathic microbiota has not yet been elucidated, as previous studies failed to identify a concrete relationship between periodontopathic microorganisms and smoking. However, it is likely that smoking, as an environmental stress factor, may affect the behavior of dental plaque microorganisms, ultimately leading to alteration of the host-parasite interaction. The goal of this study was to examine the effect of nicotine, a major component of tobacco, on the growth and protein expression of the crucial periodontal pathogen Porphyromonas gingivalis. The growth of P. gingivalis 381 was measured after bacterial cells were cultivated in liquid broth containing various nicotine concentrations. First, P. gingivalis cells were allowed to grow in the presence of a single dose of nicotine (the single exposure protocol) at 0, 1, 2, 4, and 8 mg/L, respectively. Second, P. gingivalis cells were exposed to five consecutive doses of nicotine (the multiple exposure protocol) at 0, 1, 2, and 4 mg/L, respectively. Bacterial growth was measured by optical density and protein expression was analyzed by SDS-PAGE and 2-D gel electrophoresis. In the single nicotine exposure protocol, it was observed that the growth of P. gingivalis 381 was inhibited by nicotine in a dose-dependent manner. In the multiple nicotine exposure protocol, the growth rate of P. gingivalis increased with each subsequent nicotine exposure, even though bacterial growth was also inhibited in a dose dependent fashion. SDS-PAGE and 2-D gel electrophoresis analyses revealed a minor change in the pattern of protein expression, showing differences in proteins with low molecular weights (around 20 kDa) on exposure to nicotine. The results of this study suggest that nicotine exerts an inhibitory effect on the growth of P. gingivalis, and has a potential to modulate protein expression in P. gingivalis.

Impact of supragingival therapy on subgingival microbial profile in smokers versus non-smokers with severe chronic periodontitis

BACKGROUND

The aim of this study was to assess subgingival microbiological changes in smokers versus non-smokers presenting severe chronic periodontitis after supragingival periodontal therapy (ST).

METHODS

Non-smokers (n=10) and smokers (n=10) presenting at least nine teeth with probing pocket depth (PPD) (≥5 mm), bleeding on probing (BoP), and no history of periodontal treatment in the last 6 months were selected. Clinical parameters assessed were plaque index (PI), BoP, PPD, relative gingival margin position (rGMP) and relative clinical attachment level (rCAL). Subgingival biofilm was collected before and 21 days after ST. DNA was extracted and the 16S rRNA gene was amplified with the universal primer pair, 27F and 1492R. Amplified genes were cloned, sequenced, and identified by comparison with known 16S rRNA sequences. Statistical analysis was performed by Student's t and Chi-Square tests (α=5%).

RESULTS

Clinically, ST promoted a significant reduction in PI and PPD, and gain of rCAL for both groups, with no significant intergroup difference. Microbiologically, at baseline, data analysis demonstrated that smokers harbored a higher proportion of Porphyromonas endodontalis, Bacteroidetes sp., Fusobacterium sp. and Tannerella forsythia and a lower number of cultivated phylotypes (p<0.05). Furthermore, non-smokers featured significant reductions in key phylotypes associated with periodontitis, whereas smokers presented more modest changes.

CONCLUSION

Within the limits of the present study, ST promoted comparable clinical improvements in smokers and non-smokers with severe chronic periodontitis. However, in smokers, ST only slightly affected the subgingival biofilm biodiversity, as compared with non-smokers.

Periodontitis-associated risk factors in pregnant women

OBJECTIVE

The main objective of this study was to investigate the risk factors associated with periodontitis in pregnant women.

METHODS

This study was conducted in two stages. In Stage 1, a cross-sectional study was conducted to determine the prevalence of periodontitis among 810 women treated at the maternity ward of a university hospital. In Stage 2, the factors associated with periodontitis were investigated in two groups of pregnant women: 90 with periodontitis and 720 without. A hierarchized approach to the evaluation of the risk factors was used in the analysis, and the independent variables related to periodontitis were grouped into two levels: 1) socio-demographic variables; 2a) variables related to nutritional status, smoking, and number of pregnancies; and 2b) variables related to oral hygiene. Periodontitis was defined as a probing depth ≥ 4 mm and an attachment loss ≥ 3 mm at the same site in four or more teeth. A logistic regression analysis was also performed.

RESULTS

The prevalence of periodontitis in this sample was 11%. The variables that remained in the final multivariate model with the hierarchized approach were schooling, family income, smoking, body mass index, and bacterial plaque.

CONCLUSION

The factors identified underscore the social nature of the disease, as periodontitis was associated with socioeconomic, demographic status, and poor oral hygiene.

Tobacco smoking affects bacterial acquisition and colonization in oral biofilms

Recent evidence suggests that smoking affects the composition of the disease-associated subgingival biofilm, yet little is known about its effects during the formation of this biofilm. The present investigation was undertaken to examine the contributions of smoking to the composition and proinflammatory characteristics of the biofilm during de novo plaque formation. Marginal and subgingival plaque and gingival crevicular fluid samples were collected from 15 current smokers and from 15 individuals who had never smoked (nonsmokers) following 1, 2, 4, and 7 days of undisturbed plaque formation. 16S rRNA gene cloning and sequencing were used for bacterial identification, and multiplex bead-based flow cytometry was used to quantify the levels of 27 immune mediators. Smokers demonstrated a highly diverse, relatively unstable initial colonization of both marginal and subgingival biofilms, with lower niche saturation than that seen in nonsmokers. Periodontal pathogens belonging to the genera Fusobacterium, Cardiobacterium, Synergistes, and Selenomonas, as well as respiratory pathogens belonging to the genera Haemophilus and Pseudomonas, colonized the early biofilms of smokers and continued to persist over the observation period, suggesting that smoking favors early acquisition and colonization of pathogens in oral biofilms. Smokers also demonstrated an early proinflammatory response to this colonization, which persisted over 7 days. Further, a positive correlation between proinflammatory cytokine levels and commensal bacteria was observed in smokers but not in nonsmokers. Taken together, the data suggest that smoking influences both the composition of the nascent biofilm and the host response to this colonization.

Subgingival microbial profiles of smokers with periodontitis

The subgingival microbiome is largely uncultivated, and therefore, cultivation-based and targeted molecular approaches have limited value in examining the effect of smoking on this community. We tested the hypothesis that the subgingival biofilm is compositionally different in current and never-smokers by using an open-ended molecular approach for bacterial identification. Subgingival plaque from deep sites of current and never-smokers matched for disease was analyzed by 16S sequencing. Smokers demonstrated greater abundance of Parvimonas, Fusobacterium, Campylobacter, Bacteroides, and Treponema and lower levels of Veillonella, Neisseria, and Streptococcus. Several uncultivated Peptostreptococci, Parvimonas micra, Campylobacter gracilis, Treponema socranskii, Dialister pneumosintes, and Tannerella forsythia were elevated in this group, while Veillonella sp. oral clone B2, Neisseria sp. oral clone 2.24, Streptococcus sanguinis, and Capnocytophaga sp. clone AH015 were at lower levels. The microbial profile of smoking-associated periodontitis is distinct from that of non-smokers, with significant differences in the prevalence and abundance of disease-associated and health-compatible organisms.

Epithelial cell pro-inflammatory cytokine response differs across dental plaque bacterial species

AIM

The dental plaque is comprised of numerous bacterial species, which may or may not be pathogenic. Human gingival epithelial cells (HGECs) respond to perturbation by various bacteria of the dental plaque by production of different levels of inflammatory cytokines, which is a putative reflection of their virulence. The aim of the current study was to determine responses in terms of interleukin (IL)-1beta, IL-6, IL-8 and IL-10 secretion induced by Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus gordonii in order to gauge their virulence potential.

MATERIALS AND METHODS

HGECs were challenged with the four bacterial species, live or heat killed, at various multiplicity of infections and the elicited IL-1beta, IL-6, IL-8 and IL-10 responses were assayed by enzyme-linked immunosorbent assay.

RESULTS

Primary HGECs challenged with live P. gingivalis produced high levels of IL-1beta, while challenge with live A. actinomycetemcomitans gave high levels of IL-8. The opportunistic pathogen F. nucleatum induces the highest levels of pro-inflammatory cytokines, while the commensal S. gordonii is the least stimulatory.

CONCLUSION

We conclude that various dental plaque biofilm bacteria induce different cytokine response profiles in primary HGECs that may reflect their individual virulence or commensal status.

In vitro evaluation of the effect of nicotine, cotinine, and caffeine on oral microorganisms

The aim of this in vitro study was to evaluate the effects of nicotine, cotinine, and caffeine on the viability of some oral bacterial species. It also evaluated the ability of these bacteria to metabolize those substances. Single-species biofilms of Streptococcus gordonii, Porphyromonas gingivalis, or Fusobacterium nucleatum and dual-species biofilms of S. gordonii -- F. nucleatum and F. nucleatum -- P. gingivalis were grown on hydroxyapatite discs. Seven species were studied as planktonic cells, including Streptococcus oralis, Streptococcus mitis, Propionibacterium acnes, Actinomyces naeslundii, and the species mentioned above. The viability of planktonic cells and biofilms was analyzed by susceptibility tests and time-kill assays, respectively, against different concentrations of nicotine, cotinine, and caffeine. High-performance liquid chromatography was performed to quantify nicotine, cotinine, and caffeine concentrations in the culture media after the assays. Susceptibility tests and viability assays showed that nicotine, cotinine, and caffeine cannot reduce or stimulate bacterial growth. High-performance liquid chromatography results showed that nicotine, cotinine, and caffeine concentrations were not altered after bacteria exposure. These findings indicate that nicotine, cotinine, and caffeine, in the concentrations used, cannot affect significantly the growth of these oral bacterial strains. Moreover, these species do not seem to metabolize these substances.