Impact of smoking on experimental gingivitis. A clinical, microbiological and immunological prospective study

Smoking and osteoimmunology: Understanding the interplay between bone metabolism and immune homeostasis

Smoking continues to pose a global threat to morbidity and mortality in populations. The detrimental impact of smoking on health and disease includes bone destruction and immune disruption in various diseases. Osteoimmunology, which explores the communication between bone metabolism and immune homeostasis, aims to reveal the interaction between the osteoimmune systems in disease development. Smoking impairs the differentiation of mesenchymal stem cells and osteoblasts in bone formation while promoting osteoclast differentiation in bone resorption. Furthermore, smoking stimulates the Th17 response to increase inflammatory and osteoclastogenic cytokines that promote the receptor activator of NF-κB ligand (RANKL) signaling in osteoclasts, thus exacerbating bone destruction in periodontitis and rheumatoid arthritis. The pro-inflammatory role of smoking is also evident in delayed bone fracture healing and osteoarthritis development. The osteoimmunological therapies are promising in treating periodontitis and rheumatoid arthritis, but further research is still required to block the smoking-induced aggravation in these diseases.

Translational potential

This review summarizes the adverse effect of smoking on mesenchymal stem cells, osteoblasts, and osteoclasts and elucidates the smoking-induced exacerbation of periodontitis, rheumatoid arthritis, bone fracture healing, and osteoarthritis from an osteoimmune perspective. We also propose the therapeutic potential of osteoimmunological therapies for bone destruction aggravated by smoking.

Tobacco-enhanced biofilm formation by Porphyromonas gingivalis and other oral microbes

Microbial biofilms promote pathogenesis by disguising antigens, facilitating immune evasion, providing protection against antibiotics and other antimicrobials and, generally, fostering survival and persistence. Environmental fluxes are known to influence biofilm formation and composition, with recent data suggesting that tobacco and tobacco-derived stimuli are particularly important mediators of biofilm initiation and development in vitro and determinants of polymicrobial communities in vivo. The evidence for tobacco-augmented biofilm formation by oral bacteria, tobacco-induced oral dysbiosis, tobacco-resistance strategies, and bacterial physiology is summarized herein. A general overview is provided alongside specific insights gained through studies of the model and archetypal, anaerobic, Gram-negative oral pathobiont, Porphyromonas gingivalis.

The Impact of Smoking on Peri-implant Microbiota: A Systematic Review

OBJECTIVES

Peri-implantitis is associated with bacterial plaque biofilms and with patients who have a history of periodontitis. Smoking is a risk factor for periodontitis, but the relationship between smoking and peri-implantitis is unclear. The aim of this systematic review was to assess evidence ascertaining the relationship between smoking and peri-implant microbiota.

DATA SOURCES

An electronic search was conducted in the MEDLINE/PubMed, Embase and Scopus® databases in duplicate up to January 2023 without language restrictions. Studies were considered eligible for inclusion if they involved evaluation of the peri-implant microbiota of smokers and nonsmokers. Methodological quality was assessed with the adapted Newcastle-Ottawa scale.

STUDY SELECTION

Fourteen studies were identified for inclusion in the present study, and 85.7% of the studies were defined as medium to high methodological quality. Overall, the evidence presented in this review was limited to medium to high methodological quality. The data indicates that significantly higher frequencies of anaerobic pathogens are detectable in healthy peri-implant tissues of smokers. A lower diversity of microbiota was observed in healthy peri-implant sites of smokers. In the transition from clinically healthy to a diseased status, smoking shaped a reduced peri-implant microbiota by depleting commensal and enriching pathogenic species.

CONCLUSIONS

The composition of peri-implant microbiota may be influenced by smoking. More studies are needed to determine the impact of smoking on peri-implant microbiota.

CLINICAL SIGNIFICANCE

In the transition from clinically healthy to a diseased status, smoking shaped a reduced peri-implant microbiota by depleting commensal and enriching pathogenic species. The composition of peri-implant microbiota may be influenced by smoking.

Smoking Cessation on Periodontal and Peri-Implant Health Status: A Systematic Review

Since smoking is considered among the main risk factors for the onset and progression of periodontitis and peri-implantitis, the present systematic review aimed to evaluate the effect of smoking cessation on clinical, radiographic, and gingival crevicular periodontal parameters around natural teeth and dental implants in ex-smokers compared to current and non-smokers. The study protocol was developed based on the PRISMA guidelines, the research question was formulated according to the PICO model, and the literature search was conducted through PubMed/MEDLINE, Cochrane library, and BioMed Central databases. From the 916 title/abstracts initially identified, seven articles were included in the present systematic review and assessed for quality through the ROBINS-I tool. Reported findings on clinical and crevicular periodontal parameters around natural teeth were contrasting when comparing ex-smokers to current and non-smokers; thus, individualized recommendations for previous smoker periodontal patients are currently lacking. No data on radiographic parameters were retrieved. Similarly, data on periodontal parameters around dental implants were not available, highlighting the need for focused investigations assessing the role of both smoking habit and cessation on peri-implant health status and responsiveness to treatment.

Changes in gingivitis and protective factors among adults: A 4-year prospective population-based study

OBJECTIVES

There are limited longitudinal data regarding gingival inflammation in adults. This study aimed to assess changes in gingivitis over 4 years and to determine protective factors.

METHODS

A representative sample of 1023 adults living in Porto Alegre, Brazil, was obtained in the Caries-Perio Collaboration Study. At follow-up, 402 individuals were re-examined. Gingivitis was assessed by the gingival bleeding index (GB) at both time points. Individuals were dichotomized into those showing reductions ≥ 15% and those showing reductions < 15% or increase in bleeding sites. Multivariable Poisson regression models were fitted with 11 possible risk factors, estimating relative risks (RR) and 95% confidence intervals (95% CI).

RESULTS

Percentage of individuals with GB ≥ 10% reduced from 72.4% to 53.8%. Bleeding sites significantly reduced (25.9%-20.1%), and in a higher magnitude in buccal/palatal sites (34.1%-24.0%). 31.0% of individuals presented GB reduction ≥ 15% in all sites. Toothbrushing ≥ 3 times/d increased 72% the probability of ≥15% GB reduction compared with ≤1/d (RR = 1.72; 95% CI 1.01-3.16). For each 10 pack-years smoked, the probability of ≥15% GB reduction was 3% higher (RR = 1.03; 95% CI: 1.01-1.04). At buccal/palatal sites, normal weight individuals had 26% higher probability of reducing GB than overweight-obese individuals (RR = 1.26; 95% CI: 1.01-1.62). A 5% higher decrease in GB sites was observed in the absence than the presence of periodontitis. Younger individuals had higher reduction in GB sites.

CONCLUSIONS

In the studied population, gingivitis reduced over time, with younger age, better oral hygiene, absence of periodontitis and normal weight being found to be protective factors. Smoking was associated with lower levels of gingivitis over time, probably due to its vasoconstrictive effect.

Effects of smoking on the gingival crevicular fluid levels of interleukin-17A, interleukin-17E, and oxidative stress following periodontal treatment process

OBJECTIVE AND BACKGROUND

How smoking affects periodontal inflammation and healing still needs to be revealed with all its mechanisms. In this study, the gingival crevicular fluid (GCF) levels of: (a) interleukin-17A (IL-17A) and interleukin-17E(IL-17E) with their ratios and (b) oxidative stress by means of total oxidative stress (TOS), total anti-oxidant capacity (TAOC), and their ratios as the oxidative stress index (OSI) were evaluated and compared for smoking and non-smoking periodontitis patients after a periodontitis management process including both the non-surgical and surgical treatments.

MATERIALS AND METHODS

Fifteen smoker and 15 non-smoker generalized periodontitis patients as 2 distinct groups participated in the study. Conventional clinical and radiographical examinations were utilized for the periodontitis diagnosis. The clinical data and GCF samples were collected at baseline, 4 week after non-surgical periodontal treatment (NSPT), and 4 weeks after surgical periodontal treatment (SPT). IL-17A, IL-17E, TOS, and TAOC were determined by ELISA and Rel Assay.

RESULTS

Clinical parameters in both smokers and non-smokers improved following periodontal treatment (P < .001) and their clinical data were similar for all the examination times (baseline, NSPT, and SPT) (P > .05). Following the treatment phases, the IL-17A concentration decreased and the IL-17E concentration increased in both the smokers and non-smokers (P < .01). The total amount of IL-17A decreased while the total amount of IL-17E increased in smokers throughout NSPT and SPT (P < .01). Such an alteration was seen only at SPT compared to NSPT and baseline in non-smokers (P < .01). The concentration and total amount of IL-17A were higher at baseline, and the concentration and total amount of IL-17E were lower at all examination time points in non-smokers as compared to smokers (P < .01). The 17A/E ratio decreased in both groups following the treatment phases and was higher in smokers at all the examination times (P < .01). TOS were higher and TAOC were lower in smokers versus non-smokers at all the time points, but the differences were significant only for TOS levels (P < .01). Throughout the treatment phases, the concentration and total amount of TOS decreased in smokers(P < .01) and only the total amount of TOS decreased in non-smokers (P < .01). The concentration and total amounts of TAOC increased throughout the treatments in both smokers and non-smokers without significant changes (P > .05). The baseline OSI was higher in smokers, and it decreased only in smokers following the treatment phases (P < .01).

CONCLUSIONS

Smoking and periodontal inflammation were found to alter IL-17A, IL-17E, and oxidant/anti-oxidant statuses in periodontitis patients. The intra-group assessments in smokers demonstrated more apparent alterations in the oxidant/anti-oxidant statuses and IL-17A and IL-17E levels after periodontitis management.

Respective Effects of Oral Hygiene Instructions and Periodontal Nonsurgical Treatment (Debridement) on Clinical Parameters and Patient-Reported Outcome Measures with Respect to Smoking

BACKGROUND

Oral hygiene instructions (OHI) and periodontal nonsurgical treatment (PNST) play pivotal roles in the management of periodontitis. The study aims to discern their respective effects on periodontal clinical parameters and patient-reported outcome measures (PROMs).

METHODS

Ninety-one patients were included, 34 non-smokers (NS), 25 former smokers (FS) and 32 current smoker (CS). Clinical parameters such as probing depth (PD) and bleeding on probing (BOP) were collected, and the periodontal inflamed tissue area (PISA) was calculated. Clinical parameters and PROMs were recorded before and after receiving OHI, with electronic tooth brush and interdental brushes, as well as 3 months after debridement.

RESULTS

Smokers presented a significantly higher proportion of severe periodontitis (64.7%) with generalized extension (76.5%) and with a rapid rate of progression (97.1%) compared to NS and FS. OHI led to a significant decrease of PD, BOP, and PISA (p < 0.0001) only in NS and FS. Debridement reduced PD and the percentage of PD >6 mm in all groups (p < 0.0001). OHI induced significant improvement of oral hygiene, frequency of interdental cleaning, and PROMs (p < 0.0001). Further debridement induced significant additional improvement PROMs in FS and NS (p < 0.0001).

CONCLUSION

OHI and debridement improved periodontal clinical parameters and PROMs in both NS and FS. Former smokers had comparable outcomes to non-smokers, suggesting that smoking cessation should be encouraged.

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.

Dental plaque-induced gingival conditions

OBJECTIVE

This review proposes revisions to the current classification system for gingival diseases and provides a rationale for how it differs from the 1999 classification system.

IMPORTANCE

Gingival inflammation in response to bacterial plaque accumulation (microbial biofilms) is considered the key risk factor for the onset of periodontitis. Thus, control of gingival inflammation is essential for the primary prevention of periodontitis.

FINDINGS

The clinical characteristics common to dental plaque-induced inflammatory gingival conditions include: a) clinical signs and symptoms of inflammation that are confined to the gingiva: b) reversibility of the inflammation by removing or disrupting the biofilm; c) the presence of a high bacterial plaque burden to initiate the inflammation; d) systemic modifying factors (e.g., hormones, systemic disorders, drugs) which can alter the severity of the plaque-induced inflammation and; e) stable (i.e., non-changing) attachment levels on a periodontium which may or may not have experienced a loss of attachment or alveolar bone. The simplified taxonomy of gingival conditions includes: 1) introduction of the term "incipient gingivitis;" 2) a description of the extent and severity of gingival inflammation; 3) a description of the extent and severity of gingival enlargement and; 4) a reduction of categories in the dental plaque-induced gingival disease taxonomy.

CONCLUSIONS

Dental plaque-induced gingival inflammation is modified by various systemic and oral factors. The appropriate intervention is crucial for the prevention of periodontitis.

Plaque-induced gingivitis: Case definition and diagnostic considerations

OBJECTIVE

Clinical gingival inflammation is a well-defined site-specific condition for which several measurement systems have been proposed and validated, and epidemiological studies consistently indicate its high prevalence globally. However, it is clear that defining and grading a gingival inflammatory condition at a site level (i.e. a "gingivitis site") is completely different from defining and grading a "gingivitis case" (GC) (i.e. a patient affected by gingivitis), and that a "gingivitis site" does not necessarily mean a "GC". The purpose of the present review is to summarize the evidence on clinical, biochemical, microbiologic, genetic markers as well as symptoms associated with plaque-induced gingivitis and to propose a set of criteria to define GC.

IMPORTANCE

A universally accepted case definition for gingivitis would provide the necessary information to enable oral health professionals to assess the effectiveness of their prevention strategies and treatment regimens; help set priorities for therapeutic actions/programs by health care providers; and undertake surveillance.

FINDINGS

Based on available methods to assess gingival inflammation, GC could be simply, objectively and accurately identified and graded using bleeding on probing score (BOP%) CONCLUSIONS: A patient with intact periodontium would be diagnosed as a GC according to a BOP score ≥ 10%, further classified as localized (BOP score ≥ 10% and ≤30%) or generalized (BOP score > 30%). The proposed classification may also apply to patients with a reduced periodontium, where a GC would characterize a patient with attachment loss and BOP score ≥ 10%, but without BOP in any site probing ≥4 mm in depth.

Smoking and periodontal microorganisms

Resolution of dysbiosis following treatment for periodontal disease and tobacco dependence has been reported in longitudinal intervention studies. In the present report, we evaluated the biological findings regarding the effect of smoking on the periodontal microbiome. A standardized electronic search was conducted using MEDLINE; overall, 1099 papers were extracted. Studies that addressed the relationship between tobacco and periodontal pathogens were included. Finally, 42 papers were deemed appropriate for the present review. Functional changes in periodontal pathogens exposed to nicotine and cigarette smoke extract support the clinical findings regarding dysbiosis of the subgingival microbiome. Dysbiosis of the periodontal microbiome was presented in smokers regardless of their periodontal condition (healthy, gingivitis, or periodontitis) and remained significant only in smokers even after the resolution of experimentally-induced gingivitis and following reduction of clinical signs of periodontitis with non-surgical periodontal treatment and over 3 months post-therapy. Based on these findings, smoking cessation in periodontitis patients is beneficial for promoting a health-compatible subgingival microbial community. To maximize the benefits of these interventions in dental settings, further studies on periodontal microbiome are needed to elucidate the impact of tobacco intervention on preventing recurrence of periodontal destruction in the susceptible subjects.

The presence of minor salivary glands in the peritonsillar space

Peritonsillar abscess (PTA) is traditionally considered only a purulent complication of acute tonsillitis (AT), but may be related to infection of minor salivary glands. We analysed the presence of peritonsillar minor salivary glands and inflammation patterns in 114 adult tonsils representing three patient groups: recurrent AT, chronic tonsillitis (CT), and PTA. Samples acquired from elective tonsillectomies were stored in formalin, and after preparation were microscopically examined for inflammation and fibrotic changes. Clinical features and histological characteristics were compared between the groups. Of all tonsils, the minor salivary glands were present in 77 (67.5%). Glands located near the tonsillar tissue showed signs of infection in 73 (94.8%), while only 3 (15.0%) of 20 glands located deeper in the peritonsillar space were infected. Compared to patients with recurrent AT and CT, those with PTA more often presented with periductal inflammation, p < 0.011 (PTA 82.1%, AT 42.9%, and CT 63.6%). The majority of our 114 tonsillectomy specimens, collected from patients with AT, CT, or PTA, presented with infected minor salivary glands, and inflammation of the peritonsillar space glands was evident. To further elucidate the association between these glands and PTA, tonsillar samples should be collected and analysed from patients during the acute phase of infection.

Low Biofilm Lysine Content in Refractory Chronic Periodontitis

BACKGROUND

Chronic periodontitis is controlled without antibiotics by scaling and root planing (SRP) to remove dental biofilm. It has been previously reported that the epithelial barrier to bacterial proinflammatory products is impaired when biofilm lysine falls below the minimal content of normal blood plasma. Aims were to examine whether being refractory and requiring antibiotics to supplement SRP were associated with low biofilm lysine contents.

METHODS

Sixteen patients with periodontitis and six periodontally healthy volunteers (HVs) (respective mean ages: 57 ± 6 and 36 ± 8 years) were examined. Patients with periodontitis received SRP and surgery, and HVs received prophylaxis. At quarterly maintenance or prophylaxis visits during the subsequent year, therapeutic response was good (GR, n = 9) or poor (PR, n = 7; including five cigarette smokers). Biofilm cadaverine, lysine, and other amino acid (AA) contents were determined by liquid chromatography. Cadaverine mole fraction of lysine plus cadaverine (CF) indicated biofilm lysine decarboxylase activity.

RESULTS

Biofilm lysine was 0.19 ± 0.10 and 0.20 ± 0.09 μmol/mg in GRs and HVs, but 0.07 ± 0.03 μmol/mg in PRs (Kruskal-Wallis: P <0.01). All AAs were depleted in biofilm from smokers, but only lysine was depleted in biofilm from non-smokers. CF was inversely associated with clinical attachment level (CAL) at baseline before therapy in all patients (R² = 0.28, P <0.01) and with CAL change after therapy in GR (R² = 0.49, P <0.05). Lysine and cadaverine contents discriminated PRs from GRs and HVs (Wilks' λ = 0.499, P <0.012).

CONCLUSIONS

Refractory responses requiring antibiotic therapy result from smoking and/or microbial infections that starve the biofilm and epithelial attachment of lysine. Biofilm CF is associated with periodontitis severity pretherapy and extent of therapeutic response post-therapy.