Effects of tobacco products on the attachment and growth of periodontal ligament fibroblasts

Comparative effect of anthocyanin on proliferation and migration of human gingival fibroblasts in the absence or presence of nicotine

Background

Oral fibroblast malfunction can result in periodontal diseases. Nicotine can prolong the healing process as an irritant of oral tissues. Anthocyanins have been demonstrated to have potential benefits in preventing or treating smoking-related periodontal diseases. Cyanidin chloride's (CC's) potential in oral wound healing and the viability, proliferation, and migration of human gingival fibroblasts (HGFs) were examined in the presence and absence of nicotine by an in vitro study.

Methods

The effects of different nicotine concentrations (1, 2, 3, 4, and 5 mM) on the viability and proliferation of HGF cells were evaluated in the presence and absence of different CC concentrations (5, 10, 25, and 50 μM) using the quantitative MTT assay. The scratch test was performed to evaluate the migration of CC-treated cells in the presence of 2.5-mM nicotine.

Results

No cytotoxicity was observed at 1‒100 μM CC concentrations after 24, 48, and 72 hours of exposure to HGF cells. However, a concentration of 200 μM significantly reduced cell viability by about 20% at all the three-time intervals (P<0.05). Also, 3‒5-mM concentrations of nicotine significantly reduced cell viability in a dose- and time-dependent manner. Moreover, the understudied CC concentrations decreased nicotine's adverse effects on cell migration to some extent.

Conclusion

Although the understudied CC concentrations could not significantly reduce the adverse effects of understudied nicotine concentrations on the viability and proliferation of HGF cells, they were able to reduce the detrimental effects of nicotine on cell migration significantly.

Mental health and periodontal and peri-implant diseases

Mental health disorders, particularly depression and anxiety, affect a significant number of the global population. Several pathophysiological pathways for these disorders have been identified, including the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and the immune system. In addition, life events, environmental factors, and lifestyle affect the onset, progression, and recurrence of mental health disorders. These may all overlap with periodontal and/or peri-implant disease. Mental health disorders are associated with more severe periodontal disease and, in some cases, poorer healing outcomes to nonsurgical periodontal therapy. They can result in behavior modification, such as poor oral hygiene practices, tobacco smoking, and alcohol abuse, which are also risk factors for periodontal disease and, therefore, may have a contributory effect. Stress has immunomodulatory effects regulating immune cell numbers and function, as well as proinflammatory cytokine production. Stress markers such as cortisol and catecholamines may modulate periodontal bacterial growth and the expression of virulence factors. Stress and some mental health disorders are accompanied by a low-grade chronic inflammation that may be involved in their relationship with periodontal disease and vice versa. Although the gut microbiome interacting with the central nervous system (gut-brain axis) is thought to play a significant role in mental illness, less is understood about the role of the oral microbiome. The evidence for mental health disorders on implant outcomes is lacking, but may mainly be through behaviourial changes. Through lack of compliance withoral hygiene and maintenance visits, peri-implant health can be affected. Increased smoking and risk of periodontal disease may also affect implant outcomes. Selective serotonin reuptake inhibitors have been linked with higher implant failure. They have an anabolic effect on bone, reducing turnover, which could account for the increased loss.

The role of cigarette smoking in periodontal disease and treatment outcomes of dental implant therapy

Tobacco smoking has been implicated in periodontal pathology through various mechanisms, including perturbations of the inflammatory and host responses to putative periodontal pathogens, alterations in the subgingival microbial communities, and a compromised healing potential of the tissues leading to imbalance of tissue homeostasis. This review provides the evidence for the relationship between cigarette smoking and periodontal disease in an attempt to explain possible mechanisms of how tobacco smoking may exert its negative effects on the periodontal tissues via systemic and localized pathways. Early and more recent studies explore cigarette smoking-induced changes in periodontal clinical indices; in subgingival microbial flora by employing traditional detection methods for selected microorganisms, in addition to modern techniques such as deep sequencing and bioinformatics analyses that are able to fully characterize the microbial communities; and in inflammatory and immune responses critically appraising study limitations and differences in study protocol designs. Periodontal treatment outcomes and implant therapy outcomes are reviewed in an attempt to shed light on possible mechanisms for the inferior treatment outcome noted in smokers. The potential harmful effects of passive smoking are also reviewed, providing evidence for the advantages of smoking cessation. Quitting cigarette smoking should be recommended by the dentist, and effort should be made to inform smokers about the negative effects of smoking on the periodontal status and implant therapy outcomes.

Fagerström test for nicotine dependence as an indicator in tobacco-related studies in periodontology

BACKGROUND

Smoking is considered a risk factor for periodontitis genesis and progression. Numerous clinical studies have demonstrated the negative effect of smoking, in particular the number of cigarettes consumed (NCC), on periodontal clinical parameters. However, smoking addiction assessed by the Fagerström test for nicotine dependence (FTND) has received little attention in periodontal research.

METHODS

In smoking patients presenting with periodontitis, the periodontal clinical features were measured and correlated with smoking status. The ability of FTND and NCC to predict periodontitis severity was assessed and compared.

RESULTS

Thirty-four smoking patients aged 46.5 ± 11.5 years were included. The means of NCC and FTND were 16.6 ± 5.5 and 5.2 ±1.8, respectively. NCC and FTND were correlated with each other (r = 0.57, P < 0.001). Patients had stage III (44.1%) or stage IV (55.9%) periodontitis and 73.5% presented a generalized extension of periodontitis. The combination of FTND and NCC in discerning disease severity (ROC curve analysis: AUC = 0.746, P = 0.027) was superior to each indicator separately. A discriminant score based on both indicators (D = -0.42 - 0.15 × NCC + 0.63 × FTND) derived by logistic regression showed the opposite role of the indicators and the greater relevance of FTND (P = 0.031) compared to NCC (P = 0.084) in the relationship.

CONCLUSION

This study shows that FTND could substantially complement NCC as an indicator of smoking status in periodontal research.

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.

Comparison of Periodontal Status Between Male Exclusive Narghile Smokers and Male Exclusive Cigarette Smokers

Studies evaluating the effects of narghile use on the periodontium present conflicting conclusions. This study aimed to compare the periodontal status of exclusive narghile smokers (ENSs, n = 74) to that of exclusive cigarette smokers (ECSs, n = 74). Males aged 20-40 years were recruited to participate in this comparative study. Information concerning oral health habits (number of yearly visits to the dentist, daily toothbrushing frequency) and tobacco exposure were obtained. Clinical measurements were performed on all the existing teeth, except the third molars. The number of remaining teeth and decayed/missing/filled teeth (DMFT) were noted. The plaque levels were recorded using the plaque index of Löe and Silness. The gingival index modified by Löe was used to evaluate gingival inflammation. Teeth mobility was measured using bidigital mobility. The probing pocket depth was measured using a periodontal probe. Periodontal disease was defined as the presence of at least 10 sites with a probing depth ≥5 mm. Student's t and chi-square tests were used to compare, respectively, the two groups' quantitative and qualitative data. The two groups were matched for quantities of used tobacco, age, daily toothbrushing frequency, teeth mobility, number of remaining teeth, plaque index, and DMFT. Compared to the ECS group, the ENS group had a significantly lower number of yearly visits to the dentist (mean ± SD: 0.2 ± 0.5 vs. 0.1 ± 0.2), lower probing pocket depth (mean ± SD: 2.33 ± 0.63 vs. 2.02 ± 0.80 mm), and gingival index (median [interquartile]: 0.46 [0.10-0.89] vs. 0.00 [0.00-0.50]), and it included significantly lower percentages of smokers with periodontal disease (24.3% vs. 9.5%). In conclusion, chronic exclusive narghile smoking has fewer adverse effects on the periodontium than chronic exclusive cigarette smoking.

Current Evidence on Dental Implants Outcomes in Smokers and Nonsmokers: A Systematic Review and Meta-Analysis

This systematic review aims to answer the following PICO (Participants, Intervention, Comparison, and Outcome) question: “Does smoking increase the rates of implant failure and peri-implant marginal bone loss in patients with dental implants?” An extensive electronic search of the Cochrane Central Register of Controlled Trials, PubMed, Medline, Embase, and Web of Science databases and a subsequent hand search were performed. Only randomized controlled trial, controlled clinical trials, and prospective studies published up to January 2017 were included. For dichotomous outcomes, the effect estimates for smoking are expressed as odds ratios and 95% CIs. For continuous outcomes, weighted mean differences (WMDs) and 95% CIs are presented. Three randomized controlled trials and 7 prospective studies were included. The odds ratio for implant failure among smokers was 2.92 (95% CI, 1.76–4.83) (P &lt; .001). First-year marginal bone loss in smokers ranged from 0.02 to 0.45 mm. In the nonsmokers, bone loss ranged from −0.08 to 0.42 mm. Nonsmokers lost significantly less bone during the first year (WMD = 0.11 mm, 95% CI. 0.03–0.19) and subsequent years (WMD = 0.11 mm, 95% CI, 0.03–0.19, P = .009). The available scientific evidence suggests that smoking is associated with significantly increased rates of implant failure and marginal bone loss.

The Influence of Cigarette Smoking on Various Aspects of Periodontal Health

Tobacco is one of the most important risk factors for oral diseases, including oral cancer, oral mucosal lesions and periodontal diseases. There is substantial evidence suggesting that the risk of oral diseases increases with frequent use of tobacco and that quitting smoking results in reduced risk. In this article, the influence of cigarette smoking on the periodontium will be discussed, giving importance to the effects on immune responses, alveolar bone loss, periodontal pathogens and briefly outlining the negative effects of smoking on wound healing and periodontal treatment procedures.

Nicotine inhibits osteogenic differentiation of human periodontal ligament cells under cyclic tensile stress through canonical Wnt pathway and α7 nicotinic acetylcholine receptor

BACKGROUND AND OBJECTIVES

Nicotine, the main psychoactive component of tobacco, affects cell metabolism, proliferation, adhesion and, importantly, the osteogenic differentiation of fibroblasts. Approximately 15% of all orthodontic patients are adults among who one-fifth are smokers. Hence, it is necessary to have insight into the effects of nicotine on the osteogenic differentiation of hPDLCs during orthodontic tooth movement. This study aimed to investigate the effects and mechanisms of nicotine on the osteogenic differentiation of human periodontal ligament cells (hPDLCs) under the application of cyclic tensile stress.

MATERIAL AND METHODS

hPDLCs were obtained from donor third molars. The hPDLCs were treated with nicotine and/or cyclic tensile stress that was applied with a cell stress plus unit. The effect of nicotine on cell viability was analyzed using the MTT assay. The osteogenic differentiation of hPDLCs was detected by alkaline phosphatase staining, Alizarin Red S staining, quantitative real-time polymerase chain reaction and western blotting.

RESULTS

In combination with cyclic tensile stress, nicotine prevented the tensile stress-induced increase in alkaline phosphatase activity, formation of mineralization nodules and the upregulation of mRNA and protein expression of Runt-related transcription factor 2, transcription factor Sp7 and collagen type I; however, canonical Wnt pathway was activated. Furthermore, the addition of Dickkopf-related protein 1 and α-bungarotoxin counteracted the negative effect of nicotine and rescued the osteogenic differentiation of hPDLCs, respectively.

CONCLUSION

These results indicate that nicotine prevents the increased osteogenic potential of hPDLCs induced by cyclic tensile stress by binding to an α7 nicotinic acetylcholine receptor and activating the canonical Wnt pathway.

Smoking Related Systemic and Oral Diseases

This article reviewed smoking related systemic diseases and oral diseases. Smoking is related to lung cancer, cardiovascular diseases and many other systemic diseases. Cigarette smoke affects the oral cavity first, so it is evident that smoking has many negative influences on oral cavity, for example, staining of teeth and dental restorations, wound healing, reduction of the ability to smell and taste, and development of oral diseases such as oral cancer, periodontitis, smoker’s palate, smoker’s melanosis, hairy tongue, leukoplakia, oral candidiasis and implant survival rate. The article also discusses the relationship between smoking and dental caries in detail.

Shammah (Smokeless Tobacco) and Public Health

Shammah is a preparation of smokeless tobacco (ST) that is frequently used in the Arabian Peninsula, especially in Saudi Arabia. A mixture of powdered tobacco, lime, ash, black pepper, oils and flavorings, shammah in is placed in the buccal cavity or lower labial vestibule of the mouth. The user (or dipper) spits out insoluble debris. ST is linked to a number of harmful effects such as dental disease, oral cancer, oesophagus cancer, and pancreas cancer. It also causes adverse reproductive effects including stillbirth, premature birth and low birth weight. The importation of ST products is prohibited in Saudi Arabia. Legislative action to combat the use of ST (moist snuff and chewing tobacco) in Saudi Arabia appeared in 1990. The actual percentage use may be higher than reported since shammah is illegal in Saudi Arabia and there may be some unwillingness to admit to its use. Data on ST use in the Arabian Peninsula are sparse. Most studies conducted there focused on the prevalence of shammah use among adolescents rather than among adults. This review paper aimed to understand the pattern of use of shammah and its adverse health effects. It also aimed to provide suitable epidemiological data for public health policy makers.

Comparative systems toxicology analysis of cigarette smoke and aerosol from a candidate modified risk tobacco product in organotypic human gingival epithelial cultures: A 3-day repeated exposure study

Smoking is one of the major lifestyle-related risk factors for periodontal diseases. Modified risk tobacco products (MRTP) offer a promising alternative in the harm reduction strategy for adult smokers unable to quit. Using a systems toxicology approach, we investigated and compared the exposure effects of a reference cigarette (3R4F) and a heat-not-burn technology-based candidate MRTP, the Tobacco Heating System (THS) 2.2. Human gingival epithelial organotypic cultures were repeatedly exposed (3 days) for 28 min at two matching concentrations of cigarette smoke (CS) or THS2.2 aerosol. Results showed only minor histopathological alterations and minimal cytotoxicity upon THS2.2 aerosol exposure compared to CS (1% for THS2.2 aerosol vs. 30% for CS, at the high concentration). Among the 14 proinflammatory mediators analyzed, only 5 exhibited significant alterations with THS2.2 exposure compared with 11 upon CS exposure. Transcriptomic and metabolomic analysis indicated a general reduction of the impact in THS2.2 aerosol-exposed samples with respect to CS (∼79% lower biological impact for the high THS2.2 aerosol concentration compared to CS, and 13 metabolites significantly perturbed for THS2.2 vs. 181 for CS). This study indicates that exposure to THS2.2 aerosol had a lower impact on the pathophysiology of human gingival organotypic cultures than CS.

The effect of nicotine and cotinine on human gingival fibroblasts attachment to root surfaces

BACKGROUND

Different compounds of smoking (e.g., nicotine and cotinine) are risk factors for various diseases such as oral cancer and periodontal diseases. Some studies reported the negative effects of nicotine on cell proliferation and differentiation. The present in vitro study assessed the effects of nicotine and cotinine (long-acting metabolite of nicotine) on the attachment and viability of human gingival fibroblast (HGF) cells to tooth root surfaces.

METHODS

A total of 70 teeth specimens were placed into 48-well culture plates and covered with HGF cell suspension, in complete Dulbecco's modified Eagle's medium culture medium containing 1 nM, 1 μm, 1 mM, and 5 mM of nicotine and cotinine concentrations. Cellular attachment and viability measured using an MTT assay and a scanning electron microscope were used for cell morphological evaluation.

RESULTS

After 24 h, low (nanomolar and micromolar) and high concentrations (millimolar) of nicotine and cotinine caused a significant reduction in the initial cell adhesion in comparison with the control group, but no significant difference was observed between the nicotine and the cotinine groups (p<0.05). Dentally attached cells with low concentrations of nicotine and cotinine proliferated 48 h after exposure, the same as the control group. However, dentally attached cells with high concentrations of nicotine and cotinine (especially 5 mM) did not proliferate 24 h after exposure (p<0.05).

CONCLUSIONS

Low concentrations of nicotine and cotinine caused a reduction in the initial cell adhesion. However, no significant adverse effects on the proliferation of attached cells were seen in the longer period. High concentrations of nicotine and cotinine have adverse effects on the cell adhesion and proliferation of HGF cells.

Impact of nicotine on the interplay between human periodontal ligament cells and CD4+ T cells

Periodontitis is a common infectious disease associated with destruction of periodontal ligaments and alveolar bones. CD4(+) T cell-mediated immune response is involved in the progression of periodontitis. Tobacco consumption increases the risk of periodontal disease. However, the impact of nicotine on the interaction between human periodontal ligament (PDL) cells and CD4(+) T cells remains unrevealed. Our study aims to investigate the effect of nicotine on PDL cells and the cocultured CD4(+) T cells. The PDL cell cultures were established by explants from healthy individuals, exposed to nicotine or α-bungarotoxin (α-BTX), and incubated solely or in combination with CD4(+) T cells. Afterwards, cell viability, secreted cytokines, and matrix metalloproteinases (MMPs) were evaluated. In monoculture of PDL cells, nicotine dramatically repressed cell viability and increased apoptosis. Meanwhile, α-BTX largely reversed the nicotine-induced apoptosis and increased viability of PDL cells. Compared with the monoculture, MMP-1, MMP-3, interleukin (IL)-1β, IL-6, IL-17, and IL-21 in supernatant of cocultures were markedly elevated after treatment with nicotine. Moreover, α-BTX significantly attenuated nicotine-triggered production of these components either in mono- or co-cultures. In addition, PDL cell-derived CXCL12 following nicotine treatment recruited CD4(+) T cells. Above all, nicotine deteriorated periodontitis partially by promoting PDL cell-CD4(+) T cell-mediated inflammatory response and matrix degradation.

Prevalence and association of smokeless tobacco use with the development of periodontal pocket among adult males in Dawan Valley, Yemen: a cross-sectional study

BACKGROUND

The traditional type of smokeless tobacco used in the Arabian Peninsula, particularly common in Yemen, is called shammah. This study aims to determine the prevalence of shammah use and its association with the development of periodontal pockets. Other associated factors with the development of periodontal pocket were also determined.

METHODS

This cross-sectional study included 346 adult males aged 18 years old to 68 years old. Socio-demographic characteristics, oral hygiene practices, and shammah use history were surveyed by using a structured interview questionnaire. The clinical assessment for the presence or absence of periodontal pockets was assessed on the basis of community periodontal index. The chi-square test was used to assess significant differences in study groups in terms of the presence of periodontal pockets. Multivariable logistic regression was selected to assess potential associated factors with the development of periodontal pockets.

RESULTS

Among the 346 adult males, 248 (71.7 %), 30 (8.6 %), and 68 (19.7 %) males never used shammah, were former shammah users, and were current shammah users, respectively. The significant associated factors with the development of periodontal pocket were age group (30 years old and above) (Adjusted Odds Ratio (AOR) = 2.03, 95 % CI: 1.13, 3.65; P = 0.018), low family income category (AOR = 2.35, 95 % CI: 1.39, 3.99; P = 0.001), former shammah user (AOR = 2.66, 95 %: CI: 1.15, 6.15; P = 0.022), and current shammah user (AOR = 6.62, 95 %: CI: 3.59, 12.21; P = 0.001).

CONCLUSIONS

The results revealed that periodontal pockets were significantly associated with age group (30 years old and above), low family income category, former shammah use, and current shammah use. The findings of the current study highlighted the need to develop comprehensive shammah prevention programs and reduce periodontal disease and other shammah-associated diseases.

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.

Risk factors for periodontal disease

Risk factors play an important role in an individual's response to periodontal infection. Identification of these risk factors helps to target patients for prevention and treatment, with modification of risk factors critical to the control of periodontal disease. Shifts in our understanding of periodontal disease prevalence, and advances in scientific methodology and statistical analysis in the last few decades, have allowed identification of several major systemic risk factors for periodontal disease. The first change in our thinking was the understanding that periodontal disease is not universal, but that severe forms are found only in a portion of the adult population who show abnormal susceptibility. Analysis of risk factors and the ability to statistically adjust and stratify populations to eliminate the effects of confounding factors have allowed identification of independent risk factors. These independent but modifiable, risk factors for periodontal disease include lifestyle factors, such as smoking and alcohol consumption. They also include diseases and unhealthy conditions such as diabetes mellitus, obesity, metabolic syndrome, osteoporosis, and low dietary calcium and vitamin D. These risk factors are modifiable and their management is a major component of the contemporary care of many periodontal patients. Genetic factors also play a role in periodontal disease and allow one to target individuals for prevention and early detection. The role of genetic factors in aggressive periodontitis is clear. However, although genetic factors (i.e., specific genes) are strongly suspected to have an association with chronic adult periodontitis, there is as yet no clear evidence for this in the general population. It is important to pursue efforts to identify genetic factors associated with chronic periodontitis because such factors have potential in identifying patients who have a high susceptibility for development of this disease. Many of the systemic risk factors for periodontal disease, such as smoking, diabetes and obesity, and osteoporosis in postmenopausal women, are relatively common and can be expected to affect most patients with periodontal disease seen in clinics and dental practices. Hence, risk factor identification and management has become a key component of care for periodontal patients.

Caspase 3 activity in isolated fetal rat lung fibroblasts and rat periodontal ligament fibroblasts: cigarette smoke induced alterations

Background

Cigarette smoking is the leading cause of preventable death and has been implicated in pathogenesis of pulmonary, oral and systemic diseases. Smoking during pregnancy is a risk factor for the developing fetus and may be a major cause of infant mortality. Moreover, the oral cavity, and all cells within are the first to be exposed to cigarette smoke and may be a possible source for the spread of toxins to other organs of the body. Fibroblasts in general are morphologically heterogeneous connective tissue cells with diverse functions. Apoptosis or programmed cell death is a crucial process during embryogenesis and for the maintenance of homeostasis throughout life. Deregulation of apoptosis has been implicated in abnormal lung development in the fetus and disease progression in adults. Caspases are proteases which belong to the family of cysteine aspartic acid proteases and are key components for downstream amplification of intracellular apoptotic signals. Of 14 known caspases, caspase-3 is the key executioner of apoptosis. In the present study we explored the hypothesis that cigarette smoke (CS) extract activates caspase-3 in two types of fibroblasts, both of which would be exposed directly to cigarette smoke, isolated fetal rat lung fibroblasts and adult rat periodontal ligament (PDL) fibroblasts.

Methods

Isolated fetal rat lung fibroblasts and adult PDLs were used. Cells were exposed to different concentrations of CS for 60 min. Caspase-3 activity and its inhibition by Z-VAD-fmk were measured by caspase-3 fluorometric assay. The effect of CSE on cellular viability was measured using the MTT formazan assay. Caspase-3 expression was detected by western blot analysis and cellular localization of caspase-3 was determined by immunofluorescence using fluorescence microscopy.

Results

It was observed in fetal rat lung fibroblast cells that CSE extract significantly (p<0.05) increased caspase-3 activity and decrease cell proliferation. However, no significant changes in activity or viability were observed in PDLs.

Conclusions

This indicates CS activates caspase-3 the key regulatory point in apoptosis in fetal rat lung fibroblast cells suggesting that smoking during pregnancy may alter the developmental program of fetal lung, jeopardizing the establishment of critical cellular mechanisms necessary to expedite pulmonary maturation at birth.of critical cellular mechanisms necessary to expedite pulmonary maturation at birth.

Sodium hydrogen sulfide inhibits nicotine and lipopolysaccharide-induced osteoclastic differentiation and reversed osteoblastic differentiation in human periodontal ligament cells

Although previous studies have demonstrated that hydrogen sulfide (H(2)S) stimulated or inhibited osteoclastic differentiation, little is known about the effects of H(2)S on the differentiation of osteoblasts and osteoclasts. To determine the possible bioactivities of H(2)S on bone metabolism, we investigated the in vitro effects of H(2)S on cytotoxicity, osteoblastic, and osteoclastic differentiation as well as the underlying mechanism in lipopolysaccharide (LPS) and nicotine-stimulated human periodontal ligament cells (hPDLCs). The H(2)S donor, NaHS, protected hPDLCs from nicotine and LPS-induced cytotoxicity and recovered nicotine- and LPS-downregulated osteoblastic differentiation, such as alkaline phosphatase (ALP) activity, mRNA expression of osteoblasts, including ALP, osteopontin (OPN), and osteocalcin (OCN), and mineralized nodule formation. Concomitantly, NaHS inhibited the differentiation of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in mouse bone marrow cells and blocked nicotine- and LPS-induced osteoclastogenesis regulatory molecules, such as RANKL, OPG, M-CSF, MMP-9, TRAP, and cathepsin K mRNA. NaHS blocked nicotine and LPS-induced activation of p38, ERK, MKP-1, PI3K, PKC, and PKC isoenzymes, and NF-κB. The effects of H(2)S on nicotine- and LPS-induced osteoblastic and osteoclastic differentiation were remarkably reversed by MKP-1 enzyme inhibitor (vanadate) and expression inhibitor (triptolide). Taken together, we report for the first time that H(2)S inhibited cytotoxicity and osteoclastic differentiation and recovered osteoblastic differentiation in a nicotine- and periodontopathogen-stimulated hPDLCs model, which has potential therapeutic value for treatment of periodontal and inflammatory bone diseases.

Salivary immunoglobulin classes in Nigerian smokers with periodontitis

AIM: To determine the levels of salivary immunoglobulin classes in Nigerian smokers and non-smokers with periodontitis.

METHODS: Sixty-nine individuals were recruited into this study after obtaining informed consent. They were subdivided into three groups that consisted of 20 (aged 46 ± 11 years) cigarette smokers with periodontitis (S+P); 24 (40 ± 12 years) smokers without periodontitis (S-P); and 25 (53 ± 11 years) non-smokers with periodontitis (NS+P). An oral and maxillofacial surgeon used radiographs for periodontal probing for the diagnosis of periodontitis. The smokers included subjects who smoked at least six cigarettes per day and all the periodontitis patients were newly diagnosed. About 5 mL of unstimulated saliva was expectorated by each subject into plain sample bottles. Salivary immunoglobulin levels were estimated using enzyme linked immunosorbent assay. Student’s t test was used to determine significant differences between the means. Values of P < 0.05 were regarded as significant.

RESULTS: No significant differences were observed in the mean salivary levels of the immunoglobulin classes (IgG, IgA, IgM and IgE) when S+P was compared with S-P. Mean salivary levels of IgA (520.0 ± 155.1 ng/mL vs 670.0 ± 110 ng/mL, P = 0.000) and IgM (644.5 ± 160.0 ng/mL vs 791.4 ± 43.7 ng/mL, P = 0.000) were significantly lower in the S+P compared with NS+P group. Salivary IgA (570.4 ± 145.6 ng/mL vs 670.0 ± 110 ng/mL, P = 0.008) and IgM (703.1 ± 169.3 ng/mL vs 791.4 ± 43.7 ng/mL, P = 0.012) levels were significantly lower in the S-P compared with NS+P group. Only one (5%) periodontal patient had detectable levels of salivary IgE (0.20 IU/mL). Similarly, only one smoker (4.17%) had detectable levels of salivary IgE (0.04 IU/mL) and two non-smokers (9.52%) had detectable levels of IgE (0.24 IU/mL).

CONCLUSION: Our study suggests that reduced salivary IgA and IgM levels in smokers with periodontitis could enhance increased susceptibility to periodontitis.

Endoplasmic reticulum stress modulates nicotine-induced extracellular matrix degradation in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Tobacco smoking is considered to be one of the major risk factors for periodontitis. For example, about half the risk of periodontitis can be attributable to smoking in the USA. It is evident that smokers have greater bone loss, greater attachment loss and deeper periodontal pockets than nonsmoking patients. It has recently been reported that endoplasmic reticulum (ER) stress markers are upregulated in periodontitis patients; however, the direct effects of nicotine on ER stress in regard to extracellular matrix (ECM) degradation are unclear. The purpose of this study was to examine the effects of nicotine on cytotoxicity and expression of ER stress markers, selected ECM molecules and MMPs, and to identify the underlying mechanisms in human periodontal ligament cells. We also examined whether ER stress was responsible for the nicotine-induced cytotoxicity and ECM degradation.

MATERIAL AND METHODS

Cytotoxicity and cell death were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide assay and flow cytometric annexin V and propidium iodide staining. The mRNA and protein expressions of MMPs and ER markers were examined by RT-PCR and western blot analysis.

RESULTS

Treatment with nicotine reduced cell viability and increased the proportion of annexin V-negative, propidium iodide-positive cells, an indication of cell death. Nicotine induced ER stress, as evidenced by survival molecules, such as phosphorylated protein kinase-like ER-resident kinase, phosphorylated eukaryotic initiation factor-2α and glucose-regulated protein-78, and apoptotic molecules, such as CAAT/enhancer binding protein homologous protein (CHOP). Nicotine treatment led to the downregulation of ECM molecules, including collagen type I, elastin and fibronectin, and upregulation of MMPs (MMP-1, MMP-2, MMP-8 and MMP-9). Inhibition of ER stress by salubrinal and transfection of CHOP small interfering RNA attenuated the nicotine-induced cell death, ECM degradation and production of MMPs. Salubrinal and CHOP small interfering RNA inhibited the effects of nicotine on the activation of Akt, JNK and nuclear factor-κB.

CONCLUSION

These results indicate that nicotine-induced cell death is mediated by the ER stress pathway, involving ECM degradation by MMPs, in human periodontal ligament cells.

Effects of cigarette smoke condensate and nicotine on human gingival fibroblast-mediated collagen degradation

BACKGROUND

Members of the matrix metalloproteinase (MMP) family have been shown to be involved in periodontal disease. Risk factors for periodontal disease include tobacco smoking. Cigarette smoke condensate (CSC) is comprised of thousands of chemicals. Nicotine is one of the active components in tobacco. This study compares the effects of CSC and nicotine at the level in CSC on the collagen-degrading ability of human gingival fibroblasts (HGFs) and the expression of selected MMPs and tissue inhibitors of metalloproteinases (TIMPs).

METHODS

HGFs were seeded in six-well collagen-coated plates, exposed to 100 μg/mL (2.4 μg/mL nicotine) of CSC or 2.4 μg/mL nicotine for 3 days, and then collagen degradation was analyzed. After 3 days exposure to CSC or nicotine, the conditioned media from HGFs was collected and the membrane proteins were extracted for gelatin zymography and Western blot analyses. The mRNA levels of MMP-2, MMP-14, and TIMP-2 were measured by reverse transcription-polymerase chain reaction.

RESULTS

The CSC increased collagen degradation, and increased the levels of TIMP-2, MMP-14, and the active MMP-2 in the membrane extracts, and their mRNA levels. CSC also increased the level of active MMP-2 in the conditioned media. Nicotine at the level in CSC (2.4 μg/mL) had little influence on collagen degradation, as well as on the protein and mRNA levels of MMP-2, MMP-14, and TIMP-2.

CONCLUSIONS

CSC may increase HGF-mediated collagen degradation by affecting membrane-associated MMPs and TIMPs.

Comparison of the toxicity of smoke from conventional and harm reduction cigarettes using human embryonic stem cells

This study evaluated the hypothesis that smoke from harm reduction cigarettes impedes attachment and proliferation of H9 human embryonic stem cells (hESCs). Smoke from three harm reduction brands was compared with smoke from a conventional brand. Doses of smoke were measured in puff equivalents (PE) (1 PE = the amount of smoke in one puff that dissolves in 1 ml of medium). Cytotoxic doses were determined using morphological criteria and trypan blue staining, and apoptosis was confirmed using Magic Red staining. Attachment and proliferation of hESC were followed at a noncytotoxic dose in time-lapse videos collected using BioStation technology. Data were mined from videos either manually or using video bioinformatics subroutines developed with CL-Quant software. Mainstream (MS) and sidestream (SS) smoke from conventional and harm reduction cigarettes induced apoptosis in hESC colonies at 1 PE. At 0.1 PE (noncytotoxic), SS smoke from all brands inhibited attachment of hESC colonies to Matrigel with the strongest inhibition occurring in harm reduction brands. At 0.1 PE, SS smoke, but not MS smoke, from all brands inhibited hESC growth, and two harm reduction brands were more potent than the conventional brand. In general, hESC appeared more sensitive to smoke than their mouse ESC counterparts. Although harm reduction cigarettes are often marketed as safer than conventional brands, our assays show that SS smoke from harm reduction cigarettes was at least as potent or in some cases more potent than smoke from a conventional brand and that SS smoke was more inhibitory than MS smoke in all assays.

Cigarette smoke inhalation modulates gene expression in sites of bone healing: a study in rats

OBJECTIVE

The aim of this study was to assess the effect of cigarette smoke inhalation (CSI) on gene expression in alveolar bone healing sites.

STUDY DESIGN

Wistar rats were randomly assigned to the groups: control [animals not exposed to CSI (n = 20)] and test [animals exposed to CSI, starting 3 days before teeth extraction and maintained until killing them (n = 20)]. First mandibular molars were bilaterally extracted, and the expression of alkaline phosphatase, bone morphogenetic protein (BMP) 2 and 7, receptor activator of nuclear factor κB ligand, osteoprotegerin, and d2 isoform of vacuolar adenosine triphosphatase V(0) domain were assessed by quantitative polymerase chain reaction in the newly formed tissue in the sockets.

RESULTS

Overall, data analysis demonstrated that CSI significantly affected the expression pattern of all of the studied genes except BMP-7.

CONCLUSION

The expression of key genes for bone healing may be affected by CSI in tooth extraction sites.

[Effects of smoking on periodontal disease]

INTRODUCTION

Smoking is an independent risk factor for periodontal disease and tooth loss.

STATE OF THE ART

Smoking impairs inflammatory and immune responses to periodontal pathogens, and exerts both systemic and local effects. Periodontal disease is increased both in prevalence and severity in smokers. Smoking is a predisposing factor to acute necrotizing ulcerative gingivitis and is associated with an increased rate of periodontal disease in terms of pocket formation and attachment loss, as well as alveolar bone loss. Cigar, pipe, water-pipe and cannabis smoking have similar adverse effects on periodontal health as cigarette smoking. Passive smoking is also an independent periodontal disease risk factor. Smokeless tobacco is associated with localized periodontal disease. Smokers respond less favourably to both non-surgical and surgical treatments and have higher failure rates and complications following dental implantation. Smoking cessation may halt the disease progression and improve the outcome of periodontal treatment.

CONCLUSION

Smoking cessation counselling should be an integral part of periodontal therapy and prevention.

Destructive effects of smoking on molecular and genetic factors of periodontal disease

Many epidemiological evidences have proven the association between smoking and periodontal disease. The causality can be further established by linking findings of traditional epidemiological studies with the developments in molecular techniques that occurred in the last decade. The present article reviews recent studies that address the effect of smoking on molecular and genetic factors in periodontal disease. Most findings support the fact that tobacco smoking modulates destruction of the periodontium through different pathways: microcirculatory and host immune systems, connective tissue, and bone metabolism. Although smokers experience an increased burden of inflammatory responses to microbial challenges compared to non-smokers, understanding the association between smoking and periodontal diseases involves substantial problems with respect to accuracy of measurements, and particularly, sampling of many subjects. It remains unclear whether genetic susceptibility to periodontal disease is influenced by exposure to smoking or the effect of smoking on periodontal disease is influenced by genetic susceptibility. Employment of molecular techniques may play a key role in further elucidation of mechanisms linking smoking and periodontal destruction, the direct relationship as environmental factors and indirect relationship through genetic factors.

Cigarette smoke condensate affects the collagen-degrading ability of human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Cigarette smoke condensate, the particulate matter of cigarette smoke, is composed of thousands of chemicals, including nicotine. Cigarette smoking is a risk factor for periodontal disease. This study investigated the influence of cigarette smoke condensate on the collagen-degrading ability of human gingival fibroblasts and its mechanism.

MATERIAL AND METHODS

Human gingival fibroblasts were exposed for 72 h to various concentrations of total particulate matter cigarette smoke condensate. Cell proliferation and cytotoxicity were evaluated using water-soluble tetrazolium-1 and lactate dehydrogenase, respectively. The collagen-degrading ability of human gingival fibroblasts was evaluated in collagen-coated six-well plates. Conditioned media and membrane extracts were collected for zymography and western blot analyses of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs).

RESULTS

Cell proliferation decreased and cytotoxicity increased in human gingival fibroblasts with increasing concentrations of cigarette smoke condensate. Cell proliferation decreased by more than 50% (p < 0.05) when the concentrations of total particulate matter cigarette smoke condensate were above 200 microg/mL, and cytotoxicity increased to more than 30% (p < 0.05) when the concentrations of total particulate matter cigarette smoke condensate were above 400 microg/mL. Cigarette smoke condensate increased the collagen-degrading ability of human gingival fibroblasts, especially at a concentration of 100 microg/mL (1.5-fold increase, p < 0.05) compared with the control. Cigarette smoke condensate increased the production of proMMP-1, proMMP-2, MMP-14 and TIMP-1, and decreased the production of TIMP-2, in conditioned media. Furthermore, compared with the control group, cigarette smoke condensate increased the production of MMP-2, MMP-14 and TIMP-2 in membrane extracts, especially at concentrations of 50-100 microg/mL.

CONCLUSION

Cigarette smoke condensate affects human gingival fibroblast proliferation and is toxic at total particulate matter cigarette smoke condensate concentrations of >or= 400 microg/mL. Cigarette smoke condensate can increase the collagen-degrading ability of human gingival fibroblasts by altering the production and localization of MMPs and TIMPs.

Effect of nicotine in matrix mineralization by human bone marrow and Saos-2 cells cultured on the surface of plasma-sprayed titanium implants

Smoking has an established negative impact in the clinical outcome of dental implants. This work analyses the response of human osteoblastic cells to nicotine, at the surface of plasma-sprayed commercial titanium implants. Human bone marrow (HBM) and Saos-2 cells, seeded on the surface of titanium implants and cultured in experimental conditions favoring osteoblastic differentiation, were exposed continuously to nicotine (0.0001 to 0.5 mg mL(-1)) and characterized for cell proliferation and function. Exposure of HBM cells resulted in increased cell proliferation, higher alkaline phosphatase (ALP) activity, and earlier onset of matrix mineralization at levels up to 0.2 mg mL(-1), an initial inhibitory effect in cell growth and functional activity followed by a recovery in the presence of 0.3 mg mL(-1) and a dose-dependent deleterious effect at higher levels. By contrast, exposure to nicotine did not affect cell proliferation of Saos-2 cells at levels up to 0.2 mg mL(-1), and caused only a small positive effect in ALP activity in the presence of 0.05 and 0.1 mg mL(-1); however, matrix mineralization by Saos-2 cells also occurred earlier in the cultures exposed to levels of nicotine up to 0.1 mg mL(-1). Higher concentrations caused dose-dependent inhibitory effects. Considering the high diffusion potential of nicotine, results suggest a local role of nicotine in modulating bone formation events at the implant surface.

Nicotine stimulates the expression of cyclooxygenase-2 mRNA via NFkappaB activation in human gingival fibroblasts

Nicotine, a major component in tobacco smoke, stimulates the synthesis of prostaglandin E(2). We investigated the involvement of the transcription nuclear factor kappa B (NFkappaB) in the nicotine-induced expression of cyclooxygenase-2 (COX-2), a key enzyme for prostaglandin synthesis, in human gingival fibroblasts. Nicotine-stimulated release of prostaglandin E(2) and expression of COX-2 mRNA in a time- and dose-dependent manner. The nicotine-stimulated release of prostaglandin E(2) and expression of COX-2 mRNA and protein were inhibited by an NFkappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), by approximately 50%. Nicotine stimulation of IkappaBalpha, an inhibitor of NFkappaB degradation, was also characterized by Western blotting. Mecamylamine, a specific antagonist of the nicotinic acetylcholine receptor, failed to inhibit the effect of nicotine on prostaglandin E(2) release. When human gingival fibroblasts were incubated with [3H]-nicotine, uptake of nicotine was observed. These results suggest that nicotine is taken up by human gingival fibroblasts and that it then stimulates COX-2 expression via the activation of NFkappaB and the subsequent release of prostaglandin E(2).

A histologic and histometric assessment of the influence of nicotine on alveolar bone loss in rats

BACKGROUND

Cigarette smoking has long been recognized as a risk factor for periodontal disease. The aim of this study was to perform quantitative and qualitative analyses of bone loss in the furcation region of periodontally healthy rats after daily systemic administration of nicotine or saline solution.

METHODS

Thirty adult male Wistar rats were assigned randomly to twice daily subcutaneous injections of saline solution (control, group C) or nicotine (group N). The animals were sacrificed at 37, 44, or 51 days after the first subcutaneous injection. The specimens were processed for serial histologic sections, and the area of bone loss in the furcation region of the second molar was analyzed histometrically.

RESULTS

Greater bone loss was detected in group N compared to group C on day 37 (16.36 +/- 5.84 mm(2) and 7.24 +/- 2.66 mm(2)), day 44 (15.12 +/- 4.57 mm(2) and 7.76 +/- 1.35 mm(2)), and day 51 (18.80 +/- 3.71 mm(2) and 8.74 +/- 2.61 mm(2)), respectively (P <0.05). Extension of bone loss appeared greater in the furcation region of group N where a thinner trabeculae bone was found. After day 37, bone loss did not increase significantly.

CONCLUSIONS

Daily systemic administration of nicotine resulted in significantly greater bone loss in the furcation region compared to saline solution. This indicated a close association between nicotine and periodontal morbidity in rats.

Low- and high-yield cigarette smoke inhalation potentiates bone loss during ligature-induced periodontitis

BACKGROUND

It is well recognized that cigarette consumption is a strong risk factor for periodontitis. Tobacco companies have developed a cigarette with low levels of toxic compounds; however, its effect on periodontium has not been investigated. The aim of this study was to verify the impact of smoke produced by low- and high-yield cigarettes on bone loss resulting from ligature-induced periodontitis.

METHODS

A total of 36 male Wistar rats were used in the study. A ligature was placed around one of the mandibular first molars (ligated teeth) of each animal, and they were assigned randomly to one of three groups: group 1: control (N = 10), group 2: 30 days' inhalation of smoke produced by high-yield cigarettes (N = 13), and group 3: 30 days' inhalation of smoke produced by low-yield cigarettes (N = 13). The animals were sacrificed 30 days after ligature placement, and the specimens were processed for decalcified sections.

RESULTS

Intergroup analysis of unligated teeth (without periodontal disease) did not show a significant difference regarding periodontal ligament area (2.40 +/- 0.5 mm(2), 2.72 +/- 0.7 mm(2), and 2.61 +/- 0.4 mm(2) for groups 1, 2, and 3, respectively; P >0.05). Conversely, significant differences were noted in ligated teeth (with periodontitis); bone loss was directly proportional to the level of toxic compounds in the cigarettes (5.74 +/- 0.5 mm(2), 7.40 +/- 0.50 mm(2), and 6.51 +/- 0.50 mm(2) for groups 1, 2, and 3, respectively; P <0.05).

CONCLUSION

Low- and high-yield cigarettes potentiated bone loss during experimental periodontitis in a directly proportional fashion.

Enamel matrix derivative versus guided tissue regeneration in the presence of nicotine: a histomorphometric study in dogs

AIM

The goal of this histometric study was to compare the healing process of dehiscence-type defects treated by enamel matrix derivative (EMD) or guided tissue regeneration (GTR) under the effect of nicotine in the dog model.

MATERIALS AND METHODS

Eight mongrel dogs were used. Buccal osseous dehiscences were surgically created on the mesial roots of the mandibular third and fourth pre-molars. The defects were exposed to plaque accumulation for 3 months. After this period, the defects were randomly assigned to one of the treatments: open flap debridement (OFD), EMD or GTR with a resorbable membrane. During 4 months, the dogs received subcutaneous administration of nicotine (2 mg/kg twice a day with a 12 h interval between the applications). After this period, the animals were killed and the blocks were processed. The histometric parameters evaluated included gingival recession, epithelial length, connective tissue adaptation, new cementum and new bone.

RESULTS

A superior length of new cementum was observed in the sites treated by EMD in comparison with OFD (p< or =0.05). No statistically significant differences were observed between GTR and the other groups.

CONCLUSIONS

In the presence of nicotine, EMD may promote more new cementum formation than OFD while GTR failed to provide a significant difference.