A longitudinal study of interleukin-1 gene polymorphisms and periodontal disease in a general adult population

The IL1A (?889) gene polymorphism is associated with chronic periodontal disease in a sample of Brazilian individuals

BACKGROUND AND OBJECTIVE

It has been proposed that genotypes reflective of polymorphisms in cytokine genes can predispose individuals to disease by enhancing inflammatory processes. The C/T polymorphism at position -889 of the IL1A gene influences interleukin-1alpha expression, with the T allele inducing higher expression. The aim of this study was to evaluate the association of the IL1A (-889) gene polymorphism in Brazilian individuals with different clinical forms of periodontitis and severity of disease.

MATERIAL AND METHODS

DNA was obtained from oral swabs of 163 Brazilian individuals and was amplified using the polymerase chain reaction (PCR). Products were submitted to digestion and were analyzed by electrophoresis to distinguish the C and T alleles.

RESULTS

A significant difference in the genotype distribution was observed when comparing the chronic periodontitis group with the control group, evaluating only nonsmokers (chi-squared analysis = 9.91; p = 0.007), as well as when smokers were included (chi-squared analysis = 6.36; p = 0.04). Moreover, we observed a higher incidence of the T allele in the chronic periodontitis group (37.8%) when compared with the control group (18.4%) in nonsmokers (p = 0.006, odds ratio = 2.69, confidence interval = 1.27-5.68) and also when smokers were included (p = 0.03, odds ratio = 1.87, confidence interval = 0.98-3.56). No statistical difference was observed when the aggressive periodontitis group was compared with the control group. With regard to severity of disease, no statistical difference was observed.

CONCLUSION

These data show an association of the IL1A (-889) polymorphism with chronic periodontitis in Brazilian individuals.

Distribution of Genotypes of Porphyromonas gingivalis in Type 2 Diabetic Patients with Periodontitis in Mexico

OBJECTIVE

To determine and compare the distribution of Porphyromonas gingivalis fimA genotypes in type 2 diabetes mellitus (T2DM) patients affected by periodontitis, using non-diabetic subjects with and without periodontitis as control groups.

MATERIAL AND METHODS

This study involved 75 subjects divided into three groups of 25 subjects each: Group 1 (non-T2DM without periodontitis), Group 2 (non-T2DM with periodontitis) and Group 3 (T2DM with periodontitis). The outcome variable was periodontitis, and explanatory variables were age, sex, T2DM and specific P. gingivalis fimA genotypes.

RESULTS

In non-T2DM subjects with healthy periodontal tissues, type I fimA was the most frequently detected individually (40%) or in combinations (40%). In non-T2DM subjects with periodontitis, the most frequently detected type was Ib individually (20%) or in combinations (36%). In T2DM patients with periodontitis, the most frequently detected types were types I (20%) and III (20%), but there was no statistical difference (p>0.05) with non-T2DM periodontitis subjects.

CONCLUSIONS

Type I genotype was more frequently detected in periodontally healthy sites from non-T2DM subjects than in periodontitis sites from either subjects with or without T2DM. However, in sites affected by periodontitis from T2DM subjects the predominating types were I and III, which are less virulent strains of P. gingivalis.

No correlation of five gene polymorphisms with periodontal conditions in a Greek population

BACKGROUND

Various studies have examined possible correlations between a number of cytokine gene polymorphisms and periodontal disease in populations of different origins. The present study sought the correlation between four single-nucleotide polymorphisms (IL1A+3954, IL1B+4845, TNFA-308, COL1A1 Sp1), a variable number of tandem repeats polymorphism (IL1RN intron 2) and periodontal conditions in subjects of Greek origin.

METHODS

One hundred and ninety-two healthy subjects, stratified as non-periodontitis and periodontitis (chronic and aggressive) cases, participated in the present study. Genotyping was performed by polymerase chain reaction-based techniques using the primers and conditions described in the literature. The frequencies of genotypes between study groups were compared using Genepop v3.3 genetic software and Instat statistical package.

RESULTS

No differences were observed among the groups concerning the distributions of genotypes under investigation.

CONCLUSIONS

Carriage rates of the polymorphisms under investigation in systemically healthy subjects of Greek origin are well within the range reported for Caucasians but these polymorphisms cannot discriminate between non-periodontitis and periodontitis (chronic or aggressive) cases.

Microbiological composition associated with interleukin-1 gene polymorphism in subjects undergoing supportive periodontal therapy

BACKGROUND

Interleukin-1 gene polymorphism (IL-1 gene) has been associated with periodontitis. The present study examined the subgingival microbiota by IL-1 gene status in subjects undergoing supportive periodontal therapy (SPT).

METHODS

A total of 151 subjects with known IL-1 gene status (IL-1A +4845/IL-1B -3954) (IL-1 gene) were included in this study. Clinical data and subgingival plaque samples (40 taxa) were collected. These taxa were determined by the checkerboard DNA-DNA hybridization method.

RESULTS

Gender, smoking habits (n-par tests), age, and clinical periodontal conditions did not differ by IL-1 gene status. IL-1 gene-negative subjects had a higher total bacterial load (mean difference, 480.4 x 10(5); 95% confidence interval [CI], 77 to 884 x 10(5); P <0.02). The levels of Actinobacillus actinomycetemcomitans (mean difference, 30.7 x 10(5); 95% CI, 2.2 to 59.5 x 10(5); P <0.05), Eubacterium nodatum (mean difference, 4.2 x 10(5); 95% CI, 0.6 to 7.8 x 10(5); P <0.02), Porphyromonas gingivalis (mean difference, 17.9 x 10(5); 95% CI, 1.2 to 34.5 x 10(5); P <0.05), and Streptococcus anginosus (mean difference, 4.0 x 10(5); 95% CI, 0.2 to 7.2 x 10(5); P <0.05) were higher in IL-1 gene-negative subjects, an observation specifically found at sites with probing depths <5.0 mm.

CONCLUSIONS

Bleeding on probing did not differ by IL gene status, reflecting clinical SPT efficacy. IL-1 gene-negative subjects had higher levels of periodontal pathogens. This may suggest that among subjects undergoing SPT, a lower bacterial load is required in IL-1 gene-positive subjects to develop the same level of periodontitis as in IL-1 gene-negative subjects.

Assessment of Single Nucleotide Polymorphism at IL-1A+4845 and IL-1B+3954 as Genetic Susceptibility Test for Chronic Periodontitis in Maharashtrian Ethnicity

BACKGROUND

The inflammatory response that is directed in large part by proinflammatory cytokine interleukin (IL)-1 is genetically determined, with some people having a more vigorous response than others to the same stimulus. The reason for this is speculated that the dysregulated production of IL-1 in some individuals overrides the feedback mechanisms that normally master the dose of inflammation to a level sufficient to fight microbial invasion without long-lasting damage to the tissues involved. The aims of the present study were to determine the distribution of IL-1 gene polymorphism (IL-1A+4845 and IL-1B+3954) and their association with periodontal disease severity and to determine the significance of detecting the composite genotype (IL-1A allele2+IL-1B allele2) versus detecting either of them alone.

METHODS

A total of 120 subjects were included and divided into four groups of 30 subjects each, namely, healthy, mild, moderate, and severe periodontitis groups. After a complete clinical examination, DNA was isolated from 0.5 ml blood. Specific primers were used to detect the presence of IL-1 gene polymorphism with the help of polymerase chain reaction (PCR) and subsequent allele detection with restriction fragment length polymorphism (RFLP) and separation by gel electrophoresis.

RESULTS

The distribution of the allele1 homozygous genotype was 3% in the severe periodontitis group, and the distribution for the allele2 genotype was 30%. A higly significant difference (Wilcoxon signed-rank test; P<0.001) was seen between subjects positive and negative for the composite genotype.

CONCLUSIONS

Results of the present study reinforced the association of the IL-1 genotype as a risk factor for severe chronic periodontitis. Positivity for the composite genotype was found to be significantly associated with severe chronic periodontitis (odds ratio [OR]=12.42).

IL-1 gene polymorphism and periodontal status of HIV Brazilians on highly active antiretroviral therapy

A genotype in the IL-1 gene cluster is associated with an increased risk of periodontitis. We investigated whether polymorphisms in the IL-1A +4845 and IL-1B +3954 loci affect the periodontal status of HIV-infected Brazilians on HAART. HIV-positive and HIV-negative subjects with periodontitis were genotyped for IL-1 by polymerase chain reaction and restriction enzyme digestion. Only 11.4% of patients were genotype positive. No associations between genotype positivity and HIV infection or periodontal status were found in this population.

Association of the IL-1RN2 allele with periodontal diseases

OBJECTIVES

Interleukin-1 receptor antagonist (IL-1Ra) gene (IL-1RN) polymorphism is associated with disease susceptibility and activity in several inflammatory diseases. The aim of this study was to investigate IL-1RN genotype and its associations with different periodontal diseases in a group of Turkish subjects.

DESIGN AND METHODS

A total of 293 subjects were included in this study. Genomic DNA was obtained from the peripheral blood of 52 patients with generalized aggressive periodontitis (G-AgP), 51 with chronic periodontitis (CP) and 190 reference subjects. A variable number tandem repeat (VNTR) polymorphism in the second intron of the IL-1RN gene was detected by PCR-based methods. Probing pocket depth, clinical attachment loss, plaque accumulation and bleeding on probing (BOP) were recorded. The data were analyzed by the chi(2) test, logistic regression and Mann-Whitney U test.

RESULTS

There were significant differences among the groups in the distribution of IL-1RN genotypes (P = 0.0001) and allele frequencies (P = 0.0001). The frequency of IL-1RN2 allele 2 positivity was higher in the AgP and CP group than the reference group [odds ratio (OR) 6.654, 95% CI: 3.023-16.648; OR 10.327, 95% CI: 4.758-22.412, respectively]. The percentage of sites with BOP was significantly higher in IL-1RN2+ compared to IL-1RN2- CP patients (P = 0.022).

CONCLUSION

These results suggest that IL-1RN2 allele positivity is associated with periodontal disease in a Turkish population.

Effect of myrrh oil on IL-1β stimulation of NF-κB activation and PGE2 production in human gingival fibroblasts and epithelial cells

Anecdotal and scientific evidence suggest that myrrh oil (MO) has anti-inflammatory properties. Subtoxic MO levels decrease interleukin (IL)-1beta-stimulated production of the inflammatory cytokine IL-6 by human gingival fibroblasts, but not epithelial cells. IL-1beta upregulates IL-6 via PGE(2), and via NF-kappaB, a transcription factor for many inflammatory mediator genes. NF-kappaB is inhibited by sesquiterpene compounds (from plants other than myrrh). This study determined MO effect on IL-1beta-stimulated PGE(2) production and NF-kappaB activation in gingival fibroblasts and epithelial cells. Cells were preincubated with MO, exposed to IL-1beta, cytoplasmic and nuclear fractions were isolated, and activated NF-kappaB was measured using an ELISA-based assay. IL-1beta increased nuclear activated NF-kappaB levels in fibroblasts and epithelial cells [10- and 2.5-fold over controls, respectively (p=0.0001)], and these increases were not significantly affected by MO. PGE(2) was measured in cell supernatants by ELISA, after preincubation with MO and exposure to IL-1beta. MO inhibited IL-1beta-stimulated PGE(2) production by fibroblasts (p=0.001), but not epithelial cells. The data suggest that gingival epithelial cells and fibroblasts may differ in the magnitude of NF-kappaB activation after IL-1beta stimulation, and that MO inhibition of IL-1beta-stimulated IL-6 production in fibroblasts is due in part to inhibition of PGE(2), but not NF-kappaB activation. (Supported by NIDCR DE-0725.).

Interleukin 1 genetics, inflammatory mechanisms, and nutrigenetic opportunities to modulate diseases of aging

Inflammation plays a central role in many diseases of aging, and genetic differences in the inflammatory response appear to influence different disease courses among individuals. Variations in the genes for the family of interleukin 1 (IL-1) proteins are inherited together in a small set of patterns and provide an example of the role of inflammatory genetics as a modifier of diseases of aging. The IL-1 genetic variations are associated with variation in both the inflammatory response and the clinical presentation of a range of diseases, including coronary artery disease, Alzheimer disease, gastric cancer, and periodontitis. This growing understanding of the role of genetic variation in inflammation and chronic disease presents opportunities to identify healthy persons who are at increased risk of disease and to potentially modify the trajectory of disease to prolong healthy aging. Nutrition represents one of the promising approaches to modulation of the risk of diseases of aging because of the effects of certain nutrients on gene expression. One of the most practical applications of nutritional modulation of chronic disease may be nutrients that regulate the expression of key inflammatory genes.

Disease progression: identification of high-risk groups and individuals for periodontitis

AIMS

While the role of bacteria in the initiation of periodontitis is primary, a range of host-related factors influence the onset, clinical presentation and rate of progression of disease. The objectives of this review are (1) to present evidence for individual predictive factors associated with a patient's susceptibility to progression of periodontitis and (2) to describe the use of prognostic models aimed at identifying high-risk groups and individuals in a clinical setting.

METHODS

Relevant publications in the English language were identified after Medline and PubMed database searches. Because of a paucity of longitudinal studies investigating factors including clinical, demographic, environmental, behavioural, psychosocial, genetic, systemic and microbiologic parameters to identify individuals at risk for disease progression, some association studies were also included in this review.

FINDINGS AND CONCLUSIONS

Cigarette smoking is a strong predictor of progressive periodontitis, the effect of which is dose related. High levels of specific bacteria have been predictive of progressive periodontitis in some studies but not all. Diabetics with poor glycaemic control have an increased risk for progression of periodontitis. The evidence for the effect of a number of putative factors including interleukin-1 genotype, osteoporosis and psychosocial factors is inconclusive and requires further investigation in prospective longitudinal studies. Specific and sensitive diagnostic tests for the identification of individuals susceptible to disease progression are not yet a reality. While factors assessed independently may not be valuable in predicting risk of future attachment loss, the combination of factors in a multifactorial model may be useful in identifying individuals at risk for disease progression. A number of multifactorial models for risk assessment, at a subject level have been developed but require validation in prospective longitudinal studies.

Effect of genetic variability on the inflammatory response to periodontal infection

AIM

To review the association between genetic variability and the inflammatory response induced by periodontal infection.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed from January 2000 up to and including March 2005. The search included all types of publications, published in English without other limitations. The following search terms were used: "cytokine polymorphism", "gene polymorphism", "periodontitis", "gingivitis", "inflammation" and "host-response". The papers resulting from the above search were used as an additional source for relevant articles.

RESULTS

Genetic variability was examined for the correlation to clinical indicators of inflammation such as bleeding on probing (BOP), gingival inflammation, cytokine in gingival crevicular fluid (GCF) and cytokine production by inflammatory cells. According to the current literature, most of the studies found no association between genetic variability and BOP, gingival inflammation or cytokine concentrations in the GCF. These studies were hampered by inappropriate study designs and the use of inflammatory parameters as secondary rather than primary outcome variables. The data suggest that the production of inflammatory mediators by inflammatory cells may be affected by different genetic traits but further studies are needed in order to establish this association.

CONCLUSIONS

To date, there is no clear correlation between any of the gene polymorphisms and clinical indicators of inflammation. The powering of studies to reveal associations between single or multiple nucleotide polymorphisms and inflammatory parameters will need to involve a much larger number of subjects than were used in the past. The available data (including the interleukin-1 composite genotype) do not currently support the utility of such tests in the diagnosis and prognostic assessments of periodontal diseases.

Identification of genetic risk factors for periodontitis and possible mechanisms of action

AIM

To review the literature for genetic risk factors associated with periodontitis.

METHODS

Computerized search of the literature in English using key words: Periodontitis; Genes; Mutation; Polymorphism; Risk.

RESULTS AND CONCLUSIONS

Mutations in the cathepsin C gene (CTSC) have been identified as causal for the Papillon-Lefèvre syndrome (PLS), which includes prepubertal periodontitis (PP). Some CTSC mutations are causal for PP without PLS. No relationship has been demonstrated between CTSC mutations and other forms of periodontitis. Genetic polymorphisms in a candidate gene approach have been explored as risk factors for periodontitis. There is limited evidence that some polymorphisms in the genes encoding interleukins (IL)-1, Fc gamma receptors (Fc gammaR), IL-10 and the vitamin D receptor, may be associated with periodontitis in certain ethnic groups. However relatively large variations in carriage rates of the Rare (R)-alleles among studies on any polymorphism were observed. The available studies appear under-powered and do not adequately take into account other pertinent risk factors for periodontitis. Future studies should include larger cohorts, should clearly define phenotypes and should adequately control for other risk factors. In addition to the candidate gene approach, alternative strategies need to be considered to elucidate the gene variations, which confer risk for periodontitis.

Analytical epidemiology of periodontitis

AIMS

To review the literature related to the analytical epidemiology of periodontitis generated over the past decade. This review does not deal with descriptive epidemiologic studies of the prevalence, extent and severity of periodontitis with respect to global geography, but focuses exclusively on analytical epidemiology issues, including the challenges posed by the use of different case definitions across studies, current theories and models of disease progression, and risk factors associated with the onset and progression of periodontitis.

METHODS

Relevant publications in the English language were identified after Medline and PubMed database searches.

FINDINGS AND CONCLUSIONS

There is a conspicuous lack of uniformity in the definition of periodontitis used in epidemiologic studies, and findings from different research groups are not readily interpretable. There is a lack of studies that specifically address the distinction between factors responsible for the onset of periodontitis versus those affecting its progression. Colonization by specific bacteria at high levels, smoking, and poorly controlled diabetes have been established as risk factors for periodontitis, while a number of putative factors, including specific gene polymorphisms, have been identified in association studies. There is a clear need for longitudinal prospective studies that address hypotheses emerging from the cross-sectional data and include established risk factors as covariates along with new exposures of interest. Intervention studies, fulfilling the "targeting" step of the risk assessment process, are particularly warranted. Obvious candidates in this context are studies of the efficacy of elimination of specific bacterial species and of smoking cessation interventions as an alternative to the traditional broad anti-plaque approach in the prevention and control of periodontitis. Ideally, such studies should have a randomized-controlled trial design.

Epidemiology and risk factors of periodontal diseases

Periodontal diseases are chronic inflammatory disorders encompassing destructive and nondestructive diseases of the periodontal supporting tissues of teeth. Gingivitis is a nondestructive disease ubiquitous in populations of children and adults globally. Aggressive periodontitis is characterized by severe and rapid loss of periodontal attachment often commencing at or after the circumpubertal age and is more prevalent among Latin Americans and subjects of African descent, and least common among Caucasians. Chronic periodontitis is a common disease and may occur in most age groups, but is most prevalent among adults and seniors world-wide. Approximately 48% of United States adults have chronic periodontitis, and similar or higher rates have been reported in other populations. Moderate and advanced periodontitis is more prevalent among the older age groups, and rates of 70% or more have been reported in certain populations. Chronic and aggressive periodontitis are multifactorial diseases caused primarily by dental plaque microorganisms, and with important modifying effects from other local and systemic factors. The study of the significance of demographic, environmental, and biologic variables is important for risk assessment and the control of periodontal diseases.

Linkage disequilibrium analysis of case-control data: an application to generalized aggressive periodontitis

Several studies have shown a role for the involvement of interleukin (IL)-1 gene cluster polymorphisms in the risk of periodontal diseases. In the present study, we tested polymorphisms, derived from genes of the IL-1 cluster, for association with generalized aggressive periodontitis (GAP) through both allelic association and by constructing a linkage disequilibrium (LD) map of the 2q13-14 disease candidate region. The IL-1RN (VNTR) genotype distribution observed was significantly different in GAP and control subjects (P=0.019). We also observed some evidence for an association between GAP and the IL-1B(+3953) polymorphism (P=0.039). The pattern of association in the region, represented as an LD map, identifies a recombination hot area between the IL-1B(+3953) and IL-1B(-511) polymorphisms. Multilocus modelling of association with disease gives a location for the peak association at the IL-1B(+3953) marker, although support for the peak is not significant. Haplotype analysis identifies a IL-1B(+3953)-IL-1B(-511) haplotype as having the lowest P-value in the region. Recognition of the presence of a recombination hot area between the IL-1B(+3953) and IL-1B(-511) polymorphisms will have an important bearing on future efforts to develop higher resolution SNP analysis in this region for both this and other diseases for which this cluster is implicated.

Tooth loss is associated with increased risk of gastric non-cardia adenocarcinoma in a cohort of Finnish smokers

OBJECTIVE

Tooth loss has been associated with upper gastrointestinal cancer in several studies, but only one previous study used prospectively collected data. The importance of confounding by Helicobacter pylori has not previously been addressed. The objective was to determine the association between tooth loss and upper gastrointestinal cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort and to determine the importance of potentially confounding dietary factors or H. pylori seropositivity.

MATERIAL AND METHODS

A prospective cohort study with 29,124 subjects included 49 esophageal squamous cell carcinomas, 66 esophageal/gastric cardia adenocarcinomas, and 179 gastric non-cardia adenocarcinomas occurring between 1985 and 1999. Cox proportional hazards models adjusted for age and education were used to estimate hazard ratios (HRs) and 95% CIs. Odds ratios and 95% CIs were calculated with and without adjustment for H. pylori seropositivity in a nested case-control group to determine whether H. pylori confounded the association between tooth loss and gastric cancer.

RESULTS

Tooth loss significantly increased the hazard ratio for gastric non-cardia cancer, the HR (95% CI) for edentulous subjects versus those with < 10 teeth lost was 1.65 (1.09, 2.49, respectively). No statistically significant associations were found between tooth loss and esophageal squamous cell carcinoma or esophageal/gastric cardia adenocarcinoma. Confounding by dietary factors, tobacco smoking, or H. pylori did not explain these results.

CONCLUSIONS

Tooth loss was associated with increased risk of gastric non-cardia cancer, but not esophageal squamous cell carcinoma or esophageal/gastric cardia adenocarcinoma in this Finnish cohort.

Clinical and other risk indicators for early periodontitis in adults

BACKGROUND

Periodontal diseases affect over half the adults in the U.S., disproportionately affecting minority populations. Periodontitis can be treated in early stages, but it is not clear what features indicate, or could be risk factors for, early stages of periodontal attachment loss. This study aimed to evaluate associations between clinical and other risk indicators of early periodontitis.

METHODS

A cross-sectional evaluation of 225 healthy and early periodontitis adults aged 20 to 40 years was performed. Clinical measurements, demographic information, and smoking histories were recorded. Analyses evaluated demographic and clinical associations with health and early periodontitis disease categories and periodontal attachment loss. Patterns of attachment loss at interproximal and buccal/lingual sites were evaluated.

RESULTS

Subject age, plaque, and measures of gingivitis exhibited associations with attachment loss and probing depth. More periodontal attachment loss was detected in African-American and Hispanic subjects compared to Asian and Caucasian subjects. Smoking history was associated with attachment loss. At interproximal sites, lower molars most frequently had attachment loss, whereas at buccal/lingual sites, higher proportions of lower bicuspid teeth demonstrated attachment loss compared with other sites.

CONCLUSIONS

In this study of subjects with minimal attachment loss, gingival inflammation was associated with early periodontitis. Lower molar interproximal sites were frequently associated with interproximal attachment loss, whereas lower bicuspid teeth were at risk for gingival recession on buccal surfaces.

Association of interleukin-1 polymorphisms with aggressive periodontitis

BACKGROUND

Genetic polymorphisms for interleukin (IL)-1alpha and -1beta have been proposed as potential genetic markers for periodontal diseases. Since the prevalence of these polymorphisms could be race-related, and no data exist about the frequency of these polymorphisms in the Chilean population, the aim of the current study was to investigate the association of the interleukin-1 gene polymorphisms with aggressive periodontitis (AgP).

METHODS

Thirty-six patients with AgP, 75 healthy controls, and 75 subjects of unknown periodontal status (reference population) were genotyped for the IL-1A -889 and IL-1B +3954 loci, by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed using the chi-square test, calculating odds ratios (OR) and confidence intervals (CI).

RESULTS

The prevalence of the positive composite IL-1 genotype was higher in patients (25%) than in healthy controls (12%), but the difference was not significant (P= 0.14). The IL-1B +3954 homozygous for allele 1 frequency was higher in controls than in patients suggesting a protective factor for AgP. The heterozygous for allele 2 of the IL- 1B showed a significant association with AgP (OR = 2.86, 95% CI 1.06 to 7.71, P= 0.030). No association was observed in localized AgP and generalized AgP between the extent of disease and the presence of the composite positive genotype. Because the number of smokers was too small in patients and in controls, no other analyses were performed.

CONCLUSION

The results of the present study support a positive association between AgP and the presence of the IL-1B +3954 allele 2 polymorphism.

Association of Interleukin-1 Polymorphisms With Periodontal Disease

BACKGROUND

Several studies have investigated genetic polymorphisms for cytokines as potential genetic markers for periodontitis. Some studies have found that interleukin (IL)-1A and IL-1B polymorphisms are associated with a higher severity of periodontitis, while others found no association. The aims of this study were to determine the prevalence of the IL-1A-889 and IL-1B+3954 (previously described as +3953) polymorphisms in Chileans and their association with periodontitis.

METHODS

Subjects aged 20 to 48 were selected from people requesting dental treatment at a public health center in Santiago, Chile. A case-control study of 330 cases of periodontitis patients and 101 healthy controls was performed. A full-mouth periodontal examination was performed on each subject and a structured questionnaire was conducted to determine smoking habits. Cases were categorized as having initial, moderate, or severe periodontitis according to the percentage of sites with clinical attachment loss > or =3 mm. Genomic DNA was analyzed for polymorphism in the IL-1A gene at site -889 and IL-1B gene at site +3954 by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed by chi square test, analysis of variance (ANOVA), and by calculating odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Demographic and socio-economic characteristics of subjects were similar in cases and in controls. A higher frequency of heterozygous of the IL-1A-889 was found in cases than in controls, but the difference was not significant. The heterozygous of the IL-1B+3954 was significantly higher in cases than in controls and was associated with periodontitis (OR 3.12, 95% CI 1.59 to 6.09, P = 0.001). The homozygous for allele 1 of the IL-1B+3954 was a protective factor for periodontitis (OR 0.35, 95% CI 0.19 to 0.66, P = 0.001). The prevalence of positive genotype (at least one allele 2 present at each locus) was significantly higher in cases (26.06%) than in controls (9.9%) and was significantly associated with periodontitis (OR 3.21, 95% CI 1.60 to 6.44, P = 0.001), irrespective of the smoking status and periodontitis severity. Sensitivity of positive genotype was 26%, the specificity 90%, and the positive predictive value 89%.

CONCLUSION

Within the limits of this study, the results show that individuals carrying the positive genotype have significantly greater risk for developing periodontitis.

Effect of the Interleukin-1 Genotype on Outcomes of Regenerative Periodontal Therapy With Bone Replacement Grafts

BACKGROUND

Previous studies have shown an association between a specific genotype for the inflammatory cytokine interleukin (IL)-1 and the severity of periodontal disease. The purpose of this study was to evaluate the effect of the IL-1 genotype on the outcomes of periodontal surgical regenerative treatment with bone replacement grafts.

METHODS

Forty-four patients with interproximal intrabony defects were treated with bone replacement grafts. Probing depths (PD) and clinical attachment levels (CAL) were measured before treatment and at least 9 months post-treatment. Whole-mouth plaque index (WMPI) and bleeding index (WMBI) were recorded as well. All patients were tested for the IL-1 genotype.

RESULTS

Thirteen (29.55%) of the patients were IL-1 genotype positive. There was no statistically significant difference between the genotype-positive and genotype-negative groups regarding age, smoking status, gender, WMPI, and WMBI. There was no significant difference in PD or CAL between the genotype-positive and genotype-negative groups at baseline. Genotype-positive patients had a smaller reduction in probing depth (1.86 mm versus 2.13 mm) and a greater gain of clinical attachment (1.20 mm versus 0.65 mm). These differences were not statistically significant (P = 0.70, P = 0.40). Multivariate regression analysis showed that presurgical PD significantly influenced post-surgical PD and CAL, and only WMPI significantly influenced CAL.

CONCLUSION

In this study, there was no evidence that the IL-1 genotype influences the clinical treatment outcomes of regenerative periodontal therapy with bone replacement grafts.

Monocyte activation by Porphyromonas gingivalis LPS in aggressive periodontitis with the use of whole-blood cultures

In this study, we re-visited the issue of hyper-responsiveness of monocytes to bacterial lipopolysaccharide (LPS) in aggressive periodontitis patients. We used whole-blood cultures to compare monocyte activation by Porphyromonas gingivalis LPS between Thai subjects with generalized aggressive periodontitis and those without periodontitis. Upon stimulation with P. gingivalis LPS, expression of co-stimulatory molecules on monocytes and expression of CD69 on NK and gamma delta T-cells were analyzed by flow cytometry, and the production of interleukin-1 beta and prostaglandin E(2) was monitored by ELISA. LPS stimulation resulted in a dose-dependent up-regulation of CD40, CD80, and CD86 on monocytes, and up-regulation of CD69 on NK cells and gamma delta T-cells in both the periodontitis and non-periodontitis groups. The levels of activation markers and the mediator production after LPS stimulation were quite similar for both groups. In conclusion, we did not observe hyper-responsiveness of monocytes to P. gingivalis LPS challenge in Thai patients with aggressive periodontitis.

Impact of IL-1 genotype and smoking status on the prognosis of osseointegrated implants

AIM

This study evaluated the impact of the IL-1 genotype and smoking status on the prognosis and development of complications of osseointegrated implants.

MATERIAL AND METHODS

The clinical charts of 180 consecutively admitted patients were analyzed with respect to the occurrence of biological complications in conjunction with oral implants. Biologic complications were defined as clinical conditions with suppuration from the peri-implant sulcus, development of a fistula or peri-implantitis with radiologic bone loss. All patients had received one or more ITI dental implants, which had been in function for at least 8 (range: 8-15) years. This patient population had received 292 implants. From these, 51 implants in 34 patients showed late (infectious) biologic complications, and 241 implants had survived without any biologic complications at all.

RESULTS

Of the 180 patients, 53 were smokers, who were subdivided in a series of classes according to their intensity of smoking and 127 were never smokers. Sixty-four of 180 (36%) patients tested positive for the IL-1 genotype polymorphism. This prevalence corresponds to previous reports for the prevalence of European descent populations. The results for the non-smoking group indicated no significant correlation between implant complications and a positive IL-1 genotype. However, there was a clear association for heavy smokers between a positive IL-1 genotype and implant complications. 6 of 12 or half of the heavy smokers and IL-1 genotype-positive patients had either an implant failure, i.e. loss of implant, or a biologic complication during the follow-up period.

CONCLUSIONS

These findings have led to the conclusion that there is a synergistic effect between a positive IL-1 genotype and smoking that puts dental implants at a significantly higher risk of developing biologic complications during function.

The association between neutrophil numbers and interleukin-1alpha concentrations in gingival crevicular fluid of smokers and non-smokers with periodontal disease

OBJECTIVES

To test whether neutrophil numbers are directly correlated with interleukin-1alpha (IL-1alpha) concentrations in gingival crevicular fluid (GCF) of patients with periodontitis, and to investigate the effects of smoking on these parameters.

MATERIALS AND METHODS

A total of 99 GCF samples from 33 patients (14 smokers) suffering from severe chronic periodontitis were collected using Durapore filter strips. Polymorphonuclear leucocyte (PMN) numbers were counted using a Coulter cell counter and IL-1alpha levels were determined by ELISA. Total GCF protein was measured by Bio-Rad assay as a surrogate measure of GCF volume.

RESULTS

Mean IL-1alpha concentrations were significantly reduced in smokers compared with non-smokers (non-smokers: 3.29+/-2.02 pg/microg protein, smokers 1.59+/-1.13 pg/microg protein). There was no association between PMN numbers and IL-1alpha concentrations found when analysed either by site or by patient. PMN numbers were not significantly different between the two groups (non-smokers: 1.16 x 10(6)+/-1.04 x 10(6); smokers: 7.30 x 10(5)+/-8.07 x 10(5)). Smoking did not affect mean total protein concentration of samples.

CONCLUSIONS

Smoking significantly decreased IL-1alpha concentrations in GCF without affecting GCF volume sampled. The lack of association between IL-1alpha concentration and neutrophil numbers suggests that the reduced IL-1alpha concentrations seen in smokers is independent of any possible effect of smoking on neutrophil chemotaxis, and further suggests that smoking may directly inhibit IL-1alpha production.

Cyclooxygenase-2 inhibitors decrease interleukin-1beta-stimulated prostaglandin E2 and IL-6 production by human gingival fibroblasts

BACKGROUND

Previous work showed that normal and aggressive periodontitis (AgP) gingival fibroblasts produce the bone-resorbing cytokine IL-6. PGE2 is important in regulating IL-6 production. Non-steroidal anti-inflammatory drugs inhibit PG synthesis via COX-1 and/or COX-2 isoenzymes and may inhibit periodontal destruction. COX-2 is induced after cellular activation (i.e., by inflammatory cytokines such as IL-1beta). Little is known about IL-1beta-stimulated AgP fibroblast IL-6 and PGE2 production and their regulation by COX inhibitors. The objective of this study was to determine the effects of COX-2 inhibitors on amounts of PGE2 and IL-6 made by IL-1beta-stimulated gingival fibroblasts.

METHODS

Gingival fibroblasts (2.5 x 10(4)) from healthy or severe periodontitis patients were cultured in serum-free medium, with or without IL-1beta (10(-11)M) for 24 hours, with or without the COX-1/2 inhibitor indomethacin or the selective COX-2 inhibitors NS-398, celecoxib, or rofecoxib. PGE2 and IL-6 in culture supernatants were determined by specific enzyme-linked immunosorbent assay (ELISA)s.

RESULTS

All of the COX inhibitors caused dose-dependent decreases in IL-1beta-stimulated PGE2, to a maximum of > 90% in all cell lines (P < or = 0.0001). The selective COX-2 inhibitors, but not indomethacin, caused partial (generally up to approximately 60%), dose-dependent decreases in IL-1beta-stimulated IL-6 in all cell lines (P < or = 0.003). When exogenous PGE2 was added concurrently with COX-2 inhibitors before addition of IL-1beta, IL-6 production returned to levels at or approaching that produced by cells exposed only to IL-1beta (P < or = 0.04).

CONCLUSION

The results suggest that COX-2 inhibition may be useful in helping to control fibroblast production of IL-6 in patients with severe periodontitis.

Genes and gene polymorphisms associated with periodontal disease

The scientific literature during the last ten years has seen an exponential increase in the number of reports claiming links for genetic polymorphisms with a variety of medical diseases, particularly chronic immune and inflammatory conditions. Recently, periodontal research has contributed to this growth area. This new research has coincided with an increased understanding of the genome which, in turn, has permitted the functional interrelationships of gene products with each other and with environmental agents to be understood. As a result of this knowledge explosion, it is evident that there is a genetic basis for most diseases, including periodontitis. This realization has fostered the idea that if we can understand the genetic basis of diseases, genetic tests to assess disease risk and to develop etiology-based treatments will soon be reality. Consequently, there has been great interest in identifying allelic variants of genes that can be used to assess disease risk for periodontal diseases. Reports of genetic polymorphisms associated with periodontal disease are increasing, but the limitations of such studies are not widely appreciated. While there have been dramatic successes in the identification of mutations responsible for rare genetic conditions, few genetic polymorphisms reported for complex genetic diseases have been demonstrated to be clinically valid, and fewer have been shown to have clinical utility. Although geneticists warn clinicians on the over-enthusiastic use and interpretation of their studies, there continues to be a disparity between the geneticists and the clinicians in the emphasis placed on genes and genetic polymorphism associations. This review critically reviews genetic associations claimed for periodontal disease. It reveals that, despite major advances in the awareness of genetic risk factors for periodontal disease (with the exception of periodontitis associated with certain monogenetic conditions), we are still some way from determining the genetic basis of both aggressive and chronic periodontitis. We have, however, gained considerable insight into the hereditary pattern for aggressive periodontitis. Related to our understanding that it is autosomal-dominant with reduced penetrance comes a major clinically relevant insight into the risk assessment and screening for this disease, in that we appreciate that parents, offspring, and siblings of patients affected with aggressive periodontitis have a 50% risk of this disease also. Nevertheless, we must exercise caution and proper scientific method in the pursuit of clinically valid and useful genetic diagnostic tests for chronic and aggressive periodontitis. We must plan our research using plausible biological arguments and carefully avoid the numerous bias and misinterpretation pitfalls inherent in researching genetic associations with disease.

Distribution of Interleukin-1β+3954and IL-1α–889Genetic Variations in a Thai Population Group

BACKGROUND

The severe form of chronic periodontitis (CP) has been reported to be strongly associated with the presence of allele 2 of composite IL-1beta(+3954) and IL-1alpha(-889) genetic polymorphisms (genotype positive). However, other studies have reported conflicting findings, not only on the association between the composite IL-1 gene polymorphisms and CP, but also the link between IL-1 gene polymorphisms and aggressive periodontitis (AgP). These might have resulted from differences in ethnic background and disease entities. The aim of this study was to determine the distribution of IL-1beta(+3954) and IL-1alpha(-889) genetic polymorphisms in a group of Thai subjects based on their periodontal status, including CP, AgP, and healthy groups.

METHODS

A total of 123 Thai subjects were clinically and radiographically assessed for their periodontal status. Blood samples were collected by fingerstick and adsorbed onto filter paper. The IL-1beta(+3954) and IL-1alpha(-889) genotypes were performed by polymerase chain reaction, digested with restriction enzymes, and separated by gel electrophoresis.

RESULTS

The distribution of allele 1 homozygous genotype was 97.6% and 84.6% for IL-1beta(+3954) and IL-1alpha(-889), respectively. No allele 2 homozygous genotype was detected in either of these two gene loci. Only 1.6% (2 out of 123) of the subjects were genotype positive, which was too low to determine the association between the composite genotype of IL-1beta(+3954) and IL-1alpha(-889) and severe forms of periodontal disease.

CONCLUSION

Genetic polymorphism of IL-1 genes in these two loci may not be useful in predicting the severity of periodontal disease in the Thai ethnic group.

Signs of carotid calcification from dental panoramic radiographs are in agreement with Doppler sonography results

BACKGROUND

Duplex ultrasonography (DS) is a frequently used noninvasive method for assessing carotid artery stenosis. The level of agreement between panoramic radiographs (PMX) findings of radiopacities in the area of C3-C4 and DS results has not been established.

AIMS

(1) to examine the level of agreement between DS results and PMX signs of carotid calcification and (2) to evaluate the association between periodontitis and DS results.

MATERIAL AND METHODS

Eighty-three subjects who had received a DS assessment at the University of Washington Medical Center within 36 months volunteered for a periodontal examination, including assessments of probing pocket depth (PPD), attachment level (PAL), evidence of bleeding on probing and bone loss from PMX. Two examiners independently analyzed the radiographs for evidence of carotid calcifications. The distance between the cemento-enamel junction (CEJ) to bone level (BL) CEJ-BL was used to assess alveolar bone loss as a criteria for periodontitis.

RESULTS

Twenty-nine subjects (34.9%) presented with positive DS readings. The Mantel-Haentszel common odds ratio estimate for a positive DS score and periodontitis (> 30% of teeth with distance CEJ-BL > or = 4.0 mm) was 38.4 (95% CI: 10.6-138.7, p < 0.0001). For nonsmokers only (n = 72) the odds ratio was 43.0 (95% CI: 16.7-1178.0, p < 0.0001). Evidence of bleeding on probing was 16% of sites both in the DS-positive and -negative subjects. Subjects with a positive DS result had significantly more teeth with clinical evidence of attachment loss > or = 5.0 mm (p < 0.001). The odds ratio of having periodontitis (CEJ-BL > or = 4.0 mm at > or = 30% of the teeth) and medical records confirmed diagnosis of either a stroke or an infarct or both was 7.8 (95% CI: 2.6-23.8, p < 0.001).

CONCLUSIONS

Subjects with positive DS readings of the carotid arteries due to calcified arterial plaque are accurately detected by means of conventional PMX. The likelihood of being DS positive and having radiographic evidence of periodontitis is high. A dose-response relationship between the extent of carotid calcification and severity of periodontitis was demonstrated, supporting the hypothesis of an association between periodontitis and cardiovascular diseases.

Cytokine levels during symptomatic viral upper respiratory tract infection

BACKGROUND

Previous studies suggest a role for locally produced proinflammatory cytokines in the development and expression of illness during experimental infection with a variety of respiratory viruses. However, most of these studies fail to make comparisons between symptomatic and asymptomatic infected subjects.

OBJECTIVE

To compare the pattern of nasal cytokine elaboration in asymptomatic and symptomatic subjects experimentally infected with rhinovirus-39 (RV-39).

METHODS

Healthy adults underwent experimental intranasal inoculation with a safety-tested clinical isolate of RV-39. Nasal lavages were collected, nasal symptoms were recorded, and expelled nasal secretions were weighed before and then daily for 6 days after challenge. Nasal lavages were submitted for viral culture and assayed for cytokine protein levels by enzyme-linked immunosorbent assay.

RESULTS

Twenty-nine subjects were enrolled in the study. All subjects were infected as evidenced by viral shedding and/or seroconversion. Sixteen subjects were symptomatic and 13 were asymptomatic as evaluated by subject self-report. During infection, significant increases in mean levels of nasal interleukin 6 (IL-6) (P = .01) and IL-1 (P = .02) were observed in symptomatic but not asymptomatic subjects. In symptomatic subjects, these increases were temporally related to the development of nasal symptoms and production of secretions. Mean levels of IL-8, IL-10, and tumor necrosis factor a were not increased in either group during infection.

CONCLUSIONS

The results of this study demonstrate elevations in certain locally produced cytokines during symptomatic but not asymptomatic respiratory infection with RV-39. Future studies using selected anticytokine therapies may help elucidate the precise role of cytokines in mediating disease expression.

Single-nucleotide polymorphism in the CD14 promoter and periodontal disease expression in a Japanese population

It has been reported that there is a relationship between a single-nucleotide polymorphism (SNP) in the promoter region of the CD14 gene at position -159 (C-->T) and infectious diseases. The aim of the present study was to test the hypthesis that expression of this SNP correlates with periodontal disease in a Japanese population. The CD14 genotype was determined in 163 subjects with periodontitis and in 104 age- and gender-matched control subjects without periodontitis. The genotype distribution and allele frequency within the periodontitis patients were not significantly different from those of control subjects. There was, however, a significant difference in the genotype distribution between young patients (< 35 yrs) and older patients (>/==" BORDER="0"> 35 yrs). These findings suggest that CD14 -159C/T polymorphism is not related to the development of periodontitis in a Japanese population, but that, within the periodontitis subjects, expression of the SNP may be related to early disease activity.

Serum IL-1beta levels in health and disease: a population-based study. 'The InCHIANTI study'

Interleukin-1 plays a role in normal homeostasis and in the inflammatory response which is deemed to be responsible for the development of major chronic diseases that are highly prevalent in the elderly. Aim of this study is to evaluate the factors influencing the serum levels of Interleukin-1 beta, in a large and representative population. Data were from the InCHIANTI project, a study of factors contributing to the decline of mobility in late life, which sampled people living in two sites in the surroundings of Florence. Blood samples were obtained from 1,292 participants and frozen aliquots were stored at -80 degrees C. The serum levels of several cytokines were measured by enzyme linked immunosorbent assay using an ultrasensitive commercial kit. Interleukin-1 beta serum levels were associated with congestive heart failure (p > 0.001) and angina (p = 0.02), with Ca2+ serum levels (p = 0.02), and with a history of dyslipidemia (p = 0.05). We found no association between serum IL-1beta level and age, sex, consumption of cardioactive drugs and serum levels of IL-1Ra, IL-6, sIL-6R, IL-10 and TNF-alpha. Our data could lend support to the hypothesis that IL-1beta is mainly involved in the functional alterations of cardiomyocytes under conditions marked by mononuclear cell infiltration and by downregulation of calcium.

Acquisition and loss of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia over a 5-year period: effect of a triclosan/copolymer dentifrice

OBJECTIVES

The present study describes the natural history of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia over a 5-year period and the effect of a triclosan/copolymer dentifrice on these organisms in a normal adult population.

MATERIAL AND METHODS

Subgingival plaque samples were collected from 504 adult volunteers. Probing pocket depths (PPD) and relative attachment levels were measured using an automated probe. Participants were matched for disease status (CPI), plaque index, age and gender, and allocated to receive either a triclosan/copolymer or placebo dentifrice. Re-examination and subgingival plaque sampling was repeated after 1, 2, 3, 4 and 5 years. P. gingivalis, A. actinomycetemcomitans and P. intermedia were detected and quantitated using an enzyme linked immunosorbent assay. Logistic regression and generalised linear modelling were used to analyse the data.

RESULTS

This 5-year longitudinal study showed considerable volatility in acquisition and loss (below the level of detection) of all three organisms in this population. Relatively few subjects had these organisms on multiple occasions. While P. gingivalis was related to loss of attachment and to PPD >/=3.5 mm, there was no relationship between A. actinomycetemcomitans or P. intermedia and disease progression over the 5 years of the study. Smokers with P. gingivalis had more PPD >/=3.5 mm than smokers without this organism. There was no significant effect of the triclosan dentifrice on P. gingivalis or A. actinomycetemcomitans. Subjects using triclosan were more likely to have P. intermedia than those not using the dentifrice; however this did not translate into these subjects having higher levels of P. intermedia and its presence was uniform showing no signs of increasing over the course of the study.

CONCLUSION

The present 5-year longitudinal study has shown the transient nature of colonisation with P. gingivalis, A. actinomycetemcomitans and P. intermedia in a normal adult population. The use of a triclosan-containing dentifrice did not lead to an overgrowth of these organisms. The clinical effect of the dentifrice would appear to be independent of its antimicrobial properties.

The effect of a triclosan-containing dentifrice on the progression of periodontal disease in an adult population

OBJECTIVES

The aim of the present study was to determine the effect of unsupervised, long-term use of a 0.3% triclosan/2% copolymer dentifrice on the progression of periodontal disease in a general adult population.

METHODS

Five hundred and four volunteers were enrolled in a double-blind, controlled clinical trial. Participants were matched for disease status, plaque index, age and gender. At the baseline examination, probing pocket depths and relative attachment levels were recorded and participants were assigned to either the test or control group. Re-examinations took place after 6, 12, 24, 36, 48 and 60 months. Subgingival plaque samples were collected at each examination and assayed for Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia. A generalised linear model was used to analyse the data, with a number of covariates thought to influence the responses included as the possible confounding effects.

RESULTS

The triclosan/copolymer dentifrice had a significant effect in subjects with interproximal probing depths > or =3.5 mm, where it significantly reduced the number of sites with probing depths > or =3.5 mm at the following examination, when compared with the control group (p<0.001). Furthermore, this effect increased with increasing numbers of affected sites. There was no effect of the triclosan/copolymer dentifrice in individuals without probing depths > or =3.5 mm at the previous examination. Other factors significantly affecting probing pocket depths (PPD) included increasing age, smoking and presence of P. gingivalis. PPD > or =3.5 mm were positively associated with loss of attachment some 2 years later.

CONCLUSION

This study showed that in a normal adult population, unsupervised use of a triclosan/copolymer dentifrice is effective in slowing the progression of periodontal disease.

The interleukin-1 polymorphism, smoking, and the risk of periodontal disease in the population-based SHIP study

Several studies have shown a role for interleukin-1 gene cluster polymorphisms in the risk assessment for periodontal diseases. In the Study of Health in Pomerania (SHIP), 3148 subjects were randomly selected from the population and assessed for a broad range of diseases and environmental/behavioral risk factors. From the complete study group in the age 40 to 60 years, N = 1085 subjects were genotyped for the interleukin-1 genotype composite polymorphism in relation to periodontal parameters. The study objective was to elucidate the gene-environment interaction between the risk factors smoking and IL-1 polymorphism. An increased risk of periodontal disease was found for IL-1 genotype-positive smokers: odds ratio adjusted for age, sex, education, and plaque OR = 2.50 (95% C.I. 1.21 to 5.13; p = 0.013). This was not the case with subjects who never smoked: OR = 1.09 (0.73-1.62; p = 0.676). These results support the hypothesis of gene-environmental interaction in periodontitis.

IL-1 gene polymorphism and smoking as risk factors for peri-implant bone loss in a well-maintained population

The aim of the present study was (i) to investigate the relation between specific interleukin-1 (IL-1) gene polymorphisms and peri-implant bone loss at osseointegrated ITI(R) dental implants and (ii) to explore the association between these allelic variants of the IL-1 gene complex and peri-implant mucosal inflammation, in both smoking and non-smoking individuals. A sample of 90 consecutive Caucasian patients (aged 33-88 years), treated with at least one ITI-implant participated in this retrospective investigation. Standardized periapical radiographs were taken after prosthetic rehabilitation (133.6 days, SD 136.9 days) and at the time of the re-examination, on average 5.6 years (SD 2.5 years) thereafter. The radiographs were analyzed by a calibrated examiner for changes in peri-implant bone levels. The examiner was blind with respect to clinical parameters and IL-1 status. The distance between the implant shoulder and the first visible bone-implant contact (DIB) at the respective time points were measured using a computerized method. The absolute bone level difference during the years of service (ABL) and the annual bone loss (DeltaBL/year) were calculated for all the implants. Percentages of full mouth bleeding on probing (BOP), as well as of BOP calculated separately for teeth and implants, were determined for all visits and averaged for the entire observation period. Out of the total patient sample, there were 14 heavy smokers (= 20 cigarettes/day), 14 moderate smokers (5-19 cigarettes/day), 23 previous smokers (smoking cessation > 5 years) and 39 non-smokers. Twenty-eight (31.11%) patients were IL-1 genotype positive. Upon stratification for smoking status, significant differences were found for the variables ABL (P < 0.04, U-test) and DeltaBL/year (P < 0.04, U-test) between non-smokers and heavy smokers for the IL-1 genotype positive group but not for the IL-1 genotype negative group. Moreover, significant differences in ABL (P < 0.04, U-test) and DeltaBL/year (P < 0.04, U-test) were identified between former smokers and heavy smokers for the IL-1 genotype positive group. The differences in inflammatory parameters (BOP) did not reach statistical significance. This study suggests that in heavy cigarette smokers, carriage of a functionally significant IL-1 gene complex polymorphism is associated with an increased risk for peri-implant bone loss following prosthetic reconstruction and during the supportive periodontal care phase of the treatment.