Association of interleukin-1 polymorphisms with aggressive periodontitis

A Systematic Review and Meta-Analysis on Multiple Cytokine Gene Polymorphisms in the Pathogenesis of Periodontitis

Aim

Periodontitis is an inflammatory disease that destroys both soft and hard periodontal tissues. However, a complex periodontal cytokine network remains unclear. This systematic review explored multiple cytokine gene polymorphisms in the pathogenesis of periodontitis.

Material and Methods

A systematic search was performed using the databases from previous publications, which indicated the association between cytokine polymorphisms and periodontitis pathogenesis. Meta-analysis was conducted using fixed or randomized models to calculate the significance of multiple cytokine polymorphisms. A total of 147 articles were analyzed with polymorphisms in 12 interleukins [Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4 and IL-13), Th17 (IL-1α, IL-1β, IL-6, and IL-17), and Treg cytokines (IL-10 and TGF-β)]. Doi plot was used to probe the occurrence of publication bias.

Results

The polymorphisms of IL-2 and TNF-α of Th1 cytokine family may be associated with the pathogenesis or the prevention of periodontitis risk, while the polymorphism of IFN-γ is not related to periodontitis risk. The polymorphisms for IL-4 and IL-13 of Th2 cytokine family are not found to be associated with the pathogenesis of periodontitis. For the polymorphisms of the members of Th17 cytokine family, different IL-1α polymorphisms may have inverse actions in the pathogenesis of periodontitis. IL-1β is a noteworthy cytokine biomarker in periodontitis development and progression. IL-6 may have a protective function in the inflammatory responses of periodontitis, and IL-17 has a weak relationship the inflammatory responses. The polymorphisms for the members of Treg cell cytokines may have a protective function against periodontitis risk. LFK indexes show the major asymmetry due to publication bias.

Conclusion

IL-1β is a notable cytokine biomarker in periodontitis risk. Treg cytokines favor an anti-inflammatory and protective environment. Further data are needed to confirm the present conclusion due to publication bias.

A View on Polymerase Chain Reaction as an Outstanding Molecular Diagnostic Technique in Periodontology

Objectives

This study presents a discussion on the fundamentals of polymerase chain reaction (PCR) and its use as a diagnostic tool in periodontology.

Materials and Methods

A computer-aided as well as hand-made search in PubMed and Scopus indexed journals (relevant to the topic) was done by keywords of molecular technique in periodontology, PCR, applications of PCR, and PCR in periodontics. Only the papers in the English language and outlining PCR and its association with periodontology were collected and utilized to provide a succinct review. There was no limitation for publication time.

Results

The results of our search showed that PCR has turned into a standard in diagnosis in the field of periodontology. A variety of researches has demonstrated that its sensitive, and specific characteristics make it a quick and effective technique of recognition, identification, and quantification of microorganisms. Identification of various immunoinflammatory markers at the mRNA expression level as well as ascertaining gene-related polymorphisms can also be performed.

Conclusions

The mechanisms of periodontal disease can further become clarified using PCR. Clinical Relevance. PCR as a diagnostic method can play a main part in the validation of the clinical diagnosis of periodontal disease indicating the reason, pathogenesis, clinical steps, progress, and prognosis of the disease.

Relationship between -889 C/T polymorphism in interleukin-1A gene and risk of chronic periodontitis: Evidence from a meta-analysis with new published findings

Background

Periodontitis results from an inflammatory response caused by accumulative microorganisms in periodontal sites. Several factors are involved in pathogenesis of periodontitis, for example the -889 C/T polymorphism in interleukin-1A gene. This study aimed to evaluate the relationship between this polymorphism and risk of development of chronic periodontitis by a meta-analysis based in new published findings.

Material and Methods

Thereunto a review in literature was performed in the electronic biomedical and education databases (Cochrane Library, Google Scholar, MEDLINE and PubMed) to studies published before August 2, 2015, the abstracts were evaluated and the data extraction performed by two calibrated examiners. The calculations of the meta-analysis were obtained through statistical software Review Manager version 5.2 with calculation of Odds Ratio (OR), heterogeneity (I²) and Funnel plots with P <0.05.

Results

In overall, twenty-one case/control studies were selected with 2,174 patients with chronic periodontitis and 1, 756 controls. The meta-analysis showed T allele was associated with chronic periodontitis (OR = 1.22, 95% CI: 1.09, 1.36, P = 0.0004) with decreased value to heterogeneity (I² = 15%, P = 0.28). TT genotype was associated to patients with chronic periodontitis (OR = 1.40, 95% CI: 1.07, 1.83, P = 0.01). No publication bias was found in this meta-analysis by asymmetry in Funnel plots.

Conclusions

This meta-analysis with 2,174 patients with chronic periodontitis and 1, 756 controls evidenced the -889 C/T polymorphism is associated to risk of development of chronic periodontitis with no significant value to heterogeneity to allelic evaluation.

Key words:Alleles, odds ratio, periodontal disease, cytokines.

Assessment of the relationship between periodontal disease and cardiovascular disorders: a questionnaire-based study

Background and aims

Periodontitis is an inflammatory disease, characterized by the loss of connective tissue and alveolar bone. There is an increasing evidence that periodontitis is associated with a number of chronic diseases. The aim of this study was to analyze the correlation between periodontitis and certain systemic diseases by identifying their risk factors in a population from North-West Romania.

Methods

A questionnaire-based study was conducted on participants ≥45 years of age in 4 dentistry or family medicine practices from the Cluj and Bihor counties, Romania, over a time frame spanning two months. The interviewer-administered questionnaire included 42 items assessing risk factors for periodontal and cardiovascular disease, current diagnostic and medical treatment of the participants, their diet and oral hygiene habits.

Results

Of 108 participants included in the study, 63 (58.3%) declared a previous diagnosis of periodontitis. A significant difference was observed between the participants with declared diagnosis of periodontitis (PD+) and participants without declared diagnosis of periodontitis (PD−) for fresh fruit consumption (p=0.01) and increased sport activity (p=0.009). A significant difference between groups was observed in the case of smoking duration (p=0.047), participants with >10 years of smoking were more likely to declare a diagnosis of periodontitis. Also, PD+ participants were more likely to have a family history of periodontal disease (p<0.001). Multivariate analyses suggested periodontitis as a predictive variable for atherosclerotic coronary artery disease with an OR of 4.85 (95% confidence interval 1.01–23.29, p=0.049).

Conclusion

Our study found a statistically significant association between periodontal disease and a known family history of periodontal disorders and smoking duration. Daily intake of fresh fruit and increased sport activities were found to be protective factors against periodontal disease, while periodontitis was found as a risk factor for atherosclerotic cardiovascular disease.

Interaction of IL1B and IL1RN polymorphisms, smoking habit, gender, and ethnicity with aggressive and chronic periodontitis susceptibility

Background:

Although the interleukin-1 (IL-1) plays a critical role in the pathogenesis of periodontitis, associations between IL1 gene cluster polymorphisms and the disease remains unclear.

Aims:

To investigate the importance of IL1B-511C>T (rs16944), IL1B +3954C>T (rs1143634), and IL1RN intron 2 variable number tandem repeat (VNTR) (rs2234663) polymorphisms, individually or in combination, as the risk factors of periodontitis in a Southeastern Brazilian population with a high degree of miscegenation.

Subjects and Methods:

A total of 145 individuals, with aggressive (aggressive periodontitis [AgP], n = 43) and chronic (chronic periodontitis [CP], n = 52) periodontitis, and controls (n = 50) were genotyped by polymerase chain reaction (PCR) (IL1RN intron 2 VNTR) or PCR-restriction fragment length polymorphism (PCR-RFLP) (IL1B-511 C>T and IL1B + 3954C>T) techniques.

Statistical Analysis:

The independent t-test, Chi-square, and Fisher's exact tests were used. The SNPStats program was used for haplotype estimation and multiplicative interaction analyses.

Results:

The IL1B +3954T allele represented risk for CP (odds ratio [OR] = 2.84), particularly in smokers (OR = 4.43) and females (OR = 6.00). The minor alleles IL1RN*2 and *3 increased the risk of AgP (OR = 2.18), especially the IL1RN*2*2 genotype among  white Brazilians (OR = 7.80). Individuals with the combinations of the IL1B + 3954T and IL1RN*2 or *3-containing genotypes were at increased risk of developing CP (OR = 4.50). Considering the three polymorphisms (rs16944, rs1143634, and rs2234663), the haplotypes TC2 and CT1 represented risk for AgP (OR = 3.41) and CP (OR = 6.39), respectively.

Conclusions:

Our data suggest that the IL1B +3954C>T and IL1RN intron 2 VNTR polymorphisms are potential candidates for genetic biomarkers of periodontitis, particularly in specific groups of individuals.

Polymerase chain reaction: A molecular diagnostic tool in periodontology

This review discusses the principles of polymerase chain reaction (PCR) and its application as a diagnostic tool in periodontology. The relevant MEDLINE and PubMed indexed journals were searched manually and electronically by typing PCR, applications of PCR, PCR in periodontics, polymorphism studies in periodontitis, and molecular techniques in periodontology. The searches were limited to articles in English language and the articles describing PCR process and its relation to periodontology were collected and used to prepare a concise review. PCR has now become a standard diagnostic and research tool in periodontology. Various studies reveal that its sensitivity and specificity allow it as a rapid, efficient method of detecting, identifying, and quantifying organism. Different immune and inflammatory markers can be identified at the mRNA expression level, and also the determination of genetic polymorphisms, thus providing the deeper insight into the mechanisms underlying the periodontal disease.

Association between Interleukin-1β Gene -511C>T/+3954C>T Polymorphisms and Aggressive Periodontitis Susceptibility: Evidence from a Meta-Analysis

Background

Interleukin-1β (IL-1β) is an important inflammatory cytokine. The associations between IL-1β gene −511C>T/+3954C>T polymorphisms and aggressive periodontitis (AgP) susceptibility have been conflicting. We therefore conducted a meta-analysis to investigate the association of IL-1β genetic polymorphisms with susceptibility to AgP.

Material/Methods

PubMed and Embase electronic databases were searched for relevant studies. Odds ratios (ORs) with 95% confidence interval (CIs) were used to assess the association between IL-1β polymorphisms and AgP risk. Heterogeneity, publication bias, and sensitivity analysis were performed to guarantee the statistical power.

Results

Twenty published studies involving 965 patients and 1234 control subjects were included. No significant association between IL-1β polymorphisms and AgP was found. For −511C>T (T vs. C: OR=0.966, 95%CI=0.696–1.341, P=0.869; CT vs. CC: OR=0.936, 95%CI=0.761–1.151; TT vs. CC: OR=0.892, 95%CI=0.464–1.715, P=0.719; CT+TT vs. CC: OR=1.026, 95%CI=0.795–1.323; TT vs. CC+CT: OR=0.864, 95%CI=0.436–1.713). For +3954C>T (T vs. C: OR=1.069, 95%CI=0.901–1.268; CT vs. CC: OR=0.921, 95%CI=0.699–1.212; TT vs. CC: OR=1.064, 95%CI=0.747–1.515; CT+TT vs. CC: OR=0.990, 95%CI=0.764–1.283; TT vs. CC+CT: OR=1.229, 95%CI=0.919–1.643). Subgroup analyses were conducted with HWE, ethnicity, and study design, and no significant association was detected.

Conclusions

These results demonstrate that IL-1β −511C>T and +3954C>T polymorphisms are not the risk factors for developing AgP.

Interleukin polymorphisms in aggressive periodontitis: A literature review

Aggressive periodontitis (AgP), occurs in a younger age group (≤35 years) and is associated with the rapid destruction of periodontal attachment and supporting bone. Genetic polymorphisms are allelic variants that occur in at least 1% of the population that could potentially alter the function of the proteins that they encode. Interleukins are a group of cytokines that have complex immunological functions including proliferation, migration, growth and differentiation of cells and play a key role in the immunopathogenesis of periodontal disease. The aim of this review was to summarize the findings of studies that reported associations or potential associations of polymorphisms in the interleukin family of cytokines, specifically with AgP.

Risk factors of periodontal disease: review of the literature

Objectives. This paper aims to review the evidence on the potential roles of modifiable and nonmodifiable risk factors associated with periodontal disease. Data. Original articles that reported on the risk factors for periodontal disease were included. Sources. MEDLINE (1980 to Jan 2014), PubMed (using medical subject headings), and Google Scholar were searched using the following terms in different combinations: "periodontal disease," "periodontitis," "risk factors," and "causal." This was supplemented by hand-searching in peer-reviewed journals and cross-referenced with the articles accessed. Conclusions. It is important to understand the etiological factors and the pathogenesis of periodontal disease to recognize and appreciate the associated risk factors. As periodontal disease is multifactorial, effective disease management requires a clear understanding of all the associated risk factors.

Interleukin-1α -899 (+4845) C→T polymorphism is not associated with aggressive periodontitis susceptibility: A meta-analysis based on 19 case-control studies

A number of published studies investigated the association between interleukin-1α (IL-1α) −899 (+4845) C→T polymorphism and susceptibility to aggressive periodontitis (AgP). However, the results from different studies are controversial. This study was conducted to further investigate the association between IL-1α −899 (+4845) C→T polymorphism and AgP using a meta-analysis. A search was conducted through PubMed up to May 1, 2013 and a total of 19 relevant case-control studies were identified. The results of this meta-analysis demonstrated that IL-1α −899 (+4845) C→T polymorphism is not associated with susceptibility to AgP under allele T vs. C [odds ratio (OR)=1.00, 95% confidence interval (CI): 0.88–1.14, P=0.98; I²=28.86%] or allele A vs. C comparison (OR=0.99, 95% CI: 0.85–1.14, P=0.85; I²=33.66%). The subgroup analyses based on ethnicity, source of controls and Hardy-Weinberg equilibrium (HWE) also revealed no such association. There existed a weak publication bias (Egger’s test P=0.02). In conclusion, based on the currently available evidence, there is no association between IL-1α −899 (+4845) C→T polymorphism and susceptibility to AgP.

Analysis of interleukin-1β gene polymorphism and its association with generalized aggressive periodontitis disease

Generalized aggressive periodontitis (GAP) is a subgroup of periodontal diseases among 20-35 years age group adults. Several studies have reported the association of interleukin-1β gene polymorphism with periodontal diseases among different populations. The present study aimed at investigating the presence of IL-1β polymorphism in GAP patients in Iran. Further, the presence of IL-1β(+3954) gene polymorphism was evaluated in the GAP patients (n=26) and healthy individuals (n=26). All three genotypes (A1A1 [56%], A1A2 [28%], and A2A2 [16%]) were observed in healthy individuals, whereas only A1A1 (38.5%) and A2A2 (61.5%) were the genotypes observed in the patients. There was a significant positive association between distribution of IL-1β genotypes and the risk of periodontitis disease (p=0.017). Further, there was a significant positive association between probing pocket depth and IL-1β genotypes of patients (p=0.014). However, no meaningful correlation between genotype-clinical attachment loss and genotype bleeding on probing with the risk of GAP (p=0.418, p=0.819, respectively) was found. In conclusion, findings of the present study demonstrate a positive association between IL-1β gene polymorphism and risk of periodontitis disease.

Association of single nucleotide gene polymorphism at interleukin-1beta +3954, -511, and -31 in chronic periodontitis and aggressive periodontitis in Dravidian ethnicity

BACKGROUND

Interleukin (IL)-1beta gene polymorphisms are considered a potential risk factor for periodontal disease. The aim of this study is to identify the association of IL-1beta gene polymorphisms with chronic periodontitis and aggressive periodontitis in a Malayalam-speaking Dravidian population from South India.

METHODS

The case-control study consisted of 43 patients with chronic periodontitis and 54 patients with aggressive periodontitis as cases, and the control group consisted of 101 healthy subjects. All subjects were genotyped for IL-1beta +3954, -511, and -31 loci by polymerase chain reaction amplification followed by restriction enzyme digestion and gel electrophoresis. Genotype, allele, and haplotype analyses were done.

RESULTS

Analyses for allele and genotypes showed a high frequency of the C allele and CC genotype for single nucleotide polymorphism IL-1beta +3954 in the group with chronic periodontitis and no difference for patients with aggressive periodontitis compared to controls (P <0.05). Haplotype analysis showed that IL-1beta -31 and -511 were in strong linkage disequilibrium in all groups. The IL-1beta -31 allele T was in linkage with allele T of IL-1beta +3954 in the control group.

CONCLUSIONS

In the Malayalam-speaking Dravidian population, allele C of IL-1beta +3954 appeared to be an important risk factor for chronic periodontitis. The IL-1beta -31 allele T was in linkage with allele T of IL-1beta +3954 in the control group. No gene polymorphisms were found in patients with aggressive periodontitis. More studies with a larger sample size involving the entire cluster of the IL-1beta gene are necessary to determine the exact role of IL-1beta gene polymorphisms in periodontal disease.

IL-1 Gene Cluster is Not Linked to Aggressive Periodontitis

The interleukin-1 (IL-1) gene family has been associated with susceptibility to periodontal diseases, including aggressive periodontitis (AgP); however, the results are still conflicting. The present study investigated the association between IL-1 genes and AgP using 70 markers spanning the 1.1-Mb region, where the IL-1 gene family maps, and exploring both the linkage disequilibrium (LD) and the haplotype structure in a case-control study including 95 patients and 121 control individuals. No association between AgP and IL1A, IL1B, and IL1RN genes was found in either single-point or haplotype analyses. Also, the LD map of the region 2q13–14 under the Malécot model for multiple markers showed no causal association between AgP and polymorphisms within the region (p = 0.207). In conclusion, our findings failed to support the existence of a causative variant for generalized AgP within the 2q13–14 region in an Italian Caucasian population.

Evidence-based curriculum reform: the Kentucky Experience

Evidence-based health care seeks to base clinical practice and decision-making on best evidence, while allowing for modifications because of patient preferences and individual clinical situations. Dentistry has been slow to embrace this discipline, but this is changing. In the Graduate Periodontology Program (GPP) of the University of Kentucky, an evidence-based clinical curriculum was implemented in 2004. The tools of evidence-based health care (EBHC) were used to create evidence-based protocols to guide clinical decision-making by faculty and residents. The program was largely successful, although certain challenges were encountered. As a result of the positive experience with the GPP, the college is implementing a wider program in which evidence-based protocols will form the basis for all patient care and clinical education in the predoctoral clinics. A primary component of this is a computerized risk assessment tool that will aid in clinical decision-making. Surveys of alumni of the periodontal graduate program show that the EBHC program has been effective in changing practice patterns, and similar follow-up studies are planned to assess the effectiveness of the predoctoral EBHC program.

Polymorphisms in the interleukin-1 (IL1) gene cluster are not associated with aggressive periodontitis in a large Caucasian population

Polymorphisms in the interleukin-1 (IL1) gene have been suggested to influence transcription of IL1A (interleukin-1alpha) and IL1B (interleukin-1beta) and thereby the pathophysiology of periodontitis. This case-control association study on 415 northern European Caucasian patients with aggressive periodontitis (AgP) and 874 healthy controls was conducted to examine 10 single-nucleotide polymorphisms (SNPs) in the genes of the IL1 cluster for association with IL1A, IL1B, CKAP2L (cytoskeleton-associated protein 2-like), and IL1RN (IL-1 receptor antagonist). The results do not support an association between variants in the IL1 gene cluster and AgP. This case-control study had at least 95% power to detect genuine associations with variants carrying relative risks of at least 1.5 for heterozygous carriers and 2.25 for homozygous carriers. Previous reports of an association between IL1 promoter SNPs and periodontitis might reflect subpopulation effects and have to be interpreted with care.

Association of vitamin D receptor gene polymorphisms in Chinese patients with generalized aggressive periodontitis

BACKGROUND AND OBJECTIVE

The clinical features suggest that genetic factors may have a strong influence on susceptibility to aggressive periodontitis. The aim of this study was to investigate the association of vitamin D receptor gene polymorphisms with generalized aggressive periodontitis in Chinese patients.

MATERIAL AND METHODS

A restriction fragment length polymorphism (RFLP) for 10,438,141 C to T (rs1544410, BsmI), 10,382,063 A to G (rs731236, TaqI), 10,382,143 C to A (rs7975232, ApaI) and 10,416,201 A to G (rs2228570, FokI) of vitamin D receptor gene was analysed by polymerase chain reaction, followed by digestion with restriction enzymes and gel electrophoresis. The genotypes of 51 generalized aggressive periodontitis patients and 53 periodontally healthy control subjects were analysed. The genotypic and allelic frequencies of each polymorphism site for the patients and control subjects were compared.

RESULTS

The distribution of vitamin D receptor FokI genotypes and alleles between the two groups was significantly different (p = 0.043 and p = 0.012, respectively). The F allele seemed to increase the susceptibility of aggressive periodontitis (odds ratio = 2.02, 95% confidence interval = 1.16-3.50) in Chinese patients. There was no significant difference in the genotype distribution or the allele frequencies of vitamin D receptor BsmI, ApaI and TaqI between two groups.

CONCLUSION

The study indicates that FokI polymorphism of vitamin D receptor gene might be associated with generalized aggressive periodontitis in Chinese patients. In addition, the carriage of F allele increases the risk of developing generalized aggressive periodontitis.

The association of the composite IL-1 genotype with periodontitis progression and/or treatment outcomes: a systematic review

BACKGROUND

Genetically transmitted traits such as cytokine gene polymorphisms may accentuate the host inflammatory response to the bacterial challenge and influence susceptibility to periodontitis.

OBJECTIVE

To systematically review the evidence of an association between the interleukin-1 (IL-1) composite genotype, i.e. presence of the allele 2 in the gene clusters IL-1A-889 and in IL-1B +3953, and periodontitis progression and/or treatment outcomes.

MATERIAL AND METHODS

Based on the focused question, a search was conducted for longitudinal clinical trials comparing progression of periodontitis and/or treatment outcomes in IL-1 genotype-positive (carrying allele 2) and IL-1 genotype-negative (not carrying allele 2) subjects. A search in the National Library of Medicine computerized bibliographic database MEDLINE and a manual search were performed. Selection of publications, extraction of data and validity assessment were made independently by two reviewers.

RESULTS

The search provided 122 titles of which 11 longitudinal publications were included. The heterogeneity of the data prevented the performance of a meta-analysis. While findings from some publications rejected a possible role of IL-1 composite genotype on progression of periodontitis after various therapies, other reported a prognostic value for disease progression of the positive IL-1 genotype status. When assessed on a multivariate risk assessment model, several publications concluded that the assessment of the IL-1 composite genotype in conjunction with other covariates (e.g. smoking and presence of specific bacteria) may provide additional information on disease progression. The small sample size of the available publications, however, requires caution in the interpretation of the results.

CONCLUSION

Based on these findings, (i) there is insufficient evidence to establish if a positive IL-1 genotype status contributes to progression of periodontitis and/or treatment outcomes. Therefore, (ii) results obtained with commercially available tests should be interpreted with caution.

An overview of the epidemiology of periodontal diseases in Latin America

The aim of the present review was to identify the presence of periodontal diseases and the relative importance of known risk factors in Latin American countries. The retrieved data are sparse and inconsistent, lacking information for the majority of the countries. Gingivitis is ubiquitous in the region, affecting all ages independently of the socioeconomic background. The extension of bleeding may vary greatly, ranging from 40% to 70% of sites. The prevalence of aggressive periodontitis is higher in Latin America than in industrialized countries. Prevalence ranges from 0.3% to 4.5%, and the localized form is the less prevalent. The prevalence of chronic periodontitis is high, with a large variation (40-80%) probably due to differences in methodology and diagnostic criteria. Regional differences may be relevant. Known risk factors are present in the populations studied. Non-modifiable factors such as age, gender and genetics have been associated in Brazilian and Chilean populations. Tobacco smoking and diabetes are relevant risk factors. The importance of socioeconomic status, although present as a risk factor, has been largely underestimated. Oral hygiene is extremely deficient in the area although it is a cultural habit in most populations. It can be concluded that periodontal diseases are highly prevalent in Latin American populations. Its prevalence and extent are associated with known risk factors. Oral hygiene habits are deficient. Well designed epidemiological studies with external validity are needed.

Analysis of Tumor Necrosis Factor-α, Transforming Growth Factor-β, Interleukin-10, IL-6, and Interferon-γ Gene Polymorphisms in Patients With Chronic Periodontitis

BACKGROUND

Cytokine gene polymorphisms may have an impact on the susceptibility to and progression of chronic periodontitis. In this study, we analyzed the -1082 interleukin-10 (IL-10), -308 tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 1 (TGF-beta1) (codons 10 and 25), -174IL-6, and +874 interferon-gamma (IFN-gamma) gene single-nucleotide polymorphisms in a cohort of patients with chronic periodontal disease.

METHODS

The diagnosis was made on the basis of standardized clinical and radiographic criteria. A total of 122 adult patients with chronic periodontitis and 114 unrelated, ethnically and age-matched white control subjects were genotyped by a polymerase chain reaction-sequence-specific primer.

RESULTS

The number of individuals carrying the -174IL-6 CC genotype was significantly higher in the group of patients than in the control group (odds ratio [OR] = 1.896; 95% confidence interval [CI] = 1.106 to 3.250; P = 0.0283). The TGF-beta1 (codon 25) GG (Arg(25)/Arg(25)) genotype was detected more frequently in control subjects than in periodontitis patients (OR = 0.459; 95% CI = 0.230 to 0.920; P = 0.0421).

CONCLUSION

The -174IL-6 and TGF-beta1 (codon 25) single-nucleotide polymorphisms are associated with susceptibility to chronic periodontitis in the population studied.

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.

Evaluation of RANK/RANKL/OPG gene polymorphisms in aggressive periodontitis

BACKGROUND AND OBJECTIVE

Aggressive periodontitis (AgP) is a specific type of periodontal disease that is characterized by rapid attachment loss and bone destruction. While attempting to identify genetic polymorphisms associated with AgP, previous research has focused on candidate genes that may be involved in immune responses to microbial infections. In this study, the focus was on single nucleotide polymorphisms (SNPs) in the key mediators of osteoclast differentiation and activation, which involve receptor activator of nuclear factor-kappaB (RANK), RANK ligand (RANKL) and osteoprotegrin (OPG), in the Japanese population. The aim of this study was to evaluate the association of RANK/RANKL/OPG gene polymorphisms with AgP in the Japanese population.

MATERIAL AND METHODS

We examined 99 patients with AgP and 89 controls from the Japanese population to explore the possibility of RANK/RANKL/OPG loci as candidate regions associated with the disease. All exons and relevant exon-intron boundaries of these three candidate genes were amplified by polymerase chain reaction (PCR) using 19 primers, followed by direct sequencing. The polymorphisms were identified by comparing the sequences obtained from 48 subjects.

RESULTS

We identified 27 SNPs in RANK, including 10 novel SNPs and seven SNPs each in both RANKL and OPG. A pairwise linkage disequilibrium analysis using the r2 statistic showed that some SNP pairs from the three loci are in tight linkage disequilibrium.

CONCLUSION

An association analysis with allelotypes showed that SNPs identified in the RANK/RANKL/OPG genes have no significant association with AgP in the Japanese population.

Mikrobiologische Untersuchung zur Ermittlung des Erfolges der Sofortimplantation im parodontal geschädigten Gebiss

AIM

The aim of the present study was to investigate the prevalence of periodontal marker organisms and specific interleukin-1 (IL-1) gene polymorphisms (which show a close association with periodontitis) and their effect on the success of immediate implant placement postextraction in the patient with periodontal disease.

PATIENTS AND METHODS

A group of 59 patients (22 men and 37 women aged 20-81 years, median age 55 years, 18 smokers) with chronic adult periodontitis participated in the study which included a 1-year observation period postoperatively. Prior to tooth extraction two DNA samples were obtained for the microbiological diagnosis of five anaerobic gram-negative pathogens (Haemophilus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia sensu stricto, Treponema denticola) and to identify the IL-1 gene polymorphisms. Patients were treated with a total of 95 immediate dental implants (26 Ankylos/Friadent and 69 Camlog Root-Line/Camlog Biotechnologies) placed into extraction sites, 78 of which were loaded immediately. After 1 year four failures were observed; all of these patients were smokers.

RESULTS

None of these patients showed a positive IL-1 genotype; periodontal marker organisms were only found in one patient. No significant difference was seen in the microbiological pathogens between smokers and nonsmokers. Of 59 patients, 23 (39%) tested positive for IL-1 genotype polymorphism. Smoking was shown to increase the risk of implant failure. No association was observed between failures and the IL-1 gene polymorphisms or pathogens.

CONCLUSION

In conclusion, our study shows that periodontally infected sites do not seem to be a contraindication for immediate implantation.

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.