慢性胃病患者口腔与胃内幽门螺杆菌研究

目的：研究慢性胃病患者口腔中是否存在幽门螺杆菌（Hp）,并分析胃病患者牙周状况与幽门螺杆菌的关系。方法：依据特异的尿素酶C基因和cagA基因设计引物,建立聚合酶链反应（PCR）方法。检测65例慢性胃病患者不同牙位龈上和龈下菌斑中的Hp。结果：65例慢性胃病患者胃黏膜标本中,PCR检测阳性标本58例（89．3％）,龈下菌斑Hp阳性率（47．7％）,高于龈上菌斑中的Hp阳性率（26．2％）。牙周袋深度（PD）≥4mm部位菌斑中Hp检出率显著高于PD〈4mm的部位（P〈0．05）。结论：口腔Hp是慢性胃病患者Hp感染的重要来源。     

牙周炎及胃病患者牙菌斑中的幽门螺杆菌

目的 明确牙周炎及胃病患者的牙菌斑中是否存在幽门螺杆菌（Ｈｐ）及Ｈｐ是否为细胞毒素相关基因Ａ阳性。方法 利用尿素酶Ｃ基因和ｃａｇＡ设计引物,通过聚合酶链反应（ＰＣＲ）检测口腔中的Ｈｐ。选择１３例胃病及１０例牙周炎患者,每例患者选６个有牙龈炎症的牙位取龈上、龈下菌斑,共计２７６份样本用于ＰＣＲ检测。结果 胃病组１１例患者和牙周炎组全部病例均少有１份菌斑样本检出Ｈｐ,其中尿素酶Ｃ基因在胃病组的阳性率为     

古细菌在牙周病患者龈下菌斑中的定性和定量分析

目的 探讨古细菌与牙周疾病的关系,为深入研究古细菌与人类疾病的相关性和古细菌的可能致病机制奠定基础.方法 收集侵袭性牙周炎23例、慢性牙周炎29例、慢性龈炎35例及牙周健康者38人的龈下菌斑,进行古细菌的定性和定量检测.结果 古细菌在龈下菌斑中的检出率:侵袭性牙周炎组65%,慢性牙周炎组72%,慢性龈炎组26%,健康对照组未检出.每微克湿重菌斑中的古细菌16S rRNA基因平均拷贝数:侵袭性牙周炎组6.66×106,慢性牙周炎组4.47×106,慢性龈炎组1.78×106.龈下菌斑中牙周炎组古细菌的检出率、古细菌16S rRNA基因平均拷贝数均高于龈炎组,差异有统计学意义(P＜0.05).结论 古细菌可能为牙周炎的致病因素之一.     

牙龈卟啉单胞菌在龈下菌斑和颊黏膜中的检测

目的　检测牙周健康者及牙周炎患者在颊黏膜和龈下菌斑中牙龈卟啉单胞菌的阳性率,探讨其与牙周炎发生和发展的关系。方法　选取40例牙周健康者和39例慢性牙周炎患者,分别收集颊黏膜和龈下菌斑样本,提取细菌DNA,设计细菌通用引物和牙龈卟啉单胞菌的特异引物用于PCR扩增,检测牙龈卟啉单胞菌的阳性率。结果　牙周健康组菌斑样本和颊黏膜样本牙龈卟啉单胞菌的阳性率分别为37·5%和32·5%,而牙周炎组菌斑样本和颊黏膜样本牙龈卟啉单胞菌的阳性率分别为69·23%和46·15%。牙周炎组菌斑的牙龈卟啉单胞菌阳性率高于牙周健康组,颊黏膜的牙龈卟啉单胞菌阳性率在组间无统计学差异;牙周炎组菌斑牙龈卟啉单胞菌阳性率高于颊黏膜, 牙周健康组两部位阳性率无统计学差异。结论　牙龈卟啉单胞菌除在菌斑中有高检出率外,在颊黏膜中也有较高的检出率,提示颊黏膜也是牙周细菌在口腔定植的重要部位,牙龈卟啉单胞菌也可在健康人群中检出,提示其有可能是口腔内固有菌群之一。     

不同引物检测慢性牙周炎龈下菌斑中齿垢密螺旋体

目的：利用两个不同引物对慢性牙周炎患者患病部位及相对健康部位龈下菌斑中齿垢密螺旋体（Td）进行检测,以了解Td在慢性牙周炎患者不同部位的分布及Td检出率与牙周炎临床指标的关系。方法：收集58例慢性牙周炎患者患病部位及相对健康部位龈下菌斑标本,利用PCR分别扩增53kDa外膜蛋白表达基因tdpA片段及16srRNA保守区片段。结果：58个患病部位龈下菌斑标本中tdpA及16srRNA扩增的阳性率分别为58．6％和81．0％,而相对健康部位龈下菌斑标本中PCR阳性率分别为8．62％及15．5％,患病部位Td检出率高于相对健康部位（P〈0．001）,16srRNA基因片段引物检出率高于tdpA基因片段（P〈0．05）。临床附着丧失≥5mm的患牙龈下菌斑标本中Td的检出率高于临床附着丧失〈5mm标本（P〈0．05）,不同牙周袋深度及牙龈指数标本的Td检出率之间差异无统计学意义（P〉0．05）。结论：在慢性牙周炎患者活动部位龈下菌斑中Td检出率高于相对健康部位;Td感染与慢性牙周炎关系密切;利用16srRNA保守区片段对齿垢密螺旋体进行检测检出率高于tdpA基因片段。     

成人牙周健康状况与fimA基因型牙龈卟啉单胞菌的相关性

目的分析不同fimA基因型牙龈卟啉单胞菌（P.gingivalis）在牙周健康人群和慢性牙周炎人群中的分布,探讨不同fimA基因型P.gingivalis与成人牙周状况的相关关系。方法收集牙周健康组（136例）和慢性牙周炎组（115例）的龈下菌斑样本,采用16S rRNA PCR法检测P.gingivalis,并根据各fimA基因型（Ⅰ～Ⅴ和Ⅰb）的特异性引物检测不同fimA基因型P.gingivalis菌株的分布,计算OR值和95%可信区间。结果牙周健康组和慢性牙周炎组龈下菌斑样本中P.gingivalis阳性率分别为22.1%和81.7%,多数样本中只检测到1种fimA基因型。牙周健康组中ⅠfimA型的检出率最高（占66.7%）;慢性牙周炎组中则为ⅡfimA基因型（占43.6%）,其次为Ⅳ和Ⅰb fimA基因型。慢性牙周炎的发生与P.gingivalis的关系密切（OR=16.36）,Ⅰ、Ⅰb、Ⅱ、Ⅲ、Ⅳ、ⅤfimA基因型P.gingivalis与慢性牙周炎相关性的OR值分别为0.97、13.26、36.62、4.57、22.86、1.19;ⅡfimA基因型P.gingivalis与慢性牙周炎的相关性最强,其次为Ⅳ和Ⅰb型。结论P.gingivalis菌株的fimA基因型存在差异,特异性fimA基因型P.gingivalis可能与成人慢性牙周炎的发生关系密切。     

齿垢密螺旋体在慢性牙周炎龈下菌斑中的分布

目的:采用聚合酶链反应(PCR)技术,检测慢性牙周炎患者患病部位和相对健康部位龈下菌斑中齿垢密螺旋体(Treponema denticola,Td),了解齿垢密螺旋体在不同部位龈下菌斑中的分布情况,并探讨其检出率与慢性牙周炎的关系。方法:选择58例慢性牙周炎患者患病部位和相对健康部位龈下菌斑,对齿垢密螺旋体tdpA基因片段进行扩增和克隆测序。结果:34例(58.6%)患病部位PCR为阳性,相对健康部位中5例(8.62%)PCR为阳性,患病部位齿垢密螺旋体检出率高于相对健康部位(P<0.001)。对tdpA基因克隆后测序,结果与B last比对与Gen Bank中已登陆的tdpA基因同源性为94%。结论:在慢性牙周炎患者患病部位龈下菌斑中,齿垢密螺旋体检出率高于相对健康部位,与慢性牙周炎关系密切,利用PCR方法检测Td,简便、特异性高。     

3种寡核苷酸探针对龈下菌斑中牙周致病菌的检测

目的　采用寡核苷酸探针研究龈下菌斑中3种牙周致病菌的分布。方法　利用3种寡核苷酸探针对 60例慢性牙周炎患者60个患病位点、10例健康人的10个健康对照位点龈下菌斑中的牙龈卟啉单胞菌、福赛类杆菌、牙密螺旋体进行检测。结果　牙周炎位点龈下菌斑中的牙龈卟啉单胞菌、福赛类杆菌、牙密螺旋体的检出率分别为91·67%,90·00%和95·67%,明显高于健康对照位点;有83·33%的牙周炎位点同时检出3种致病菌,3种细菌检出情况为两两正相关(P<0·01)。结论　牙龈卟啉单胞菌、福赛类杆菌、牙密螺旋体在慢性牙周炎患者龈下菌斑中的检出率很高,它们间可能存在相互协同致病作用。     

牙龈卟啉单胞菌PG0717基因与慢性牙周炎的相关性研究

目的检测慢性牙周炎患者和牙周健康者龈下菌斑中牙龈卟啉单胞菌（P.gingivalis）PG0717基因,探讨PG0717基因与牙周临床指数之间的关系。方法选取慢性牙周炎（CP）患者90例和牙周健康者90例,共采集龈下菌斑标本540个;记录临床牙周指数（牙周探诊深度、临床附着丧失和探诊出血）;设计特异性引物检测P.gingivalis阳性龈下菌斑标本的PG0717基因。结果在P.gingivalis阳性龈下菌斑中,CP组PG0717基因检出率显著高于对照组,分别为56.22%和41.27%（掊2=4.50,P＜0.05）;随着牙周探诊深度、临床附着丧失加重和探诊出血趋势的增加,CP组该基因检出率呈现增高趋势。结论PG0717基因与P.gingivalis的致病性有关。     

伴放线放线杆菌在龈下菌斑和颊黏膜分布研究

目的:比较伴放线放线杆菌(actinobac illus actinomycetem com itans,A.a)在不同类型牙周炎患者龈下菌斑和颊黏膜中的分布。方法:通过聚合酶链反应(polym erase chain reaction,PCR)对侵袭性牙周炎患者(AgP)、慢性牙周炎患者(CP)、牙周健康者口腔龈下菌斑和颊黏膜中的A.a进行检测,分析该菌分别在两部位的相对含量。结果:AgP组菌斑和颊黏膜样本中A.a阳性检出率均为41.7%,分别高于CP组(菌斑16.7%、颊黏膜10.0%)和牙周健康组(菌斑和颊黏膜均为0%)。AgP组A.a在菌斑和颊黏膜的相对含量分别为38.5%和22.2%,高于CP组(菌斑19%、颊黏膜12.75%)。结论:A.a不仅存在于龈下菌斑中,也能够粘附于颊黏膜;A.a是AgP的主要优势菌也参与了CP的菌群组成。     

The association of osteoprotegerin gene polymorphisms with periodontitis

Background:  It has been demonstrated that genetic variation accounts for approximately half of the variance in periodontitis. The reported association of polymorphisms in the osteoprotegerin (OPG) gene with osteoporosis suggests that the OPG gene may also influence the genetic risk for periodontitis.
Subjects and methods:  We investigated the distribution of OPG gene polymorphisms in 49 patients with aggressive ( n  =   14) or chronic ( n  =   35) periodontitis and 49 control subjects without periodontitis, using polymerase chain reaction (PCR)–restriction fragment length polymorphism and PCR–single strand conformation polymorphism followed by direct sequencing.
Results:  A total of seven known polymorphisms and one new mutation, G373A, were identified. The T950 and G1181 alleles were more common in patients with periodontitis ( P  =   0.028 and P  =   0.047, respectively) than in control subjects. Especially, G1181 allele was associated with patients with aggressive periodontitis.
Conclusion:  The TG haplotype of T950C and G1181C polymorphisms in the OPG gene may be useful genetic markers for the prediction of periodontitis. Further studies in a larger population are required to determine whether these alleles directly contribute to periodontitis susceptibility.     

Genetic polymorphisms in the MMP-1 and MMP-3 gene may contribute to chronic periodontitis in a Brazilian population

OBJECTIVES: Matrix metalloproteinase-1 and -3 (MMP-1, MMP-3) represent proteinases that degrade macromolecules of the extracellular matrix. These enzymes play a fundamental role during destruction of periodontal tissues. Genetic polymorphisms were characterized in the promoter region of the MMP-1 and MMP-3 genes. The aim of this study was to investigate the relationship between these genetic variations with chronic periodontitis in a Brazilian population. MATERIAL AND METHODS: Non-smoking subjects (n = 114) exhibiting sites > or = 5 mm clinical attachment loss were recruited for study. Control subjects (n = 109) should not exhibit clinical signals of periodontitis. MMP-1 (-1607 1G/2G, -519 A/G) and MMP-3 (-1612 5A/6A) gene promoter polymorphisms were genotyped using PCR-RFLP methods. RESULTS: Analysis of polymorphisms showed no differences in distribution of the -1607 1G/2G and -519 A/G variants in the MMP-1 gene between the healthy and periodontitis group (p > 0.05). However, the distribution of genotype frequencies of the -1612 5A/6A polymorphism in the MMP-3 gene showed that the 5A/5A genotype was significantly more frequent in the periodontitis group (p = 0.008). The same was not observed in the 5A/6A genotype once only one 5A allele is carried. We also observed a trend to increase the frequency of the MMP-1/MMP-3 haplotype (2G/5A) in the periodontitis group (p = 0.08). CONCLUSION: On the basis of the results, no significant association is found for the MMP-1 polymorphisms with susceptibility of periodontitis, while the MMP-3 gene polymorphism may contribute to periodontal tissue destruction during periodontitis in Brazilian subjects.     

RAGE基因多态性与2型糖尿病伴慢性牙周炎遗传易感性的相关研究

［摘要］ 目的 探讨晚期糖基化终产物受体(receptor for advanced glycation end products, RAGE)基因的5个SNP位点在2型糖尿病伴慢性牙周炎、单纯慢性牙周炎、健康对照北方汉族人群中分布的差异,从而研究RAGE基因是否为糖尿病和牙周炎可能的致病易感基因。方法 运用飞行时间质谱法检测19例2型糖尿病伴慢性牙周炎患者(DM组),22例单纯慢性牙周炎组(CP组)以及54例健康对照组(H组)全血基因组DNA中5个单核苷酸多态性(single nucleotide polymorphism, SNP)位点。结果 rs17846808、rs1800625、rs184003、rs2070600、rs3134940基因多态性在三组间分布无差异。DM组中的rs3134940 A/A（野生纯合子）基因型人群的龈沟出血指数(sulcus bleeding index,SBI)显著高于(A/G+G/G,杂合子和突变纯合子)基因型人群的SBI。CP组中的rs1800625 (T/C+C/C)和rs3134940 (A/G+G/G,杂合子和突变纯合子)基因型人群缺失牙数显著性增高。结论 RAGE基因并非2型糖尿病以及慢性牙周炎的易感基因。rs3134940 G等位基因可能在2型糖尿病伴慢性牙周炎进展过程中起到一定保护作用。     

Genetic variations in the human gelatinase A (matrix metalloproteinase-2) promoter are not associated with susceptibility to, and severity of, chronic periodontitis

BACKGROUND: Gelatinase A (matrix metalloproteinase-2 [MMP-2]) has been shown to play an important role in the pathogenesis of several disorders, including periodontal diseases. In this study, we test the hypothesis that variations in this gene influence the development and severity of chronic periodontitis. METHODS: Four promoter polymorphisms (-1575G/A, -1306C/T, -790T/G, and -735C/T) were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods in 149 patients with mild to severe chronic periodontitis and 127 age-matched controls in the Czech population. RESULTS: No significant differences in distribution of the -1575G/A, -1306C/T, and -735C/T variants between periodontitis and control groups were detected in our study. However, a trend to decreased frequency of the -790 GG homozygotes was observed in patients with chronic periodontitis compared to healthy controls (P = 0.036, P (corr) >0.05). Haplotype analysis of four single nucleotide polymorphisms (SNP) in the MMP-2 gene showed no significant association of any haplotype with chronic periodontitis. CONCLUSION: Our findings suggest that polymorphisms in the MMP-2 gene promoter do not contribute significantly to the interindividual periodontitis susceptibility and/or severity in European Caucasians, and they are not regulatory variants in this disease.     

Association between lactoferrin gene polymorphisms and aggressive periodontitis among Taiwanese patients

Background and Objective: A dramatic difference in the frequencies of the Lys/Arg single nucleotide polymorphism in the lactoferrin genotype between a small population of patients with localized juvenile periodontitis and healthy subjects has been reported. As the single nucleotide polymorphism could be associated with ethnicity, the present study aimed to investigate the association between polymorphisms of the lactoferrin gene and periodontitis. Material and Methods: Sixty‐five patients with aggressive periodontitis, 278 with chronic periodontitis and 88 healthy controls were genotyped for the Lys/Arg polymorphism of the lactoferrin gene at position 29 [reference sequence (rs) 1126478] in the N‐terminal alpha‐helical region. Results: The frequencies of the GG genotype and the G allele were highest in the aggressive periodontitis group, followed by the chronic periodontitis group and then the healthy controls. The frequency of the G allele was significantly higher in aggressive periodontitis and chronic periodontitis groups than in healthy controls (p = 0.0037 and 0.0212). Although the difference of the GG genotype distribution between subjects with chronic periodontitis and healthy controls did not reach significance, the distribution of genotypes between aggressive periodontitis and healthy controls was significantly different. The association of the gene polymorphism and aggressive periodontitis still existed, even after adjusting for age, gender and smoking status by logistic regression analysis (GG/AG+AA: odds ratio = 2.16, 95% confidence interval = 1.09–4.35, p = 0.0287). After the study, subjects were further stratified by their smoking status; the GG genotype was still significantly associated with the risk of aggressive periodontitis in the nonsmoking group (odds ratio = 2.69, p = 0.018). However, there were no statistical differences between chronic periodontitis vs. healthy controls and aggressive periodontitis vs. healthy controls in the smoking group. Conclusion: The present study revealed that the A/G polymorphism in the lactoferrin gene might be associated with aggressive periodontitis. The A allele might reduce the risk of development of aggressive periodontitis in a Taiwanese population. Our results also support the hypothesis that lactoferrin genetic polymorphisms could play a role in the risk for periodontitis separate from the smoking factor. The functionality of this gene’s polymorphisms has to be further elucidated.     

5 polymorphisms in the transforming growth factor-beta 1 gene (TGF-beta 1) in adult periodontitis

OBJECTIVES: Transforming growth factor-beta (TGF-beta) represents a family of polypeptide growth factors, involved in inflammation and regulation of immune responses. The purpose of this study was to determine whether polymorphisms in the TGF-beta 1 gene may confer susceptibility to adult periodontitis. MATERIAL AND METHODS: We studied 90 patients with adult periodontitis together with 108 unrelated subjects. 3 polymorphisms located in the 5'region at positions -988 (C/A), -800 (G/A) and -509 (C/T) and 2 polymorphisms located at codons 10 (L10P) and 25 (R25P) of exon 1 were investigated by PCR methods. RESULTS: There was no statistically-significant difference in genotype or allele frequency distributions between patients and reference group for the -800G/A, -509C/T, L10P and R25P polymorphisms (p>0.05 in all cases). The -988 A polymorphism was present neither in our patients nor in unrelated subjects. Upon stratification for smoking status no significant differences were found in the TGF-beta 1 genotype or allele frequencies either between adult periodontitis smokers compared to control smokers, or between periodontitis non-smokers and control non-smokers. CONCLUSION: These data indicate that the mentioned polymorphisms of the TGF-beta 1 gene do not influence susceptibility to adult periodontitis. There was no association between any polymorphisms in the TGF-beta 1 gene, severity of periodontitis and the smoking status in our study.     

Correlation between levels of fibrinogen, beta455 g/A fibrinogen gene polymorphism and chronic periodontitis]

OBJECTIVE: To investigate the relationship between plasma levels of fibrinogen, the-beta455 G/A fibrinogen gene polymorphism and the severity of periodontal inflammation and to explore the possible role of fibrinogen in the association of periodontitis with coronary heart disease (CHD). METHODS: A total of 121 patients with moderate to severe periodontitis and periodontally healthy and gingivitis controls were enrolled in the study. Peripheral blood samples were collected and the plasma fibrinogen levels were determined by the clotting method of Clauss. Polymerase chain reaction and restriction fragment length polymorphism analysis with Hae III were used to examine the -beta455 G/A fibrinogen gene polymorphism. RESULTS: Fibrinogen levels were significantly higher in moderately or severely chronic periodontitis patients [(3.45 +/- 0.68) g/L] than periodontally healthy and gingivitis controls [(2.47 +/- 0.42) g/L, P < 0.001]. The carrier status of the A allele at position -455 in the beta fibrinogen gene was associated with elevated fibrinogen levels and the frequency of the-A455 allele in the beta fibrinogen gene in the patient group was significantly higher than in the control group (P = 0.032). Carriers of the -A455 allele were about 3-fold more likely to have moderate or severe periodontitis as compare to individuals without the -A455 allele( OR = 3. =135, P= 0.008). CONCLUSIONS: Fg-beta455 G/A polymorphism may contribute to the elevated plasma fibrinogen levels and put individuals at higher risk of having severe periodontitis. As the independent risk factor of CHD, fibrinogen levels and Fg-beta455 G/A polymorphism may play a role in the pathogenesis of periodontitis.     

Association of the -159 CD14 gene polymorphism and lack of association of the -308 TNFA and Q551R IL-4RA polymorphisms with severe chronic periodontitis in Swedish Caucasians

BACKGROUND: Severe forms of periodontitis are suggested to have a genetic basis. OBJECTIVE: The aim of the present investigation was to study the association of gene polymorphisms related to some immune regulation components (G-308A TNFA, Q551R IL-4RA and C-159T CD14) with severe chronic periodontitis. MATERIALS AND METHODS: Sixty patients (aged 36-74 years; mean 54.5+/-8.5) with severe and generalized chronic periodontitis were included. The patients exhibited bone loss >50% at all teeth. Thirty-nine periodontally healthy subjects between 35 and 78 years of age (mean 51.0+/-10.9) were recruited as controls. DNA was isolated from peripheral blood cells and genotyping was performed by combination of PCR and restriction endonuclease mapping. RESULTS: While gene polymorphisms for TNFA and IL-4RA did not show any association with severe chronic periodontitis, the analysis of the -159 CD14 gene polymorphism revealed significant differences between test and control groups. The proportion of subjects that exhibited the TT genotype was significantly smaller in the group with severe periodontitis than in periodontal healthy group (p=0.028; Fisher's exact test). The C allele carriage was 90% in the periodontitis group and significantly higher than in the healthy control group (72%). CONCLUSION: It is suggested that the -159 CD14 gene polymorphism is associated with chronic periodontitis in Caucasian subjects of a north European origin.     

Association of interleukin-10 gene promoter polymorphisms with chronic and aggressive periodontitis

Oral Diseases (2012) 18 , 271–279 Objective: Interleukin‐10 gene promoter polymorphisms have been associated with interleukin‐10 decreased production, thereby playing a role in the pathogenesis of periodontitis. This study aimed to investigate whether interleukin‐10 single nucleotide polymorphisms at positions ‐1087(G/A) and ‐597(C/A) are associated with generalised chronic periodontitis and localised aggressive periodontitis. Methods: Genomic DNA samples were isolated from 276 unrelated Jordanian participants. Subjects were categorised into 86 periodontally healthy controls, 105 chronic periodontitis patients and 85 localised aggressive periodontitis patients. Genotype frequencies were calculated, and differences were determined using Pearson chi‐squared test, and odds ratio and 95 % confidence intervals were included. Results: The frequencies of the ‐1087A and ‐597A alleles were significantly more common in chronic periodontitis patients than controls. The A‐positive allele genotypes (GA, AA) at position ‐1087 and A‐positive allele genotypes (CA, AA) at position ‐597 appeared to increase the risk of having chronic periodontitis. No significant differences were observed in the genotype frequencies between localised aggressive periodontitis patients and controls. Conclusions: These findings indicate the possible use of interleukin‐10 single nucleotide polymorphisms as genetic markers in chronic periodontitis patients and further emphasise the molecular differences between chronic periodontitis and aggressive periodontitis.     

Polymorphisms in the +252(A/G) lymphotoxin-alpha and the -308(A/G) tumor necrosis factor-alpha genes and susceptibility to chronic periodontitis in a Czech population

BACKGROUND: Periodontitis is an inflammatory disease that leads to irreversible attachment loss, bone destruction and eventually tooth loss. Tumor necrosis factor (TNF), a pluripotent proinflammatory cytokine that is able to induce tissue destruction and bone resorption, has been implicated in the pathogenesis of periodontal disease. METHODS: In this study, we investigated an association between chronic periodontitis and two previously described bi-allelic polymorphisms in the TNF locus: a G to A transition at position -308 in the 5'promoter region of the TNF-alpha gene and an NcoI restriction fragment length polymorphism (RFLP) in the first intron (position +252A/G) of the lymphotoxin alpha (LT-alpha) gene. Genomic DNA was obtained from 132 patients with chronic periodontitis together with 114 age- and gender-matched unrelated control subjects. RESULTS: The TNF-alpha (-308G/A) polymorphism itself showed no association with chronic periodontitis, whereas the frequency distribution of the LT-alpha (+252A/G) genotypes showed statistically significant differences between patients and the reference group. The proportion of individuals carrying the LT-alpha 1/1 genotype was significantly lower in the group of patients with chronic periodontitis (0.8%) than in the control group (8.8%) (P < 0.0094, Pcorr < 0.05). However, the significant differences in the frequencies of the combined genotypes (TNF-alpha and LT-alpha) between the control and the patient groups were found using a simulation by applying the Monte-Carlo method (P < 0.01). CONCLUSION: Our data suggest that combined genotypes composed of the TNF-alpha and LT-alpha gene polymorphisms may influence the susceptibility to chronic periodontitis. We also showed that, comparing the two genes, the 1/1 genotype of the NcoI polymorphism in the first intron of the LT-alpha gene is a more informative marker and it may be one of the protective genetic factors against chronic periodontitis in our population.