冠心病人口腔龈下菌斑中血链球菌、中间普氏菌的比较研究

目的:探讨口腔龈下菌斑中血链球菌、中间普氏菌与冠心病的关系。方法:检查与记录60例研究对象(冠心病组与对照组各30例)的牙龈指数(GI)、菌斑指数(PLI)、牙周袋探诊深度(PD)。应用生化法检测两组研究对象龈下菌斑中的血链球菌数,并用定性随机引物酶链反应法对两组研究对象龈下菌斑中的中间普氏菌进行了鉴定。结果:冠心病组的PD、PLI和龈下菌斑中的血链球菌数及中间普氏菌检出率明显高于对照组(P(0.05)。结论:冠心病组的牙周健康状况相对更差,与冠心病有关的口腔细菌除血链球菌外,龈下菌斑中的中间普氏菌也与冠心病的发病关系密切。     

小型猪双侧腮腺萎缩后唾液流率及口腔细菌变化的观察

目的 观察小型猪腮腺萎缩后混合唾液流率的变化以及对口腔主要致病菌的影响.方法 10只小型猪分成两组,每组5只,其中一组双侧腮腺注入甲紫致腺体萎缩,另5只作为健康对照组.分别在萎缩后第12、24个月收集混合唾液并观察唾液流率的变化;同时检测小型猪龈下菌斑和混合唾液中口腔主要致病菌数量并与健康对照组比较.结果 腮腺萎缩后第12个月混合唾液流率自(1.36±0.74)ml/min下降到(1.32±0.65)ml/min,第24个月唾液流率自(0.72±0.34)ml/min上升到(0.86±0.57)ml/min;龈下菌斑中的核梭杆菌、后牙龈下菌斑中厌氧菌总数、产黑菌数量均明显高于健康对照组;第12个月前牙和第24个月后牙的龈下菌斑中变形链球菌有短暂升高,而需氧菌总数、乳酸菌和放线菌数量无明显变化.唾液中除变形链球菌和产黑菌在腮腺萎缩早期有轻度上升外,其余细菌数量均无明显变化.结论 双侧腮腺萎缩后明显降低口腔中唾液总量,导致牙菌斑中的致龋菌和牙周致病菌数量上升.     

含抗变形链球菌IgY抗体的溶液对菌斑的作用

目的　观察含 0 1%抗变形链球菌IgY抗体的溶液对变形链球菌及菌斑量的作用效果。方法　采用双盲法 ,试验组 4 4名小学三年级学生使用含IgY抗体的溶液 2 1d ,对照组 4 1人使用安慰剂。试验前后对所有学生的菌斑指数、菌斑量、唾液和菌斑中的变形链球菌进行了检测。结果　试验组学生试验前的菌斑重量是 (46 4± 31 2 )mg ,试验后的菌斑重量是 (36 6± 2 5 6 )mg ,试验前后的差异有极显著性 (P =0 0 0 7) ,与试验前相比菌斑量减少了 2 1 1%。对照组学生的菌斑重量在试验前后分别是 (45 0± 2 3 8)mg和 (41 2± 2 5 9)mg ,二者差异无显著性 (P =0 2 86 )。唾液和菌斑中的变形链球菌量没有显著变化。结论　含 0 1%抗变形链球菌IgY抗体的溶液有减少菌斑形成的作用。     

127名汉族青年口腔唾液一氧化氮含量检测

目的 :研究健康汉族青年唾液中一氧化氮 (NO)含量正常参考值限 ,及其与口腔龋病、龈炎的关系。方法 :分别采集口腔正常 (42名 )、有龋病 (49名 )或龈炎 (36名 )的健康汉族青年学生口腔唾液 ,由专业人员用NO检测试剂盒 ,比色并计算出唾液中NO含量。结果 :男性唾液中NO含量值限为 0～ 2 40mol/L ,均值为(6 7.0 2 5± 39.0 6 5 ) μmol/L ;女性唾液中NO含量值限为 0～ 2 39μmol/L ,均值为 (76 .397± 34 .85 6 ) μmol/L。口腔正常组、龋病组、龈炎组唾液NO含量均值 ,分别为 (6 8.2 86± 37.432 ) μmol/L ,(6 8.6 82± 34 .6 2 7) μmol/L和 (79.70 0±40 .0 0 7) μmol/L ,经统计学检验 ,3组间唾液NO含量无显著差异 (P >0 .0 5 )。 结论 :汉族青年唾液NO含量正常参考值在 11～ 140 μmol/L ,唾液中NO含量在浅、中度龋和轻度龈炎者中 ,未见明显增高 (P >0 .0 5 )。     

正畸粘接用玻璃离子粘固剂的抑菌性能研究

目的　探讨正畸粘接用玻璃离子粘固剂对托槽周围菌斑中致龋菌是否有抑制作用。方法　选择 2 2例患者 ,采用自身对照方法 ,分别用玻璃离子粘固剂和复合树脂粘接剂粘接托槽 ,1个月后采集托槽周围菌斑 ,进行细菌培养和微生物分析。结果　 2种粘接剂托槽周围菌斑的总菌落形成单位数 (cloneformingunit ,CFU)差异无显著性 (复合树脂粘接剂为 2 4× 10 10 CFU/L ,玻璃离子粘固剂为 2 8× 10 10 CFU/L ,P =0 6 73)。与复合树脂粘接剂相比 ,应用玻璃离子粘固剂后并未明显减少托槽周围菌斑中变形链球菌的数量和百分比。结论　正畸粘接用玻璃离子粘固剂不能在较长时间内有效抑制托槽周围致龋菌的生长繁殖     

龋病和牙周病主要致病菌分布的影响因素

目的 本研究分析龋病和牙周病主要致病菌的分布与研究人群人口统计学特征、口腔卫生状况和习惯及吸烟、饮酒习惯之间的关系.方法 选纽约港医疗保健系统和纽约贝勒维医疗中心2009年3月30日至2011年4月27日之间的98名应试者的人口统计学变量、口腔健康状况、口腔健康维护行为及吸烟、饮酒习惯等数据库信息及唾液和牙菌斑样本DNA进行实验研究.唾液和牙菌斑样本DNA,进行实时定量PCR,SPSS19.0统计软件分析实验所得数据,卡方检验比较不同细菌的分布情况,Kruskal-Wallis非参数检验比较不同组别DNA水平的差异.结果 性别、收入水平、受教育程度和身高体重指数不同组间,所有被测细菌均无显著性差异.口腔健康状况(包括牙齿和牙龈)较差组的人群牙龈卟啉单胞菌,牙密螺旋体,福赛斯坦纳菌,变异链球菌和远缘链球菌的检出率均高于口腔健康状况较好的2组.从不使用牙线组的牙周主要致病菌的检出率均高于其他3组,牙密螺旋体的检出率有显著性差异(P=0.023).吸烟者与饮酒者的被测细菌与不吸烟不饮酒者有所不同.牙龈卟啉单胞菌,牙密螺旋体,伴放线放线杆菌,福赛斯坦纳菌4种细菌在牙菌斑中的DNA水平均高于唾液.相关性分析结果表明,四种细菌在唾液中和龈下菌斑中的DNA水平具有显著相关性(P<0.001).结论 口腔健康状况、使用牙线、吸烟、饮酒可能影响龋病和牙周致病菌的分布,龈下菌斑中的牙周致病菌含量高于唾液,不同个体的龈下菌斑中牙周致病菌的DNA水平与唾液密切相关.     

PCR方法对牙周炎患者唾液中牙龈卟啉单胞菌的检测

目的用PCR方法,检测牙周病患者唾液中牙龈卟啉单胞菌(Porphyromonas gingivalis,P.g),并探讨采用唾液标本与龈下菌斑标本检测结果的一致性.方法选择临床54例牙周炎患者病例,分别取其静止唾液和龈下菌斑标本,设计P.g菌16SrDNA引物,分别对2种标本进行PCR扩增,观察P. g菌的检出率,并计算kappa值.结果静止唾液和龈下菌斑标本中P.g菌的检测结果具有高度一致性,其检出率分别为83.3%(45/54)和79.6%(43/54),Kappa值为0.755,准确度达92.6%.结论本研究所用的引物可用于口腔中P.g菌的检测,特别是研究中采用的唾液标本,取材方便,有可能代替龈下菌斑标本.     

第一恒磨牙窝沟菌群组成

目的　分析儿童第一恒磨牙窝沟菌群的组成,为进一步分析窝沟致龋细菌与龋的关系打下基础。方法　取健康第一恒磨牙咬合面窝沟处菌斑接种于BHIS、MSA和RogosaSL培养基,分析菌群构成;API 2 0Strep试剂盒鉴定链球菌。结果　窝沟菌斑中以镜检革兰氏染色阳性杆菌居多,占总菌的(6 1 .87±4 .85 ) %,其次是革兰氏染色阳性球菌(37.6 8±5 .6 1 ) %。菌斑中的优势链球菌为变形链球菌(S .mutans) (1 8.2 6±4 .73) %、血链球菌(S .sanguis) (3.32±1 .2 9) %、缓症链球菌Ⅰ型(S .mitisⅠ) (2 .5 5±0 .96 ) %和口腔链球菌(S .oralis) (0 .76±0 .36 ) %。结论　儿童健康恒磨牙窝沟菌群中,杆菌数多于球菌;这些杆菌与疾病特别是龋病的关系有待于进一步的研究。     

糖尿病患者唾液葡萄糖含量分析

目的 :研究糖尿病患者唾液中葡萄糖含量的改变 ,并观察高血糖状态下唾液糖与血糖的关系。方法 :实验组为 6 0例糖尿病患者 ,对照组为 6 0例正常人。收集实验组及对照组清晨非刺激状态下自然分泌的全唾液 ,进行葡萄糖含量分析 ,同时行空腹血糖分析。结果 :糖尿病组的唾液葡萄糖含量为 ( 1.95 0±0 .179)mmol/L ,高于对照组的 ( 0 .95 3± 0 .12 4)mmol/L ,二者有显著性差异 (P <0 .0 1)。糖尿病组的唾液葡萄糖含量与血糖浓度有显著直线相关性 (P <0 .0 5 )。结论 :糖尿病患者唾液腺分泌功能发生改变 ,这可能是机体在长期高血糖状态下对唾液腺的损害 ,可视为糖尿病这一全身性代谢疾病的口腔局部表现     

口腔血链球菌与牙周病

血链球菌是口腔正常菌群组份之一,随着牙齿的萌出早期定植牙面,通过植物血凝素样附着素、非植物血凝素样附着素与唾液中受体特异结合,粘附于获得性膜上,以疏水作用维持其稳定,可与多种细菌发生聚集反应,在龈上、龈下菌斑形成中起重要作用。血链球菌通过产生过氧化氢和血链素拮抗牙周病的可疑致病菌,是牙周主要有益菌。     

Correlations between bacterial levels in autologous subgingival plaque and saliva of adult Sudanese

The aim of this study was to assess levels of oral bacteria and their correlations in paired samples of saliva and subgingival plaque in a population of adult Sudanese. Whole saliva and pooled subgingival plaque samples from six probing sites of one tooth in each jaw were obtained from 56 Sudanese adults (mean age 35.2+/-8.9 years). Levels of 24 oral bacteria in the autologous saliva and pooled plaque sample of each subject were assessed by DNA probes and checkerboard DNA-DNA hybridization. There were significantly ( P< or =0.01) higher percentages of subjects with > or =10(5) bacterial cells of Prevotella intermedia, Campylobacter rectus, Veillonella parvula, Streptococcus mutans, Lactobacillus acidophilus, Streptococcus anginosus, Streptococcus salivarius, and Leptotrichia buccalis and significantly ( P< or =0.01) lower percentages with Treponema denticola in saliva than in subgingival plaque. The detection frequencies at > or =10(6) bacterial cells were significantly higher for Selenomonas sputigena, S. anginosus, Streptococcus sanguis, and S. salivarius and significantly lower for Porphyromonas gingivalis in saliva than in subgingival plaque ( P< or =0.01). Porphyromonas gingivalis, Fusobacterium nucleatum, S. sputigena, S. sanguis, and Streptococcus mitis demonstrated significant ( P< or =0.05) positive correlations between their levels in plaque and saliva. This study indicates that the levels of P. gingivalis, F. nucleatum, S. sputigena, S. sanguis, and S. mitis correlate significantly in saliva and subgingival plaque and that higher accuracy of detection and assessment of the levels of these bacteria in the oral cavity may be achieved by concurrent sampling of saliva and subgingival plaque.     

Antibiotic resistance of subgingival species during and after antibiotic therapy

AIM: The purpose of the present investigation was to determine the percentage and identity of antibiotic-resistant species in subgingival plaque and saliva samples from chronic periodontitis patients treated by scaling and root planing followed by orally administered amoxicillin or metronidazole. METHOD: In all, 20 chronic periodontitis patients were selected for study. After clinical and microbiological monitoring, subjects were randomly assigned to receive either orally administered amoxicillin at the dosage of 500 mg, 3 times daily for 14 days or orally administered metronidazole at the dosage of 250 mg, 3 times daily for 14 days. For the antibiotic resistance determinations, subgingival plaque samples were taken from six posterior teeth at baseline, and 90 days; and from two randomly selected teeth at 3, 7 and 14 days during and after antibiotic administration. Samples were plated on enriched blood agar plates with or without either 2 micro g/mL metronidazole or 2 micro g/mL amoxicillin. Colonies were counted at 7 days. Significant differences in percentage of resistant organisms over time were determined by the Quade test. Microbial growth was washed from antibiotic-containing media and the identity of species determined using checkerboard DNA-DNA hybridization. Data were compared with those obtained in a previous study from subjects receiving SRP only or SRP followed by 14 days of orally administered doxycycline. The level of doxycycline used to determine antibiotic resistance in that study was 4 micro g/mL. RESULTS: The mean percentage of resistant isolates increased during antibiotic administration and returned to baseline levels by 90 days post therapy. The mean percentages (+/- SEM) of isolates resistant to 2 micro g/mL metronidazole were 53 +/- 9, 65 +/- 9, 79 +/- 4 and 69 +/- 7 at baseline, 3, 7 and 14 days during antibiotic administration, and 57 +/- 4, 64 +/- 5, 62 +/- 7 and 47 +/- 6 at 3, 7, 14 and 90 days after antibiotic administration. At the same time points, the percentage of resistant isolates to amoxicillin was 0.5 +/- 0.2, 22 +/- 12, 14 +/- 5 and 37 +/- 11 during, and 31 +/- 11, 8 +/- 3, 3 +/- 2 and 3 +/- 0.6 after, administration. Antibiotic-resistant isolates of resistant species detected during or after therapy were also detected prior to therapy. The most prevalent resistant species in the metronidazole-treated group were: A. naeslundii 1, S. constellatus, A. naeslundii 2, S. mitis, S. oralis, A. odontolyticus, S. sanguis, and in the amoxicillin-treated group: S. constellatus, P. nigrescens, E. saburreum, A. naeslundii 1, S. oralis, P. melaninogenica and P. intermedia. CONCLUSIONS: Systemic antibiotic administration transiently increased the percentage of resistant subgingival species, but a major component of subgingival plaque remained sensitive to the agents during their administration. Antibiotic-resistant isolates of resistant species could be detected in samples both prior to and after therapy. However, % antibiotic-resistant isolates returned to baseline levels 90 days after antibiotic administration.     

Streptococcus mutans in plaque and saliva after mouthrinsing with SnF2

Abstract – Mouthrinses with SnF2 in 11 subjects significantly reduced ( P <0.01) the total colony forming units (CFU) count and the numbers of Streptococcus mutans and Streptococcus sanguis in plaque. The numbers of S. mutans and S. sanguis were significantly more reduced than was the total CFU count. After rinsing with SnF2 S. sanguis was present in 97% and S. mutans in only 42% of plaque samples from tooth surfaces where they were detected after rinsing with water. SnF2 also significantly reduced ( P <0.01) the number of S. mutans in saliva. Mouthrinses with NaF did not markedly affect the number of S. mutans either in plaque or in saliva.     

Systemic doxycycline administration in the treatment of periodontal infections (II). Effect on antibiotic resistance of subgingival species

The purpose of this investigation was to determine the proportion and prevalence of doxycycline resistant species in subgingival plaque samples taken during and after doxycycline administration. 20 subjects with adult periodontitis were randomly assigned to test (n = 10) or control groups (n = 10). Saliva samples as well as subgingival plaque samples taken from the distal surface of 6 posterior teeth were collected at baseline. All subjects received full mouth SRP and the test group systemic doxycycline at the dosage of 100 mg/day for 14 days. Saliva samples and plaque samples from the distal surface of 2 randomly selected teeth were taken at 3, 7 and 14 days during and after antibiotic administration. Control subjects were sampled at the same time points. Samples were anaerobically dispersed and serially diluted in PRAS Ringer's solution and plated on enriched Trypticase soy blood agar plates with or without 4 microg/ml doxycycline. After 7 days of anaerobic incubation, colonies were counted on both sets of plates. Microbial growth was washed from the doxycycline-containing media and the species identified using 40 DNA probes and checkerboard DNA-DNA hybridization. Differences in proportions of resistant species between test and control groups were tested for significance at each time point using the Mann Whitney test and over time within each group using the Quade test. The mean % (+/-SEM) of isolates resistant to 4 microg/ml doxycycline in the plaque samples of the test subjects increased from 6+/-2 to 48+/-9% during doxycycline administration, decreasing to 25+/-6% 2 weeks later and 9+/-2% at 90 days. In saliva, the % of resistant isolates rose from 13+/-1% to 81+/-10% during doxycycline administration falling to 46+/-8% 2 weeks later and 22+/-5% at 90 days. The % of resistant isolates did not change significantly in plaque or saliva samples of the control subjects at the same time points. For all subject visits combined, the most prevalent resistant species were: Streptococcus anginosus, Streptococcus oralis, Streptococcus intermedius, Streptococcus sanguis, Streptococcus mitis, Veillonella parvula, Actinomyces gerencseriae, Streptococcus constellatus, Actinomyces naeslundii genospecies 2, Streptococcus gordonii, Eikenella corrodens and Actinomyces naeslundii genospecies 1. Doxycycline resistant strains of these species were detected in both plaque and saliva samples prior to therapy and in the control group. Despite the finding of increased resistance, approximately 50% of the organisms present at periodontal sites at the end of 14 days of doxycycline administration tested sensitive to the agent.     

The effectiveness of InGaAsP diode laser radiation to detect subgingival calculus as compared to an explorer

BACKGROUND: The aim of the present study was to compare the ability of the diode laser to detect residual calculus with that of an explorer. METHODS: The root surface of 40 extracted human teeth, each partially covered with subgingival calculus, was instrumented with curets under simulated clinical conditions in a manikin. The samples were randomly assigned to two study groups. In group A, the root surface was treated with an explorer until it appeared free of mineralized deposits upon examination. The samples in group B were instrumented until the relative intensity of fluorescence as induced with diode laser radiation was below a threshold value of 5. The root surface of each sample was then examined for residual calculus using standardized digital images. The statistical analysis was performed with a non-paired t test at a level of significance of 5% (P < 0.05). RESULTS: The root surface of single-rooted teeth showed residual calculus on 0.19 +/- 0.37 x 10(7) microm2 in the laser group and on 0.11 +/- 0.26 x 10(7) microm2 in the explorer group (P = 0.19). For multirooted teeth, the mean calculus-covered area was 0.50 +/- 0.48 x 10(7) microm2 for the teeth evaluated with an explorer and 0.27 +/- 0.43 x 10(7) microm2 for the diode laser group (P = 0.02). CONCLUSION: The present findings indicate that the detection of subgingival calculus is significantly improved using 655 nm diode laser radiation compared to an explorer for molars but not for single-rooted teeth.     

Efficacy of manual and powered toothbrushes (II). Effect on microbiological parameters

BACKGROUND/AIM: The purpose of the present investigation was to determine the effect of self-performed supragingival plaque removal using either manual (Crest Complete) or power (Braun 3D Plaque Remover) toothbrushing on supra and subgingival plaque composition. METHODS: 47 periodontal maintenance subjects completed this single-blind 6 month longitudinal study. At baseline, samples of supra and separately subgingival plaque were taken from the mesial aspect of each tooth in each subject using sterile curettes and individually analyzed for their content of 18 bacterial taxa using checkerboard DNA-DNA hybridization. After random assignment to groups receiving either a manual (n=25) or power toothbrush (n=22), subjects received instruction in oral hygiene and used their assigned toothbrush 2x daily for 6 months. Clinical monitoring and microbiological sampling were repeated at 3 and 6 months. Significant differences in microbiological measures over time were sought using the Quade test and between brushing groups at each time point using the Mann-Whitney test. RESULTS: Mean total counts were significantly reduced for supra- and subgingival plaque samples in the manual group and subgingival samples in the powered brushing group. Actinomyces naeslundii and Actinomyces israelii/gerencseriae were the most numerous organisms detected at baseline and showed the greatest reductions in counts in both brushing groups. Streptococcus constellatus/intermedius was significantly reduced in both groups, while Streptococcus mitis/oralis/sanguis was significantly reduced in the manual toothbrushing group. Mean counts of species were more markedly altered in subgingival plaque. Major reductions occurred in both groups for A. naeslundii, A. israelii/gerencseriae, Peptostreptococcus micros, Veillonella parvula, Prevotella intermedia/nigrescens, S. mitis/oralis/sanguis and S. constellatus/intermedius. All taxa examined were reduced in prevalence (% of sites colonized) in the subgingival plaque samples for both brushing groups. The reductions in prevalence were greater for A. naeslundii, S. constellatus/intermedius, V. parvula, A. israelii/gerencseriae, S. mitis/oralis/sanguis, P. micros, Streptococcus mutans and P. intermedia/nigrescens. Mean prevalence was decreased more for Porphyromonas gingivalis, Campylobacter rectus/showae, Treponema denticola and Bacteroides forsythus in supragingival plaque than subgingival plaque. CONCLUSIONS: The major finding was the effect of supragingival plaque removal on the composition of the subgingival microbiota. Counts and prevalence of most taxa examined were markedly decreased in both toothbrushing groups. This reduction should translate to a decreased risk of periodontal disease initiation or recurrence. Further, the decreased prevalence of periodontal pathogens in supragingival plaque lowers potential reservoirs of these species.     

Real-time interaction of oral streptococci with human salivary components

Oral streptococci are present in large numbers in dental plaque and several types interact with the enamel salivary pellicle to form a biofilm on tooth surfaces. The respective affinity of individual streptococci for salivary components has an influence on the etiologic properties of oral biofilm in the development of dental caries. We studied real-time biospecific interactions between oral streptococci and salivary components utilizing biosensor technology to analyze surface plasmon resonance. Streptococcus sanguis and Streptococcus mutans showed significant responses for binding to salivary components, in comparison with other bacteria. Further, the association rates (4.1 x 10-11/bacterium) and dissociation rate (5.7 +/- 0.9 x 10-3 Second(s)-1) were higher for S. sanguis than for S. mutans (2.4 x 10-11 and 2.9 +/- 0.8 x 10-3) and Streptococcus mitis (1.3 x 10-11 and 3.5 +/- 1.3 x 10-3). However, the association equilibrium constants (8.2 S/bacterium) for S. mutans was 2 times higher in than S. mitis (3.8) and slightly higher than S. sanguis (7.2). These findings may provide useful information regarding the mechanism of early biofilm formation by streptococci on the tooth surface.     

中、重度慢性牙周炎与冠心病相关性的研究

目的探讨中、重度慢性牙周炎与冠心病的相关性以及急性期蛋白成分纤维蛋白原（Fg）在其中的作用。方法选择不同牙周和心血管健康状态者共95人,分为健康对照（HC）组、牙周炎（MSP）组、冠心病（CHD）组和MSP+CHD组,检测牙周临床指数、血浆Fg质量浓度和冠心病常规血清学指标,采用单因素方差分析和协方差分析法分析3种指标间的关系。结果4组研究对象的Fg质量浓度分别为（2.36±0.37）、（3.63±0.73）、（4.08±0.84）和（4.14±0.96）g/L,中、重度慢性牙周炎患者（MSP组和MSP+CHD组）血浆Fg质量浓度明显高于HC组（P<0.01）;排除血压和体重指数的影响后,中、重度慢性牙周炎患者发生CHD的可能性高于牙周健康者（OR=2.527,P=0.047）。结论中、重度慢性牙周炎可能是冠心病的危险因素,而Fg则可能是联系二者的生物学基础之一。     

Intraoral distribution of Actinobacillus actinomycetemcomitans in young adults with minimal periodontal disease

The aim of the present study was to investigate the intraoral distribution of Actinobacillus actinomycetemcomitans in young adults with minor signs of periodontal disease but harboring the organisms in the oral cavity. 17 healthy volunteers, 20 to 27 years of age, participated. Samples from mucosal surfaces of the oro-pharyngeal cavity and saliva (n = 221) as well as subgingival plaque from every tooth (n =477) were selectively cultivated for A. actinomycetemcomitans. Species identity and presence of the leukotoxin encoding gene, ltxA, were checked by multiplex polymerase chain reaction. Moreover, the leukotoxin promoter region was analyzed. No isolate harbored a 530 bp deletion in the promoter region of the leukotoxin gene, signaling minimally toxic strains. 42.1 +/- 30.4% extracrevicular and 34.4 +/- 29.5% subgingival samples were culture-positive. In extracrevicular samples, the organism could easily be recovered from cheek mucosa (62%), saliva (59%) and the palatal tonsils (41%). Mean log-transformed numbers of A. actinomycetecomitans colony forming units (CFU/ml) in culture-positive material ranged between 1.8 from the hard palate and 2.3 from 10 microl saliva. The highest prevalence in subgingival plaque was observed at maxillary 3rd molars (55%) followed by maxillary lateral incisors (50%) and mandibular 3rd molars (41%). Mean log-transformed counts of CFU/ml ranged between 2.2 at maxillary 3rd molars and 3.4 at upper central incisors. When adjusted for jaw, site and tooth type, the odds of isolating higher numbers of the organism were increased with every mm probing depth by a factor of 1.35 (p <0.05). The odds ratio for bleeding on probing was 1.38. Thus, in this young adult population with minor periodontal disease, A. actinomyetemcomitans was mainly associated with some deviation from gingival health. Of concern might be a minority of subjects (29%) with an extremely wide distribution of the organism in the oral cavity.