Risk indicators of aggressive periodontitis in a Jordanian population

BACKGROUND

Knowledge of the risk indicators of aggressive periodontitis (AgP) will help clinicians to better diagnose the disease, put a treatment plan that involves modification of modifiable risk indicators, understand non-modifiable risk indicators, and may potentially serve as an aid in developing preventive programs. The objective of the present study was to assess risk indicators of aggressive periodontitis (AgP) in Jordan including socio-demographic factors, oral hygiene habits, smoking, family history and parents' consanguinity.

METHODS

A total of 162 patients (81 AgP and 81 controls), attending the Periodontology clinic at Jordan University of Science and Technology, Dental Teaching Centre, were interviewed and examined. All AgP subjects had full periodontal and radiographic examination. The data recorded included socio-demographic and economic variables, oral hygiene and smoking habits, family history and parents' consanguinity.

RESULTS

Most AgP patients were young females, had ≤12 years of education, lived in urban areas and brushed their teeth ≥ once daily. Risk indicators of AgP included: age > 35 years, female gender and positive family history.

CONCLUSIONS

Risk indicators associated with AgP in this study population were: age > 35 years, female gender and positive family history of periodontal disease.

Potential Risk for Localized Aggressive Periodontitis in African American Preadolescent Children

PURPOSE

This study aimed to evaluate the potential risk for localized aggressive periodontitis (LAgP) in African American children by detection of the potential periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa) using polymerase chain reaction (PCR) and microbiome analysis.

METHODS

Twenty-one pre-adolescents (age range equals 10.7 to 13.1 years old) were recruited, for this IRB-approved study. Oral examination included limited periodontal examination determining bleeding index (BOP) and periodontal probing (PD). An oral mucosa sample was used for analysis.

RESULTS

Nine of 21 children were Aa+ by PCR. The Aa+ group had a significantly higher proportion of teeth with BOP and PD greater than four mm than the Aa- group (P=0.014 and 0.006 for percent BOP and percent PD equal to or greater than four mm, respectively; Mann Whitney Test). No significant differences in microbe abundance or composition were found from comparison of Aa+ versus Aa- samples.

CONCLUSIONS

Detection of Aa from preadolescent African American children was associated with signs of periodontal inflammation. Although none of these children were diagnosed with LAgP, PCR targeting Aa could be a risk factor. Further study is indicated; however, the usefulness of PCR in dental practice setting to assess risk may be cost-effective for early diagnosis and prevention of LAgP.

Transcription factor STAT1 gene polymorphism is associated with the development of severe forms of periodontal disease

INTRODUCTION

Periodontal disease (PD) is one of the most common inflammatory diseases, affecting about 10 % of the world population. The establishment of PD is influenced by polymorphisms in genes involved with the inflammatory response. Signal Transducer and Activator of Transcription (STAT)-1 is a transcription factor that plays a key role in the intracellular signaling triggered by cytokines and, thus, its activation is critical in inflammatory diseases.

AIM AND METHODS

We aim to evaluate the occurrence of association between STAT-1 (rs3771300) polymorphism and distinct clinical forms and severity of PD; we genotyped 180 subjects using realtime PCR.

RESULTS AND CONCLUSION

We observed that the presence of the G allele for STAT-1 was associated with twice as high of a chance to develop aggressive periodontitis, and the most severe form of the disease.

Occurrence of aggressive periodontitis in patients at a dental school in southern Brazil

Aggressive periodontitis is a rare, severe and rapidly progressing periodontal disease. Early diagnosis is of utmost importance for establishing treatment in order to stop periodontal destruction and prevent tooth loss. The aim of this study is to describe the occurrence of aggressive periodontitis in patients at a Dental School in Brazil by means of a cross-sectional study. First, records from patients aged 15-36 years were consecutively scrutinized. Patients should not have systemic diseases. The search went up to 383 valid records. By means of periapical radiographs, the distance between the cement-enamel junction and the bone crest was measured. Records in which there was severe bone loss or periodontal destruction incompatible with the age of the patient were selected. Patients with bone loss > or = 3mm were called to answer a questionnaire and undergo periodontal examination, in order to confirm or dismiss the diagnosis of aggressive periodontitis. From a total 383 records, 55.1% (211) were female and 44.9% (172) were male. In 3.9% (15) of the records, presumed diagnosis was aggressive periodontitis, and 12 out of those 15 eligible patients (80%) came in for clinical examination and confirmation or dismissal of the diagnosis. Aggressive periodontitis was diagnosed in 7 patients, corresponding to 1.8% of the total. Of these, 4 (1% of the total) presented generalized aggressive periodontitis and 3 (0.8% of the total) presented localized aggressive periodontitis. In 5 patients (1.3%) chronic periodontitis was diagnosed. It may be concluded, within the limits of the study, that aggressive periodontitis at this Dental School is compatible with world prevalence values, suggesting the need for periodontal diagnosis as from adolescence, considering the possible damage caused by this disease.

[Correlation of gene polymorphism and risk of aggressive periodontal disease]

The study included 179 patients aged 18-45 years (56 with aggressive periodontal disease and 123 with no clinical signs of periodontitis). Gene polymorphism was analyzed by means of real-time PCR and kissing probes in order to reveal marker panel for aggressive periodontal disease predisposition. Significant difference was found for gene MMP9 in rs17576 position for A allele (55.2% in aggressive periodontal disease patients and 69.5% in control group) and in rs3918242 position for C allele (67.7 and 81.7%, respectively).

[A preliminary study on the genetic mode of aggressive periodontitis in Chinese Han nationality]

OBJECTIVE

To investigate the potential genetic mode of aggressive periodontitis (AgP) in Chinese Han nationality.

METHODS

A total of 233 subjects from 73 nuclear families were recruited. All probands were diagnosed according to the criteria of AgP in 1999 classification of periodontal diseases. Ninety parents, 35 siblings and three grandparents and two offspring were examined based on full-mouth periodontal chartings (including parameter of probing depths, attachment loss, bleeding on probing at six sites per tooth) and full-mouth periapical radiographs. The genetic ratio was calculated and analyzed by the methods of Edwards and simple segregation.

RESULTS

The prevalence of AgP in probands' siblings was close to the square root of the prevalence of general population. The segregation ratio was 0.2419, which was close to the theoretical ratio for autosomal recessive inheritance. However, autosomal dominant inheritance could not be rejected in families whose parent(s) suffered from severe chronic periodontitis.

CONCLUSIONS

The genetic heterogeneity of AgP existed in Chinese Han nationality. The genetic mode was autosomal recessive inheritance in general, and autosomal dominant inheritance could not be excluded in families whose parent(s) suffered from severe chronical periodontitis. The results imply the genetic heterogeneity of AgP, and further demonstrate that AgP was a multifactorial disease with major genetic component in the disease etiology.

Single nucleotide polymorphisms in interleukin-1gene cluster and subgingival colonization with Aggregatibacter actinomycetemcomitans in patients with aggressive periodontitis

Periodontitis is initiated by the subgingival occurrence of periodontopathogens. It is triggered by a specific host-dependent immune response that is influenced by genetic predisposition. Polymorphisms in the interleukin-1 (IL-1) gene cluster have been suggested to influence the pathogenesis of periodontitis. A total of 159 periodontitis patients (chronic disease: n = 73, aggressive disease: n = 86) and 89 periodontitis-free controls were included in the study. Polymorphisms IL-1α (rs1800587), IL-1β (rs16944, rs1143634), IL-1 receptor (rs2234650), and IL-1 receptor antagonist (rs315952) were determined by polymerase chain reaction with sequence-specific primers (PCR-SSP). Subgingival bacterial colonization was assessed using a polymerase chain reaction/DNA probe test (micro-Ident). Haplotype block structure was determined using Haploview 4.2. Statistical analyses were performed applying SPSS 17.0 considering dominant, recessive, and codominant genetic models. In this case-control study, no association between genomic variants of the IL-1 gene cluster and the incidence of severe periodontitis could be shown. Carriers of the rare genotypes of rs1800587 (p(corr) = 0.009), rs1143634 (p(corr) = 0.009) and composite genotype (rs1800587+rs1143634) (p(corr) = 0.031) had a twofold higher risk for subgingival occurrence of Aggregatibacter actinomycetemcomitans. In forward stepwise binary logistic regression analyses considering age, gender, smoking, and approximal plaque index as potential confounders these significant associations were demonstrated. Despite the genetic background of IL-1 gene cluster could be shown to be associated with subgingival colonization of A actinomycetemcomitans, there is no evidence that it is an independent risk indicator for periodontitis.

Aggressive periodontitis: the silent tooth killer

Aggressive periodontitis comprises a group of rapidly progressive forms of periodontitis characterized by early onset of clinical manifestations at a young age and a distinctive tendency for cases to aggregate in families. Though once believed to be a rare condition, recent evidence suggest that aggressive periodontitis is more common than assumed. The etiology of aggressive periodontitis is probably due to the expression of highly virulent causative agents in combination with high levels of susceptibility of the individual patient. In addition, there are several factors, such as cigarette smoking and ethnicity, that are associated with higher prevalence or severity of aggressive periodontitis. Since the disease usually appears at a young age, the importance of early detection is paramount in order to avoid tooth loss in early childhood or adolescence.

FAM5C contributes to aggressive periodontitis

Aggressive periodontitis is characterized by a rapid and severe periodontal destruction in young systemically healthy subjects. A greater prevalence is reported in Africans and African descendent groups than in Caucasians and Hispanics. We first fine mapped the interval 1q24.2 to 1q31.3 suggested as containing an aggressive periodontitis locus. Three hundred and eighty-nine subjects from 55 pedigrees were studied. Saliva samples were collected from all subjects, and DNA was extracted. Twenty-one single nucleotide polymorphisms were selected and analyzed by standard polymerase chain reaction using TaqMan chemistry. Non-parametric linkage and transmission distortion analyses were performed. Although linkage results were negative, statistically significant association between two markers, rs1935881 and rs1342913, in the FAM5C gene and aggressive periodontitis (p = 0.03) was found. Haplotype analysis showed an association between aggressive periodontitis and the haplotype A-G (rs1935881-rs1342913; p = 0.009). Sequence analysis of FAM5C coding regions did not disclose any mutations, but two variants in conserved intronic regions of FAM5C, rs57694932 and rs10494634, were found. However, these two variants are not associated with aggressive periodontitis. Secondly, we investigated the pattern of FAM5C expression in aggressive periodontitis lesions and its possible correlations with inflammatory/immunological factors and pathogens commonly associated with periodontal diseases. FAM5C mRNA expression was significantly higher in diseased versus healthy sites, and was found to be correlated to the IL-1β, IL-17A, IL-4 and RANKL mRNA levels. No correlations were found between FAM5C levels and the presence and load of red complex periodontopathogens or Aggregatibacter actinomycetemcomitans. This study provides evidence that FAM5C contributes to aggressive periodontitis.

Prevalence of aggressive periodontitis in 15-18 year old school-children in Tehran, Iran

OBJECTIVE

Aggressive periodontitis is one of the periodontal diseases that affects systemically healthy individuals usually under the age of 30 years. The disease is characterized by rapid bone destruction which is inconsistent with the amount of bacterial plaque. The purpose of this cross-sectional study is to determine the prevalence of aggressive periodontitis among students aged 15 to 18 years in high schools of Tehran, Iran.

RESEARCH DESIGN

Based on systematic and cluster random sampling, 5,590 students were selected. Probing pocket depth on six areas of incisors and first molars was carried out. Students with pocket depth > or = 4 mm on more than one tooth were referred for radiographic examination. In cases where the distance between the crest of interdental septa and CEJs were > or = 2 mm, full clinical and radiographic examination were performed.

RESULTS

Only seven persons, four girls and three boys, had the diagnostic criteria of localized aggressive periodontitis. One patient was diagnosed with generalized aggressive periodontitis. Therefore, the prevalence of aggressive periodontitis among 15-18 years old school- children was 0.13% in this study.

CONCLUSION

The present study indicates that the prevalence of aggressive periodontitis in Tehran is low and similar to the studies of the same age range and diagnostic criteria in other countries.

The impact of periodontal disease on the quality of life of individuals with Down syndrome

OBJECTIVE

This study aimed to determine the prevalence of periodontal disease among children and adolescents with Down syndrome and the possible repercussions of such pathology in the quality of life of the group in question.

METHOD

The sample consists of 93 individuals with Down syndrome 6 - 20 years old, living in Brazil (Minas Gerais). Periodontal probing was carried out on every site of each tooth. The Plaque Index and periodontal clinical parameters were recorded. A broad interview was carried out with the mothers, consisted of an adaptation of the Oral Health Impact File OHIP-14 that was used to measure the negative repercussions of periodontal disease in the daily lives of these individuals.

RESULTS

The prevalence of gingivitis was 91%, whereas periodontitis was found in 33% of the individuals. When the impact of periodontal disease on the quality of life was correlated with the clinical periodontal parameters, it was observed that there are significant statistical differences among them: bleeding on probing, probing depth and attachment loss. These same results, correlated with all the different groups that are categorised according to the diagnosis of periodontal disease, also show significant differences.

CONCLUSIONS

Periodontal disease can be considered as a condition with high prevalence within the group in question, which has negative effects on the quality of life of the subjects. These effects are aggravated by the seriousness of the disease.

Aggressive Periodontitis Among Young Israeli Army Personnel

BACKGROUND

The aim of this study was to assess the prevalence of aggressive periodontitis among young Israeli army recruits and to evaluate its association with smoking habits and ethnic origin.

METHODS

The study population consisted of 642 young army recruits (562 men [87.5%] and 80 women [12.5%]), aged 18 to 30 years (average: 19.6 +/- 1.6 years), who arrived at a military dental clinic for dental examinations between January and December 2004. Subjects filled out a questionnaire regarding their ethnic origin and family periodontal history, followed by radiographs and a clinical periodontal examination of four first molars and eight incisors.

RESULTS

Aggressive periodontitis was found in 5.9% of the subjects (4.3% localized and 1.6% generalized). At least one site with a probing depth > or =5 mm was found in 20.1% of the subjects. A radiographic distance between crestal bone height and the cemento-enamel junction >3 mm was found in 43 (6.7%) subjects. Current smokers (39.9%) (P = 0.03) and subjects of North African origin (P <0.0001) correlated with a high prevalence of aggressive periodontitis.

CONCLUSION

A relatively high prevalence of aggressive periodontitis was found in young Israeli army recruits, which was particularly associated with smoking and ethnic origin.

The highly leukotoxic JP2 clone of Actinobacillus actinomycetemcomitans and progression of periodontal attachment loss

The JP2 clone of Actinobacillus actinomycetemcomitans has been implicated in the etiology of periodontitis in adolescents. The aim of this two-year longitudinal study was to describe clinical attachment loss (CAL) progression and to assess its association with baseline occurrence of the JP2 and non-JP2 types of A. actinomycetemcomitans. Clinical re-examination of 121 adolescents in Morocco was performed. Progression of CAL > or = 1 mm, > or = 2 mm, > or = 3 mm, and > or = 4 mm on at least one site was found in 58%, 48%, 22%, and 6% of the subjects, respectively. Subjects who, at baseline, harbored the JP2 clone had a significantly higher progression of CAL than did subjects harboring non-JP2 types of A. actinomycetemcomitans. Subjects harboring non-JP2 types displayed a marginally higher CAL progression than did subjects who were culture-negative for A. actinomycetemcomitans.

Oral health of psychiatric in-patients in Hong Kong

BACKGROUND

Poor oral health has been reported among various psychiatric populations. Little is known regarding the oral health among psychiatric patients in Asia.

AIMS

To examine the oral health status of a group of Chinese psychiatric in-patients in a long-term rehabilitation facility.

METHODS

A dental survey using the WHO standardised dental evaluation form was conducted in adult psychiatric patients in a rehabilitation programme. A qualified dentist examined all consenting patients.

RESULTS

Ninety-one patients (64.8% male; mean age: 44.7 +/- 9.9 years; mean length of illness: 20.3 +/- 11.5 years) were included in the study, the majority (80.2%) diagnosed with schizophrenia. Malocclusion was found in 79.1% of patients. The mean number of missing teeth was 9.5 +/- 8.9. Bleeding on probing, calculus, shallow and deep pockets were found in 7.1%, 71.8%, 72.9% and 28.2% of patients, respectively. Dental caries were found in 75.3% of dentate patients. The mean number of caries per patient was 5.5 +/- 6.1. Fifty-four per cent of patients needed dental extraction and 78.8% required conservative dental treatment. Older age and length of illness were significantly associated with poor dental health.

CONCLUSIONS

Oral health status of chronic psychiatric patients seems to be considerably worse than that of the general population. Mental health professionals should pay more attention to preventive oral health habits of psychiatric patients.

Juvenile periodontitis--a review of literature

Juvenile Periodontitis (JP), a condition that was previously regarded as a rare disease has of recent come into the fore as a model for the study of inflammatory periodontal disease. It has also been found to be considerably more common in occurrence than previously thought. This article reviews the literature on the epidemiology, aetiology, pathogenesis, clinical features, histopathological and immunological findings, differential diagnosis, treatment and prognosis of JP. The objective of this article is to give the clinician the current opinions of researchers in all aspects of the disease as compared to previous age long views. It is observed that there are contradictory reports on the epidemiology, etiology and treatment of the disease and hence the need for further studies in these areas.

A case of prepubertal periodontitis and prevalence of gingivitis in a population attending a university clinic in Rosario, Argentina

The present study was based on the finding of a case of prepubertal periodontitis, a low prevalence pathology. One hundred and fifty-two infant patients attending the Department of Odontopediatrics of the Faculty of Dentistry of the National University of Rosario over the period April 1995-September 1996 were included in the present study. The reason for consultation was dental caries. However, the high general prevalence of gingivitis (50%) was remarkable. This may be due to deficient oral health care awareness at home and at school. The prevalence of prepubertal periodontitis (PPP) in the population under study (one case of localized PPP) was 0.66%. These data are in agreement with international reports that account for a prevalence value of less than 1%. A relevant difference with other reported cases could be that this patient complained of upper respiratory tract disorders and, occasionally, ear infections. These symptoms appear in the generalized but not the localized forms of the disease.

Classifying periodontitis among adolescents: implications for epidemiological research

OBJECTIVES

To evaluate the performance of four clinical classification systems proposed for periodontitis in young subjects when applied to epidemiological data on clinical attachment loss. We assess the extent to which the use of different case definition systems may influence the outcome of descriptive and analytical epidemiological studies.

METHODS

The data originate in a screening examination for periodontitis carried out among 9162 high school students. Each of four previously published classification systems was applied to the data. The prevalence of cases according to each system was estimated and the association between case status, as defined by each system, and a set of candidate determinant variables was assessed using multivariable logistic regression analyses.

RESULTS

The four classification systems yielded rather different prevalence estimates. For localized periodontitis the estimates varied by a factor of 10, and for generalized periodontitis, these varied by a factor of 30. The results of the logistic regression analyses using the different case-definitions essentially confirmed the results of a population-based analysis. However, the precision of the estimates decreased with decreasing numbers of cases identified by the classification systems.

CONCLUSIONS

From an epidemiological point of view there is little justification for the use of the complicated classification systems. An approach based on the simple definition of a case as a person with clinical attachment loss, e.g. >/=3 mm, is preferable.

Prevalence of aggressive periodontitis in school attendees in Uganda

AIM

The prevalence and severity of early onset periodontitis (EOP) among students attending secondary schools in two regions of Uganda was studied.

MATERIAL AND METHODS

690 students (393 males and 297 females) aged 12-25 years (mean 17 years), representing a range of tribal groups, were recruited from six schools in the peri-urban Central and rural Western regions of Uganda. The study subjects were clinically examined in field conditions by a single calibrated examiner to measure gingival recession and probing depth at six sites per tooth, with subsequent calculation of clinical periodontal attachment level for each site. Subjects exhibiting >or= 4 mm of clinical periodontal attachment loss at approximal surfaces of one or more teeth were classified with EOP. A structured written questionnaire obtained demographic characteristics of the study subjects.

RESULTS

199 (28.8%) study subjects showed clinical features of EOP, of which 16 (2.3%) subjects exhibited generalized EOP, 29 (4.2%) localized EOP, and 154 (22.3%) incidental EOP. The percentage of EOP-affected males was significantly higher than females (33.8% vs. 22.2%, P < 0.001). EOP prevalence tended to increase with increasing age, but no association was found between EOP prevalence and socioeconomic status or residency in urban vs. rural areas of Uganda. Molars and mandibular incisors generally demonstrated the highest occurrence of >or= 4 mm attachment loss. Clinical periodontal attachment loss of >or= 5 mm was mainly seen at first molars and incisors, suggesting that these two tooth types are first affected with attachment loss. Approximal tooth surfaces showed greater probing depth and attachment loss than buccal and lingual surfaces. Gingival recession was most prevalent at mandibular anterior teeth, whereas gingival margin coronal to CEJ was most frequently observed at second molars and maxillary incisors.

CONCLUSION

A relatively high prevalence of EOP (28.8%) was found in young Ugandan school attendees, with 6.5% of these showing severe disease. EOP in Uganda was significantly more prevalent in males than females, and most frequently characterized by approximal involvement of molars and mandibular incisors. Etiologic and predisposing factors associated with the high occurrence of EOP in Uganda, as well as therapeutic and preventive measures of the disease in this population, remain to be delineated.

Periodontal diseases, caries, and microbial composition of the subgingival plaque in children: a longitudinal study

The present study compares periodontal parameters, caries, and levels of colony forming units (CFU) of bacteria from subgingival plaque of permanent teeth, to those of primary teeth examined 4 years previously. Six children who had periodontitis and 5 who had no periodontitis in primary teeth (groups A and B respectively) were examined. The microbial examination included the number of CFU of the total anaerobic count, Actinobacillus actinomycetemcomitans, Streptococcus mutans and Porphyromonas gingivalis. The differences in CFU values for the permanent teeth between groups A and B were not significant. Group A had significantly higher gingival inflammation values in the permanent teeth than group B. Permanent teeth had significantly higher CFU values of P. gingivalis than the primary teeth. Based on the present limited sample, the number of CFU from bacteria of the subgingival plaque of primary teeth are not an adequate predictor of periodontal disease or caries in the permanent teeth.

[Prevalence of aggressive periodontitis in adolescents and young adults from Vale do Paraíba]

The aim of the present study was to determine the prevalence of localized and generalized aggressive periodontitis, as well as of incidental attachment loss, in a population of adolescents and young adults aging between 15 and 25 years (19.4 +/- 3.44) from Vale do Paraíba - SP, who searched for general dental care at the Department of Dentistry, University of Taubaté, São Paulo. Six hundred patients, 244 male and 356 female subjects, were included in the studied sample. The periodontal status of this population was evaluated by measuring the depth of periodontal pockets, as well as attachment loss. The data were confirmed by means of radiographic examination. Measurements were performed in six sites per tooth. Ten subjects (1.66%) were diagnosed as having localized aggressive periodontitis, 2 males (aging 18.5 +/- 2.12 years) and 8 females (aging 19.2 +/- 3.91 years); 22 (3.66%) presented with generalized aggressive periodontitis, 6 males (aging 19.1 +/- 3.06 years) and 16 females (aging 20.1 +/- 2.71 years); and 86 individuals (14.3%) presented with incipient periodontitis, 29 males (aging 20.2 +/- 2.87 years) and 57 females (aging 21.1 +/- 2.79 years). There was a positive correlation between the female gender and the occurrence of periodontal disease.

Beyond the specific plaque hypothesis: are highly leukotoxic strains of Actinobacillus actinomycetemcomitans a paradigm for periodontal pathogenesis?

Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LIP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LIP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens.

Early-onset periodontitis in Morocco is associated with the highly leukotoxic clone of Actinobacillus actinomycetemcomitans

A particular clone (JP2) of Actinobacillus actinomycetemcomitans with increased leukotoxin production has been isolated from individuals with early-onset periodontitis (EOP). The aim of this study was to determine the frequency of carriers of this clone and its association with EOP in Moroccan schoolchildren. Of 217 plaque samples, 131 (60.4%) were culture-positive for A. actinomycetemcomitans. A total of 19 of these isolates had a 530-bp deletion in the leukotoxin promoter region characteristic of the JP2 clone. A strong association between the presence of A. actinomycetemcomitans with the 530-bp deletion and EOP was found (adjusted OR = 29.4; 95% Cl = 8.3 - 104.4; p < 0.0005), while no association could be demonstrated between the presence of A. actinomycetemcomitans without the deletion and EOP (adjusted OR = 1.3; 95% CI = 0.5 -2.9; p = 0.750). The study demonstrates that the endemic presence, in a human population, of the highly leukotoxic JP2 clone may result in an unusually high prevalence of EOP.

Periodontal disease in American Indians and Alaska Natives

OBJECTIVE

The primary purpose of this paper is to provide information on the periodontal disease status of Native Americans using a variety of data sources. The impact of periodontal disease on the provision of dental care within the Indian Health Service (IHS) is also discussed.

METHODS

Four data sources were used to evaluate the periodontal disease status of Native Americans: IHS periodontal disease monitoring system (1962-78), 1984 IHS Patient Oral Health Survey, 1990 WHO community-based survey (ICS-II), and the 1991 IHS Patient Oral Health Survey.

RESULTS

There appears to be a trend toward a higher prevalence of incipient and overt periodontal disease among Native Americans over time. The prevalence of overt periodontal disease (periodontal pockets > 5.5 mm) is higher among Native American diabetic patients than nondiabetic patients (34% vs 19%).

CONCLUSIONS

Due to the variety of indices used by the IHS during the last 20 years, it is difficult to make direct comparisons of the available periodontal disease data. However, it appears that the prevalence of periodontal disease among Native Americans is increasing. Type II diabetes accounts for significant increases in periodontal disease and tooth loss in Native American populations. Certain forms of early onset periodontal disease also may pose significant threats to the oral health of Native Americans.

Dental caries and periodontal conditions among primary school children in Morogoro municipality, Tanzania

OBJECTIVE

To describe the occurrence of dental caries and periodontal conditions among standards three and four primary school children in Morogoro municipality and compare the obtained oral health indicators with the goals stipulated in the National Plan for Oral Health by the year 2002.

DESIGN

Cross sectional study of the oral health status among eight to 15-year old primary school children.

SETTING

Primary schools in Morogoro municipality, Tanzania.

SUBJECTS AND METHODS

A total of 1,297 standards three and four children in five primary schools randomly selected from a list of 36 primary schools of Morogoro municipality were examined for oral health status. Dental caries and periodontal status were recorded using the criteria described in the WHO manual for Oral health Surveys, Basic Methods (1997). Oral cleanliness was assessed using plaque index.

MAIN OUTCOME MEASURES

Dental caries prevalence, experience and its distribution by tooth type and jaw and prevalence and severity of periodontal conditions and oral cleanliness.

RESULTS

Seventy six percent of the children were caries free, and the mean DM-T was 0.41. No fillings were encountered. Seventy six per cent of carious lesions were in pits and fissures of lower molars. Only 21% of the caries lesions were in the pits and fissures of upper molars. Seventy five per cent of the children had all sextants with no gingivitis or calculus. Mean sextants with gingivitis, calculus and visible plaque were 0.25, 0.69 and 2.44 respectively.

CONCLUSIONS

Standard four and standard four children in Morogoro municipality primary schools had very low levels of dental caries, good oral hygiene and a very low prevalence of gingivitis. No restorative treatment had been provided to these pupils. It is recommended that Morogoro municipality should start a dental caries treatment programme in primary schools in order to attain the national goal of 10% of the "F" component of DMF-T by the year 2002.

Proximal caries in juvenile periodontitis patients

BACKGROUND

Caries is recognized as the prevalent proximal dental disease in adolescents, while proximal bone loss is minimal to non-existent in this population. Adolescents demonstrating an inverse disease pattern, i.e., minimal caries and active periodontitis, could provide powerful clues with regard to both diseases. However, data are inconsistent. This study was designed to clarify this relationship by comparing proximal caries prevalence in a juvenile periodontitis (JP) group to a matched non-periodontally diseased control group.

METHODS

Two groups (cases [JPs] and control patients [CPs]) were matched for age, sex, and race and evaluated for decayed, missing, filled teeth and surfaces (DMFS) by radiographic analysis. Statistical analysis was performed by ANOVA and Student t test. The study consisted of four phases. Phase I was based on data from a previous study that failed to include race in the analysis. Thus, the original 23 JP patients (mostly African-Americans from New York City) were rematched for race as well as sex and age with CPs from Newark, NJ. The effect of water fluoridation (found in NYC) was evaluated in Phase II by matching the 23 original CPs (mostly Caucasian from NYC) with 23 CPs from NJ. Since differences were seen, we rematched our original JPs from NYC with a new set of race-matched CPs from NYC (Phase III). Finally, 13 JP patients from the University of Medicine and Dentistry of New Jersey (UMDNJ) were matched with CPs from NJ (Phase IV).

RESULTS

Phase I and III indicated that JP patients had significantly less proximal caries than their matched CPs (P < or =0.05). Phase II confirmed the role of fluoride in caries reduction. Phase IV (NJ sample) supported our previous data and suggested that JP patients had less proximal caries than CPs (P < or =0.05).

CONCLUSIONS

JP patients had significantly less proximal caries than their matched CPs when groups were balanced and radiographic evaluations were performed. In-depth studies of JP patients could provide important clues about both caries and periodontal disease etiology and pathogenesis.

Epidemiology of periodontal diseases: an update

This article provides a brief review of findings from epidemiological studies of periodontal disease that have been generated over the past five years. In line with the conclusions of the 1996 World Workshop in Periodontics, the recent data support the concept that early onset periodontitis appears to be rather infrequent, while advanced adult periodontitis, leading to severe loss of supporting periodontal tissues and tooth loss, does not exceed a prevalence of 10-15% in most populations. However, a number of important issues remain unresolved. It is still not clear whether the prevalence of these diseases has shown an overall decline in recent years. In fact, retention of teeth in older age may contribute to an increase. Analytical epidemiological studies have been increasingly successful in identifying a handful of risk factors for disease onset and progression. These include colonisation at high levels by certain subgingival bacteria, environmental exposures such as cigarette smoking, and systemic conditions such as diabetes mellitus. Importantly, the molecular basis of host susceptibility has recently begun to be unraveled. Research efforts are now focused on creating multi-factorial models to assess the risk for disease, prior to the development of irreversible damage. Importantly, the role of periodontal infections as a modifier of systemic health is being increasingly explored.

Analysis of serum antibody responses to periodontopathogens in early-onset periodontitis patients from different geographical locations

Serum antibody specificity to oral micro-organisms was used to delineate the pathogens associated with early-onset periodontal diseases in a Turkish population. Additionally, comparison of the findings to those derived from a clinically similar US patient population described differences in bacterial specific antibody between these 2 geographic regions. Serum from 89 (LJP), 86 (RPP) and 94 (normal) subjects was analyzed (ELISA) to determine IgG antibody to 14 oral micro-organisms. All LJP patients from Turkey exhibited elevated antibody levels to A. actinomycetemcomitans (serotypes c and a significantly increased), while antibody levels to A. actinomycetemcomitans Y4 and JP2 (serotype b) were significantly higher in US LJP patients. 50% of the Turkish RPP patients also showed elevated anti-A. actinomycetemcomitans antibody, although the US RPP patients exhibited significantly higher antibody levels and frequency of elevated antibody to the A. actinomycetemcomitans serotypes. Healthy subjects and LJP and RPP patients from the US exhibited higher antibody levels to all 3 P. gingivalis serogroups compared to those from Turkey, although, the frequency of elevated antibody to the P. gingivalis serogroups was significantly higher in LJP and RPP patients from Turkey than from the US. Interestingly, 87% and 77% of the LJP patients in the Turkish population had elevated antibody responses to P. gingivalis and E. corrodens, respectively, which was not observed in the US LJP patients. These data suggested that considerable variation exists in the systemic antibody levels to periodontopathogens between these 2 countries. This supports potential differences in subgingival colonization or antigenic composition of these pathogens between patient populations from different geographical regions.

The description of a unique population with a very high prevalence of localized juvenile periodontitis

The reported prevalence of localized juvenile periodontitis (LJP) amongst teenagers and young adults varies greatly. The etiology of LJP has been related to Actinobacillus actinomycetemcomitans (Aa), and it has also been suggested that there may be a transmission of Aa within families resulting in the familial distribution of the disease. This study describes the high prevalence of LJP in adolescents, 12-20 years of age, from a group of nuclear families living and functioning in a closed, closely knit community. The survey was carried out on a population of teenagers that had attended the same school and their siblings. All students attending that school and their siblings were examined. They were given a periodontal examination and a questionnaire relating to their demographic details and their personal oral hygiene habits. The periodontal examination was limited to the incisors and first molar teeth. Plaque index (PlI), gingival index (GI), the presence or absence of bleeding on probing (BOP), probing pocket depth (PPD) and recession were measured. All patients having at least two of the examined sites with probing pocket depth > or =5 mm or one site > or =6 mm were considered as possible sufferers from LJP and had a full mouth periapical radiographic survey carried out using a paralleling technique to confirm the diagnosis. At the sites with probing pocket depth > or =5 mm, a Shei ruler was used to measure the % of the root coronal to the alveolar bone. A cut off point of > or =20% was used as a measure of true bone loss confirming the clinical diagnosis of LJP. 86 individuals from 30 families comprised the population of interest. There were 44 males and 42 females with a mean age of 14.7+/-2.3. Of the 86 individuals examined, 33 individuals from 15 families were diagnosed as having LJP (38.4%). None of the individuals examined showed any evidence of the generalized form of juvenile periodontitis. The mean age of the LJP patients was 15+/-2.3 yrs. with a 1:1.75 male to female ratio. Except for 2 pairs of families with genetic ties, no familial connections could be traced between the different nuclear families affected by LJP despite repeated and intensive questioning. There were no significant differences in the PlI and the GI between the groups while the LJP group had significantly higher BOP, PPD and PAL than the non-LJP group. These finding strongly suggest an environmental influence in the etiology of the disease.

A review of localized juvenile periodontitis (LJP): Part I. Clinical features, epidemiology, etiology, and pathogenesis

Localized juvenile periodontitis (LJP) is not commonly encountered in dental practice. Yet, when it is encountered, prompt and effective therapy is required to combat the severity of disease and its rapid progression. Failure to understand its diagnosis and etiology leads to failures in management of LJP. The clinical features, etiology, and pathogenesis of LJP are reviewed to provide the clinician with a sufficient understanding to appropriately manage or refer LJP patients.

The distribution and transmission of Actinobacillus actinomycetemcomitans in families with localized juvenile periodontitis

The prevalence and distribution of A. actinomycetemcomitans in families where at least one family member (proband) suffered from localized juvenile periodontitis was investigated. 25 probands with localized juvenile periodontitis (LJP) and their 78 close family members were screened for the presence of A. actinomycetemcomitans. Among these 25 families, 10 contained at least one additional family member colonized with oral A. actinomycetemcomitans. Genomic DNA from subgingival A. actinomycetemcomitans strains from each of the probands and their family members were amplified and characterized by the polymerase chain reaction (PCR) using a single primer known to distinguish A. actinomycetemcomitans strains. The PCR products from each strain were separated by electrophoresis on a 1% submarine agarose gel containing ethidium bromide and visualized by UV light transillumination. The studies showed that 41.2% of the parents and 58% of the siblings in this LJP-based population harbored the bacterium. Comparison of the PCR generated amplitypes showed that there was a wide distribution of amplitypes among the probands and immediate relatives. No clear transmission paths were observed in this specific population.

Periodontal diseases in the United States population

Recent epidemiologic surveys and studies have provided important information on the prevalence, extent, and severity of periodontal diseases in the United States. Over 50% of adults had gingivitis on an average of 3 to 4 teeth. Subgingival calculus was present in 67% of the population. Adult periodontitis, measured by the presence of periodontal pockets > or = 4 mm, was found in about 30% of the population on an average of 3 to 4 teeth. Severe pockets > or = 6 mm were found in less than 5% of the population. Attachment loss > or = 3 mm was found in 40% of the population. Gingival recession accounted for a significant amount of attachment loss. The prevalence of early-onset periodontitis ranged from less than 1% in 14- to 17-year-olds to 3.6% in young adults aged 18 to 34. Extensive and severe periodontitis was much more prevalent in minorities, people with less than a high school education, and those who had seen a dentist infrequently and had subgingival calculus. Smoking and diabetes have been identified as risk factors, especially diabetics with poor metabolic control, a long duration of the disease, and extensive subgingival calculus. Under managed care, there has been an expansion of soft tissue management programs in the offices of general dentists and referral guidelines which limit referral of patients with moderate periodontitis. Quality-assurance mechanisms will be essential for the diagnosis and treatment of persons with periodontitis.

Clinical features of early-onset periodontitis

The authors estimate the prevalence of early-onset periodontitis, or EOP, in U.S. adolescents and describe the clinical features that occur at an early stage in those who have EOP. In 1986 and 1987, about 10.0 percent of African-American, 5.0 percent of Hispanic and 1.3 percent of white U.S. adolescents had EOP. Clinical features that may be useful in the early detection of EOP include overt gingival inflammation, dental calculus and a high rate of caries, restorations and tooth loss.

Localized juvenile periodontitis and Actinobacillus actinomycetemcomitans in a Brazilian population

Localized juvenile periodontitis (LJP) has been used as a model for studying periodontal disease, and its prevalence is considered to be higher in third-world countries (0.3-8%) than in industrialized countries (0.1%). Mostly, the disease has been associated with Actinobacillus actinomycetemcomitans (A.a.) but lack of association has also been reported. The aim of this study was to identify LJP patients in geographically different Brazilian populations and assess the presence of A.a. in their periodontal lesions. 7843 children, 12-19-years of age, from the cities of Rio de Janeiro, Votorantim and Belo Horizonte were screened, and LJP patients were identified by strict clinical and radiographical criteria. A final LJP prevalence of 0.3%, with a 99% confidence interval between 0.16% to 0.47%, was found. The prevalence in the subpopulations varied between 0.1-1.1% in the different areas. Subgingival bacterial samples were obtained from the oral cavity of 25 patients and their family members. 80% of these patients, 39.5% of their family members, 35.3% of their parents, and 43.9% of all siblings were culture positive for A.a. All but one of the families had at least one member in addition to the patient who was culture positive for A.a. In 3 families, > 1 member showed radiographic and clinical signs of LJP. 30% of non-LJP subjects coming from one of the areas with higher LJP prevalence harbored A.a. We conclude that LJP is highly associated with A.a. in this Brazilian population.

Periodontal diseases: epidemiology

1. The interpretation of epidemiological data of periodontal disease is difficult, due to inconsistencies in the methodology used. It is not possible, therefore, to accurately assess if the prevalence of the periodontal diseases shows a world-wide decline. As long as the disease is assessed through accumulated clinical attachment loss, retention of the natural dentition in older ages entails increased prevalence in these cohorts. Contemporary epidemiological studies should ideally employ full-mouth examination of the periodontal tissues. Partial recording estimates are generally biased, especially when the prevalence of the disease is low. 2. Early-onset periodontitis is infrequent in all populations. Adult periodontitis is rather prevalent; however, advanced disease affects limited subfractions of the population (probably less than 10 to 15%). Although prevalence figures vary with race and geographic region, in most cases, the progression pattern of the disease seems compatible with the retention of a functional dentition throughout life. 3. Of a plethora of behavioral and environmental risk markers identified by multi-variate analysis, smoking and presence of certain subgingival microorganisms have been proven to be true risk factors. The same holds true for diabetes mellitus, a systemic condition that confers a risk for periodontal disease which is independent of the effect of other significant factors. 4. In certain cases, periodontal infections appear to have a systemic impact on the host. Most recent data indicate that periodontal disease may confer risk for coronary heart disease and pre-term low birth weight.

Dental caries and tooth loss in adolescents with early-onset periodontitis

The aim of this study was to assess the caries experience and tooth loss over 6 years in subjects with early-onset periodontitis as compared to their matched controls, and to describe the characteristics of teeth lost during this period. A multi-stage probability sample representing 8th to 12th grade U.S. schoolchildren were screened during the 1986/1987 school year to identify subjects with early-onset periodontitis (cases). The examination included measuring the clinical attachment level, presence of caries and dental restorations, and tooth loss. A random sample of controls without early-onset periodontitis were selected for a follow-up examination and were matched to cases on gender, race, age, and geographic location. A total of 266 subjects, with a mean age of 16 years at baseline, were examined during the 1992/1993 school year and were classified into localized (LJP) and generalized juvenile periodontitis (GJP), incidental attachment loss (IAL), and control groups. Whites had more caries experience than Blacks and Hispanics, but there were no significant differences in tooth loss between the ethnic groups. The LJP and the IAL groups, respectively, had higher and lower overall caries experience than the control group. The LJP group had a significantly higher number of missing teeth at follow-up, and exhibited more extensive tooth mortality during 6 years than the control group. The GJP group also showed more tooth loss than the control group, but the difference was not statistically significant. In the LJP, GJP, IAL, and control groups, respectively, 43%, 32%, 26%, and 18% of the subjects lost teeth over 6 years due to disease. The findings showed differences in caries activity between the early-onset periodontitis groups and a variation by race. The findings suggest that loss of periodontal support was the principal cause for tooth loss in the LJP and GJP groups, and that dental caries was the principal cause for tooth extraction in the IAL and the control groups.

Gingival state and dental calculus in early-onset periodontitis

This study was undertaken to 1) compare the prevalence of gingival inflammation and dental calculus in adolescents with early-onset periodontitis and their matched controls and 2) assess and compare the relationship between the presence of dental calculus and the extent of gingival bleeding and attachment loss in these subjects. The study group consisted of 1,285 13 to 20 year-old individuals, 651 males and 634 females, selected from a national survey of the oral health of U.S. adolescents in 1986/1987. It included 709 (55.2%) Blacks, 224 (17.4%) Hispanics, and 352 (27.4%) Whites. Eighty-nine subjects had localized or generalized juvenile periodontitis (JP), 218 had incidental attachment loss (IAL), and 978 were without clinical attachment loss (controls). The controls were matched to cases on gender, race, age, and geographic location. The subjects were examined clinically to assess the percentage of sites with gingival bleeding and supragingival calculus only and subgingival calculus with or without supragingival calculus. The IAL and JP groups had significantly more gingival bleeding and subgingival calculus than the controls. Also, the JP group had significantly higher prevalence of both conditions than the IAL group. The percentage of sites with supragingival calculus was not different between the groups, but varied by ethnicity. Hispanics with JP had the highest percentage of sites with gingival bleeding and subgingival calculus, and the lowest percentage of sites with only supragingival calculus. The results demonstrate that gingival inflammation and subgingival calculus are associated with early periodontal breakdown, and contradict earlier reports of early-onset periodontitis not being associated with these factors.

Early-onset periodontitis: progression of attachment loss during 6 years

We studied the pattern of progression of early-onset periodontitis and the change in the extent and severity of the periodontal condition in adolescents who were followed for 6 years. In a national survey of the oral health of U.S. children, 14,013 adolescents were examined clinically in 1986/1987 to assess the periodontal attachment loss of teeth. Individuals with early-onset periodontitis within this population were identified and classified into localized juvenile periodontitis (LJP), generalized juvenile periodontitis (GJP), and incidental attachment loss (IAL) groups. Ninety-one subjects, 13 to 20 years old at baseline, were examined 6 years later. They included 51 males and 40 females; and 72 Blacks, 6 Hispanics, and 13 Whites. They were clinically re-examined and then reclassified according to their periodontal status at follow-up. The severity and extent of these diseases continued to increase during the study period. In teeth that were affected at baseline, the lesions had progressed to include deeper portions of the periodontium, and more of the teeth unaffected at baseline exhibited periodontal attachment loss at follow-up, thus changing the disease characteristics and the basis for the clinical classification. Of the individuals classified with LJP at baseline, 62% continued to have LJP 6 years later and 35% developed GJP. Of those classified with GJP initially, all but two (82%) continued to have GJP at follow-up. Among the IAL group, 28% of subjects developed LJP or GJP, and 30% were reclassified in the no attachment loss group. Molars and incisors were the teeth most often affected in all three groups. The mean change in attachment loss over 6 years in the LJP, GJP, and IAL groups was 0.45, 1.12, and 0.13 mm, respectively. The present findings demonstrate the limitations of the currently used morphological criteria in the classification of early-onset periodontitis. The findings also suggest that the difference between LJP and GJP is in the number and type of teeth involved, and that the two classifications progress similarly, with some cases of LJP developing into GJP.

[Comparison of the evaluation of the periodontium status in 12-year- old children in 6-year interval (years of research 1987 and 1993)]

The comparison of the evaluation results of the periodontium status has been made in 12 years old children from Warsaw, Sulejówek and Wiazowna region at 6 years interval. In both studies the same criteria have been applied. A significant improvement in the periodontium status was observed in the second study. The percentage of different periodontal treatment requirements has been reduced from 81% (in the initial study) to 35% the second study.

Incidence of early periodontitis in a group of young individuals during 8 years: associations with selected potential predictors

The aim of the present study was to assess the incidence of early radiographic bone loss in a birth cohort over 8 years and to assess possible associations between incidence of bone loss and reported dental behavior, ethnic background, and previous orthodontic treatment. In a case control study comprising a proportion of the study population, the detection of black pigmented Bacteroides and Actinobacillus actinomycetemcomitans and their association with early radiographic bone loss was assessed. At the beginning of the study in 1984, there were 2,767 subjects. In 1992 sets of bite-wing radiographs were obtained from 215 subjects, who also filled out a questionnaire concerning their present and past dental behavior, ethnic background, and orthodontic treatment. Radiographic alveolar bone loss was recorded if the distance from the cemento-enamel junction to the alveolar crest exceeded 2 mm. Thirteen subjects (6%) showed new sites with bone loss over the 8-year period. Subgingival plaque was sampled from these 13 subjects and from 13 control subjects. None of the independent variables could be associated with the observed incidence of radiographic bone loss in this cohort, with the possible exception of the presence of A. actinomycetemcomitans which was detected in about 50% of the new sites with bone loss.

The prevalence of localized juvenile periodontitis in Saudi subjects

The purpose of this study was to determine the prevalence and sex ratio of localized juvenile periodontitis (LJP) cases in a selected Saudi population, to compare these values with different societies, and to correlate the sex ratio with the presence of Actinobacillus actinomycetemcomitans in the afflicted sites. In a retrospective study over a 3-year period 23 cases of LJP were diagnosed from a group of 5,480 subjects with different forms of periodontal disease. The overall prevalence was 0.42%. The female to male ratio was 1.88:1. The difference in the sex ratio was statistically significant (X = 5.490, P < .05). No statistically significant difference in the sex ratio association regarding the sites afflicted by Actinobacillus actinomycetemcomitans was found.

Identification and characterization of genetic cluster groups of Actinobacillus actinomycetemcomitans isolated from the human oral cavity

Actinobacillus actinomycetemcomitans is recognized as a primary pathogen in localized juvenile periodontitis (LJP). Restriction fragment length polymorphisms (RFLP) within a collection of subgingival plaque isolates of this bacterium were identified and characterized as the first step in understanding the pathogenesis of LJP. Over 800 isolates, from members of 18 families (LJP families) with at least one member with active LJP or a documented history of the disease and one or more siblings, less than 13 years of age, having no clinical evidence of LJP and 32 healthy control subjects, were assigned to one of 13 distinct RFLP groups (II to XIV) by using a previously characterized 4.7-kb DNA probe cloned from the reference strain FDC Y4. Isolates belonging to RFLP groups II, IV, V, and XIII predominated subgingival sites in the subjects. Members of RFLP groups II, IV, VII, VIII, X, and XI were recovered only from LJP family subjects, while group XIII and XIV variants were found exclusively in healthy controls. A synthetic oligonucleotide, homologous to the 5' end of the leukotoxin gene (lktA), and the A. actinomycetemcomitans plasmid, pVT745, were tested for their abilities to subdivide the 13 RFLP groups. The leukotoxin probe specifically identified all RFLP group II variants because of the absence of a HindIII site in the upstream noncoding region of the lkt gene complex. The plasmid probe was not as selective but may be useful for identifying clinical isolates belonging to RFLP group I. The use of these probes for the identification of genetic variants of A. actinomycetemcomitans that may be preferentially colonize diseased and healthy subjects will facilitate the study of the role of this important pathogen in periodontal diseases.