The natural history of periodontal disease. The correlation of selected microbiological parameters with disease severity in Sri Lankan tea workers

Evaluation and association of periodontal status with levels of Porphyromonas gingivalis in chronic periodontitis with and without Type 2 diabetes mellitus following nonsurgical periodontal therapy using quantitative polymerase chain reaction: An interventional study

Background:

The aim of the present study was to detect and correlate the levels of Porphyromonas gingivalis with clinical parameters after nonsurgical periodontal therapy (NSPT) in chronic periodontitis patients with or without Type 2 diabetes mellitus (T2DM), using quantitative polymerase chain reaction (Q-PCR) method.

Materials and Methods:

Sixty patients equally divided into three groups, i.e., periodontally healthy (Group I), chronic periodontitis (CP) (Group II), and CP with T2DM patients (Group III) were assessed through clinical parameters of probing pocket depth (PPD) and clinical attachment level (CAL) and were correlated for the presence of P. gingivalis in the respective groups. PPD, CAL, and saliva samples for microbiological evaluation were assessed at baseline, 1-, and 3-month post-NSPT.

Results:

Significant reduction of PPD was found 1.26 ± 0.22 versus 0.43 ± 0.33 mm in Group I, 4.62 ± 0.78 versus 2.58 ± 0.60 mm in Group II, and 6.28 ± 1.52 versus 4.01 ± 1.38 mm in Group III post-NSPT at 3 months. Similarly, a notable reduction of CAL was exhibited in both Group II (5.28 ± 0.80 vs. 3.12 ± 0.77 mm) and Group III (7.14 ± 1.59 vs. 4.51 ± 1.38 mm) patients after NSPT at 3 months. A greater reduction of P. gingivalis concentrations was observed in both Group II and Group III at 3-month post-NSPT.

Conclusion:

The substantial improvement of clinical parameters was found to be in correlation with the load of P. gingivalis, which was reduced more in Group II than in Group III, emphasizing the applicability and sensitivity of Q-PCR method for its assessment.

'Periodontal health and disease in an older population: A 10-year longitudinal study'

OBJECTIVES

To investigate alveolar bone loss (ABL), which is an indicator of periodontitis, and to identify risk factors for ABL in an older population between 2008 and 2018.

METHODS

This longitudinal study used data from a questionnaire survey and a clinical examination administered on two occasions ten years apart to 273 individuals who were 65 years and 75 years in 2008.

RESULTS

The mean number of teeth decreased significantly over the ten-year study period, while the proportion of individuals with calculus and moderate ABL visible on radiographs increased. For both ages, the number of teeth decreased by a mean of 2 teeth. The proportions of participants reporting poor general health, daily medication, xerostomia, living singly, visiting dental care irregularly and being in need of extra support in their homes all increased over the observation period.

CONCLUSIONS

Despite an increased progression of moderate alveolar bone loss, a fairly good dentition and chewing capacity was retained in this older population. However, the individual's age and fragility are important indicators that need to be considered when planning oral health care and the availability of dental care.

Natural progression of periodontal diseases in Chinese villagers based on the 2018 classification

BACKGROUND

Based on the 2018 classification, we aimed to determine the prevalence, distribution, and progression of periodontitis in the rural Chinese population without access to dental care.

METHODS

In all, 404 subjects (28.7 ± 8.9 years, M:F = 182:222) were randomly enrolled in 1992 and re-called in 1996. With the new classification, the prevalence and distribution of stage, grade, and extent were characterized. Stage progression was compared with the progression of clinical attachment loss (CAL) and radiographic bone loss (RBL).

RESULTS

At baseline, 94.1% villagers suffered from periodontitis, of whom 53.7% were in stage III/IV. The prevalence of stage III/IV increased from 18.2% in the age group of 15 to 24 years to 60.9% in 25 to 34-year-old group and 88.7% in the 35 to 44-year-old group. Significantly more stage III/IV, generalized, and grade C periodontitis were found in male villagers than female villagers. In 1996, the prevalence rate of periodontitis increased to 98.5%, with 80.0% in stage III/IV. Further, 84.2% villagers presented with grade C periodontitis based on longitudinal ΔCAL. The rate of progression (≥1 site with ΔCAL ≥3 mm) was 63.7%. Stage progression correlated significantly with CAL and RBL progression in stage I/II, but this association was not found in stage III/IV. Among subjects with disease progression in stage III/IV, 90.4% shifted from localized to generalized cases. Furthermore, ceiling effects were observed in stage III/IV.

CONCLUSIONS

In villagers without access to dental care, 94.1% suffered from periodontitis, with more than half having stage III/IV disease based on the 2018 classification. The majority cases presented with rapid periodontal progression. Although stage progression correlated significantly with CAL and RBL progression in stage I/II, ceiling effects existed in stage III/IV.

Current concepts and an alternative perspective on periodontal disease

BACKGROUND

Epidemiological data from countries worldwide show a consistent pattern implying that a fraction of around 10% of those over 40-50 years in all populations will exhibit severe periodontitis with the potential risk of losing teeth during their life-time. The subgingival microbiota shows striking similarities between populations irrespective of disease severity and can only marginally explain the clinical pattern. It is also difficult to explain this pattern by genetic and acquired risk factors such as systemic disease (e.g. diabetes) or habits (e.g. smoking) even if they may have a confounding effect on the disease.

MAIN TEXT

Inflammation of the gingiva appears to be a normal and physiological response to the presence of commensal bacteria along the gingival crevice and in the dental biofilm. Over many years of exposure to the dental biofilm, the chronic inflammation in the gingiva gradually results in a loss of attachment and bone loss. Numerous laboratory and clinical studies have provided insight into the potential role of determinants that are associated with periodontitis. However, it has been difficult to relate the findings to the pattern of the distribution of the disease observed in epidemiological studies. We propose a simple and parsimonious model that considers all the multitude of potential determinants as creating effectively random noise within the dental biofilm to which the tissues react by accumulating the effects of this noise.

CONCLUSIONS

We suggest that such a model can explain many of the epidemiological features of periodontal breakdown over time, and we discuss its clinical implications.

Plaque-induced gingivitis: Case definition and diagnostic considerations

OBJECTIVE

Clinical gingival inflammation is a well-defined site-specific condition for which several measurement systems have been proposed and validated, and epidemiological studies consistently indicate its high prevalence globally. However, it is clear that defining and grading a gingival inflammatory condition at a site level (i.e. a "gingivitis site") is completely different from defining and grading a "gingivitis case" (GC) (i.e. a patient affected by gingivitis), and that a "gingivitis site" does not necessarily mean a "GC". The purpose of the present review is to summarize the evidence on clinical, biochemical, microbiologic, genetic markers as well as symptoms associated with plaque-induced gingivitis and to propose a set of criteria to define GC.

IMPORTANCE

A universally accepted case definition for gingivitis would provide the necessary information to enable oral health professionals to assess the effectiveness of their prevention strategies and treatment regimens; help set priorities for therapeutic actions/programs by health care providers; and undertake surveillance.

FINDINGS

Based on available methods to assess gingival inflammation, GC could be simply, objectively and accurately identified and graded using bleeding on probing score (BOP%) CONCLUSIONS: A patient with intact periodontium would be diagnosed as a GC according to a BOP score ≥ 10%, further classified as localized (BOP score ≥ 10% and ≤30%) or generalized (BOP score > 30%). The proposed classification may also apply to patients with a reduced periodontium, where a GC would characterize a patient with attachment loss and BOP score ≥ 10%, but without BOP in any site probing ≥4 mm in depth.

Prevalence of periodontitis and alveolar bone loss in a patient population at Harvard School of Dental Medicine

Background

Although several studies assessed the prevalence of alveolar bone loss, the association with several risk factors has not been fully investigated. The aim of this article is to measure the prevalence of periodontitis by calculating the mean alveolar bone loss/level of posterior teeth using bitewing radiographs among the patients enrolled in the clinics at Harvard School of Dental Medicine and address risk factors associated with the disease.

Methods

One thousand one hundred thirty-one patients were selected for radiographic analysis to calculate the mean alveolar bone loss/level by measuring the distance between the cementoenamel junction and the alveolar bone crest on the mesial and distal surfaces of posterior teeth. Linear regression with Multi-level mixed-effect model was used for statistical analysis adjusting for age, sex, race, median household income, and other variables.

Results

Mean alveolar bone level of the whole sample was 1.30 mm (±0.006). Overall periodontitis prevalence for the sample was 55.5% (±1.4%). Moderate periodontitis prevalence was 20.7% (±1.2%), while 2.8% (±0.5%) of the whole sample had severe periodontitis. Adjusted mean alveolar bone loss was higher in older age groups, males, Asian race group, ever smokers, and patients with low median household income.

Conclusion

The effect of high household income on the amount of bone loss can be powerful to the degree that high household income can influence outcomes even for individuals who had higher risks of developing the disease. Public health professionals and clinicians need to collaborate with policy makers to achieve and sustain high quality of healthcare for everyone.

Radiographic alveolar bone level and levels of serum 25-OH-Vitamin D3 in ethnic Norwegian and Tamil periodontitis patients and their periodontally healthy controls

BACKGROUND

Studies suggest association between low serum 25-OH-Vitamin D₃ (VitD) and chronic destructive periodontal diseases. The main sources of VitD is sun exposure and fat fish. Subjects with dark skin will therefore generate less VitD as response to sun exposure. The aim of the study was to assess the radiographic bone level and levels of serum VitD in ethnic Norwegian and Tamil periodontitis patients and their respective healthy controls.

METHODS

Twenty-seven Tamil periodontitis patients living in Norway were compared to 21 Tamil controls as well as to 21 Norwegian periodontitis patients and 23 Norwegian controls. Marginal bone level was diagnosed on radiographs. VitD levels were diagnosed in blood samples by high-performance liquid chromatography-mass spectrometry.

RESULTS

VitD levels were lower in Norwegian periodontitis patients than in controls, while no significant differences were observed between Tamil periodontitis patients and controls despite the significant difference between RBL between the periodontitis patients and controls in both groups. When calculating the odds ratio for having periodontal disease in both populations together, it appeared that one unit increased serum VitD (i.e. 1 nmol/L) decreased the odds of having radiographic bone loss by 4%.

CONCLUSION

According to logistic regression, and after correcting for confounding factors, VitD levels showed significant association with the presence of periodontitis, as expressed by radiographic bone loss, in all patients combined.

Natural history of periodontitis: Disease progression and tooth loss over 40 years

OBJECTIVES

To assess long-term attachment and periodontitis-related tooth loss (PTL) in untreated periodontal disease over 40 years.

MATERIAL AND METHODS

Data originated from the natural history of periodontitis study in Sri Lankan tea labourers first examined in 1970. In 2010, 75 subjects (15.6%) of the original cohort were re-examined.

RESULTS

PTL over 40 years varied between 0 and 28 teeth (mean 13.1). Four subjects presented with no PTL, while 12 were edentulous. Logistic regression revealed attachment loss as a statistically significant covariate for PTL (p < .004). Markov chain analysis showed that smoking and calculus were associated with disease initiation and that calculus, plaque, and gingivitis were associated with loss of attachment and progression to advanced disease. Mean attachment loss <1.81 mm at the age of 30 yielded highest sensitivity and specificity (0.71) to allocate subjects into a cohort with a dentition of at least 20 teeth at 60 years of age.

CONCLUSIONS

These results highlight the importance of treating early periodontitis along with smoking cessation, in those under 30 years of age. They further show that calculus removal, plaque control, and the control of gingivitis are essential in preventing disease progression, further loss of attachment and ultimately tooth loss.

Relative effectiveness of azithromycin in killing intracellular Porphyromonas gingivalis

Invasive infections by Porphyromonas gingivalis are associated with persistent periodontal attachment loss and can be difficult to eliminate by scaling and root planing. Azithromycin (AZM) inhibits P. gingivalis and is actively accumulated by most human cells. We used an in vitro infection model to compare the effectiveness of AZM in killing intracellular P. gingivalis to the combined regimen of amoxicillin (AMX) and metronidazole (MET). Transport of [3H]-AZM by human gingival fibroblasts was characterized. Monolayers of Smulow-Glickman gingival epithelial cells or gingival fibroblasts were infected with P. gingivalis (strain 33277 or W83). After extracellular bacteria were eliminated with teicoplanin, infected cells were treated with therapeutic concentrations of AZM, AMX, or AMX + MET. Viable intracellular bacteria were released by cell lysis and plated on blood agar for enumeration. Antimicrobial activity against planktonic P. gingivalis was also evaluated. While survival of intraepithelial P. gingivalis 33277 was not significantly different after treatment with the three regimens, survival in infected fibroblasts was significantly lower after AZM treatment (65.9 ± 5.5%) compared with AMX (92.2 ± 3.5%) or AMX + MET (79.8 ± 5.2%, P < 0.01). Carnitine, a competitive inhibitor of AZM transport, reduced killing by AZM by ~55% (P < 0.05). Survival of intrafibroblast P. gingivalis W83 was also significantly lower after AZM treatment compared with the other regimens (P < 0.05). At therapeutic concentrations, AZM was significantly more active against intracellular P. gingivalis than against planktonic P. gingivalis (P < 0.0083). Gingival epithelial cells and fibroblasts possess a transport system that accumulates AZM and enhances elimination of intracellular P. gingivalis. Compared with the combination of AMX and MET, AZM was equally effective against intraepithelial P. gingivalis 33277 and significantly more effective against both strains of P. gingivalis from infected gingival fibroblasts. The results suggest that AZM could be a reasonable alternative to the regimen of AMX and MET for periodontal patients who should not take these agents due to known side effects or compliance issues.

A 4-year prospective study of the progression of periodontal disease in a rural Chinese population

OBJECTIVES

The natural progression of periodontitis in the Chinese population is not well researched. We investigated the progression of periodontal disease over 4 years in 15-44-year-old Chinese villagers with no access to regular dental care.

METHODS

In 1992, 486 villagers were enrolled, and in 1996, 413 villagers were re-examined. Probing depth (PD) and clinical attachment level (CAL) were examined at six sites per tooth. Sites with ΔCAL ≥3 mm were defined as active sites. Cross-sectional and longitudinal analyses were performed using means and percentile plots.

RESULTS

The mean CAL increased by 0.26 mm over 4 years. The incidence of periodontitis (at least one site with CAL ≥3 mm) was 8%. The incidence of periodontitis among those with no periodontal disease at baseline was 44.9%. Seventy-eight percent of the subjects had at least one active site. In the 15-24-year group, 244 of 401 active sites had gingival recession, while only 51 active sites had both gingival recession and deeper pockets. In the 25-34-year and 35-44-year groups, almost one-third of the active sites (329/1087) and more than one-third of the active sites (580/1312) respectively had a combination of gingival recession and deeper pockets.

CONCLUSIONS

In this study, we demonstrated that in Chinese population without regular dental care, both the initiation of periodontitis and progression of previously existed periodontitis contributed to the natural progression of periodontitis and periodontal pocketing played a greater role with age increasing.

CLINICAL SIGNIFICANCE

This rare study reports the natural progression of periodontal disease in a group of Chinese villagers (15-44 years) with virtually no access to regular dental care.

The oral microbiome and the immunobiology of periodontal disease and caries

The composition of the oral microbiome differs from one intraoral site to another, reflecting in part the host response and immune capacity at each site. By focusing on two major oral infections, periodontal disease and caries, new principles of disease emerge. Periodontal disease affects the soft tissues and bone that support the teeth. Caries is a unique infection of the dental hard tissues. The initiation of both diseases is marked by an increase in the complexity of the microbiome. In periodontitis, pathobionts and keystone pathogens such as Porphyromonas gingivalis appear in greater proportion than in health. As a keystone pathogen, P. gingivalis impairs host immune responses and appears necessary but not sufficient to cause periodontitis. Historically, dental caries had been causally linked to Streptococcus mutans. Contemporary microbiome studies now indicate that singular pathogens are not obvious in either caries or periodontitis. Both diseases appear to result from a perturbation among relatively minor constituents in local microbial communities resulting in dysbiosis. Emergent consortia of the minor members of the respective microbiomes act synergistically to stress the ability of the host to respond and protect. In periodontal disease, host protection first occurs at the level of innate gingival epithelial immunity. Secretory IgA antibody and other salivary antimicrobial systems also act against periodontopathic and cariogenic consortia. When the gingival immune response is impaired, periodontal tissue pathology results when matrix metalloproteinases are released from neutrophils and T cells mediate alveolar bone loss. In caries, several species are acidogenic and aciduric and appear to work synergistically to promote demineralization of the enamel and dentin. Whereas technically possible, particularly for caries, vaccines are unlikely to be commercialized in the near future because of the low morbidity of caries and periodontitis.

Characterization and serotype distribution of Aggregatibacter actinomycetemcomitans isolated from a population of periodontitis patients in Spain

OBJECTIVE

There is no study characterizing the variability of Aggregatibacter actinomycetemcomitans isolates in periodontitis patients in Spain. It is therefore the aim of this investigation to study the serotype distribution of A. actinomycetemcomitans strains isolated from periodontitis patients in Spain. The polymorphism of the genes that codifies the leukotoxin and the operon of the cytolethal-distending toxin (cdt) will also be investigated.

DESIGN

From a total of 701 patients samples, 40 A. actinomycetemcomitans-positive periodontitis patients were included in the study (mean age 45.3, 62.5% females) and their clinical periodontal status was assessed. On average, 1-3 isolates from each patient were sub-cultured and characterized by PCR.

RESULTS

Using culture the prevalence of A. actinomycetemcomitans was 5.7%. The most frequent serotype was "b", being 30 patients infected by a unique serotype, while 7 patients showed co-colonization, mostly with serotypes "a" and "b". From the 79 pure isolates obtained, 24 were from serotype "a", 30 from serotype "b", 12 from serotype "c" and 4 from serotype "d". Further characterization of these samples showed that none of these 79 isolates demonstrated the 530-bp deletion in the leukotoxin's promoter region that characterizes the JP2 strain. Conversely 65.8% of the isolates were cdt+.

CONCLUSIONS

The most common serotypes were "a" and "b", being serotype "b" the most prevalent in mono-colonization, while serotypes "e" and "f" were not detected. In the majority of samples, operon that codifies the cdt (65.8%) and the genes responsible for the codification of leukotoxin (100%) were found. None of the isolates were JP2 strains.

Association of interleukin-1 gene variations with moderate to severe chronic periodontitis in multiple ethnicities

Background and Objective

Genetic markers associated with disease are often non-functional and generally tag one or more functional “causative” variants in linkage disequilibrium. Markers may not show tight linkage to the causative variants across multiple ethnicities due to evolutionary divergence, and therefore may not be informative across different population groups. Validated markers of disease suggest causative variants exist in the gene and, if the causative variants can be identified, it is reasonable to hypothesize that such variants will be informative across diverse populations. The aim of this study was to test that hypothesis using functional Interleukin-1 (IL-1) gene variations across multiple ethnic populations to replace the non-functional markers originally associated with chronic adult periodontitis in Caucasians.

Material and Methods

Adult chronic periodontitis cases and controls from four ethnic groups (Caucasians, African Americans, Hispanics and Asians) were recruited in the USA, Chile and China. Genotypes of IL1B gene single nucleotide polymorphisms (SNPs), including three functional SNPs (rs16944, rs1143623, rs4848306) in the promoter and one intronic SNP (rs1143633), were determined using a single base extension method or TaqMan 5′ nuclease assay. Logistic regression and other statistical analyses were used to examine the association between moderate to severe periodontitis and IL1B gene variations, including SNPs, haplotypes and composite genotypes. Genotype patterns associated with disease in the discovery study were then evaluated in independent validation studies.

Results

Significant associations were identified in the discovery study, consisting of Caucasians and African Americans, between moderate to severe adult chronic periodontitis and functional variations in the IL1B gene, including a pattern of four IL1B SNPs (OR = 1.87, p < 0.0001). The association between the disease and this IL1B composite genotype pattern was validated in two additional studies consisting of Hispanics (OR = 1.95, p = 0.04) or Asians (OR = 3.27, p = 0.01). A meta-analysis of the three populations supported the association between the IL-1 genotype pattern and moderate to severe periodontitis (OR 1.95; p < 0.001). Our analysis also demonstrated that IL1B gene variations had added value to conventional risk factors in predicting chronic periodontitis.

Conclusion

This study validated the influence of IL-1 genetic factors on the severity of chronic periodontitis in four different ethnicities.

Association of three bacterial species and periodontal status in Chinese adults: an epidemiological approach

Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia are oral pathogens associated with periodontitis. The association between these three bacteria and periodontal disease has been reported in populations of many countries. However, corresponding data in Chinese populations are still lacking. The aim of this study was to detect these pathogens in subgingival plaque collected from 468 subjects with chronic periodontitis in a group of Chinese adults by using a PCR method and to determine the degree of association between the target bacteria and periodontal status based on logistic regression analysis. A. actinomycetemcomitans, P. gingivalis, and T. forsythia were found in 20.5%, 70.7%, and 77.1% of the subjects, respectively. About one-third (36.1%) of subjects had chronic periodontitis. Upon univariate analysis, age, male gender, current smoking status, diabetes, and the presence of A. actinomycetemcomitans or P. gingivalis were positively associated with chronic periodontitis, whereas education and income exhibited inverse associations with chronic periodontitis. Upon multivariate analysis, education, current smoking status, diabetes, and the presence of A. actinomycetemcomitans and P. gingivalis remained significant. The adjusted odds ratios for having chronic periodontitis were 2.5 and 3.4 in subjects positive for A. actinomycetemcomitans and P. gingivalis, respectively. However, no significant association was observed between the presence of T. forsythia and periodontal status. This study assesses the prevalence of periodontal pathogens and chronic periodontitis and the associations with sociodemographic characteristics among this group of Chinese adults. These findings also suggest that PCR should be considered for field oral epidemiologic studies and may be necessary in investigations presenting major logistic challenges.

Porphyromonas gingivalis strain diversity

Porphyromonas gingivalis is implicated in the etiology of chronic periodontitis. Genotyping studies suggest that genetic variability exists among P. gingivalis strains; however, the extent of variability remains unclear and regions of variability remain largely unidentified. To assess P. gingivalis strain diversity, we previously used heteroduplex analysis of the ribosomal operon intergenic spacer region (ISR) to type strains in clinical samples and identified 22 heteroduplex types. Additionally, we used ISR sequence analysis to determine the relatedness of P. gingivalis strains to one another and demonstrated a link between ISR sequence phylogeny and the disease-associated phenotype of the strains. In the current study, heteroduplex analysis of the ISR was used to determine the worldwide genetic variability and distribution of P. gingivalis, and microarray-based comparative genomic hybridization (CGH) analysis was used to more comprehensively examine the variability of major heteroduplex type strains by using the entire genome. Heteroduplex analysis of clinical samples from geographically diverse populations identified 6 predominant geographically widespread heteroduplex types (prevalence, > or = 5%) and 14 rare heteroduplex types (prevalence, <2%) which are found in one or a few locations. CGH analysis of the genomes of seven clinically prevalent heteroduplex type strains identified 133 genes from strain W83 that were divergent in at least one of the other strains. The relatedness of the strains to one another determined on the basis of genome content (microarray) analysis was highly similar to their relatedness determined on the basis of ISR sequence analysis, and a striking correlation between the genome contents and disease-associated phenotypes of the strains was observed.

Invasive differences among Porphyromonas gingivalis strains from healthy and diseased periodontal sites

BACKGROUND AND OBJECTIVE

The purpose of this study was to determine any difference between Porphyromonas gingivalis isolates from periodontally healthy sites as compared to those from diseased sites with respect to the ability to invade host cells.

MATERIAL AND METHODS

Subgingival plaque samples were obtained from periodontally healthy and diseased sites using paper points. P. gingivalis colonies were isolated and tested, using an antibiotic protection assay, for their ability to invade KB cells. P. gingivalis 381 and Escherichia coli MC1061 were used as controls.

RESULTS

Mean values of 16.79 +/- 0.86 x 10(3) colony-forming units/mL and 26.14 +/- 2.11 x 10(3) colony-forming units/mL were observed in invasion assays for isolates from periodontally healthy and diseased sites, respectively. P. gingivalis present in diseased sites had significantly greater invasive abilities than strains isolated from healthy sites. No statistical difference was noted between male or female subjects concerning the degree of invasion; isolates from diseased sites from both genders had significantly greater invasion abilities than those from healthy sites. A significant correlation was found between the increased invasive capabilities of P. gingivalis isolates vs. an increased probing depth.

CONCLUSION

The increased invasion noted with P. gingivalis isolates from diseased sites vs. healthy sites, and the increased invasive capabilities with increasing probing depth, indicate that P. gingivalis isolates have a varying ability to invade host cells in the periodontal pocket.

Effect of inactivation of the Arg- and/or Lys-gingipain gene on selected virulence and physiological properties of Porphyromonas gingivalis

Proteolytic enzymes produced by Porphyromonas gingivalis are thought to play critical roles in the pathogenesis of periodontitis. The aim of this study was to investigate the effect of gingipain cysteine proteinase gene inactivation on selected pathological and physiological functions of P. gingivalis. Our results showed that Arg- and Lys-gingipain activities are critical components for the efficient growth of P. gingivalis in human serum. However, when the serum was supplemented with peptides provided as pancreatic casein hydrolysate, the gingipains did not appear to be essential for growth. The effect of gingipain gene inactivation on the susceptibility of P. gingivalis to serum bactericidal activity was investigated using standardized human serum. The wild-type strain, P. gingivalis ATCC 33277, was largely unaffected by the bactericidal activity of human serum complement. On the other hand, mutants lacking Arg-gingipain A, Arg-gingipain B, or Lys-gingipain activity were susceptible to complement. Since gingipains are mostly located on the outer membrane of P. gingivalis, inactivation of the genes for these enzymes may modify cell surface properties. We showed that gingipain-deficient mutants differed in their capacities to assimilate radiolabeled amino acids, cause hemolysis, express adhesins, hemagglutinate, and form biofilms. Lastly, the gingipains, more specifically Arg-gingipains, were responsible for causing major cell damage to human gingival fibroblasts. In conclusion, our study indicated that, in addition to being critical in the pathogenic process, gingipains may play a variety of physiological roles in P. gingivalis, including controlling the expression and/or processing of virulence factors. Mutations in gingipain genes thus give rise to pleiotropic effects.

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

OBJECTIVES

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Subgingival microbiota of Brazilian subjects with untreated chronic periodontitis

BACKGROUND

Different periodontopathogenic microbiota have been associated with periodontal diseases in several populations. The present investigation determined the subgingival microbiota of untreated chronic periodontitis Brazilians using the checkerboard DNA-DNA hybridization technique.

METHODS

Twenty-five periodontitis patients (mean age, 41 +/- 2; mean probing depth [PD], 3.3 +/- 0.2; mean attachment level [AL], 3.6 +/- 0.2) with no history of previous periodontal therapy and a control group of 14 healthy subjects (mean age, 34 +/- 0.6; mean PD, 1.8 +/- 0.2; mean AL, 1.7 +/- 0.1) were selected. Measurements of PD, AL, bleeding on probing, plaque accumulation, and suppuration were recorded at 6 sites/tooth. Subgingival plaque samples were obtained from 4 sites in each tooth/subject in both groups. The presence and levels of 41 subgingival species were determined in 4,032 plaque samples using whole genomic DNA probes and the checkerboard method.

RESULTS

Periodontal pathogens, as well as some unusual species (E. faecalis, E. coli and Bartonella sp.), were detected significantly more often and/or in higher levels in the periodontitis group (P < 0.05). Most species were more frequently detected in interproximal sites. B. forsythus, P. gingivalis, E. nodatum, and F. nucleatum ss vincentii showed a significant positive correlation with mean PD and AL (P < 0.05).

CONCLUSIONS

The subgingival microbiota of Brazilians with untreated chronic periodontitis were complex, including high proportions of periodontopathogens commonly found in other populations, as well as some unusual species.

Subgingival microbiota of indigenous Indians of Central America

OBJECTIVE

To define the subgingival microbial profiles of adult subjects from a previously identified rural community of indigenous Indians in Guatemala, Central America.

MATERIALS AND METHODS

A full-mouth periodontal examination was performed in 114 adult subjects from 45 families. Plaque samples were collected from both deep and shallow periodontal pockets and checkerboard DNA-DNA hybridization was employed to identify 17 species previously associated with periodontitis or health.

RESULTS

Plaque deposits and gingivitis were universal and widespread, and periodontal pocketing > or =5 mm was highly prevalent (84% of subjects). Streptococcus sanguis, Actinomyces naeslundii genospecies 2 and Fusobacterium nucleatum were significantly more prevalent in shallow sites. At the subject level, Actinomyces naeslundii and Peptostreptococcus micros were significantly more prevalent in periodontally-healthy subjects. Actinobacillus actinomycetemcomitans was not detected in any sample.

CONCLUSION

There was no association between periodontal disease status and presence of suspected periodontal pathogens. These latter results conflict somewhat with those from treated populations. However, in this population where extensive plaque deposits and gingivitis are universal, the presence of putative pathogens may be more reflective of the local environment.

The natural history of periodontal disease in man. Risk factors for progression of attachment loss in individuals receiving no oral health care

BACKGROUND

Few investigations have reported on risk factors for periodontal attachment loss over time in subjects with no home or professional dental care. The purpose of this report was to identify potential risk factors for progression of periodontal attachment loss among male Sri Lankan tea laborers who participated in a 20-year investigation of the natural history of periodontal disease.

METHODS

Data for this report were obtained from the 154 subjects who participated in the 1970 baseline and the final 1990 examinations and included data from their interim examinations performed in 1971, 1973, 1977, 1982, and 1985. Oral health assessments included: 1) attachment levels in millimeters on mesial and mesio-buccal surfaces of all but third molar teeth; 2) plaque index (PI); 3) gingival index (GI); 4) calculus index (CI); 5) caries index (DMFS); and 6) presence or absence of teeth. Other variables included age, history of smoking, and/or use of betel nut. Statistical analyses used multivariate repeated measures analysis of variance (ANOVA).

RESULTS

The final adjusted model indicated that attachment loss increased significantly with age (X2 = 74.0; df = 1), GI (X2 = 45.5; df = 1), CI (X2 = 52.7; df = 1) and follow-up time (X2 = 219.8; df = 6, P<0.0001 for all variables).

CONCLUSIONS

Age, GI, CI, and time were significantly associated with mean attachment loss over 20 years. Neither PI, history of smoking, or history of betel nut use were significantly associated with attachment loss over time.

Untreated periodontal disease in Indonesian adolescents. Subgingival microbiota in relation to experienced progression of periodontitis

BACKGROUND/AIMS

In an Indonesian population deprived of regular dental care, the experienced progression of disease between baseline (1987) and follow-up (1994) was investigated in relation to the composition of the subgingival microbiota at follow-up. At baseline the age ranged from 15 to 25 years. Clinical and microbiological evaluation was completed in 158 of the 167 subjects available at follow-up.

METHODS

Plaque index (PI), pocket depth (PD), bleeding on probing (BOP), and attachment loss (AL) were scored at the approximal surfaces of all teeth and subgingival calculus on the approximal surfaces of the Ramfjord teeth only (number of sites with subgingival calculus: NSC). A pooled sample of the deepest pocket in each quadrant was evaluated using microbiological culture techniques.

RESULTS

At baseline the mean values of the clinical parameters were AL=0.35 mm, PI=1.01, BOP=0.80 PD=3.25 mm and NSC=6.04 and at follow-up AL=0.75 mm, PI=1.16, BOP=1.19, PD=3.34 mm and NSC=5.85. All parameters except PD and NSC showed a statistically significant increase. At follow-up the prevalence of Actinobacillus actinomycetemcomitans was 40%, of Porphyromonas gingivalis 67%, of Prevotella intermedia 66%, of Fusobacterium nucleatum 79%, of Bacteroides forsythus 16%, of Campylobacter rectus 4%, and of P. micros 6%. No differences in clinical parameters were found between groups with or without these micro-organisms. In 129 subjects AL of > or =2 mm at > or =1 site was found. Logistic regression showed three significant odds-ratio's for experienced progressive periodontitis: Plaque index (12.2), gender (3.4) and Actinobacillus actinomycetemcomitans (2.9).

CONCLUSIONS

The results of this retrospective study suggest that plaque is the most important parameter related to experienced disease progression, and that the presence of A. actinomycetemcomitans may be associated with increased chance of disease progression.

Quantitative real-time PCR for Porphyromonas gingivalis and total bacteria

Accurate quantitation of the number of cells of individual bacterial species in dental plaque samples is needed for understanding the bacterial etiology of periodontitis. Real-time PCR offers a sensitive, efficient, and reliable approach to quantitation. Using the TaqMan system we were able to determine both the amount of Porphyromonas gingivalis and the total number of bacterial cells present in plaque samples. Using species-specific primers and a fluorescent probe, detection of DNA from serial dilutions of P. gingivalis cells was linear over a large range of DNA concentrations (correlation coefficient = 0.96). No difference was observed between P. gingivalis DNA alone and the same DNA mixed with DNA isolated from dental plaque, indicating that P. gingivalis levels can be determined accurately from clinical samples. The total number of cells of all bacterial species was determined using universal primers and a fluorescent probe. Standard curves using four different bacterial species gave similar results (correlation coefficient = 0.86). Levels of both P. gingivalis and total bacteria were determined from a series of human plaque samples. High levels of P. gingivalis were observed in several of the samples from subjects with periodontitis and none of those from healthy subjects. Real-time quantitative PCR provided a sensitive and reliable method for quantitating P. gingivalis. In addition, it allowed the determination of the total number of bacterial cells present in a complex sample so that the percentage of P. gingivalis cells could be determined.

Identification of Porphyromonas gingivalis strains by heteroduplex analysis and detection of multiple strains

Heteroduplex analysis has been used extensively to identify allelic variation among mammalian genes. It provides a rapid and reliable method for determining and cataloging minor differences between two closely related DNA sequences. We have adapted this technique to distinguish among strains or clonal types of Porphyromonas gingivalis. The ribosomal intergenic spacer region (ISR) was amplified directly from a subgingival plaque sample by PCR with species-specific primers, avoiding the need for culturing the bacteria. The PCR products were then directly compared by heteroduplex analysis with known strains of P. gingivalis for identification. We identified 22 distinct but closely related heteroduplex types of P. gingivalis in 1,183 clinical samples. Multiple strains were found in 34% of the samples in which P. gingivalis was detected. Heteroduplex types were identified from these multistrain samples without separating them by culturing or molecular cloning. PCR with species-specific primers and heteroduplex analysis makes it possible to reliably and sensitively detect and identify strains of P. gingivalis in large numbers of samples.

Porphyromonas gingivalis strain variability and periodontitis

To determine if there is variability in virulence among strains of Porphyromonas gingivalis in human periodontitis, their distribution in a group of subjects with clear indicators of periodontitis and in a healthy, age-matched control group was examined. The presence of heteroduplex types of P. gingivalis in the two groups was determined with a PCR-based assay. This assay relied on detection of polymorphisms in the ribosomal internal spacer region (ISR). ISR fragments generated by PCR with P. gingivalis-specific primers were hybridized to fragments from reference strains, and the formation of heteroduplexes from the hybridization of nonidentical sequences was observed by polyacrylamide gel electrophoresis. Characteristic fingerprints from comparison with a panel of reference strains allowed the identification of heteroduplex types in clinical samples. One hundred thirty adults with periodontitis and 181 controls were sampled. With this approach, 11 heteroduplex types of P. gingivalis were detected in the population. Sufficient numbers were available for statistical analysis of six of these types. Heteroduplex type hW83 was found to be very strongly associated with periodontitis (P = 0.0000), and two additional types, h49417 and hHG1691, were also significantly associated with disease. The remaining types, h23A4, h381, and hA7A1, were detected more frequently in subjects with periodontitis than in healthy subjects, but the difference was not significant. These data indicate that virulence in human periodontitis varies among strains of P. gingivalis, and they identify an apparently highly virulent subgroup.

Sequencing of the ribosomal intergenic spacer region for strain identification of Porphyromonas gingivalis

The ribosomal intergenic spacer regions (ISRs) of 19 laboratory strains and 30 clinical samples of Porphyromonas gingivalis were amplified by PCR and sequenced to provide a strain identifier. The ISR is a variable region of DNA located between the conserved 16S and 23S rRNA genes. This makes it an ideal locus for differentiation of strains within a species: primers specific for the conserved flanking genes were used to amplify the ISR, which was then sequenced to identify the strain. We have constructed a P. gingivalis ISR sequence database to facilitate strain identification. ISR sequence analysis provides a strain identifier that can be easily reproduced among laboratories and catalogued for unambiguous comparison.

Oral ecology and person-to-person transmission of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis

The ecological characteristics of the oral cavity are dissimilar for A. actinomycetemcomitans and for P. gingivalis, as judged by differences in their colonization preferences and patterns, associations with periodontal disease parameters, relationships with the subgingival microbiota and the type of periodontitis and their clonal persistence in the oral cavity. These features also suggest that as a periodontal pathogen, A. actinomycetemcomitans is different from P. gingivalis. Probably in most infected individuals, low levels of A. actinomycetemcomitans can persist for years in equilibrium with the host and the resident oral microbiota. However, it is well established that A. actinomycetemcomitans can cause disease in some individuals or in some circumstances when the regulatory mechanisms are unable to maintain homeostasis in the ecosystem. Elevated A. actinomycetemcomitans proportions of the biota can be regarded as a sign of ecological imbalance, leading to increased risk of periodontal destruction. There is also evidence showing elevated pathogenic potential of certain A. actinomycetemcomitans clones. Although A. actinomycetemcomitans seems to be relatively rarely transmitted between cohabiting adults, transmission can occur to periodontally healthy children of A. actinomycetemcomitans-positive parents. Parents and children may share factors that promote successful oral colonization of A. actinomycetemcomitans, or the window of opportunity is in childhood. Therefore, to prevent parent-child transmission of A. actinomycetemcomitans, bacterium-positive parents of young children are optimal targets for enhanced information and treatment. In selected populations, screening for specific clones of A. actinomycetemcomitans has been employed in prevention of peridontitis. Future research aiming at finding the reasons which cause the changes in the oral homeostasis to allow the growth of A. actinomycetemcomitans may give insight into novel prevention strategies for A. actinomycetemcomitans-associated periodontitis. Compared with A. actinomycetemcomitans, P. gingivalis shows a different pattern of coexistence with the host. In periodontal health or in children, P. gingivalis is absent or only rarely detected. When present, P. gingivalis is commonly recovered in high numbers from dentitions exhibiting inflamed periodontitis and poor oral hygiene. Contrary to A. actinomycetemcomitans, the data on the vertical transmission of P. gingivalis are limited. The major infection route of P. gingivalis seems to be between adults, indicating that P. gingivalis commonly colonizes in an established oral microbiota. These characteristics suggest that the degree of tolerance between P. gingivalis and the host is inferior to that between A. actinomycetemcomitans and the host. It appears that the association of P. gingivalis with disease is a rule rather than an accidental incident. On these grounds, it seems that the host-P. gingivalis relationship approaches antibiosis. Since P. gingivalis infection is related to a typical periodontal eco-pathology, the susceptibility to person-to-person transmission of this pathogen may be controlled by periodontal treatment and emphasizing the significance of high standard oral hygiene.

Periodontitis-associated marker bacteria in an urban North American patient population: application of a commercial immunoassay

We used an immunoassay to demonstrate marker organisms (Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans) in 3 private practice populations (F-ME periodontist, 55 patients; MHM periodontist, 179 patients; and EWM general dentist, 19 patients). Occurrence of the marker organisms involves the whole oral environment, not just individual sites, as shown by close correlation between presence of the marker organisms in 2 independent sites/samples within a single mouth. Presence of the marker P. gingivalis (and P. intermedia) relates closely to periodontal pocketing while presence of A. actinomycetemcomitans does not have this pocket-associated characteristic. There was no significant relationship between presence of the marker organisms and the number of teeth in a mouth, and in the periodontal practice patients there was no significant effect of gender on occurrence of the marker organisms. A. actinomycetemcomitans and the other 2 markers were found over the entire age range (12 to 75) of our patients. Regular periodontal treatment reduced occurrence of all marker organisms and increased the frequency of marker-negative patients and sites. Occurrence of the marker organisms above immunoassay threshold levels appears to represent how receptive a patient is to each individual organism. Most patients appear receptive to the presence of P. intermedia whether treated or not. Significantly fewer patients who underwent regular treatment show the presence of P. gingivalis or A. actinomycetemcomitans when compared to untreated patients. Diagnostic application of microbial markers requires ongoing clinical assessment of patients and careful clinical judgment. 1391.

Prevalence of Porphyromonas gingivalis and periodontal health status

Periodontitis is a common, progressive disease that eventually affects the majority of the population. The local destruction of periodontitis is believed to result from a bacterial infection of the gingival sulcus, and several clinical studies have provided evidence to implicate Porphyromonas gingivalis. If P. gingivalis is a periodontal pathogen, it would be expected to be present in most subjects with disease and rarely detected in subjects with good periodontal health. However, in most previous studies, P. gingivalis has not been detected in the majority of subjects with disease, and age-matched, periodontally healthy controls were not included for comparison. The purpose of the study reported here was to compare the prevalence of P. gingivalis in a group with periodontitis to that of a group that is periodontally healthy. A comprehensive sampling strategy and a sensitive PCR assay were used to maximize the likelihood of detection. The target sequence for P. gingivalis-specific amplification was the transcribed spacer region within the ribosomal operon. P. gingivalis was detected in only 25% (46 of 181) of the healthy subjects but was detected in 79% (103 of 130) of the periodontitis group (P < 0.0001). The odds ratio for being infected with P. gingivalis was 11.2 times greater in the periodontitis group than in the healthy group (95% confidence interval, 6.5 to 19.2). These data implicate P. gingivalis in the pathogenesis of periodontitis and suggest that P. gingivalis may not be a normal inhabitant of a periodontally healthy dentition.

The periodontal disease problem. A comparison between industrialised and developing countries

There is no reason to believe that periodontal diseases in industrialised and developing countries are in principle different. That is, not in the sense that the problem is caused by a different set of periodontal diseases, with different micro-organisms and a different natural history, needing a different approach towards prevention and treatment. Indeed, from a public health perspective the relative similarities in periodontal conditions around the world are far more striking than the differences. The view that periodontal diseases are a much more prevalent and a severe problem in the developing countries seems to be true only in terms of poorer oral hygiene and considerably greater calculus retention, already at a young age, but not so clear for periodontal destruction in adults.

Characterization of serum antibodies to Porphyromonas gingivalis in individuals with and without periodontitis

Although Porphyromonas gingivalis is a defined pathogen in periodontal disease, many subjects control the infection without experiencing loss of attachment. Differences in host susceptibility to the disease may be reflected in the pattern of humoral antibodies against specific P. gingivalis antigens. The aim of this study was to determine the presence of antibodies against immunodominant P. gingivalis antigens as well as the isotype and subclass of anti-P. gingivalis antibodies against outer membrane antigens in four groups of patients: P. gingivalis-positive, 1) with and 2) without periodontitis, and P. gingivalis-negative, 3) with and 4) without periodontitis. Antigens of molecular weight 92, 63, and 32 kDa and lipopolysaccharide were found to be immunodominant. Group 1 subjects showed a significantly higher response to the 92 and 63 kDa antigens compared with other groups. The response to lipopolysaccharide was significantly higher in group 1, and lower in group 4 than in groups 2, 3. Immunoglobulin G1 (IgG1), IgG2 and IgM antibodies against P. gingivalis outer membrane were present in all subjects, while only some subjects were seropositive for IgG3, IgG4 and IgA. There were no differences in concentrations for IgG1, IgG3 and IgM. The IgG2 concentration in group 4 was significantly higher than in groups 1 and 2, while the IgG4 concentration in group 4 was significantly lower than in other groups. The frequency of seropositivity for IgG4 and IgA was lowest in group 4, while IgG3 seropositivity was almost exclusively seen in healthy patients in groups 2, 4. These findings suggest that the presence of IgG3 may reflect non-susceptibility to the disease, while lack of IgG4 may be indicative of periodontal health and lack of infection.

Comparison of the subgingival microbiota of periodontally healthy and diseased adults in northern Cameroon

Our study is the 1st report on subgingival microbiota in adult Cameronians. The aim was to investigate, using the checkerboard DNA-DNA hybridization technique, the prevalence of 18 oral species in subgingival plaque samples obtained from sex- and age-matched Cameronian adults with and without periodontal destruction. We also compared cultivation and the Affirm DP test with the checkerboard technique in their capability to detect some selected species among the 18. 21 adult periodontitis patients and 21 periodontally healthy subjects were examined and the results were compared statistically. Each periodontitis patient had at least 4 pockets of > or = 6 mm depth, while the healthy subjects had no sites more than 3 mm deep. Results of the checkerboard analysis showed that significantly (p < 0.05) more periodontitis patients tested positive for most of the 18 bacterial species. The Gram-positive species Actinomyces naeslundii, Streptococcus mitis and Streptococcus sanguis, known as microbiota of healthy sites, were detected significantly more frequently in the healthy group. Cultivation demonstrated P. gingivalis, B. forsythus, A. actinomycetemcomitans, P. intermedia and F. nucleatum in significantly lower %s of patients as compared to the checkerboard technique. Furthermore, the Affirm DP test detected P. gingivalis and B. forsythus in significantly fewer patients than did the checkerboard technique. A. actinomycetemcomitans was detected in 52.3% of the patients by the latter technique while the Affirm DP test failed to detect the bacterium in any of the samples. Overall, the results of the present study confirm the importance of the screening method and indicate that the prevalences of the investigated putative periodontal pathogens and beneficial species in the healthy and diseased adult Cameronians were similar to those reported for adults in the West and in some developing countries.

Principles of evaluation of the diagnostic value of subgingival bacteria

This paper describes steps in the process of evaluating subgingival bacteria assays for the diagnosis of periodontal disease. The first step examines the infectious etiology of periodontal disease in pointing to specific oral bacteria as periodontal pathogens. Second is characterization of the laboratory test to detect and quantitate these pathogens as to sensitivity, specificity, and positive and negative predictive value. Third is the role of the laboratory test in the diagnosis of the different forms of periodontal disease which is related to the current clinical rather than microbiological definition of these diseases. The fourth and most important step is an analysis of the significance of subgingival bacterial tests in clinical decision-making.