61. Etiology – Local: Microbiology and Periodontal Diseases                                     

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  1. specific and non specific plaque hypotheses
  2. the microbiologic changes after the cessation of tooth cleaning
  3. the bacteria in health, gingivitis and periodontitis
  4. the transmissibility of periodontal pathogenic bacteria between people, sites and implants
  5. the bacteria in diagnosis
  6. the risk assessment, prognosis and natural history of periodontitis
  7. Adult Periodontitis Microbiology
  8. Refractory Periodontitis Microbiology
  9. Bacterial tissue invasion
  10. review articles

General - Plaque & Gingivitis:What are the specific and non specific plaque hypotheses?

  1. Loeshe W., Giordano, J: Treatment paradigms in periodontal disease. Compend Contin Educ Dent. 1997;18:221-226, 228-230, 232


Trace the clinical and microbiological changes that occur after cessation of tooth cleaning.

  1. Loe H, et al : Experimental gingivitis in man. J. Periodontol. 36:177-187, 1965

Types of Bacterial Pathogens. Which bacteria are associated with health? Gingivitis?

  1. Listgarten MA. The structure of dental plaque. Periodontol 2000 1994:5:52-65

  2. Lie M et al.: Occurrence of Prevotella intermedia and Prevotella nigrescens in relation to gingivitis and gingival health J Clin Periodontol 2001;28:189-193

  3. Tanner A et al. Microbiota of health, gingivitis and initial periodontitis. J Clin Periodontol 1998;25:85-98

Can bacteria associated with periodontal disease be transmitted from one individual to another? From one site to another? Between teeth and implants?

  1. Van Winkelhoff AJ, Boutaga K. Transmission of periodontal bacteria and models of infection. J Clin Periodontol. 2005;32 Suppl 6:16-27.

  2. Quirynen M, Vogels R, Peeters W, van Steenberghe D, Naert I, Haffajee A. Dynamics of initial subgingival colonization of 'pristine' peri-implant pockets. Clin Oral Implants Res. 2006 Feb;17(1):25-37.

Bacteria in Diagnosis

  1. Listgarten MA, Hellden L: Relative distribution of bacteria at clinically healthy and periodontally diseased sites in humans. J. Clin. Periodontol. 5:115- 1978.

  2. Offenbacher S, et al: The microbial morphotypes associated with periodontal health and adult periodontitis: Composition and distribution. J. Clin. Periodontol. 12: 736- , 1985.

  3. Baab D, Opsvig E : Subgingival microflora in bleeding and nonbleeding pockets. J. Clin. Periodontol. 13:795- 1986.


Miscellaneous

  1. Socransky S, et al : Difficulties encountered in the search for the etiologic agents of destructive periodontal diseases. J. Clin. Periodontol. 14:588 - , 1987.

  2. Preus et al. The natural history of periodontal disease. The correlation of selected microbiological parameters with disease severity in Sri Lankan tea workers. J. Clin. Periodontol. 22:674- 678, 1995.

  3. Machtei et al. Longitudinal study of prognostic factors in established periodontitis patients. JClin Periodontol 1997;24:102-109

  4. Grossi SG et al. Assessment of risk for periodontal disease. Risk indicators for attachment loss. J Periodontol 1994; 65:260-267


Adult Periodontitis Microbiology

  1. Listgarten M. Pathogenesis of periodontitis. J Clin Periodontol 1986;418-430

  2. Armitage G, et al: Relationship between the percentage of subgingival spirochetes and the severity of periodontal disease. J. Periodontol. 53:550- ,1982.

  3. Loesche WJ, Syed SA, Schmidt E, Morriso EC: Bacterial profiles of subgingival plaque in periodontitis. J. Periodontol. 56:447-456, 1985.

  4. Slots J, Listgarten M : Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans in human periodontal disease. J. Clin. Periodontol. 15:85- , 1988.

  5. Getka T, Alexander D, Parker W, Miller G: Immunomodulatory and superantigen activities of bacteria associated with adult periodontitis. J. Periodontol. 1996; 67: 909-917

  6. Socransky SS, Haffajee AD, et al: Microbiological complexes in subgingival plaque. J. Clin. Periodontol. 1998; 25: 134-144

  7. Ximénez-Fyvie LA, Haffajee AD, Socransky SSMicrobial composition of supra- and subgingival plaque in subjects with adult periodontitis. J Clin Periodontol. 2000 Oct;27(10):722-32.

  8. Tran et al. Persistent Presence of Bacteroides forsythus as a Risk Factor for Attachment Loss in a Population With Low Prevalence and Severity of Adult Periodontitis. J periodontal 2001; 72(1): 1-10

  9. Mombelli A, Casagni F, Madianos PN. Can presence or absence of periodontal pathogens distinguish between subjects with chronic and aggressive periodontitis? A systematic review. J Clin Periodontol 2002; 29(Suppl. 3):S10–S21.

  10. Slots J: Oral viral infections of adults. Periodontol 2000  2009; 49:60.

Refractory Periodontitis Microbiology

  1. Socransky SS, Smith C, Haffajee AD: Subgingival microbial profiles in refractory periodontal disease. J Clin Periodontol  2002; 29:260.

  2. Ana Paula V. Colombo,Susan Bennet, Sean L. Cotton, J. Max Goodson, Ralph Kent, Anne D. Haffajee, Sigmund S. Socransky, Hatice Hasturk, Thomas E. Van Dyke, Floyd E. Dewhirst, and Bruce J. Paster: Impact of Periodontal Therapy on the Subgingival Microbiota of Severe Periodontitis: Comparison Between Good Responders and Individuals With Refractory Periodontitis Using the Human Oral Microbe Identification Microarray J. Periodontol. October 2012, Vol. 83, No. 10, Pages 1279-1287

Bacterial Invasion

  1. G. Tribble, R. Lamont- Bacterial invasion of epithelial cells and spreading in periodontal tissue. . Periodontology 2000, vol. 52, 2010, 68-83

Review Articles

  1. Darveau et al. The microbial challenge in periodontitis. Periodontol 2000 1997; 14: 12-32

  2. Tatakis DN, Kumar PS. Etiology and pathogenesis of periodontal diseases. Dent Clin North Am. 2005 Jul;49(3):491-516, v.

  3. Socransky SS, Haffajee AD. Microbial mechanisms in the pathogenesis of destructive periodontal diseases: a critical assessment. J Periodontal Res. 1991 May;26(3 Pt 2):195-212.

  4. Kornman K : The role of supragingival plaque in the prevention and treatment of periodontal diseases: A review of current concepts. J. Periodontal Res. (Suppl) 16:5, 1986

  5. Greenstein G, Polson A : Microscopic monitoring of pathogens associated with periodontal disease - A review. J. Periodontol. 56:740, 1985.

  6. Socransky SS, Haffajee A: The bacterial etiology of destructive periodontal disease. Current concepts. J. Periodontol 63: (Suppl #4) 322-331, 1992

General - Plaque & Gingivitis: What are the specific and non specific plaque hypotheses?

Loesche 1997                      ARTICLE

P: Review article about treatment paradigms in periodontal disease

D:

Nonspecific plaque hypothesis

- The overgrowth of any or all bacterial species on the tooth surfaces causes an inflammatory response in the approximating gingival tissue

- There is no need to diagnose a bacterial infection as a result of a specific organism

- Keeping the bacterial load below the level that triggers tissue loss has been the goal of periodontal therapy

Specific plaque hypothesis

- Limited number of bacterial species are specifically involved in most forms of periodontal disease

- Studies involving immunological reagents and DNA probes have significantly associated Pg, Tf, and Td with periodontal disease

Comparison of treatment protocols based on non-specific and specific plaque hypotheses

% of patients who go to maintenance phase of treatment after:

Nonspecific hypothesis

Specific hypothesis

SRP#

24

24*

SRP

9

+ Surgery

60

84*

+ Metro

72

+ ATBs

13

97*

+ Surgery

18

Failure

3

Failure

1

*% Cummulative of patients who go to maintenance phase with specific treatment

#Nonspecific hypothesis protocol extracted hopeless teeth prior to treatment

Trace the clinical and microbiological changes that occur after cessation of tooth cleaning.

Loe 1965                      ARTICLE

Purpose: Attempt to produce gingivitis in patients with healthy gingiva and study the sequence of changes in the microbial flora and in the gingiva.

M&M: Withdrew all measures of OH in 12 healthy patients with clinically normal gingiva, and once inflammatory changes were noted, gave patients OHI (brushing and wood massage sticks) and hygiene was renewed. Bacteria flora examined at intervals from start of experiment to establishment of clinical gingivitis

Results: During period of no cleaning: Gross accumulation of soft debris and development of marginal Gingivitis in all cases. No major difference in tendency to form plaque was noted between maxillary or mandibular, or between different groups of teeth; lingual surfaces did accumulate less debris. The soft debris did not mature into clinically detectable calculus. The interdental areas of max molars were more affected by gingivitis and the lingual of mandibular premolars showed the best gingival condition. Time to develop gingivitis was 10-21 days.

Mean plaque index Mean gingival index

At start 0.43 0.27

At end of no cleaning 1.67 1.05

After resuming cleaning 0.17 0.11

BL: Described 3 stages of bacterial colonization:

  1. Immediate increase in cocci. Small accumulations of leukocytes.

  2. 2-4 days: filaments and slender rods predominate (Gram -). Leukocytes increase in size.

  3. 6-10 days: vibrios and spiros present

  4. OH reinstated and saw gingival health and normal flora in 7 days: G+ cocci and short rods.

Time necessary to develop gingivitis varied from 10-21 days.

Types of Bacterial Pathogens. Which bacteria are associated with health? Gingivitis?

Listgarten 1994:                      ARTICLE

P: Discussion on the structure of dental plaque

D: Plaque is the nonmineralized microbial accumulation that adheres tenaciously to tooth surfaces, restorations, and prosthetic appliances, shows structural organization with predominance of filamentous forms, is composed of organic matrix derived from salivary glycoproteins and extracellular microbial products, and cannot be removed by rinsing or water spray (quoted from textbook by Nolte)

BL: Knowing bacterial composition may help with diagnosis and tracking disease progression. However, the mere presence of one or more pathogenic species in a subject is insufficient to produce significant deterioration in the periodontal status of this individual. Periodontal disease is multifactorial, and takes into account host and environmental factors as well as local bacterial interactions that can modulate the virulence of otherwise pathogenic species.

Lie 2001                      ARTICLE

P: To study the occurrence of Prevotella Intermedia (Pi) and Prevotella Nigrescens(Pn) in relation to gingival gingivitis, gingival health and experimental gingivitis in dental plaque and in oral mucous membranes.

M&M: 25 subjects with a mean age of 22 years and in good general health were selected on the basis of having gingivitis (>30% BOP) and absence of pockets5mm and aproximal attachment loss. Pre-trial period: All subjects received several appointments for OHI and sc/rp. Only when they had <20% bleeding sites they entered an “experimental gingivitis” trial period. During 14 days, the participants had to abstain from all OH measures in both upper and lower jaw. Thereafter they were allowed to resume their regular OH procedures. Microbiological samples were taken before entering into the study (intake), day 0 and day 14 of the experimental gingivitis patients. Samples were taken from the dorsum of the tongue, the tonsils, supra-g and sub-g plaque from mesial surfaces of all first molars. Plaque scores and BOP were also assessed. Black to brown pigmented colonies were presumed to be Pi and/or Pn. Pi and Pn were differentiated on the basis of electrophoretic mobility of the enzymes malate dehydrogenase and glutamate dehydrogenase.

R: In natural gingivitis (intake) the % of bleeding sites was 37% and while after treatment at the state of gingival health was reduced to 7%. After 14 days of experimental gingivitis bleeding increased to 23%. 73% of the samples were positive for the anaerobic microbes presumed to be Pi and/or Pn. In natural and experimental gingivitis 25/25 subjects were positive for Pi and/or Pn and in gingival health 23/25 subjects. Of the 889 isolates that were successfully purified and differentiated almost all subjects were colonized with Pn whereas half of the study population harbored Pi. 24/25 subjects were Pn positive and 13/25 subjects were Pi positive.

C: Almost all subjects were colonized with Pn whereas half of the population harbored Pi. These 2 species were isolated from both dental plaque and mucosal sites and were found to colonize the oral cavity simultaneously. In natural gingivitis, at the start and after 14 days of experimental gingivitis, Pn was the predominant microorganism.

Tanner 1998                      ARTICLE

P: To longitudinally monitor periodontally healthy subjects to detect periodontal attachment level loss, and to characterize the microbiotas characterizing sites and subjects showing: initial periodontal lesions, gingivitis or health.

M+M: 56 healthy adult subjects (20-60 years old) with minimal periodontal attachment loss, avg PD= 2mm, were clinically monitored at 3-month intervals for 1 year. Clinical measurements at each visit included: PD, AL, PI and GI. Subjects were divided into 4 clinical categories: disease active, recession, healthy, and gingivitis. Disease active subjects exhihited at least one disease active site, at either an interproximal or buccal (recession) location. Subject categories of gingival health or inflammation (gingivitis) were determined from mean measurements for a subject over all monitoring visits. Healthy subjects averaged <20% sites red and <2% sites BOP over the course of monitoring, while gingivitis subjects averaged either >20% sites

red and/or >2% sites BOP. Sites showing >1.5 mm periodontal attachment loss during monitoring were sampled as active lesions for microbial analysis. Active (interproximal and/or buccal) sites were sampled when detected. Healthy and gingivitis sites were sampled at the end of clinical monitoring. Plaque samples were too small to be divided for use in both culture and DNA probe assays, therefore different sites were sampled for culture and DNA probe analysis. All subjects had samples taken from one gingivitis and one healthy site.

R: Culture Studies:

Active sites- Interproximal- predominant species were T. forsythia, C. rectus, and S. noxia.

Active sites- Buccal- predominant species were A. naeslundii and S. oralis.

Gingivitis- predominant species were A. naeslundii. C. gracilis, and T. forsythia (at lower levels than active sites).

Health-associated species included S. oralis, A. naeslundii and A. gerencseriae.

DNA probe data:

Identified higher mean levels of T. forsythia and C. rectus with active compared to inactive periodontitis sites. Pg and Aa were detected infrequently. Cluster analysis of the cultural microbiota grouped 8/9 active interproximal lesions in one subcluster characterized by a mostly gram-negative microbiota, including T. forsythia and C. rectus.

BL: There is an association between T. forsythia, C. rectus and S. noxia with initial periodontal lesions and suggests that these species are responsible for converting sites from periodontal health to disease. The cultured microbiota from interproximal and buccal active sites differed, suggesting that a different mechanism may be involved in increased attachment loss between those areas.

Can bacteria associated with periodontal disease be transmitted from one individual to another? From one site to another? Between teeth and implants?

Van Winkelhoff 2005                      NO ARTICLE

P: To review the literature on bacterial typing techniques and summarize the information on clonal distribution of Aa and Pg in family units based on different typing techniques in order to establish the likelihood for person-to-person transmission of these pathogens.

D: Aa and Pg are detected infrequently in perio health, which makes them prime candidates to study person-to-person transmission. Transmission is dependent on host factors (sexual behavior, hygiene, occupation, nutrition, immunity, general health), microbial factors (infectiousness, pathogenicity, virulence, survival in human and animal hosts including resistance towards immune response and drugs) and environmental factors (temperature, humidity, oxygen tension). Changes in any of these factors will affect the likelihood of transmission. Whether perio bacteria can be transmitted via aerosols is currently not known.

When transmission is directly from parent to offspring it is referred to as vertical. Horizontal transmission occurs between unrelated individuals by contact, respiratory, or fecal-oral. Essential factors for transmission include the source, number of microorganisms shed, frequency of effective contacts and survival in the environment.

To date, there is no evidence that Aa or Pg occur outside the human host. The survival of perio pathogens in salica outside the oral cavity is not known. Indirect inoculation may occur when a contaminated toothbrush is used within several hours of use. The minimal infection does and the required number of exposures to transfer Aa or Pg form not person to another is unknown as well. Salivary Aa and Pg has been shown to be of the same clonal type as those found in the sub-g plaque in the majority of patients.

The frequency of vertical transmission nof Aa is estimated between 30-60% based on detection of identical genotypes in children and parents. Vertical transmission of Pg may occur, but has only been rarely observed. The Tuite-McDonnel 1997 study suggested that vertical transmission of Pg can occur, but this study does not provide conclusive evidence as genotyping has not been performed. Horizontal transmission of Aa and Pg between spouses may range from 14-60% for Aa and between 30-75% for Pg. Transmission of Aa between siblings has been suggested, but infection by the same source cannot be ruled out.

Quirynen 2006                      ARTICLE

Purpose: To test the hypothesis that the composition of maturing subgingival plaque in the pristine periimplant tissues would soon (within 2 weeks) be comparable to the subgingival microbiota of teeth in the same quadrant.

Materials and methods: 42 partially edentulous Caucasians (18 females, 5 smokers) volunteered for the study. They had previously received at least two 2-stage implants. All of them were in good condition and none of them had used antimicrobials during the 3months prior to the study.

Most of the patients had a history of gingivitis or mild to moderate perio and had been treated with oral hygiene improvement, SRP (32 pts) and perio surgery (8 pts). All perio therapy had been completed 3 months prior to implant placement (6-11 months before abutment connection). Proportion of PDs of 5mm or more was 7.1% and 3 pts at the end of the study had several PDs of 6mm or more.

Split-mouth design. 3-8 months after placement healing abutments were placed. Pts were instructed to rinse with 0.2% CHX twice a day for one week. At 1 (19 subjects), 2, 4, 13 (all subjects) and 26 and 78 (29 subjects) weeks after abutment insertion subgingival plaque samples were taken implants (test sites) and teeth (control sites) within the same jaw. 12 different sites were selected per patient, three of which with the following clinical conditions: implant sites with shallow pockets (3mm or less)m implant sites with deeper pockets (more than 3mm), tooth sites with shallow pockets (4mm or less) and tooth sites with deeper pockets (4mm or more).

PD, sulcus bleeding Index and PI were recorded except for week one.

Results: The mean periodontal parameters for the 29 patients who completed the entire study did not differ significantly around teeth and implants for shallow pockets. For the medium and deeper sites though the scores were often significantly higher around teeth. Scores were also higher for medium comparing to shallow sites within tooth sites and to a lower extent within implant sites.

At week 2, the subgingival plaque in freshly created peri-implant pockets already exhibited a complex microbiota with high proportion of members of the red and orange complexes. These proportions showed minor changes over time and resemble these of the established microbiota around teeth PDs4mm or less. Teth with deeper PDs showed higher proportion of red complex series. The counts for red and orange complex species remained stable around teeth but increased significantly around implant at 2, 4 and 13 weeks.

At 26 weeks total counts were nearly identical for all conditions around teeth and implants.

The ratio anaerobic/aerobic species was slightly higher for teeth with deeper probings (6mm or more) but was relatively constant for teeth with shallower pockets and implants.

Conclusion: Bacteria associated with periodontitis could colonize peri-implant pockets within a week. Their numbers are relatively low initially but appeared to reach a stable level within a week.

Cr: Selection of shallow and deeper sites around implants was initially based on the thickness of the tissue at abutment connection (they avoided probing in the initial healing phases).

Despite authors mention that final restorations were placed after two months so that the subgingival plaque formation remains undisturbed the first month, it is mentioned that some of the patients had temporary crowns and bridges after abutment placement.

Bacteria in Diagnosis

Listgarten and Hellden (1978)                      ARTICLE

Purpose: To present a technique used to classify bacterial samples and illustrate the differences that exist between healthy and diseased sites.

Materials and methods

Results:

Coccoid

Rods

Fusi &fil

Motile

Spirochetes

Healthy

74.3

16.5

7.2

0.3

1.8

Diseased

22.3

18.0

7.5

12.7

37.7

BL: Motile: Non-motile (Coccoid, Rods, Filaments, Fusiforms) ratio for healthy sites was 1:49 and for diseased sites 1:1. Data may be useful for comparison to detect the effect of various tx modalities on the periodontal flora and determine the presence or absence of disease.

Offenbacher-Olde- van Dyke 1985                      ARTICLE

P: To compare different bacteria types associated with the sub-G flora in patients with periodontitis to patients with a healthy periodontium using lavage technique.

M&M:  Subgingival plaque samples were obtained from 162 sites in 27 adult Periodontitis patients (AAP type III and IV) and 162 sites in 27 healthy patients. The distribution of 10 microbial morphotypes was determined by darkfield microscopy.

R:Small motile coccobacillus was the predominant morphotype in both healthy and diseased sites.

- Non motile organisms < 1-2 % of sample from healthy and diseased sites.

Spirochetes, cocci and fusiforms had high frequency in health.

In diseased patients, spirochetes, filaments and small non motile rods were significantly increased.

Analysis of individual sites showed no significant difference between healthy and diseased sites.

BL: Increased Spirochetes & Fusiforms found in Perio pts. The numerical density of other types is NSD when comparing healthy to diseased sites. Thus, the increase in the % of small spirochetes in disease is due to a site-localized four-fold increase in numerical density within the non-adherent plaque.

Baab 1986                      ARTICLE

P: To compare the subgingival flora from 4-6 mm pockets in order to learn whether on not bleeding correlates with the presence of potentially pathogenic flora.

M&M: Eleven pts with at least one 4-6 mm pocket in each quadrant were chosen. They had not received prophylaxis during the previous 4 months. Data collected from 2 non-bleeding and 2 bleeding sites. The examiner probed only the 4-6mm using a pressure sensitive probe, waited 30 sec for bleeding, and selected one site from each quadrant. After removing supragingival plaque with a scaler, a curette was used to remove the bacterial contents from the base of the pocket. The sample was prepared and studied at 800x magnification. The first 100 cocci, motile rods, spirochetes, and other morphotypes were counted; bacterial percentages were calculated and expressed as percentages of the total count. Means of PD, attachment levels, and bacterial %’s from bleeding and non-bleeding sites were compared.

R: Forty three pockets from 11 pt were analyzed. Percents of microbial types at each site varied widely both between pts, and within the same pt. The proportion of spirochetes ranged from 0-20%, motile rods 1-16%, and cocci from 20-86% for both types of sites. Mean values for all clinical and microbial measurements in bleeding and non-bleeding sites were not statistically significant. The percent of spirochetes was significantly correlated to PD, CAL, and gingival inflammation.

BL: BOP is not significantly correlated with changes in composition of the subgingival flora assessed by phase-contrast microscopy.

Miscellaneous

Socransky-Haffajee-Smith-Dzink- 1987                       ARTICLE

Purpose: To outline the difficulties researchers face with when looking for the etiologic agents of periodontal disease

Discussion: Discusses technical problems in obtaining subgingival plaque samples of the right size from the right place at the right time, as well as trouble in the dispersion, cultivation, and identification of the samples. Second set of problems is conceptual, including difficulties in differentiating between periodontal diseases and determining the state of activity of the periodontal lesions. The complexity of microbiota presents a challenge, as there are realistic estimates of 300 or more species residing in subgingival sites. If periodontal disease is caused by combinations of two or more microbial species, the complexity would increase enormously (44,850 combinations of two species which might cause disease). Another problem is trying to distinguish overgrowths of opportunistic species form increases in number of true pathogens. It also appears that different infections occur at the same time in a single oral cavity, and as a result there are numerous analytical problems with the data gathered.

Conclusion: Improvement in technological assessments of the microbiota and clinical evaluation of the disease should lend to more reasoned tests and approaches to be taken in the future. Using selective media, immunofluorescent techniques, and DNA probes will verify or discard these agents as etiologic agents.

BL: As a result of all of these difficulties researchers are faced with, the etiologic agents of periodontal disease are not clearly defined.

Preus 1995                      ARTICLE

P: To assess the prevalence of A.a, P.g and Pi and their association with periodontal disease in Sri Lankan tea workers.

M&M: 268 subjects. 2 sites/subject were chosen based on GI, attachment loss, and PD. All sites chosen for microbiological sampling were isolated and supragingival plaque was removed. Sterile paper points were used to collect sub-G plaque samples. Immunofloresecne was used to identify species, as well as culturing in order to confirm the indirect immunofluorescense data. Samples were grouped by no disease (GI ≤1) gingivitis only (GI≥2 no AL), moderate periodontitis (PD ≤5mm), advanced periodontitis (≥6mm).

R: P. intermedia was found in 76% P. gingivalis 40% of tea labors. A.A. was found in 15% of the participants. P. gingivalis, P. intermedia were significantly associated with increasing severity of disease. A.A was found in equal frequencies in all disease states

C: There is an association between these bacteria and periodontal disease in the Sri Lankan population.

Machte 1997                      ARTICLE

P: to study longitudinally, a large amount of clinical, microbiological and immunological indicators, and to try to determine whether the presence of one or more of these parameters at baseline would correlate positively with increased attachment loss and/or bone loss.

M&M: Following initial screening, 79 patients 25-66 years of age, with interproximal CAL 6mm in 2 or more teeth and PD 5mm in one or more sites were included. Exclusion criteria: patients with fewer than 14 teeth, systemic disease, periodontal therapy in the past 2 years, antibiotic therapy in the last 3 months or taking NSAIDS. PI, GI, calculus index, PD and AL were recorded at baseline (3months post- initial exam) and were repeated every 3 months for another 9 months (total of one year from initial exam). Full mouth x-rays were taken at baseline and at 12 months. Sub-gingival plaque samples were taken at baseline and at every 3 months. Serum and GCF samples were gathered at each visit and assayed using ELISA for IgG subclasses. Samples were also drawn at each visit for a quantitative of serum cotinine level.

R: The overall mean attachment loss and bone loss were very close over the year: 0.159mm and 0.16mm. Average probing depth showed minimal change (-0.03), thus showing that most attachment loss was through recession. Smokers showed greater attachment loss and radiographic bone loss than non-smokers. Mean attachment loss was three times greater in smokers compared to non-smokers (0.27 vs 0.091mm). Radiographic bone loss was twice as much in smokers compared to non-smokers (0.235 vs 0.12mm). Plaque, calculus and GI in baseline, showed no correlation with any of the changes in perio parameters at the end of the year. Past severity of periodontal involvement (as reflected in baseline measurements) showed direct correlation with outcomes of progressive periodontal breakdown. Tf, Pi, and Pg were frequently found in all of these patients, and the patients with higher numbers of these bacteria showed further disease progression. Subjects with mean baseline PD were at greater risk for future bone loss 1 year later (OR 2.97). Smokers were at SS greater risk for further attachment loss when compared to nonsmokers (OR of 5.4). Subjects that harbored Tf, were at 7X greater risk for increased pocket depth.

C: Past periodontal destruction, smoking habits, Tf, Pg, Pi are prognostic factors for further periodontal breakdown.

Grossi 1994                      ARTICLE

P: To investigate the role of systemic diseases, socio-economic factors, smoking, occupational hazards, and subgingival bacteria as risk indicators for attachment loss.

M+M: Cross-sectional study of 1,426 subjects (25-74 years old) residing in Erie County, New York area. Subjects broken into case group (with attachment loss) and control group (no attachment loss). 5 categories for CAL loss: healthy (0-1mm AL), low (1.1-2.0 mm Al), moderate (2.1-3.0 mm AL), high (3.1-4.0 mm AL), and severe (4.1 to 8.0 mmAL). Approximately 3% of the sample had attachment loss >5 mm. Statistical analysis conducted to assess associations between the extent of periodontal disease and patient characteristics (including age, smoking, systemic diseases, exposure to occupational hazards, and subgingival microbial flora). Age and smoking amount were further stratified. Control for gender, socioeconomic status, subgingival calculus.

R: Age was the factor most strongly associated with attachment loss, with odds ratios for subjects 35 to 44 years old being 1.72 to odds ratio for subjects 65 to 74 years old being 9.01. Diabetes mellitus was the only systemic disease positively associated with attachment loss with an odds ratio of 2.32. Smoking had relative risks ranging from 2.05 for light smokers increasing to 4.75 for heavy smokers. The presence of two bacteria, Porphyromonas gingivalis and Bacteroides forsythus (now T. forsythia), in the subgingival flora represented risks of 1.59 and 2.45.

BL: Age, smoking, diabetes mellitus, and the presence of subgingival P. gingivalis and T. forsythia are risk indicators for attachment loss. The odds ratio for having attachment loss increased with age and higher rates of smoking.

Adult Periodontitis Microbiology

Listgarten 1986:                      ARTICLE

P: To review the pathogenesis of periodontitis with an emphasis on the changes in the last decade.

D: Periodontitis is an inflammatory disease of the periodontium, which is characterized by loss of the tissues supporting the tooth. Its primary etiology is an ill-defined series of microbial infections, which may be composed of more than 300 species currently recognized in the oral cavity. Of the 300 species of bacteria in the oral cavity, only 5% are considered to be strongly associated with periodontitis, with 1% being present in over 90% of all cases of periodontitis. Other factors associated with periodontitis are occlusal trauma, hormonal alterations, and leukocyte dysfunctions. It may be necessary to differentiate between periodontitis and gingivitis with pre-existing bone loss, since the clinical implications as well as the microbial etiology may differ significantly.

Adult periodontitis is the most common form of periodontitis and after age 40 is present in almost 100% of the population (differs between authors due to lack of widely accepted criteria to diagnose periodontitis). Pattern of tissue loss tends to be bilaterally symmetrical. It is possible that the bacteria accumulate symmetrically due to anatomical factors that are present symmetrically in the mouth. Data appears to indicate that breakdown occurs in episodic, random episodes of active disease (Socransky). The tissue destruction is dependent on host/parasite balance, which may be disturbed by either accumulation of plaque (decrease in OH) or immune suppression (these may be transient, but permit tissue destruction to take place). Transition from health to clinically detectable disease is characterized by prolonged periods of remission and even spontaneous reversals of the disease process (Socrasky 1984).

There is still a lack of clinically useful diagnostic tests to determine disease activity. Clinical findings may reflect the result of previous disease activity, but we still do not know how to determine when active destruction is taking place. It has been suggested that bacterial invasion of the tissues may be the underlying cause of the elusive episodes of disease activity which, through cumulative damage, lead to the progressive destruction of periodontal support (no real evidence to support this yet).

Armitage 1982                      ARTICLE

Purpose: To determine the correlations between various clinical assessments of inflammatory periodontal disease and the percentage of motile bacteria in the sub-gingival flora in sites of varying states of periodontal disease.

Materials and methods: 60 volunteers, 42 males and 18 females, mean age 40.5 years were selected, and two sites were studied in each pt. Inclusion criteria: no oral prophylaxis in the past 9 months, no antibiotic therapy in the past 6 months, no current pregnancy, no history of diabetes, blood dyscrasias or rheumatic fever.

Two sites from each patient were selected so that 20 sites total can be assigned to each of the 6 categories, ranging from health to advanced periodontitis. The following measurements were recorded for each site: Plaque Index (PI), Gingival exudate (GE), gingival index (GI), Probing Depth (PD), CT attachment loss (AL), bleeding tendency upon gentle probing (BT) and Periodontal Disease Index (PDI) prior to collecting the subgingival plaque samples. Dark field microscopy was used to determine the percentage of bacteria to three categories: nonmotile, spirochetes and other motile bacteria, and statistical analysis was performed.

Results: Statistically significant positive correlations were found between the percentage of subgingival spirochetes and PI, GE, GI, BT, PD, AL and PDI, with the percentage of spirochetes increasing with greater severity of periodontal disease. Clinically healthy sites harbored much lower percentages of motile bacteria than did clinically diseased sites. Most of the observed variation in the percentage of motile bacteria could be accounted for by variations in the percentage of spirochetes. The most significant increase in the relative percentages of subgingival spirochetes occurred when BOP was observed as a sign of inflammation and/or when probing depth and attachment loss exceeded 3 mm. The mean percentage of spirochetes was 2 to 3 times higher at sites exhibiting bleeding than at sites that did not bled.

Conclusion: Significant associations were found between commonly used clinical parameters of periodontal disease and the percentage of motile bacteria at subgingival sites. BOP showed a particularly strong association.

If the presence of motile bacteria is really a valid indication of disease activity, then commonly used clinical parameters of periodontal disease may provide a more time-effective and site-specific means of detecting disease.

Loesche 1985                      ARTICLE

Purpose : To examine a large number of subgingival plaques removed from untrated and successfully treated periodontal patients, to determine wheter characteristic bacterial profile could be identified and relate it to clinical appearance.

Bi is now Pi and Bg is now Pg

Materials and methods

Results

Discussion

Slots 1988 (review)                      ARTICLE

P: To review the association between Aa, P. intermedia, and P. gingivalis and severe forms of human periodontal disease.

Review: In periodontal health, non-motile rods and cocci constitute approx. 95% of the microflora, and spirochetes are rarely encountered. In gingivitis, there is a decrease in the proportion of cocci and a parallel increase in motile rods and spirochetes. In adult periodontitis, the proportions of motile rods and spirochetes are further increased, with motile rods being 14%, and spirochetes 38% of pocket microorganisms. In localized juvenile periodontitis, Aa constitutes from 90-100% of the microorganisms. Culture studies have identified at least 300 bacterial species in the periodontal pocket.

P. gingivalis, P. intermedia and Aa have presented in 129/130 progressing perio lesions in a recent study. P. gingivalis was found in 42% of those sites and, was only present in 6% of non-progressing sites. The authors of this study concluded that P. gingivalis, P. intermedia, and Aa must all be considered to distinguish between progressing and non-progressing perio lesions.

Aa may be difficult to treat by mechanical means in localized juvenile periodontitis. Studies have shown failure in these cases when they were treated with mechanical therapy alone. Studies that had combined systemic tetracycline have eradicated of markedly suppressed Aa.

P. gingivalis and P. intermedia have the capacity to inhibit neutrophil chemotaxis and, they have a capsule with anti-phagocytic properties. These strains also possess elaborated proteases with the potential to degrade opsonizing immunoglobulin and complement proteins.

Aa is a small, non-motile, facultative, gram negative rod which produces a large number of cytotoxic factors. It possesses leukotoxic activity against neutrophils and monocytes, a lymphocyte suppressive factor, a fibroblast inhibitory factor, an epithelial cell suppression factor, and a highly potent LPS which is capable of stimulating in vitro bone resorption and induces classical endotoxin responses. It is because of this virulence that permits this organism to colonize gingival CT.

BL: There is mounting evidence that P.gingivalis, P. intermedia, and Aa are associated in different forms of periodontitis. When conventional, non-specific therapy fails, a more specific approach may be beneficial.

Getka 1996                      ARTICLE

P: To evaluate the influence of products from Pg and Aa on lymphocytes obtained from healthy and periodontally diseased patients.

M&M: 6 patients with advanced periodontitis (> 5mm loss of attachment and BOP in at least 4 sextants) and 26 healthy controls were studied. All subjects were over 35 years of age, in good health and with no history of systemic antibiotics in the previous 3 months. Human peripheral blood mononuclear cells (PBMC) were harvested and were co-cultured with Pg and Aa. Pokeweed mitogen (PWM) and toxic shock syndrome toxin-1(TSST-1) were used to stimulate lymphocyte responses. Thymidine incorporation was used to assess cell viability.

R: Aa and Pg homogenates induced lymphocyte proliferation when relatively low concentrations were employed but evoked suppression of lymphocytes at elevated levels. More specifically, responses to TSST-1and PWM were inhibited at high concentrations of bacterial homogenate. However, as the concentration was reduced, responses induced by PWM were restored while TSST-1 induced responses remained inhibited. No significant differences were seen between healthy and periodontally diseased individuals.

BL: Both Pg and Aa can produce substances that act on lymphocytes to cause immunosuppression.

Socransky 1998                      ARTICLE

Purpose: To examine relationships among bacterial species in subgingival plaque samples and relate the complexes to clinical parameters of periodontal disease

M+M: 185 patients were selected for the study. 160 had evidence of prior attachment loss and 25 were periodontally healthy patients. Subgingival plaque samples were taken from the mesio-buccal aspect of each tooth in 185 subjects. The presence and levels of 40 subgingival species were determined in 13,261 plaque samples using whole genomic DNA probes and checkerboard DNA-DNA hybridization technique. Clinical assessments were made at 6 sites per tooth at each visit. Similarities between pairs of species were computed. Community ordination was performed using principal components analysis and correspondence analysis.

Results: 5 major complexes were consistently observed using any of the analytical methods.

1st complex: Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola.

2nd complex: Fusobacterium nucleatum/periodonticum subspecies, Prevotella intermedia, Prevotella nigrescens and Peptostreptococcus micros. Species associated with this group included: Eubacterium nodatum, Campylobacter rectus, Campylobacter showae, Streptococcus constellatus and Campylobacter gracilis.

3rd complex: Streptococcus sanguis, S. oralis, S. mitis, S. gordonii and S. intermedius.

4th complex: 3 Capnocytophaga species, Campylobacter concisus, Eikenella corrodens and Actinobacillus actinomycetemcomitans serotype a.

5th complex: Veillonella parvula and Actinomyces odontolyticus. A. actinomycetemcomitans serotype b, Selenomonas noxia and Actinomyces naeslundii genospecies 2 (A. viscosus) were outliers with little relation to each other and the 5 major complexes.

The 1st complex related strikingly to clinical measures of periodontal disease particularly pocket depth and bleeding on probing.

BL: This study represents an initial attempt at evaluating inter relationships among subgingival species, as certain associations were seen repeatedly using different analytical techniques.

Ximénez-Fyvie 2000                      ARTICLE

P: to compare the microbial composition of supra and subgingival plaque in 23 adult perio pts.

M/M: 1,170 samples of supra and subG plaque were collected from the mesial aspect of every tooth (supra and subG) from each pt and evaluated for the presence and levels of 40 bacterial taxa using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Gingival color, bop, plaque accumulation, suppuration, PD and CAL were recorded at 6 sites per tooth. The quantity, proportion and prevalence of each species in supra and subG plaque were computed for each subject.

Results: All 40 taxa were detected in both supra and subG plaque. Actinomyces species were the most prevalent in both supra and subG. 75 to 100% of supra and 62 to 100% of subgingival sites were colonized by at least one of the 
5 Actinomyces species. Supragingival samples exhibited significantly higher
counts of Actinomyces naeslundii genospecies 1, Actinomyces israelii, Actinomyces odontolyticus, Neisseria mucosa, Streptococcus gordonii, Capnocytophaga ochracea and Capnocytophaga sputigena when compared with mean counts in subgingival samples taken from the same tooth surfaces. SubG plaque samples presented significantly higher counts of Prevotella nigrescens, Pi, Bacteroides forsythus (Tf) and Pg. Subgingival samples exhibited a significantly higher proportion of red and orange complex species, while supragingival plaque exhibited higher proportions of green and purple complex species as well as Actinomyces species. Suspected periodontal pathogens could be detected in supragingival plaque from sites where subgingival samples were negative for the same species.

Conclusions: The data indicate that supragingival plaque can harbor putative periodontal pathogens, suggesting a possible role of this environment as a reservoir of such species for the spread or reinfection of subgingival sites.

Tran 2001                       ARTICLE

P: To assess if the persistent presence of Aggregatibacter Actinomycetemcomitans, Tannerella forsythia and Porphyromonas gingivalis is a risk factor for future attachment loss in subjects with either mild or no periodontal disease.

M&M: This study used database and stored plaque samples from a previous cross-sectional study.205/1,090 subjects agreed to return for the longitudinal study. Subjects had gingivitis and/or early periodontitis. Sub-gingival plaque was collected from proximal surfaces of a posterior sextant at 6-month intervals for 2 years. During the monitoring period, 44 subjects had either attachment loss or attachment gain. Using multiplex polymerase chain reaction (PCR), all plaque samples from those 44 subjects were analyzed for the presence of A.a, T.f and Pg.

R: Demographic variables such as age, gender and smoking status and baseline clinical measures did not differ significantly for subjects losing AL, gaining AL and subjects both losing and gaining AL. Throughout the study period, A.a was detected in 50-86.8% of the subjects, T.f in 65.9-89.5% of the sites and P.g in 69.2-76.3% of the sites. Subjects with attachment loss and those with attachment gain had a high prevalence of these 3 periodontal pathogens. At the site level, no significant difference was found between sites with AL loss, gain or no change in the presence of any of the periodontal pathogens. At the subjects level, persons with T.f present in at least one individual site had 3.7 times higher odds of losing attachment than subjects negative for T.f at the baseline visit. Subjects with a persistent presence of T.f at any site across all visits had 5.3 times higher odds of having at least one site in their mouth losing attachment compared to subjects with occasional or no presence of T.f.

C: The persistent persistence of T.f identified subjects at higher risk, but not which specific sites in those subjects would lose attachment.

Mombelli 2002                      ARTICLE

P: To determine the extent to which the presence or absence of periodontal pathogens can distinguish between chronic and aggressive periodontitis.

M+M: Systematic review of cross sectional and longitudinal studies looking at microbiological data pertaining to chronic (ChP) and aggressive periodontitis (AgP). MEDLINE search performed, as well as hand search of journals from 1990-July 2001. Strict inlclusion criteria looking at presence or absence of five periodontal pathogens: Aa, Pg, Pi, Bf (now Tf), Cr.

R: Included papers were able to report the presence or absence of some or all of the specific bacteria of interest. More papers were included that analyzed presence or absence of Aa, either examining the bacteria itself, the presence of leukotoxin, or specific Aa serotype b. The least reported bacteria examined in this review were Tf and Cr. The included papers did not have the current AAP classification of aggressive periodontitis; instead the terms LJP, GJP and EOP were used. The presence or absence of Aa could be evaluated in 11 papers. Pg was analyzed in 7, Pi was evaluated in 6, Tf was analyzed in 2, and Cr was analyzed in 2.

11 Aa studies: of all AgP cases, 62% were Aa +. Of all ChP cases, 28% were Aa +. However, as there were more ChP pts in these studies, out of 665 Aa positive subjects, only 25% were diagnosed clinically as AgP (75% diagnosed as ChP). Looking at serotypes, Aa serotype b was uniquely associated with AgP.

7 Pg studies: 71% of AgP were Pg+ and 54% of ChP were Pg +. 6 Pi studies: 63% of AgP were Pi + and 50% of ChP pts were Pi +.

2 studies examined Tf: Tf was more often + in pts w/AgP but no numeric data and no data on ChP pts.

2 studies examined Cr : conflicting results; no analysis done

BL: The presence or absence of Aa, Pg, Pi, Tf, Cr could NOT determine between subjects with AgP and those with ChP. If serotype analysis was done, Aa serotype b was exclusively associated with AgP; however, the majority of patients diagnosed with AgP did not necessarily have Aa serotype B.

Slots 2009                      ARTICLE

P: To present an overview of major mammalian viruses and viral diseases in the human oral cavity of adults.

D: Human viruses are involved in the development of various types of oral ulcers, oral tumors, classical oral infectious diseases and periodontitis. Herpes simplex virus-1 and CMV are linked to oral ulcer; Epstein-Barr virus, herpes virus-8 and papillomaviruses to oral tumors; and Epstein Barr virus and CMV to aggressive perio. Deep kissing can spread Epstein-Barr virus, herpes virus-8 and papillomaviruses, and should perhaps be considered a risky sex practice. Also, parents may avoid kissing infants and small children on their mouth. Herpes viruses and papillomaviruses modify antiviral host responses in order to persist for the lifetime of the infected host. Important virus-encoded countermeasures include avoidance of inhibition of innate and adaptive immune responses and of apoptosis. NUG and it progressive disease variants are currently typically found in HIV-infected patients and in severely malnourished individuals of the developing world.

Periodontitis has been associated with an increased risk of tongue cancer, pancreatic cancer, and lung, kidney and hematological cancers. This may be caused by a shared viral infection or another type of joint etiology of the diseases, or by a commonality in host response functions. Whether the observed association between periodontitis and cancer constitutes a causal connection or merely a coincidence remains to be determined.

Several lines of evidence incriminate the herpes viruses in the etiopathogeny of marginal and apical periodontitis. Advanced perio lesions harbor high counts of herpes viral genomes, often exceeding 1 million in a single subgingival site. Herprsvirus-infected periodontitis sites show more extensive tissue breakdown that herpes virus-free sites, and a herpes viral active infection or multiple transactivating herpes viruses in the periodontium are associated with an elevated risk of progressive disease. CMV and other herpes viruses can up-regulate the expression of tissue-destructive MMPs from gingival fibroblasts and presumably also from other cell types of the inflamed periodontium. An important pathogenetic synergy probably exists between perio herpes viruses and periodontopathogenic bacteria. Herpes viruses may create a better environment for the up-growth of pathogenic bacteria by inducing immunosuppression (interfere with complement, neutrophil and macrophage functions), or by generating new attachment sites for bacteria in infected cells or in the basement membrane following destruction of the periodontal pocket epithelium. It is also possible that periodontopathogenic bacteria may support the multiplication of herpes viruses (Pg augmented virulence of CMV in mice).

-This article presents 6 tables (each 1 page long) that very briefly describe the viruses related to the oral cavity.

Refractory Periodontitis Microbiology

Socransky 2002                      ARTICLE

Purpose: To define microbial profiles associated with refractory periodontitis and to seek such profiles in periodontitis and periodontally healthy individuals.

Materials and methods: 36 subjects that already had SRP, modified Widman flap and systemically administered tetracycline, they showed either full mouth mean attachment loss or >3 sites with attachment loss >2.5mm after each therapy (refractory subject population. 27 periodontally healthy individuals (inflammation could be present but no AL more than 4mm), 35 well-maintained elder (66 years of age or more) and 115 untreated (at least 4 sites with PD more than 4mm and/or 4 sites with AL more than 4mm) adult periodontitis subjects. Exclusion criteria included females who were pregnant or nursing, any systemic condition that could influence the course of periodontal disease or required antibiotic premedication coverage for routine periodontal Tx. Subginigval plaque samples from the mesiobuccal aspect of each tooth in each subject were collected and analyzed for 40 species using DNA-DNA hybridization. Same sensitivity for each species was achieved.

Results: Elevated prevalence and levels of red and orange complex bacteria in refractory and periodontitis groups comparing to the other two groups.

The total counts were highest in the periodontitis subjects and lowest in the refractory group.

Counts and proportions of Actinomyces species were higher in periodontally healthy and well-maintained elder individuals.

In patients with refractory periodontitis there were four different cluster groups depending on the proportions of red complex bacteria and Actinomyces species. Cluster group II showed the lowest mean PD and mean AL, while the deepest mean PD was found in cluster group IV.

Conclusion: The unusual profiles of refractory periodontitis lead to the question whether these have resulted from previous, perhaps very aggressive periodontal therapy. Three out of four profiles were found to the other groups, suggesting that these 3 profiles were not caused by dental intervention, but may represent profiles difficult to be controlled by perio treatment. The fourth profile though (I) was not seen in any of the other groups, and might be resulted from previous therapy, particularly those involving antibiotics.

Refractory periodontitis subjects are not an homogenous group and in general had similar microbiota to that observed in untreated periodontitis.

Detection of different microbial profiles in refractory subjects suggests that individual treatments may have to be designed.

Colombo 2012                      NO ARTICLE

Purpose: To compare the changes to the subgingival microbiota of individuals with “refractory” periodontitis (RP), ot treatable periodontitis (good responders(GR)) before and after periodontal therapy by using the Human Oral Microbe Identification Microarray (HOMIM) analisys.

Materials and methods

Results

Discussion

Conclusion

Bacterial Invasion

Tribble 2000 (Review)                      ARTICLE

P: To discuss the current understanding of pathogenic and commensal interactions with periodontal tissues, with a specific focus on P.g. intracellular invasion and molecular modulation of host cells.

D: Tissue destruction, mediated either by the host or by bacteria, is a hallmark of periodontal disease, and with the consequent loss of barrier function it is not surprising that periodontal bacteria are frequently detected within gingival tissues. A number of oral bacteria have been observed to locate inside host cells (intracellular invasion), these bacteria include: P.g., T.f., A.a, F.n., P.i., E.c., and T.d. Once colonized, these cells are not necrotic or apoptotic but remain viable. Electron microscopy has shown P.g. inside host cells, along with T.f., A.a., and T.d., which had been found within gingival and buccal epithelial cells in both healthy pts and those with periodontitis. Residence within host cells provides bacteria with a nutrient rich environment that is protected from the host immune system. They may use this safe locale to safely persist and replicate. These bacteria that remain intracellular are less likely to be removed by SRP and are more resistant to antibiotics.

In addition to the multi species etiology of periodontal disease, bacteria can co-operate with one another to facilitate invasion. P.g. (or its outer membrane vesicles) enhances the invasion of T.f. into epithelial cells. F.n. can transport non-invasive strep cristatus and F.n. can enhance the invasion of P.g. Periodontal bacteria can also enhance the invasion of P. aeruginosa into epithelial cells, which may provide a mechanistic basis for the epidemiological association between periodontal disease and respiratory tract infections.

Initial interaction with epithelial cells: Attachment can occur by the engagement of membrane receptors by bacterial surface ligands, which can alter the cellular machinery to mediate pathogen entry into the cell. The mechanisms of adhesion of P.g. include fimbrae, which are composed of the FimA structural subunit protein along with minor proteins FimC, D, E. The FimA subunit directly engages integrins on the epithelial surface and this initiates an integrin-associated signaling cascade that triggers bacterial internalization. The focal adhesion adaptor and signaling proteins paxillin and focal adhesion kinase (FAK) are recruited to sites of P.g. attachment and the resulting information flow converges on the cytoskeleton substructure.

Internalization: The interaction of P.g. FimA fimbriae with epithelial cell surface integrins initiates a cellular response that recruits FAK (focal adhesion kinase) and paxillin to the cytoplasmic membrane. This produces a phosphorylation signal and subsequent protein remodeling. This process is complete in approx. 15 mins. When P.g. enters host cells, all major cell-signaling pathways are reprogrammed.

Adaptation to the intracellular environment: Bacteria will adapt to the cells environment through gene and protein regulation. Studies have shown that during P.g. attachment, genes encoding oxidative, stress response components, and heat shock proteins are up-regulated. P.g. also produces a series of enzymes to overcome the drastic transition from extra to intracellular. It is also energy efficient and advantageous for P.g. to stay in the cell as it becomes capable of utilizing metabolic substrates that are available within the cell.

Intracellular localization: Once inside the cell, bacteria must quickly act to prevent exposure to lysosomes. Some pathogens remain within a membrane bound vacuole and subsist freely in the cytoplasm. When P.g. invades a cell, it must initially be encompassed within a compartment derived from the host membrane. Once inside, it can escape and survive unbound in the cytoplasm for extended periods of time and it can even replicate. P.g. can also invade endothelial cells where it can live in membrane bound compartments (autophagosomes). Once in them, it can block fusion with lysosomes and use protein debris as its nutrient source. It has been speculated that the invasion of coronary artery endothelial cells by oral bacteria may be a contributing factor to the link between periodontal disease and cardiovascular disease.

Phenotype of colonized cells: There is a spectrum of physiological and morphological outcomes that may result from bacterial invasion. Gingipain proteases are secreted to make protein nutrients available for the asaccharolytic P.g.. High levels of these enzymes can damage host cells and connective tissue and can induce apoptosis. Hence, strains of P.g. that produce high levels of gingipains will be more cytotoxic. Additional damage to periodontal tissues can result from activation of MMPS by P.g. gingipains.

Invasion of periodontal tissues: P.g. has been detected in the periodontal connective tissue implying that cell-to-cell spread of bacteria is a common event. Transmission from cell to cell is mediated by a membranous projection with a structural scaffold component of actin filaments. By moving deeper into the epithelial layers, P.g. can ensure access to viable, non-shedding epithelial cells. P.g. can penetrate the basement membrane into connective tissues. Gingipain proteases will then degrade the matrix and tight junction components, which allows P.g. to approach the alveolar bone.

Impact on innate immune surveillance: P.g. has the ability to suppress IL-8 secretion following invasion of host cells (localized chemokine paralysis) along with down-regulation of intracellular adhesion molecule (ICAM 1). Both reduced IL-8 and ICAM-1 will impair neutrophil infiltration of gingival tissues, and consequently debilitate local innate immunity and eventually disrupt the ecological balance between host and subgingival flora, contributing to the initiation of disease.

Review Articles

Darveau 1997                      ARTICLE

P: Review article about the microbial challenge in periodontitis

D: Over 300 bacterial species are recognized as being present in the human oral cavity. A dynamic equilibrium exists between dental plaque bacteria and the innate host defense system. Dental plaque bacteria have adapted survival strategies that favor growth in this environment, while the host normally limits growth by a combination of innate and adaptive immune responses. Dental plaque is a microbial biofilm. Biofilms are defined as matrix-enclosed bacterial populations adherent to each other and/or to surfaces or interfaces. The microbial coating of a freshly cleaned tooth surface occurs rapidly. Within the first few hours a pellicle forms on the tooth surface that consists of proteins and glycoproteins found in saliva and crevicular fluid. Pellicle formation, in addition to enhancing initial bacterial colonization, provides surfaces for additional bacterial attachment.

Dental plaque growth

- Plaque doubling times are rapid in early development and slower in more mature films

- There are two different types of dental plaque biofilms. Supragingival plaque forms above the gingival margin and subgingival plaque forms below this point.

- Host plays role in inhibition of supra- and subgingival plaque growth by secretory immunoglobulin A, lysozyme, peroxidases, antimicrobial proteins for supragingival plaque and antibody and lymphocytes for subgingival plaque

- Low levels of E-selectin and intracellular adhesion molecule expression have been detected in clinically healthy periodontal tissue. Monocyte chemotaxis protein 1 and IL-8 have been detected. IL-8 was found to form a gradient of expression, greatest at the area closet to the bacterial-epithelial cell interface. The low-level expression of these mediators of inflammation in clinically healthy tissue is consistent with an efficient innate host surveillance system of gingival tissue.

Role of dental plaque biofilm in periodontal disease

- Dental plaque biofilm cell fragment shedding provides a constant source of bacterial antigens that govern the innate host response. Bacteria continuously release cell surface components into the oral cavity and the gingival sulcus. G- bacteria in particular are known to release large amounts of cell wall material as outer membrane vesicles. Not only do shed bacterial components come in contact with the epithelial cells, LPS has been reported to pass through an intact epithelial cell barrier and concentrate around blood vessels in the lamina propria. Bacterial products therefore have the potential to interact with nearly all cell types present in the periodontium

- Dental plaque biofilm microbial composition can influence innate host inflammatory surveillance. E-selectin, intracellular adhesion molecule, monocyte chemotaxis protein one and IL-8 have been shown to be expressed in clinically healthy periodontal tissue.

- Dental plaque bacterial composition may result in a destructive inflammatory response. The microbial composition associated with gingivitis apparently releases material that results in a local tissue reaction of inflammation. In contrast to healthy periodontal tissue and gingivitis, the host mounts a destructive inflammatory response in periodontitis. The reasons for the initiation and continuation of a destructive inflammatory response remain unknown. However, a general pattern appears to be emerging demonstrating that the bacteria suspected of being associated with periodontitis are more potent at inducing bone loss than those not suspected of being periodontal pathogens

- The expression of bacterial virulence requires participation from the dental plaque biofilm community. It appears that combination of bacteria rather than just one act coordinately to further dental plaque biofilm growth. Two best-studied periodontal pathogens are Pg and Aa. They have the ability to secrete a number of virulence factors. Pg in particular is well known for its ability to secrete an abundant array of extracellular proteases.

Microbial composition

- Associated with gingival health: G+, streptococci and actinomyces, with about 15% G- rod species

- Associated with gingivitis: Increased microbial load and a corresponding increase the percentage of G- organism (15-50%)

- Associated with periodontitis: Less clear. World Workshop on Periodontal Disease has identified Pg, Tf, and Aa as causative agents

Tatakis 2005(review):                      ARTICLE

P:To review current aspects of the etiology and pathogenesis of periodontal disease.

D:

Biofilm-single cells and microcolonies enclosed in a highly hydrated, predominantly anionic exopolymer matrix. These sessile cells behave in profoundly different ways from their free-floating counterparts.

Review goes on to discuss identification and characteristics of genetic defects that predispose to periodontitis (Downs, Papillon-Lefevre, Nuetropenia etc), role of risk factors in dz susceptibility, and discovery of new host-derived cellular and molecular mechanisms implicated in periodontal tissue destruction.

Socransky 1991                      NO ARTICLE

Defines virulence factors as the set of unique properties which permit a bacterial species to colonize a target, defend itself from the host and tissue damage.

Factors affecting colonization (infection): 1. Attach to one or more of the surfaces, 2) multiply, 3) compete successfully against other species desiring that habitat and 4) defend itself from host defense mechanisms.

Tables 5-7 provide examples of the bacterial preparations employed, the diversity of the substances or mammalian cells examined and the different response variables assayed. Seem to emphasize certain “suspected pathogens notably Aa and Pg; however, other oral species produce biologically active compounds which exhibit similar properties.

The data indicate an essential role in the pathogenesis of destructive periodontal diseases.

Kornman 1986                      NO ARTICLE

P: A review of current concepts of supragingival plaque and its role in gingivitis and periodontits, as well as disease prevention by plaque control.

D: Gingivitis- As established by the experimental gingivits studies by Loe, plaque is responsible for gingivitis. Loesche and Syed 1978, Syed and Loesche 1978 and Moore 1982 found during the first 3wks of plque accumulation, A. israelii increase proportionately at the expense of G(+) cocci and that changes in Actinomyces spp, Fusobacterium , Veilonella and Treponema also have positive correlates with clinical gingivitis. Gingivitis development depends on the accumulation of supraG plaue and that regular and thorough removal of will prevent it (Lang, Cunning &Loe 1973).

Periodontitis- This alone is insufficient to say with certainty supraG plaque is causative of periodontitis. Longitudinal studies in dogs and monkeys have indicated periodontitis follows plaque accumulation leading to gingivitis. Saxe 1967 demonstated in Beagle dogs sites wich were allowed plaque accumulation to occur show a significant more amount of attachment loss when compared to cleaned sites. In Lindhe 1975’s study, not all of the experimental dogs demonstrtaed loss of attachment. This suggests that although gingivitis precedes all periodontitis, not all gingivitis cases sites progress predictably to periodontitis. The relationship between the amount of plaque and the threshold for disease is most likely dependent on the specific bacterial composition of the plaque and the resistance of the host. Therefore, the amount of plaque which is necessary for disease induction in one individual may differ from the amount required for induction in another. Control of periodontal diseases requires regular disruption of the subgingival microfiora and control of supragingival plaque. Currently, the most predictable means of preventing disease is the regular efficient removal of supragingival plaque by either mechanical or chemical means, or a combination of both.

Greenstein 1985                       ARTICLE

P: To review the role of microscopic monitoring in detecting periodontal disease.

Advantages and disadvantages of microscoping assessments versus culturing.

Cultural studies reported that periodontal diseases were associated with an overall increase in the number of bacteria. Subsequent investigations in the late 1970s supported the concept of bacterial specificity which indicated that specific bacteria were associated with different periodontal diseases. Cultural studies are also expensive and time consuming. Advantages of chairside microscopy include rapidity of bacterial evaluation by morphotypes, less expensive monitoring, less equipment and personnel required, the capability to do total cell counts and determine proportions of bacterial cell forms. Limitations of this method include inability to study individual microbes or determine susceptibility to antibiotic therapies.

Problems associated with bacterial sampling and statistical analysis

Bacterial sampling: Listgarten recommended removing supra-g plaque prior to sampling to avoid contaminating sub-g specimens with supra-g microorganisms. Mousques et al. demonstrated that repeated sampling of sites may affect their microbial composition. Even returning to sample identical locations is difficult, because the bacterial composition varies in different aspects of the same lesion. Collection of specimens at different pocket depths introduce another variable, since there is evidence indicating the % of spirochetes and motile rods may be related to depth of the pocket. Indiscriminate counting of organisms within sub-g complexes (i.e. motile forms) has many pitfalls since few overt pathogens have been identified. Therefore it is possible that the wrong organisms are being monitored.

Statistics: To avoid the difficult task of sampling all pockets, investigators have pooled sites to reflect diseased or healthy regions. However, this may be inadequate since important findings at an individual site may be overlooked. Pooled data from sites which may or may not demonstrate disease activity must be evaluated judiciously.

Conventional light microscopic illumination is ineffective in examining specimens because diffraction of light in saliva does not enhance visualization of bacteria. Recent investigations have used phase contrast and dark- field microscopy to monitor sub-g flora. Dark-field microscopy is usually used by researchers because organisms appear whitish against a black background making counting easier. Listgarten and Hellden determined the relative distribution of bacteria at clinically healthy and periodontally diseased sites in humans. Diseased sites were associated with increased number of motile rods, spirochetes and a decrease of coccoid rods. Ascertaining bacterial populations may help in evaluating the efficacy of therapy and determination of absence or presence of disease activity. Lindhe et al. also reported that with increasing severity of distraction, there was an increase of motile forms and a decrease of coccoid forms. Researchers have been careful to indicate that even though that these organisms have been associated with diseased pockets, this can’t be interpreted as a proof of causality of disease. It is unclear whether monitored organisms represented by these morphotypes are involved in the pathogenesis of periodontal disease. Clinical diagnosis, based on increased numbers of bacteria sampled from advanced disease sites which have been identified by other clinical parameters does not enhance diagnosis unless the pathologic potential of these morphotypes can be established.

At present it does not appears possible to define disease activity on the basis of counts of bacterial morphotypes. Investigators have been unable to determine threshold values for potential pathogenic populations. Until the interrelationship between organisms and pathogenesis has been clarified, chairside microscopic monitoring of bacterial populations should be interpreted cautiously.

Socransky 1992                      ARTICLE

P: Review of the current concepts of the bacterial etiology of periodontitis.

DISC: This review describes some of the changing concepts in the etiology of destructive periodontal diseases. These changes are driven by discrepancies between microbial and clinical status and by parallel recognitions in infectious disease microbiology.

Infection does not mean instantaneous disease. Current data suggests that pathogens are necessary but not sufficient for disease activity to occur. Factors which influence activity include susceptibility of the individual host and the presence of interacting bacterial species which facilitate or impede disease progression. The local environment of the periodontal pocket may be important in the regulation of expression of virulence factors by pathogenic species.

In order for disease to result from a pathogen:

1. It must be a virulent clonal type.

2. Possess the chromosomal and extra chromosomal genetic factors to initiate disease.

3. The host must be susceptible to this pathogen.

4. The pathogen must be in sufficient quantities to exceed the threshold for that host.

5. It must be located at the right place.

6. Other bacterial species must foster or at least not inhibit the process.

7. The local environment must be one which is conductive to the expression of the species' virulence properties.

BL: Currently, with our greater understanding of the biologic basis of disease, combinations of diagnostic tests will be useful in determining not only the pathogens of disease, but the therapies best suited for control.

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