The authors have taken the liberty of presenting this manuscript in two parts. The first is a brief primer on microbial ecology, because, although the importance of microbial ecology in periodontal diseases is widely recognized, most of us do not know precisely what is meant by the term. The second section is a rather extensive overview of current studies of oral microbial ecology based almost entirely on recent in vivo studies.

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Periodontal microbial ecology.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in human periodontal disease: occurrence and treatment.

Background: Scaling and root planing (SRP) are the bases of non-surgical therapy in the treatment of periodontitis. However, results from this therapy are often unpredictable and dependable from many different factors.

Objectives:  The aim of this systematic review was to evaluate the effectiveness of the adjunctive use of systemic antimicrobials with scaling and root planing (SRP) vs. SRP alone in the treatment of chronic (CP) or aggressive periodontitis (AgP).

Search strategy:  Use of computerized databases, namely MEDLINE, the Cochrane Oral Health Group Specialty Trials Register and EMBASE; reference lists from relevant articles were hand-searched; and a hand-search of selected journals until April 2001.

Selection criteria:  Studies were selected if they were designed as controlled clinical trials in which systemically healthy patients with either AgP or CP were treated with SRP plus systemic antimicrobials in comparison with SRP alone or with placebo, for a minimum of 6 months. Main outcome measures were clinical attachment level (CAL) change and probing pocket depth (PPD) change.

Data collection and analysis:  Two reviewers extracted independently information regarding quality and study characteristics, in duplicate. Kappa scores determined their agreement. Main results were collected and grouped by drug, disease and PPD category. For the quantitative data synthesis, the data was pooled (when mean differences and standard errors were available), and either a Fixed Effects or Random Effects meta-analysis was used for the analysis.

Results:  After an initial selection, 158 papers were identified by the manual and electronic searches; 25 papers were eligible for inclusion. Their quality assessment showed that randomization and allocation concealment methods were seldom reported and blindness was usually not defined clearly. In general, selected studies showed high variability and lack of relevant information for an adequate assessment. Overall, SRP plus systemic antimicrobial groups demonstrated better results in CAL and PPD change than SRP alone or with placebo groups. Only limited meta-analyses could be performed, due to the difficulties in pooling the studies and the lack of appropriate data. This analysis showed a statistically significant additional benefit for spiramycin (PPD change) and amoxicillin/metronidazole (CAL change) in deep pockets.

Conclusion:  Systemic antimicrobials in conjunction with SRP, can offer an additional benefit over SRP alone in the treatment of periodontitis, in terms of CAL and PPD change, and reduced risk of additional CAL loss. However, differences in study methodology and lack of data precluded an adequate and complete pooling of data for a more comprehensive analyses. It was difficult to establish definitive conclusions, although patients with deep pockets, progressive or ‘active’ disease, or specific microbiological profile, can benefit more from this adjunctive therapy.

A systematic review on the effect of systemic antimicrobials as an adjunct to scaling and root planing in periodontitis patients.

The pathogenic potential of Fusobacterium nucleatum and its significance in the development of periodontal diseases, as well as in infections in other organs, have gained new interest for several reasons. First, this bacterium has the potential to be pathogenic because of its number and frequency in periodontal lesions, its production of tissue irritants, its synergism with other bacteria in mixed infections, and its ability to form aggregates with other suspected pathogens in periodontal disease and thus act as a bridge between early and late colonizers on the tooth surface. Second, of the microbial species that are statistically associated with periodontal disease, F. nucleatum is the most common in clinical infections of other body sites. Third, during the past few years, new techniques have made it possible to obtain more information about F. nucleatum on the genetic level, thereby also gaining better knowledge of the structure and functions of the outer membrane proteins (OMPs). OMPs are of great interest with respect to coaggregation, cell nutrition, and antibiotic susceptibility. This review covers what is known to date about F. nucleatum in general, such as taxonomy and biology, with special emphasis on its pathogenic potential. Its possible relationship to other periodontal bacteria in the development of periodontal diseases and the possible roles played by OMPs are considered.

Taxonomy, biology, and periodontal aspects of Fusobacterium nucleatum.

Aims: To review the literature related to the analytical epidemiology of periodontitis generated over the past decade. This review does not deal with descriptive epidemiologic studies of the prevalence, extent and severity of periodontitis with respect to global geography, but focuses exclusively on analytical epidemiology issues, including the challenges posed by the use of different case definitions across studies, current theories and models of disease progression, and risk factors associated with the onset and progression of periodontitis.

Methods: Relevant publications in the English language were identified after Medline and PubMed database searches.

Findings and conclusions: There is a conspicuous lack of uniformity in the definition of periodontitis used in epidemiologic studies, and findings from different research groups are not readily interpretable. There is a lack of studies that specifically address the distinction between factors responsible for the onset of periodontitis versus those affecting its progression. Colonization by specific bacteria at high levels, smoking, and poorly controlled diabetes have been established as risk factors for periodontitis, while a number of putative factors, including specific gene polymorphisms, have been identified in association studies. There is a clear need for longitudinal prospective studies that address hypotheses emerging from the cross-sectional data and include established risk factors as covariates along with new exposures of interest. Intervention studies, fulfilling the “targeting” step of the risk assessment process, are particularly warranted. Obvious candidates in this context are studies of the efficacy of elimination of specific bacterial species and of smoking cessation interventions as an alternative to the traditional broad anti-plaque approach in the prevention and control of periodontitis. Ideally, such studies should have a randomized-controlled trial design.

Analytical epidemiology of periodontitis

28 patients, 13 smokers and 15 non-smokers with untreated advanced periodontal disease, were subjected to a series of oral hygiene instructions and treated with non-surgical periodontal therapy. Baseline values regarding clinical data did not differ significantly between the groups. 6 months following therapy the full-mouth bleeding score among smokers was 36.5% as compared to 22.7% for non-smokers (p < 0.05). Probing depth was reduced by 1.9 mm for smokers and by 2.5 mm for non-smokers. This difference was statistically significant (p < 0.05). The level of P. gingivalis and P. intermedia/nigrescens was reduced in both groups as compared to baseline. A. actinonmycetemcomitans, however demonstrated a slight increase in mean values at 6 months. This was especially notable for smokers in which A. actinomycetemcomitans were more difficult to eradicate. Conclusively, the microbiological response found in this study seems to be in conformity with the clinical response with little influence of the smoking habits.

The clinical and microbiological effects of non‐surgical periodontal therapy in smokers and non‐smokers

Oral complications are common in patients with haematological malignancies who undergo chemotherapy treatment. A pilot study including 16 haematological patients was carried out to evaluate the oral status using an Oral Assessment Guide (OAG) and to test the reliability of the OAG. The oral assessments were made daily by registered nurses at a Department of Internal Medicine in Sweden. Once a week a dental hygienist made the oral assessments independent of the registered nurses in order to provide data for calculations of inter-rater reliability. All patients had varying degrees of alterations in the oral cavity, especially in the mucous membranes, teeth/dentures and gums. The inter-rater agreement between the nurses and the dental hygienist was good for saliva and swallow, and moderate for voice and gums. Assessments to detect alterations in the oral cavity afford the opportunity for early and individualized interventions and may decrease the risk of oral infections. It is necessary to train the nurses to ensure high levels of reliability in the oral assessments. The OAG seems to be a reliable and clinical useful tool for assessing the oral cavity status and determining changes.

Testing an oral assessment guide during chemotherapy treatment in a Swedish care setting: a pilot study

The purpose of this study was to assess the clinical effect of treatment aimed to suppress Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis below detection level and Prevotella intermedia below 5% of the cultivable periodontal pocket flora. Sixteen patients and a total of 111 periodontal pockets with probing depth > or = 6 mm were included in the study. Twelve patients and a total of 77 sites completed the 5-year study. The results demonstrated clinical improvement of probing depth and gain of clinical attachment level of 3.4 mm and 1.2 mm, respectively. Treatment to eliminate indicator bacteria continued for 3 years before the aim was fulfilled. In order to eliminate A. actinomycetemcomitans from a majority of the sites, a combination of surgery and generalized tetracycline treatment was performed. A recolonization or regrowth of the indicator bacteria exceeding detection levels took place in several sites. The presence of A. actinomycetemcomitans. P. gingivalis, and P. intermedia, alone or in combination, correlated with attachment level change on the individual level. No such correlation was obtained by using presence of plaque, bleeding on probing, or three other bacteria (Campylobacter rectus, Eikenella corrodens, and Fusobacterium nucleatum) not used as treatment goal markers.

Treatment of periodontal disease based on microbiological diagnosis. Relation between microbiological and clinical parameters during 5 years.

Sixteen patients with advanced periodontitis (more than 3 sites with a probing depth ≥ 6 mm) were treated with the aim of eliminating Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis and reducing Prevotella intermedia below 5% of the total viable count. The patients were followed clinically and microbiologically for over 5 years and showed a Highly individual pattern with respect to presence of indicator bacteria, type of treatment needed to accomplish treatment goals, clinical response, and bacterial and disease recurrencies. The results of this study suggest that presence of the indicator bacteria in microbial samples taken after treatment may identify patients at risk for recurrent periodontitis. J Periodontol 1996;67:879–887.

Treatment of Periodontal Disease Based on Microbiological Diagnosis. A 5-Year Follow-Up on Individual Patterns

The influence of sampling procedure and of laboratory processing on the recovery of Bacteroides gingivalis, Bacteroides intermedius, and Actinobacillus antinomycetemcomitans from periodontitis sites was evaluated. Thirty-three adult subjects with severe periodontitis participated in the study. In all, 462 samples from 81 sites were examined. The samples were taken using the paper point technique. The cultivations were performed by use of enriched Brucella agar for determination of total colony-forming units and Bacteroides species, and trypticase soy bean agar for determination of A. actinomycetemcomitans. The risk of getting a false negative result was 4% for B. gingivalis, 20% for B. intermedius, and 38% for A. actinomycetemcomitans. It was considerably reduced if duplicate samples were taken. The sampling procedure alone explained up to 98% of the false-negative results.

Stefan Renvert

Papers

The clinical and microbiological effects of non‐surgical periodontal therapy in smokers and non‐smokers

Testing an oral assessment guide during chemotherapy treatment in a Swedish care setting: a pilot study

Treatment of periodontal disease based on microbiological diagnosis. Relation between microbiological and clinical parameters during 5 years.

Treatment of Periodontal Disease Based on Microbiological Diagnosis. A 5-Year Follow-Up on Individual Patterns

Variance in recovery of periodontitis-associated bacteria caused by sampling technique and laboratory processing.