Principles of evaluation of the diagnostic value of subgingival bacteria

Screening for periodontopathogenic bacteria in severe chronic periodontitis in a Moroccan population

OBJECTIVE

Bacteria play an important role in destructive periodontitis. The aim of this study was to screen for five highly pathogenic bacteria: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola, in Moroccan patients presenting with severe chronic periodontitis and to compare results with those of patients presenting with severe aggressive periodontitis.

MATERIALS AND METHODS

Twenty-three patients were included at the periodontology unit (School of dental medicine, University Mohammed 5 Souissi, Rabat, Morocco). The study was made on two groups: a test group of patients presenting with severe chronic periodontitis, and a control group of patients presenting with severe aggressive periodontitis. Plaque sampling was performed at the four deepest sites in each patient. The five studied bacteria were detected by PCR.

RESULTS

The prevalence of A. actinomycetemcomitans and T. denticola was relatively low in the test group (13.3% and 20% respectively) compared with controls (37.5% and 37.5% respectively), without any statistical difference between the two groups. Furthermore, P. gingivalis and T. forsythia were frequently detected in both groups, without any statistical difference.

CONCLUSION

The results of this preliminary study proved the presence of the studied periodontopathogenic bacteria both in severe chronic periodontitis and severe aggressive periodontitis.

Does routine analysis of subgingival microbiota in periodontitis contribute to patient benefit?

In clinical periodontology it is common practice to sample subgingival plaque from periodontitis patients and to search for the presence of alleged periodontal pathogens using routine laboratory techniques such as culture, DNA-DNA hybridization or real-time PCR. Usually, special attention is given to the recognition of 'red complex' microorganisms and to Aggregatibacter actinomycetemcomitans. Recently, molecular open-ended techniques have been introduced which are distinct from the more 'classical' approaches in that they do not preselect for certain species. In this study, we investigated to what extent the outcome of these techniques has changed our insight into the composition of the subgingival microbiota and whether this has consequences on clinical decision making. The open-ended approaches showed that the composition of subgingival plaque is much more complex than previously thought. Next to the 'classical' putative periodontal pathogens, several non-culturable and fastidious species are now recognized as being associated with periodontitis, thus enlarging the group of suspected periodontal pathogens. We conclude that routine analyses of subgingival plaque in the clinic are not necessarily of benefit to the patient.

Multiplex polymerase chain reaction assay for simultaneous detection of black-pigmented Prevotella species in oral specimens

Prevotella species are a major component of the oral microflora and some have been implicated in various forms of periodontal disease. Despite the importance of understanding the prevalence of these organisms in the oral microflora, no rapid, simultaneous detection system for these species has been reported. This study developed a multiplex polymerase chain reaction assay for the simultaneous detection of four oral black-pigmented Prevotella species in various oral specimens. This assay will be useful for determining the prevalence of these organisms in the oral ecosystem. Furthermore, this assay system should prove a useful tool for analyzing the role of black-pigmented Prevotella species in the mouth.

Diagnostic testing as a supportive measure of treatment strategy

The bacteriological tests in periodontology have been available to clinicians since the end of the 1980s. Despite the vast and varied information that they contribute to the literature on this topic, some controversy has arisen with regard to the use of these tests. Clinicians faced with a multitude of clinical forms of periodontal disease in their patients can count on laboratory examinations to help them in the therapeutic process. These biological examinations can offer help in five areas of application: support in diagnosis and prognosis, verification of the efficiency of the treatment, indication of the correct antibiotic therapy and choice of the most appropriate molecules. The clinician's needs determine the type of bacteriological technical analysis used: bacterial culture or genetic identification using the molecular techniques. Each technique has its advantages and disadvantages. Knowing these limits allows the most appropriate choice to be made, depending on the clinical situation. The richness of information provided by culture in the anti-microbial susceptibility test and the non-targeted aspect of this test make this technique very interesting for the diagnosis of periodontitis. However, the targeted aspect of molecular techniques (PCR), their excellent sensibility and their rapidity make them prevail, particularly in the control and maintenance phases. Furthermore, despite the constant development of bacterial identification techniques, these examinations are little used by dental surgeons as these examinations are little known. They are also difficult to interpret and generate heavy additional costs.

DNA probes and primers in dental practice

In clinical microbiology, molecular genetic techniques are increasingly being used to detect and/or differentiate uncultivable, anaerobic, or fastidious microorganisms. During the past decade, DNA probe hybridization and in vitro amplification by polymerase chain reaction have also been introduced to detect oral pathogens. The present review describes experiences with methods and commercial test systems for the detection of pathogens in periodontitis and caries.

Periodontal disease as a specific, albeit chronic, infection: diagnosis and treatment

Periodontal disease is perhaps the most common chronic infection in adults. Evidence has been accumulating for the past 30 years which indicates that almost all forms of periodontal disease are chronic but specific bacterial infections due to the overgrowth in the dental plaque of a finite number of mostly anaerobic species such as Porphyromonas gingivalis, Bacteroides forsythus, and Treponema denticola. The success of traditional debridement procedures and/or antimicrobial agents in improving periodontal health can be associated with the reduction in levels of these anaerobes in the dental plaque. These findings suggest that patients and clinicians have a choice in the treatment of this overgrowth, either a debridement and surgery approach or a debridement and antimicrobial treatment approach. However, the antimicrobial approach, while supported by a wealth of scientific evidence, goes contrary to centuries of dental teaching that states that periodontal disease results from a "dirty mouth." If periodontal disease is demonstrated to be a risk factor for cardiovascular disease and stroke, it will be a modifiable risk factor since periodontal disease can be prevented and treated. Since the antimicrobial approach may be as effective as a surgical approach in the restoration and maintenance of a periodontally healthy dentition, this would give a cardiac or stroke patient and his or her physician a choice in the implementation of treatment seeking to improve the patient's periodontal condition so as to reduce and/or delay future cardiovascular events.

Simultaneous detection of Bacteroides forsythus and Prevotella intermedia by 16S rRNA gene-directed multiplex PCR

In a 16S rRNA gene-directed multiplex PCR, Prevotella intermedia- and Bacteroides forsythus-specific reverse primers were combined with a single conserved forward primer. A 660-bp fragment and an 840-bp fragment that were specific for both species could be amplified simultaneously. A total of 152 clinical samples, subgingival plaque and swabs of three different oral mucosae, from 38 periodontitis patients were used for the evaluation.

Acceptance Program Guidelines. Products and methods for the diagnosis and/or management of periodontitis. Council on Scientific Affairs. American Dental Association

SCOPE

These Guidelines apply to the design of clinical trials to evaluate products and methods which are intended to be used for the detection and diagnosis of periodontitis. The general purpose for such products and methods would be to assist in the identification of sites or subjects with existing periodontitis or, at increased risk of periodontitis, or for the development or progression of periodontitis. Clinical use of such diagnostics might occur: 1) during initial evaluation (screening, pre-treatment risk assessment, diagnosis, treatment-planning); 2) during treatment or management (monitoring therapeutic endpoints, identifying therapeutic targets); and 3) post-treatment (establishment of recall intervals, early detection of recurrent disease). The specifics of clinical trial design for each of these related, but separate, clinical functions may differ depending on a variety of circumstances.