Gram-negative obligate anaerobes

P.gingivalis - P.intermedia - B.forsythus - Fusobacterium sp. - Selenomonas sp. - spirochetes

Gram-negative faculative anaerobes

A.actinomycetemcomitans - Campylobacter rectus - Eikenella corrodens

Gram-positive obligate anaerobes

Peptostreptococcus micros - Eubacterium sp.

Periodontal therapy aims to eliminate the potentially pathogenic microorganisms, allowing the residual pockets to be colonised by species of bacteria that are not associated with disease activity (commonly referred to as beneficial species). These bacteria include Veillonella parvula, Actinomyces sp., Streptoccus oralis, Streptococcus mitis and Capnoctyphaga ochracea. For the vast majority of patients, mechanical removal of subgingival plaque and calculus, coupled with excellent supragingival plaque control, will halt the loss of periodontal attachment. However, some patients will continue to exhibit inflammation, as evident through bleeding on probing, and continued loss of` attachment at one or more sites in their mouth. It is at this stage that the use of antibiotics as an adjunct to further periodontal therapy is sometimes considered.

The decision to use antibiotics must be based upon a knowledge of the likely bacteria to be causing the problems. As the bacteria involved are usually anaerobes, culturing of plaque samples is very difficult and expensive. DNA probe techniques are being developed to identify a range of bacteria, but at this stage their availability for use in a general practice setting is limited. Therefore, the choice of antibiotic to be used is usually based upon the findings of clinical trials reported in the literature, as well as taking into account the form of periodontitis experienced by the patient, and any modifying medical conditions. 

Acute Necrotizing Ulcerative Gingivitis

A suggested approach to the management of this painful condition is: 

1) gentle debridement to remove plaque and debris; 

2) prescription of chlorhexedine and an oxygenating mouthwash; 

3) prescription of Flagyl (metronidazole) 200mg, three times a day for seven days; 

4) review after three to seven days to begin periodontal therapy. 

If you suspect compliance problems with the patient taking a course of antibiotics, the prescription of Tinidazole (Fasigyn) 2 grams stat is as effective as Flagyl. Giving the patient 4 x 500mg tablets at chairside overcomes any compliance problems and provides adequate blood levels for 2 to 3 days at which time the patient may be reviewed. 

The prescription of an antibiotic seems to reduce the pain associated with ANUG more quickly than debridement plus mouthwash alone.

Juvenile Periodontitis

The facultative anaerobic bacteria, Actinobacillus actinomycetemcomitans (or A.a), is the predominate cultivable bacteria associated with this type of disease. While non-surgical or surgical debridement of affected sites may eliminate this bacteria and lead to resolution, it appears that antibiotics as art adjunct to debridement provide a more predictable long term result for many patients. The antibiotic of choice for these patients is doxycycline, 100mff once a day for 21 days
 

Rapidly Progressive Periodontitis

Many cases of rapidly progressive periodontitis stabilise after the affected sites are thoroughly debrided, effective oral hygiene is established and maintenance therapy is performed regularly. However, some patients continue to show loss of attachment in spite of these factors. Others will experience the occurrence of one or more periodontal abscesses after treatment. In these situations, the decision to use antibiotics as an adjunct to further root debridement is justified. 

From the literature, a two week course of doxycyline (100 mg, once a day), along with surgical or non-surgical debridement, can lead to stabilisation of the disease process. However, it appears that tetracycline- resistant strains of pathogenic bacteria are beginning to emerge, and hence some patients will respond better to a combined course of amoxycillin (250 mg three times a day) and rnetronidazole (200 rng, t.i.d.) for seven days. It is important to realise that amoxycillin alone is ineffective in controlling periodontal infections, and therefore should not be prescribed. Similarly, because many periodontal pathogens secrete beta-lactamase (which makes them resistant to penicillins), penicillins are inappropriate for the management of periodontal infections.

Adult-type Periodontitis

Adult-type periodontitis should respond in a predictable way to thorough non-surgical root debridement and excellent plaque control. If sites continue to break down in spite of this approach, then surgery to gain access to sites that may have been difficult to clean is the next treatment of choice. No additional antibiotic therapy should be necessary for this procedure. 

Antibiotic cover for periodontal procedures in patients with medical conditions

The prevention of infective endocarditis due to bacteraemia arising from periodontal treatment is essential. Any procedure that induces gingival bleeding can result in a bacteraemia, and hence patients at risk must be protected by antibiotic cover for periodontal probing, scaling and root-planing, and periodontal surgery. It is important for dentists to remain up to date with current recommendations.

There are a number of guidelines available from various medical authorities, and these may differ slightly in their recommendations. It is essential for dentists to discuss any proposed dental treatment with the patient's cardiologist for advice regarding the selection of the most appropriate antibiotic regime

The most up-to-date overview of microbiological aspects of periodontal diseases can be found in the journal Periodontology 2000, Volume 5, 1994. This volume, titled Microbiology and immunology of periodontal diseases, includes a chapter on on antimicrobial strategies for treatment of periodontal diseases written by J. Max Goodson.
 

This material has been compiled with the assistance of Dr Louise Brown, Lecturer in Periodontics at the University of Melbourne.

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