Systemic periodontal antibiotic therapy aims to reinforce mechanical periodontal treatment, not to substitute it, and to support host defenses in overcoming the infection by killing susceptible periodontal pathogens that remain after conventional mechanical treatment.

Prime candidates for systemic antimicrobial therapy are patients who exhibit continuing loss of periodontal attachment despite diligent conventional mechanical (primarily surgical) periodontal therapy such as:

• refractory periodontitis – it is related to persistent subgingival infection and perhaps impaired host resistance;
• aggressive or early-onset periodontitis – it includes localized juvenile and rapidly progressing periodontitis, which are both linked to alterations in host immune response and possible genetic predisposition.

Patients with acute periodontal infections (periodontal abscess) may benefit from a short-term antibiotic therapy in conjunction with mechanical treatment. However, patients with gingivitis and chronic periodontitis usually respond well to conventional therapy and derive little or no additional benefit from systemic antibiotics.

1. Tetracyclines - these antibiotics are indicated in periodontal infections in which A. actinomycetecomitans (Aa) is a prominent pathogen, such as in localized juvenile periodontitis. However, in mixed infections they may not provide sufficient arrest of disease progression.

Suggested drug regimen:
• Tetracycline 250 mg/ qid/ 14-21 days
• Doxycycline 100 mg/ 2 stat, then 1 tab qd for 14 days

2. Metronidazole - it may arrest disease progression in refractory periodontitis. This drug is used in combination therapy with Amoxicillin or Cipro.
3. Metronidazole with Amoxicillin or Cipro - this combination provides a relatively predictable eradication of subgingival periodontal bacteria in Early-Onset or Aggressive periodontitis and in Refractory periodontitis. Cipro is used instead of Amoxicillin in adult patients who are allergic to Penicillins.

Suggested drug regimen:
• Amoxicillin 500mg/ tid/ 8-14 days or Cipro 500mg/ bid/ 8-14 days
• Metronidazole 250mg/ tid/ 8-14 days or Metronidazole 500mg/ bid/ 8-14 days

4. Clindamycin - this drug may be efficient in treatment of refractory periodontitis. It should be prescribed with caution due to its potential to cause pseudomembranous colitis.

Suggested drug regimen:
• Clindamycin 300 mg/ tid/ 7 days
5. Amoxicillin - Clavulanic Acid (Augmentin) - it may represent alternative to Clindamycin. It is useful for treatment of refractory periodontitis and as a post-surgical regimen in regenerative procedures.

Suggested drug regimen:
• Augmentin 250mg/ tid/ 7-14 days
6. Suggested treatment for periodontal abscess:
   • Amoxicillin 500mg/ 1g stat/ then tid/ 3-7 days. If allergic to Penicillin:
   • Clindamycin 300mg/ 600 mg stat/ then tid/ 3-7 days, or
   • Azithromycin 500mg/ 600 mg stat/ then qd/ 2-3 days

After initial antibiotic treatment, patient evaluation is necessary to determine the need for further therapy.

After completion of systemic antibiotic therapy, patient should be placed on an individually tailored maintenance program. Recurrence of periodontal disease may prompt repeated microbiological testing and subsequent antibiotic and conventional therapy. Systemic antibiotic therapy should be prescribed with great caution because of the emerging bacterial resistance and its inability to eradicate all periodontal pathogens.

Recent advertising campaigns increased consumer interest in Periostat, which is referred to as "a pill to cure periodontal disease". Periostat is merely a 20mg capsule of Doxycycline Hyclate. Suggested drug regimen is 20-40 mg a day taken for 3 months, and then repeated in another 3 months. Periostat is approved by the FDA as an adjunct to root planning in the treatment of adult periodontitis. The rationale for using Periostat is its potential ability to reduce collagenase activity, not its antibiotic property, thereby aiding in local immune response against periodontal bacteria.

Like any other newer product, Periostat has not been evaluated extensively. There is only one long-term (9-month duration) study, which focused on changes in pocket depth and attachment level after adjunctive use of Periostat with scaling and root planning. Even though statistically adjunctive Periostat therapy showed improvement in mean probing depth and attachment levels, in reality observed changes were less than 1 mm! Anyone interpreting these results should account for potential operator's error during repeated measurements, which is at least 1 mm, and the crudeness of these measurements. In controlled periodontal studies clinically significant difference can only be confirmed if the difference between the measurements is over 2 mm.

At present, there are no data to support the use of Periostat in the treatment of specific periodontal diseases other than adult periodontitis. Although, the manufacturers of Periostat claim that their product does not produce bacterial resistance, there are no long-term studies to prove that. Please, keep in mind, that Tetracyclines, which include Periostat, have been extensively used in medicine and dentistry for decades, and the potential for existing bacterial resistance is very high. Furthermore, it should be noted that adjunctive use of Periostat to enhance conventional therapies is not a substitute for meticulous home care, professional maintenance, root planning and appropriate periodontal treatment designed to minimize bacterial load, facilitate proper home care and save teeth.

Also, there is no data to suggest that Periostat may suppress the progression of periodontal disease. Therefore, the common notion that "taking this pill may help avoid periodontal treatment now or in the future" does not have any valid ground. Patients might be misled by this type of advertising and delay necessary treatment, which in consequence may jeopardize their oral health and lead to tooth loss.