Antimicrobial Therapy as Adjunct to Periodontal Treatment: Effect of Timing

Single center, randomized placebo controlled crossover clinical trial with a one-year follow-up. Eighty participants with Aggregatibacter actinomycetemcomitans-associated chronic or aggressive periodontitis were randomized into two treatment groups. A: Antibiotics (3/d 500 mg metronidazole plus 375 mg amoxicillin for 7 days) during the first, non-surgical phase of periodontal therapy (T1), and placebo during the second, surgical phase (T2). B: Placebo during T1, and antibiotics during T2. Persistence of sites with a probing depth (PD) >4 mm and bleeding on probing (BOP) was the primary outcome. Evaluations were made three months after T1, as well as 6 and 12 months after T2.

Inclusion criteria

• Untreated moderate to advanced periodontitis (at least 4 teeth with a probing pocket depth (PD) >4 mm, clinical attachment loss of at least 2 mm and radiographic evidence of bone loss)
• Presence of at least 12 scorable teeth (not including 3rd molars, teeth with orthodontic appliances, bridges, crowns or implants)
• Aggregatibacter actinomycetemcomitans-positive

Exclusion criteria

• Systemic illnesses (i.e. diabetes mellitus, cancer, HIV, bone metabolic diseases or disorders that compromise wound healing, radiation or immunosuppressive therapy)
• Pregnancy or lactation
• Systemic antibiotics taken within the previous two months
• Use of non-steroid anti-inflammatory drugs
• Confirmed or suspected intolerance to 5-nitroimidazole-derivatives or amoxicillin subgingival SRP or surgical periodontal therapy in the last year