According to Dr. Bjarne Klausen from Esbjerg, Danish National Clinical Guidelines for the use of antibiotics in dental practice had recently been finalized. See a quick guide here [pdf]. As regards periodontal infection, he writes,
We formulated a focused question that was in line with the Scandinavian consensus: Should prescription of antibiotics be considered in patients with sufficient oral hygiene, if their periodontal condition does not respond to conventional treatment?
Well, they did not find a single relevant study. How’s that? Isn’t it so that dozens if not hundreds of studies had been performed since the early discovery by Jørgen Slots in Copenhagen identifying an unidentified gram-negative rod in abundance in what was then localized juvenile periodontitis? Soon later it was clear that this bug was Actinobacillus (now Aggregatibacter) actinomycetemcomitans, and that it could best be targeted by systemic antibiotics in conjunction with traditional mechanical/surgical periodontal treatment. Soon after a couple of case series by van Winkelhoff et al. in 1989 and 1992, Amoxicillin plus Metronidazole (the infamous “van Winkelhoff cocktail”) became extremely popular and has since then been mentioned in national guidelines for the treatment of severe periodontitis where A. actinomycetemcomitans could be found in abundance.