AimTo compare immediate surgery to scaling and root planing (SRP) in the treatment of advanced periodontitis focusing on the prevalence of residual pockets after treatment and cost-effectiveness (1); to elucidate the adjunctive effects of azithromycin in a second-treatment phase (2) up to 36months. Materials and MethodsThirty-nine patients (18 males, 21 females; mean age: 54.6) received oral hygiene instructions and were randomly allocated to surgery (n=19) or SRP (n=20). Patients with residual pockets (6mm) at 6months received re-debridement of these sites and systemic azithromycin. Clinical measurements were performed at 12, 24 and 36months whereby residual pockets underwent re-debridement. Patients were evaluated in terms of clinical response parameters and cost-effectiveness. Chair-time was used to assess the financial impact of treatment. ResultsOnly six patients in the surgery group required additional treatment at 6months, whereas 14 patients in the SRP underwent this therapy. Both treatment arms were equally effective in terms of clinical outcome demonstrating <2% residual pockets at 36months. Surgery imposed an extra 746 Euro on the patient up to 6months compared to SRP. At 36months, 69 Euro of this amount could be offset due to the lower need for re-treatment during maintenance phase. ConclusionsSurgery was ultimately associated with a significantly lower need for re-treatment during supportive care, however, at significantly higher costs over the 3years.