The aim of this study is to determine the efficacy of the usage of a probiobitc lozenge in patients with residual bleeding pockets of ≥ 5mm 3 months following scaling and rootplaning. Simultaneously the additional benefit of subgingival application of probiotics via oil drops will be investigated.

The aim of this study is to determine the efficacy of the usage of a probiobitc lozenge in patients with residual bleeding pockets of ≥ 5mm following scaling and rootplaning. Simultaneously the additional benefit of subgingival application of probiotics via oil drops will be investigated.

Recruitment: This study will be a single centre (Department of Oral Health Sciences, University Hospitals Leuven), double blind, randomized, placebo controlled clinical trial with within each patient a split mouth design. The randomization (by means of a computer program) and double blind design are thought to minimize the bias of the investigator and patients.

Selection of the study population: Adults, who consult at the department of Periodontology at the University Hospital Leuven, and who fit the inclusion criteria will be asked to participate in this study.

Inclusion Criteria:

• 40 patients
• ≥ 18 years of age
• scaling and rootplaning received at least 3 months ago
• Patients diagnosed with residual pockets (at least 2), with the definition of residual pockets:> 5mm or 5 and BOP+
• Willing and able to give written informed consent

Exclusion Criteria:

• patients with aggressive periodontitis
• patients who smoke
• pregnant or lactating woman
• patients with poorly controlled diabetes
• patients taking bisphosphonate mediation
• patient who had taken systemic antibiotics 3 months prior to treatment