Non Surgical Therapy of Periodontitis in Diabetes Patients: the Adjunctive Use of Probiotics

Diabetes patients will be consecutively selected among those attending the Faculty of Odontology, University Complutense (Madrid, Spain). Patients fulfilling the required criteria will be invited to participate in the study, will be informed on the study purposes, and will be invited to sign and IRB approved informed consent.The study will be designed as a doubled-blind, placebo controlled, parallel, randomized clinical trial with a 6-month follow-up. The patients will be examined for clinical parameters and microbiological sampling, and randomised into two different groups.The following study visits will be scheduled:

Screening visit Potential patient eligibility will be based on the inclusion/exclusion criteria already presented. Patients will be informed about their periodontal condition and treatment needs. Patients willing to participate in the study will be given additional information about the study and upon signing a consent form, they will be appointed for the graduate clinic of Periodontology.

Baseline visit Patients will undergo a comprehensive oral and periodontal examination. Full-mouth clinical measurements of PPD and clinical attachment level (CAL) will be taken at 6 sites per tooth, excluding third molars, and will be rounded to the nearest millimetre using a UNC-15 probe (Hu-Friedy, Chicago, IL, USA). Panoramic radiographs and/or full-mouth periapical radiographs will also be taken, as standard procedures of the postgraduate clinic. Microbiological samples will be taken. The patient smoking history will be recorded and participants will be categorized as: current smokers (those who smoked at least one cigarette per day); never smokers (those who had never smoked in their life); and former smokers (those who had stopped smoking at least 1 year previously). Other relevant aspects of the medical history will be also collected, including the evaluation of the glycated haemoglobin (HbA1c) levels by means of standard laboratory procedures.

Treatment visits Subjects will receive non-surgical periodontal therapy in the form of full-mouth SRP, in two consecutive days, in combination with 0.12% chlorhexidine (Gum Chlorhexidine Oral Rinse, Etoy, Switzerland) application by means of rinsing prior to and at the end of each SRP session. All patients will receive standardized oral hygiene instructions, including the use of a manual toothbrush (GUM® Activital Toothbrush), and interdental brushers (GUM® Trav-ler and GUM® Soft Picks). Instructions will be periodically reinforced.

Immediately after oral hygiene instructions, patients will be randomly allocated to the test or control groups. One investigator before patient recruitment will generate the randomization sequence by blocks. Random assignment into two groups will be carried out with the use of a computer program. Containers will be designed to maintain examiner blinding. The patients will be randomly allocated, with the help of a computer, in two groups:

• Test group: Subjects in the test group will take two probiotic lozenges per day for 3 months (one in the morning and one in the afternoon after brushing their teeth), starting after the last session of SRP. Lozenges will contain L. reuteri (2 x 108 colony forming units/tablet of strains ATCC 55730 and ATCC PTA 5289; Sunstar GUM Periobalance).
• Placebo group: Subjects assigned to the placebo group will take lozenges exactly like the test ones but without bacteria.

Follow up visits after 3 and 6 months Follow up visits will have the objective to monitor the clinical and microbiological changes in the periodontal condition and to evaluate the bacterial re-colonization pattern in the subgingival niche. This phase will include two recall visits, at which clinical measurements will be repeated and microbiological samples will be collected. Oral hygiene will be reinforced. Glycated haemoglobin levels will be assessed.