A randomized controlled clinical trial was conducted on 16 patients (8 males and 8 women) who were diagnosed chronic periodontitis. All the patients has been divided by randomization in two groups: control group treated with placebo gel and experimental group treated with gel based on ozonated EVO olive oil.

Both group after the evaluation of inclusion and exclusion criteria during the first visit, were subjected to hygiene treatment of removal tartar deposit, considered as standard of therapy for periodontitis.

After 15 days the hygiene treatment, patients were been randomized in two groups following the flow chart (t0) starting with: periodontal probing, microbiological samples and the first administration of gel. Next week (t1), has been collected the compliance and did the second administration of gel; the procedures will be the same also for another week (t2), until the last week (t3) when has been registered the second periodontal probing and did the second microbiological samples.

Data were collected to software Microsoft Excel and all the data analysis were conducted on this software to highlight significant differences between both groups. As the primary outcome was continuous variable and assuming normal distribution bilateral parametric test T-student was performed. An alpha error of 5% was considered, Beta error was not calculated as this was a pilot study.

Inclusion Criteria:

• Patients with stage II, III, or IV periodontitis according to the new 2017 World Workshop periodontal classification
• Patients of either sex and older than 18 years of age
• Probing Pocket Depth (PPD) greater than or equal to 4 mm at 3 sites
• Patients who have signed consent to the study
• Collaborating patients

Exclusion Criteria:

• age < 18 years and/or inability to provide written informed consent;
• absence of family or social welfare support;
• non-drug-induced gingival hypertrophy,
• severe smokers (more than 20 cigarettes per day),
• consumers of high levels of alcohol,
• patients on corticosteroid treatment,
• diabetic patient,
• immunodepressive therapies,
• chemotherapies,
• radiotherapies,
• pregnancy states;
• lack of collaboration for ongoing postoperative reevaluations.