Metronidazole in periodontal surgical therapy

INTERVENTION: Participants are randomly assigned to treatment groups in ascending order, at the time of surgery, according to a balanced distribution system (random block design, block size = 6). 1. Test group: blisters consisted of 500 mg metronidazole, to be taken three times per day for 7 days after the last surgery 2. Placebo group In the initial evaluation, a clinical examination is carried out to establish the periodontal diagnosis. Clinical measurements include: PD and gingival recession/overgrowth (REC), measured to the nearest millimeter; CAL, calculated as the sum/rest of PD and REC; bleeding on probing (BOP), assessed dichotomously. Plaque index (PlI) is also assessed. In each quadrant, the most accessible location with the deepest PD and BOP is selected. Subgingival plaque samples are obtained at the same sites throughout the study at the deepest site of each quadrant. All participants receive motivational sessions on oral hygiene instructions and scaling and root planning. Six weeks after the last session of SRP, the re‐evaluation is performed and a new full periodontal examination is performed. Those presenting multiple locations with PD =5 mm with BOP in =1 quadrant received periodontal surgery through open flap debridment. After the last surgical procedure is performed, the medication is provided to the participants, with the instructions to start with the drug regime, three times a day for 7 days. Clinical parameters are recorded 3 months after the last surgery session, and then after 6 and 12 months. Following the active treatment, at 3, 6, 9 and 12 months all patients receive a full mouth professional mechanical plaque removal (PMPR), including SRP as needed and polishing of all dental surfaces prese CONDITION: Severe generalised chronic periodontitis (generalised stages III‐IV, grades B‐C periodontitis) ; Oral Health ; Chronic periodontitis PRIMARY OUTCOME: Probing Depth (PD), measured using a UNC‐15 mm periodontal probe (Hu‐Friedy, Leinmen, Germany) at baseline and 12‐month visit SECONDARY OUTCOME: ; At baseline, 3 months after the last surgery session, and then after 6 and 12 months:; 1. Probing Depth distribution [/overgrowth (measured to the nearest millimeter), Clinical Attachment Loss (calculated as the sum/rest of PD and REC) and open pockets measured using a UNC‐15 mm periodontal probe (Hu‐Friedy, Leinmen, Germany); 2. Plaque Index recorded using the O'Leary Index; 3. Bleeding on Probing measured using a dichotomous analysis (presence or absence); ; 4. Microbiological variables (frequency of detection and counts of each targeted bacteria) samples analysed by multiplex quantitative polymerase chain reaction (qPCR), at baseline and after 12 months following surgical therapy; INCLUSION CRITERIA: 1. Severe generalized chronic periodontitis (Armitage, 1999), corresponding to generalized stage III‐IV periodontitis, with grades B‐C (Caton et al., 2018; Papapanou et al., 2018; Tonetti, Greenwell, & Kornman, 2018) 2. A least 10 teeth in function, excluding third molars 3. Sites with PD> 5 mm, in =2 teeth in =1 quadrant 4. Radiographic evidence of bone loss =30% in, at least, 30% of the dentition 5. Older than 18 years