A pioneer periodontal surgical approach employing the closed surgical technique (CST) has been designed to gain access to isolated interdental periodontal defects and retain the soft-tissue architecture. This technique is based on a modified tunnelling technique to retract full-thickness gingival flaps from the osseous defect in a closed manner retaining intact the interproximal papilla thus, suturing is not required. A randomised controlled clinical trial will determine the efficacy of the CST versus the access flap employing papilla preservation techniques over a period of 6 months.

This randomised controlled clinical trial will compare the CST over the access flap employing papilla preservation techniques to treat isolated interdental defects in terms of gain in clinical attachment levels, radiographic evidence of bone apposition and local reduction of pro-inflammatory cytokines over a period of 6 months.

1. First visit - initial examination - at least 3 months after initial non-surgical periodontal treatment (Step 1, 2) Update general and dental history Screening of subjects for suitability; Consent form; Randomization of suitable subjects Intra-oral photography Full-mouth charting: Probing pocket depth (PPD), Clinical Attachment Level (CAL), Plaque Index (PI), Bleeding on Probing (BoP), Gingival Recession (Rec) Oral hygiene instructions (soft toothbrush, modified Bass, interdental cleaning) Full mouth supragingival scaling
2. Second visit - Baseline - T0 Collection of Gingival Crevice Fluid (GCF) using sterilized paper strips Radiographic examination of the site (Long-cone paralleling technique using a digital sensor attached to a custom-made silicone bite block for reproducible radiographs) Periodontal site-selected clinical assessment Periodontal surgery (control: access flap with papilla preservation techniques or test: the CST) under local anaesthesia Modification of oral hygiene instructions; post-operative instructions Intra-oral photography
3. Third visit - T1 (2 weeks post-operatively) Suture removal (only in control group) Wound healing visual monitoring by the Early Healing Index (1-5) Oral hygiene instructions Intra-oral photography Questionnaire for subjective feelings and satisfaction
4. Fourth visit - T2 (6 weeks post-operatively) Oral hygiene instructions Intra-oral photography
5. Fifth visit - T3 - Re-evaluation (6 months post-operatively) GCF collection using sterilized paper strips Periodontal full-mouth charting Site-selected periodontal clinical assessment; Probing Pocket depth (PPD), Clinical Attachment Level (CAL), Plaque Index (PI), Bleeding on Probing (BoP), Gingival Recession (Rec Radiographic examination of the site Oral hygiene instructions Intra-oral photography

Inclusion Criteria:

• Systematically healthy subjects, not having consumed antibiotics 3 months before surgical periodontal treatment (baseline)
• Smokers <5 cig/day, former smokers or no smokers
• Periodontal patients fulfilling non surgical initial periodontal treatment at least 3 months before surgical periodontal treatment (baseline day) and presenting at least one residual pocket with PPD and CAL ≥6mm and bleeding on probing, located interproximally with intrerdental site ≥2mm.
• Compliant patients presenting high standards of oral hygiene (full mouth Plaque Index <20%) strictly susceptible in Supportive Periodontal Treatment

Exclusion Criteria:

• Untreated active periodontal inflammation
• Poorly controlled systematic diseases
• Disorders compromise wound healing
• Bisphosphonate medications
• Patients under radiotherapy or chemotherapy
• Drug-indused gingival hyperplasia
• Pregnancy or lactation
• Poor compliance during steps 1 and 2 of cause-related periodontal treatment
• Compromised oral hygiene (full mouth Plaque Index >30%), circumferential bone defect or narrow intrerdental site ≤2mm.

Overall data but not on an individual basis will be disclosed and shared

Treatment is disclosed to the examiner after all data have been collected.