Table 1 Systemic and specific adopted inclusion criteria

Absence of relevant medical conditions: Medical history of good health (particularly ruling out bone disease, uncontrolled or poorly controlled diabetes, unstable or life-threatening conditions, or requiring antibiotic prophylaxis were excluded).

Defect anatomy:

Presence of at least one intrabony defect in patient with periodontal disease.

Excessive gingival display or gingival margin asymmetries required a surgical correction in periodontally-healthy patients

Smoking status: Non-smokers and without a story of alcohol abuse.

Good oral hygiene: full-mouth plaque score (FMPS) ≤20 %

Compliance: only patients showing high levels of compliance (as assessed during the cause-related phase of therapy) were selected.

Low level of residual infection: full-mouth bleeding score (FMBS) ≤20 %.

Pregnancy or lactation and underage were excluded.

Endodontic status: Experimental teeth had to be vital or properly treated with root canal therapy.