PICF collection
STERILE
PICF samples were collected at baseline (T0) and 6 months after treatment (T1). The respective sites were gently air-dried and isolated with sterile gauze to prevent contamination with saliva. A sterilized paper collection strip (PerioPaper strips, Oraflow Inc, Plainview, NY, USA) was inserted into the gingival sulcus of the experimental site until slight resistance for 30 s. Samples were disposed in case contamination with blood was observed. A calibrated electronic volume quantification device (Periotron 8000, Oralflow Inc, Plainview, NY, USA) was used for volumetric assessment. Paper strips from each site were put in Eppendorf tubes and subsequently stored at − 80 °C until further analysis. Protein extraction was performed after sample thawing according to an elution procedure specified previously [