Randomization, Allocation Concealment and Blinding Patients were randomly assigned to treatment modality by using a randomization scheme prepared prior to study initiation and to treatment in blocks of 6. The patients were allocated to either reconstruction of the defect with PTG (Test group) or closure of the flap after implant debridement (OFD/Control). Documentation of treatment allocation for each patient was placed in separate, sealed opaque envelopes that were opened and revealed to the surgeon after debridement of the defect and implant surface was finished. Clinical examiners remained blinded to the treatment assigned.