ObjectivesThe primary aim was to evaluate the success of the defect closure (tight or open) of oroantral communications (OAC) after treatment with platelet-rich fibrin (PRF) clots or a buccal advancement flap (BAF). Secondary outcome measurements were the evaluation of the wound healing, the displacement of the mucogingival border (MGB), and the pain level.Material and methodsFifty eligible patients with an OAC defect larger than 3 mm were randomly assigned to either PRF (test group,n= 25) or BAF (control group,n= 25) for defect closure. In a prospective follow-up program of 21 days, the defect closure healing process, the wound healing course using Landry’s wound healing index (score: 0–5), the displacement of the MGB, and the postoperative pain score were evaluated.ResultsFive patients in each group were lost to follow-up resulting in 40 patients (20 in each group) for continuous evaluation. On postoperative day 21 (study endpoint), no difference regarding success rate (defined as closure of OAC) was noticed between the test (90%; 18/20) and control group (90%; 18/20). A univariate analysis showed significant differences for age and defect size/height for the use of PRF between successful-tight and open–failed defect healing. At the final evaluation, a significantly (p= 0.005) better wound healing score, a lower displacement of the MGB as well as lower pain-score were seen for the use of PRF.ConclusionsBased on the findings of the current study, the use of platelet-rich fibrin represents a reliable and successful method for closure of oroantral communications. The use of PRF clots for defect filling is associated with lowered pain levels and less displacement of the mucogingival border.Clinical relevanceThe defect size should be taken into account when choosing the number and size of PRF plugs.