 The aim of this study was to evaluate the effect of PRF by assessing gingival crevicular fluid GCF levels of MMP-8, MMP-9, tissue inhibitor of matrix metalloproteinase TIMP-1 and interleukin-1beta IL-1β during the early and late stages of healing following coronally advanced flap CAF plus PRF or CAF plus connective tissue graft CTG treatment. 