The aim of this study was to investigate which factors play a major role in the healing of Class II mandibular furcation defects treated with different surgical techniques. Twenty-five systemically healthy subjects with periodontitis stage III grade B and Class II buccal mandibular furcation involvement received one of the following open flap debridement approaches: Group 1 (n = 10), no further treatment; Group 2 (n = 10), piezoelectric contouring of the furcation roof; Group 3 (n = 9), piezoelectric contouring of the furcation roof and bone grafting; Group 4 (n = 10), piezoelectric contouring of the furcation roof and bone grafting with coronally positioned flap. Clinical and radiologic variables-bleeding on probing, probing depth (PPD), vertical and horizontal bone level (CAL and PH), gingival recession, root trunk length, radicular separation, and furcation perimeter (FP)-were evaluated at baseline and 180 days and 1 year after surgery. All clinical parameters were statistically analyzed. Surgical techniques caused clinical (CAL, PPD, PH) and radiographic (FP) improvements. Regenerative techniques and the coronally positioned flap yielded a major radiographic reduction of furcation areas. All therapies resulted in significant horizontal and vertical PPD reduction and CAL gain.