The aim of this study was to compare modified Widman flap surgery (MW) to coronally advanced flap surgery combined with carbon dioxide laser root conditioning (CAF + CO2) from baseline to 15 years of follow-up. Each of 25 patients participating in this study were treated using a split-mouth design: In one quadrant, the teeth received MW surgery (control), and on the other side, after a full-thickness flap was raised, a CO2 laser was used and the fullthickness flap was repositioned coronally and sutured (CAF + CO2, test). Plaque Index, Gingival Index, probing depth, and clinical attachment level were monitored from baseline to 15 years. For probing depths >= 7 mm, CAF + CO2 sites provided greater pocket reduction (P .01), and data on clinical attachment level showed a significant difference between control and test sites at 5 to 6 mm (P .001) and >= 7 mm (P .001). This study showed that CAF + CO2 therapy resulted in significantly higher improvements than MW surgery.