This study evauated guided tissue regeneration in Class II furcation defects after use of a polylactic acid biodegradable barrier innine patients with mandibular molare defects. Following an initial hygenic phase, surgical flaps were evaluated, and the sites were scaled and root planed. Defect perimeter was measured, and a customized barrier (600 to 750 mm thick) that adhered directly to tooth and bone was applied. At baseline, sites were measured for probing depth (6.2± 0.5 mm), gingival margin location (-0.6 ± 0.6 mm), and attachment level both vertically (6.9 ± 0.7 mm) and horizontally (5.3±0.5mm). Clinically, barriers fragmented and became displaced in 3 to 6 weeks. Substantial granulation tissue was sometimes present between barrier and root surfaces. Six months postsurgery, gingival margin location was close to the presurgical level (-0.4 ± 0.8mm). There was clinically and statistically significant improvement in all other parameters: a mean reduction of 3.1 mm in probing depth, a gain of 3.3 mm in vertical attachment level, and a gain of 3.0 mm in horizontal attachment level. These results suggested favorable regenerative outcomes.