Platelet Derived Growth Factor Stimulates Bone Fill and Rate of Attachment Level Gain

Inclusion Criteria: * probing depth of 7mm or greater at baseline * following debridement, 4mm or greater vertical bone defect depth with at least one intact bony wall * sufficient keratinized tissue to allow complete tissue coverage of the defect * a radiographic base of the defect at least 3mm coronal to the apex of the tooth * no evidence of localized aggressive periodontitis * smoke less than 1 pack of cigarettes per day Exclusion Criteria: * failure to maintain adequate oral hygiene * pregnant women or women intending to become pregnant * history of oral cancer within last 6 months or HIV * history within last year of periodontal surgery on study tooth * study tooth mobility greater than 2 * study tooth exhibiting a class 3 furcation defect * signs of untreated acute infection at the surgical site, apical pathology, root fracture, severe root irregularities, cemental pearls, cementoenamel junction (CEJ) projections not easily removed, untreated carious lesions at the CEJ or on the root surface, subgingival restorations or restorations with open margins at or below CEJ * history within 6 months of weekly or more frequent use of smokeless chewing tobacco, pipe or cigar smoking, or more than 20 cigarettes a day * allergy to yeast derived products * investigational therapy within 30 days of surgery