Inclusion Criteria:  Aged 18 to 65 years, male or female; patients were clinically diagnosed with chronic periodontitis according to the international classification of periodontal disease in 1999;  Only solitary lesion site requires surgical treatment and must meet the following criteria:  The baseline PD≥7 mm ; After debridement during operation, the defect of the vertical bone at the adjacent surface ≥4mm, and at least one alveolar buccal wall can be detected; The wideness of the keratinized gingiva≥2 mm; Based on the X-Ray image, the dental crowns at the bottom of the bone socket should be at least 3mm;  Exclusion Criteria:  The test tooth has open surgical debridement history within the most recent one years; Known allergy to collagen of animal origin; Clinical or radiographic signs of untreated acute infection at the surgical site, apical pathology, root fracture, severe root irregularities, cemental pearls, cemento-enamel projections not easily removed by odontoplasty, untreated carious lesions at the cemento-enamel junction (CEJ) or on the root surface, subgingival restorations and/or restorations with open margins at or below the CEJ;