This is a randomized, paralleled, control trial to validate the effectiveness and safety of Lando® absorbable collagen membrane for oral bone repair.

Inclusion Criteria:

• 18~65 years old;
• Subjects, whose single teeth (adjacent teeth intact) of incisor, canine or premolar is removed and bone graft is needed for alveolar ridge preservation, and need a delayed implant repair in more than 26 weeks.
• voluntary participation and sign on the informed consent form

Exclusion Criteria:

• Participated in other clinical trials in 90 days before joined in the trial
• Having received in 90 days before joined in the trial and / or will receive the head and neck radiation therapy or chemist during the study
• Having received in 90 days before joined in the trial and / or will receive any drug treatment that may affect bone metabolism;
• patients with heart disease;
• patients with abnormal liver and kidney function;
• poor diabetes control;
• low or abnormal immunity, anaphylaxis and the researchers judged to be of clinical significance;
• HIV infected patients;
• bleeding tendency or coagulation disorders and researchers judged to be of clinical significance;
• mental disorder;
• women who are pregnant or breast-feeding or preparing for pregnancy in the next 26 weeks;
• severe smokers;
• patients with periodontitis without basic periodontal treatment;
• the fracture of alveolar process after tooth extraction;
• The loss of bone wall on any side of alveolar fossa was more than 2/3.
• other cases that researchers believe not suitable for the participants of the trial