Cell sheet technique possess the properties of conserving the ECM, rich molecules and retaining cell vitality, and will promote the capacity of cell adhesion and proliferation. The stem cell based cell sheet therapy has been utilized in many fields and scored the satisfactory results. Periodontitis is a chronic disease which causes the destruction of the periodontal tissue and leads to the teeth loss in the end. The routine cell-based therapy to the periodontitis was confronted with many difficulties. In the investigators previous preclinical research, +the investigators fabricated periodontal ligament stem cell (PDLSC) pellets and cell sheet fragment and applied them in the periodontal defect area for tissue regeneration and periodontitis treatment. And the investigators carried out a comprehensive study of the PDLSC allograft. The host responses and implanted cell fates were recorded. After the scientific investigation of the preclinical study, the investigators designed the preliminary clinical trial of PDLSC cell sheet for the chronic periodontitis therapy in the aims to test the PDLSC fates and explore one ideal transplantation mode.

our protocol mainly includes following steps:

1. select periodontitis patients :all patients were given the comprehensive examination on the oral condition including clinical examination, radiological evaluation and the immune system tests
2. select healthy donor teeth for PDLSC isolation and expansion.
3. fabricate the cell sheet and prepare the PDLSC cell sheet pellets and cell sheet fragment.
4. patients given the routine mechanical and chemical treatment for 4 weeks were randomized divided into 4 groups according to the visit time: i) the cell sheet fragment plus bio-ss transplantation; ii) the cell sheet pellets plus bioss transplantation; iii) the bio-ss transplantation and iv) the control.
5. all the operations were carried out as the routine GBR procedures.
6. the clinical, radiological examination and the changes of the immune system at the point of 1 day before and 4weeks, 12weeks, 24weeks and one year after the intervention were recorded and compared.

Inclusion Criteria:

1. adult chronic periodontitis
2. pathological lesion is stable after the routine mechanical and chemical treatment.
3. the local pathological lesion has the subbony defect
4. the oral heath was kept approved.
5. there are more 2 teeth with the continued lesion

Exclusion Criteria:

1. the age>50 year or < 40year
2. the patient has the genetic background of the periodontitis.
3. the bone destruction was larger than 2/3 of the root length.
4. the preclinical treatment was stable.
5. the severe systematic diseases.
6. the patients who can not cooperate with the whole the observation.