A Clinical And Histological Study On Ridge Preservation After Tooth Extraction

Objectives:With the development of implant restoration, it has become one of the best methods to restore lost teeth. Now, the concept of implant osseointegration has been widely accepted, and dental implant has been applied in clinic maturely. Bone mass in three dimensions of alveolar bone is an essential requirement for successful implant, but the height and width of alveolar bone will decrease after tooth extraction. The ridge preservation after tooth extraction can effectively maintain original alveolar bone in three dimensions and ensure the long-term implant success rate and aesthetic effect. On the one hand, although a large number of animal and clinical studies have confirmed GBR used in ridge preservation can retard the absorption of alveolar bone. But clinically the implant is placed in4-6months after ridge preservation, and it does not get the optimal time of implant placement. On the other hand, nowadays, there is little study on evaluation of soft tissues after GBR applied in ridge preservation, especially the attached gingival. And there is no combination of clinical studies with histological research on the ridge preservation to confirm alveolar bone changes. This study is to evaluate the change of alveolar bone and attached gingival in different postoperative time after GBR in ridge preservation, and further to study the alveolar bone in histology. The study aims to evaluate the clinical significance of ridge preservation in both clinical and histological aspect.Methods:Select the standard of12cases in implant center of Shandong University Stomatological Hospital. Patients were scanned by Cone Beam Computed Tomographic in the day of the surgery and3and6months after operation. Then, measure the height and width of alveolar bone and the width of attached gingival in ridge preservation sites, and do statistical analysis. Six months later, removed a small amount of alveolar bone for HE staining in implant surgery to observe osteogenesis after GBR, and testify the consistency with clinical results.Results:1. Compare the height and width of alveolar bone between the day of surgery and the one of3and6months after operation respectively, which had statistical significance(P<0.05). Compare the difference between the height and width of alveolar bone of the day of surgery and the one of3months after operation, to the difference between the values of3and6months after operation, which had statistical significance(P<0.05). It confirmed alveolar bone was not yet stabled and still absorbed, but the absorption was decreased and stabilized gradually.2. Compare the width of attached gingival between3and6months after surgery, it had no statistical significance (P>0.05). It explained the attached gingival was stabled after postoperative3months.3. Histological results showed a large number of new bone formation which was mature and compact, but there were still some bone substitute materials remained. Besides, a lot of fibrous connective tissue could also be observed.Conclusions:1. GBR applied in the ridge preservation, a little alveolar bone was absorbed in6months after operation, but the absorption of alveolar bone was decreased between3and6months after operation and stabilized gradually the best time to implant placement could be six months, or even six months later.2. Soft tissue did not collapse and the width of attached gingival might be stab-ilized in3months after ridge preservation. It is propitious to the maintenance of oral hygiene and esthetic effect in implant restoration. 3. The alveolar bone after ridge preservation had new bone formation, which promoted osteogenesis. Combining with clinical studies, it indicated that the sites have enough alveolar bone and good bone to ensure that the implant can be implanted successfully.