The successful use of osseointegrated implants to replace missing teeth has been demonstrated for both the completely and the partially edentulous patients. Many studies have confirmed an excellent long- term prognosis. The successful outcome of any implant procedure is surely dependent on the interrelationship of the various components that includes the following: biocompatibility of the implant material, macroscopic and microscopic nature of the implant surface, the status of the implant bed in both a health(noninfected) and a morphologic(bone quality) context, the surgical technique, the undisturbed healing phase, the subsequent prosthetic design, and long-term loading phase. Periodontally compromised patients have poor status of the implant bed and periodontal pathogen. No longitudinal data are available whether these factors affect the prognosis of implants. In this study, 102 machined Branemark implants are inserted to analyze the success rate of 1-4 years and marginal bone loss in 49 chronic periodontitis patients. The following conclusions could be drawn from this study.

1. The cumulative success rate of implants at the 4-year of loading was 95.10%.

2. 5 failed implants have been removed. One implant have been removed due to infection, two implants were removed due to failure of osseointegration. and other two implants were removed due to mechanical failure caused by over-loading.

3. Mean marginal bone loss from the time of loading was 0.94mm at first year, 1.12mm at second year, 1.25mm at third year.

These results suggest that implant therapy is good treatment modality in chronic periodontitis patients, and periodontal treatment including oral hygiene program is completed prior to insertion of implants.