A 3-year prospective multicenter follow-up report on the immediate and delayed-immediate placement of implants

A total of 264 implants was placed in 143 patients using different immediat e or delayed-immediate implant placement techniques in 12 different centers participating in a prospective multicenter study. The reason for tooth ext raction was evaluated; bone quality and quantity were classified; socket de pths were registered; and data on implant type, size, and position were col lected. One hundred thirty-nine suprastructures were placed on 228 implants in 126 patients. A follow-up evaluation was done on 125 patients after 1 y ear of loading and on 107 patients after 3 years of loading. Clinical param eters (bleeding or not bleeding, pocket depth, and implant mobility) were e valuated after 1 and 3 years, and the marginal bone level after 1 year of l oading was measured on radiographs. Clinical comparisons were performed to evaluate implant loss in relation to implant type, size, position, bone qua lity and quantity, socket depth, reason for tooth extraction, and placement method. In addition, life table analysis was done for cumulative implant s urvival rates. There was no clinical difference with respect to socket dept h or when comparing the different placement methods. A higher failure rate was found for short implants in the posterior region of the maxilla and whe n periodontitis was cited as a reason for tooth extraction. Mean marginal b one resorption from the time of loading to the 1-year follow-up was 0.8 mm in the maxilla and 0.5 mm in the mandible. Over a period of 3 years, the im plant survival rate was 92.4% in the maxilla and 94.7% in the mandible.