A systematic review on survival and success rates of implants placed immediately into fresh extraction sockets after at least 1 year

Background: Type I immediate implant placement has gained popularity because it may reduce treatment time, number of surgeries and post-extraction bone loss. However, this is potentially challenged by inadequate keratinized mucosa for flap adaptation and difficulties in achieving primary stability. Moreover, it has been proven that post-extraction bone loss is an inevitable biological process, which affects treatment outcomes.

Objectives: To estimate survival and success rates of implants and the implant-supported prostheses, the prevalence of biological, technical and aesthetic complications, and the magnitude of soft and hard tissue changes following implant placement immediately into fresh extraction sockets.

Material and methods: An electronic search in MEDLINE (PubMed) and the Cochrane Library from 1991 to July 2010 was performed to include prospective studies on immediate implants with a mean follow-up time of at least 1 year. The survival rates were computed using the STATA statistical software. Weighted means of soft and hard tissue changes were obtained by the inverse variance method.

Results: A total of 46 prospective studies, with a mean follow-up time of 2.08 years, were included. The annual failure rate of immediate implants was 0.82% (95% CI: 0.48-1.39%), translating into the 2-year survival rate of 98.4% (97.3-99%). Among the five factors analysed (reasons for extraction, antibiotic use, position of implant [anterior vs. posterior, maxilla vs. mandible), type of loading], only the regimen of antibiotic use affected the survival rate significantly. Lower failure rates were found in groups that were provided with a course of post-operative antibiotics. The success of implant therapy was difficult to assess due to scarce reporting on biological, technical and aesthetic complications. Soft tissue changes occurred mostly in the first 3 months after the provision of restoration, and then stabilized towards end of the first year. Marginal bone loss predominantly took place in the first year after implant placement, with a magnitude generally less than 1 mm. Controversy on hard tissue preservation with platform-switching technique remained unsolved.

Conclusions: Despite the high survival rate observed, more long-term studies are necessary to determine the success of implant treatment provided immediately after tooth extraction. Special attention has to be given to aesthetic outcomes.