Which is the best choice after tooth extraction, immediate implant placement or delayed placement with alveolar ridge preservation? A systematic review and meta-analysis.

A comprehensive literature search on implant placement protocols after tooth extraction (immediate, early, delayed, or later) was performed up to 2018. The screening process selected only randomized clinical trials (RCTs) from PubMed, Embase, Cochrane Library, Web of Science, Scopus, LILACS, and grey literature. A series of pairwise meta-analyses was carried out to evaluate implant performance in each protocol. The primary outcomes were implant survival and esthetic outcome, measured by pink esthetic score (PES), and the secondary outcomes were peri-implant bone resorption and implant complications. The outcomes were at least 1 year after implant surgery. A total of 5056 studies were found, of which 16 were included for qualitative analysis and 9 for quantitative analysis. The meta-analysis showed increased risk of implant failure by 3% in the immediate implant protocol. PES analysis showed no statistical significant difference between immediate or delayed protocols (p = 0.16). However, the subgroup analysis showed that the anterior region presented better results with immediate implants, while the molar region presented better results with delayed implants. The quantitative analysis showed no statistical difference in peri-implant bone resorption between the immediate and delayed implant protocols (p = 0.42). Due to the lack of studies with a low risk of bias, further RCTs are needed for definitive conclusions.