This review is based on a Cochrane systematic review entitled 'Interventions for replacing missing teeth: dental implants in fresh extraction sockets (immediate, immediate-delayed and delayed implants)' published in The Cochrane Library (see http://www.cochrane.org/ for information). Cochrane systematic reviews are regularly updated to include new research, and in response to comments and criticisms from readers. If you wish to comment on this review, please send your comments to the Cochrane website or to Marco Esposito. The Cochrane Library should be consulted for the most recent version of the review. The results of a Cochrane review can be interpreted differently, depending on people's perspectives and circumstances. Please consider the conclusions presented carefully. They are the opinions of the review authors, and are not necessarily shared by the Cochrane Collaboration. Purpose: To evaluate success, complications, aesthetics and patient satisfaction among immediate, immediate-delayed and delayed implants in post-extractive sockets and whether and when augmentation procedures are necessary and which is the most effective augmentation technique. Materials and methods: The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE were searched up to the 2nd of June 2010 for randomised controlled clinical trials (RCTs) with a follow-up of at least 1 year in function comparing immediate, immediate-delayed and delayed implants, or comparing various bone augmentation procedures around the inserted implants. Outcome measures were prosthesis and implant failures, complications, patient satisfaction and preference including aesthetics, aesthetics evaluated by a dentist, peri-implant marginal bone level changes, etc. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two review authors. The statistical unit of the analysis was the patient. Results were expressed as fixed effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CIs). Results: Fourteen eligible RCTs were identified but only seven trials could be included. Four RCTs evaluated implant placement timing. Two RCTs compared immediate versus delayed implants in 126 patients and found no statistically significant differences. One RCT compared immediate-delayed versus delayed implants in 46 patients. After 2 years, patients in the immediate-delayed group perceived the time to functional loading significantly shorter, were more satisfied and an independent blinded assessor judged the level of the peri-implant marginal mucosa in relation to that of the adjacent teeth as more appropriate (RR = 1.68; 95% CI 1.04 to 2.72). These differences disappeared 5 years after loading, and significantly more complications occurred in the immediatedelayed group (RR = 4.20; 95% CI 1.01 to 17.43). One RCT compared immediate with immediately delayed implants in 16 patients for 2 years and found no differences. Three RCTs evaluated different techniques of bone grafting for implants immediately placed in extraction sockets. No statistically significant differences were observed when evaluating whether autogenous bone is needed in postextractive sites (one trial with 26 patients) or which was the most effective augmentation technique (two trials with 56 patients). Conclusions: There is insufficient evidence to determine the possible advantages or disadvantages of immediate, immediate-delayed or delayed implants, therefore these preliminary conclusions are based on few underpowered trials often judged to be at high risk of bias. There is a suggestion that immediate and immediate-delayed implants may be at a higher risk of implant failure and complications than delayed implants, on the other hand the aesthetic outcome might be better when placing implants just after tooth extraction. There is not enough reliable evidence supporting or refuting the need for augmentation procedures at immediate implants placed in fresh extraction sockets or whether any of the augmentation techniques is superior to the others. Keywords: dental implants, post-extractive implants, randomised controlled clinical trial, systematic review Conflict-of-interest statement: None declared.