Abstract: A total of 50 trials were potentially eligible for inclusion, of which 42 trials were excluded. We included eight RCTs with a total of 233 extraction sites in 184 participants. One trial was judged to be at unclear risk of bias and the remaining trials were at high risk of bias. From two trials comparing xenograft with extraction alone (70 participants, moderate quality evidence), there was some evidence of a reduction in loss of alveolar ridge height (MD -2.60 mm; 95% CI -3.43 to -1.76) and width (MD -1.97 mm; 95% CI -2.48 to -1.46). This was also found in one trial comparing allograft with extraction (24 participants, low quality evidence): ridge height (MD -2.20 mm; 95% CI -0.75 to -3.65) and width (MD - 1.40 mm; 95% CI 0.00 to -2.80) and height. From two RCTs comparing alloplast versus xenograft no evidence was found that either ridge preservation technique caused a smaller reduction in loss of ridge height (MD -0.35 mm; 95% CI -0.86 to 0.16) or width (MD -0.44 mm; 95% CI -0.90 to 0.02; two trials (55 participants); moderate quality evidence). There was insufficient evidence to determine whether there are clinically significant differences between different ARP techniques and extraction based on the need for additional augmentation prior to implant placement, complications, implant failure, or changes in peri-implant marginal bone levels and probing depths of neighbouring teeth. We found no trials which evaluated parameters relating to clinical attachment levels, specific aesthetic or prosthodontic outcomes. There is limited evidence that ARP techniques may minimise the overall changes in residual ridge height and width six months after extraction. There is also lack of evidence of any differences in implant failure, aesthetic outcomes or any other clinical parameters due to the lack of information or long-term data. There is no convincing evidence of any clinically significant difference between different grafting materials and barriers used for ARP. Further long term RCTs that follow CONSORT guidelines (www.consort-statement.org) are necessary.

Plain-language summary: Authors from Cochrane Oral Health carried out this review and the evidence is up to date from 22 July 2014. Eight trials were included with a total of 233 extraction sites (teeth taken out) in 184 participants. Participants were adults aged 18 years or older, in good general health, needing one or more permanent teeth to be taken out and the consideration of the use of ARP (alveolar ridge preservation techniques) with the possibility of using dental implants at a later date. The review looked at the effects of four techniques and materials used for preserving the tooth extraction socket. Three studies compared socket preservation to tooth extraction alone, while five studies compared two or more different materials. There is limited evidence that socket preservation (ARP) can reduce bone loss compared to tooth extraction alone to allow for dental implant placement. There is no evidence that socket preservation makes any important differences to the look or lasting quality of crowns or bridges. There is no convincing evidence of any significant difference between different materials and barriers used for socket preservation. The quality of the evidence is judged as low due to high risk of bias of the majority of the included studies. Some evidence of reporting bias is suspected, as only two of the included trials did not receive any industry support. Further long-term randomised controlled trials that follow CONSORT guidelines (www.consort-statement.org) are required.