Marginal bone loss in relation to platform switching implant insertion depth: An update.

A review is made, analyzing marginal bone loss in relation to the depth of implant insertion with platform switching, according to the position of the neck (supracrestal, crestal or subcrestal), and evaluating survival of the implants. A PubMed search was made of the studies in animals and humans published between 2005 and 2011, specifying platform insertion depth (supracrestal, crestal or subcrestal) and registering marginal bone loss from the time of prosthetic restoration to the end of follow-up (minimum 6 months). A total of 30 studies were included. The bone loss associated with implants placed at supracrestal level was slightly smaller than in the case of implants placed at subcrestal level, though statistical significance was not reached. The mean marginal bone loss values were 0.0 mm to 0.9±0.4 mm for the implants with the neck located at supracrestal level; 0.05 mm to 1.40±0.50 mm for those at subcrestal level; and 0.26±0.22 mm to 1.8±0.39 mm for those in a crestal location, after 6-60 months of follow-up. The survival rate was 88.6-100% for the implants with the neck positioned at crestal level, versus 98.3-100% below the crest, and 100% above the crest. The heterogeneity of the studies (surgical technique, platform surface texture, radiographic measurement techniques, etc.) made it difficult to establish a relationship between marginal bone loss and the supracrestal, crestal or subcrestal location of platform switching. Key words:Dental implants, platform switching, insertion depth, crestal insertion level, bone loss.