Implant-abutment junction

The implant-abutment junction, also known as the microgap or IAJ, is the external margin where the coronal aspect of a dental implant and its prosthetic abutment or restoration connect. The location of the IAJ as well as its unique morphology can affect how much bone resorption occurs following the placement of the implant. Recent studies have suggested that in order to prevent as much crestal bone loss following implant placement as possible, bone level implants should be placed subcrestally while tissue level implants should be placed equicrestally. In addition to the implant placement location, microbial presence can also be a concern at the implant-abutment junction. The leakage of bacteria into the microgap can cause inflammation and even infection at the implant site that can eventually lead to the loss of crestal bone. In order to prevent this further possible complication, a tight microbial seal achieved by a very precise fit between the implant and the abutment must be achieved.