The implant / abutment interface connection, is generally described as an internal or external connection. The distinctive factor that separates the two groups is the presence or absence of a geometric feature that extends above the coronal surface of the implant. The infiltration of the bacteria at implant abutment interface has been shown to depend on the type of implant-Abutment connection and their sealing capacity.This article is a review on the importance of implant – abutment interface and factors effecting the implant – abutment connection.