[Advance and review: implant-abutment microgap].

Implant-abutment microgap (IAM) exists in two-piece implant systems. Researchers have proved that IAM influences success rate of dental implants in the long term. The relationship between IAM and the biological, mechanical complication of dental implants has been proven in some studies. Implant-abutment connection type, abutment material and insertion torque may all have impact on IAM size. On the other hand, ways to reduce or seal this gap are discussed in some literature. The relationship between IAM and bacteria colonization, long-term implantation complication and its influencing factors are discussed in this review.