The most critical factor when cementing an implant crown to an abutment is to avoid cement you may not subsequently detect, from getting into the sulcus. This undetected cement will cause peri-implantitis.
To prevent this from occurring, prior to cementation of the crown, place two gingival retraction cords into the sulcus. You will end up with the cords overlapping in the interproximal areas. Start the first cord on the distal aspect of the abutment just palatal to the crowns interproximal contact point.
This cord extends onto the facial aspect and to the mesial aspect of the abutment, just palatal to the contact point. The second cord is placed in the palatal sulcus, extending just facial to the mesial and distal contact points. Be certain to place the cord apical to the margin to prevent trapping it under the crown margin during cementation. Use minimal cement, but be sure that the margins of the crown are coated to prevent voids, which can lead to micro-leakage. Remove all excess cement before removing the gingival retraction cords.
You may ask: “Why use two retraction cords?” Two are recommended to make their removal easier and to prevent any remaining cement caught on the cord from being dragged through the interproximal areas.