Osstem healing abutment can be either standard or customized. The use of a standard abutment is indicated if the implant is placed in an almost ideal prosthetic position. The advantages of standard abutments are time efficiency in the overall treatment and therefore shortening of the technical manufacturing time. Divergences between implants supporting multi-unit prostheses can be corrected with angled standard abutments. In the esthetic zone, it is important that the collar height of a prefabricated abutment is not a uniform 360 degrees, as the interproximal position of the crown margin would be placed too far submucosally. Therefore, the ideal design of a standard abutment should be similar to a tooth preparation, following the contour of the gingival margin. Clinical limitations exist regarding the position of the implant in a vertical dimension. If the implant is placed too apically, standard abutments are not indicated, especially for screw-retained reconstructions, as they do not provide enough support for the veneering ceramic.

How to choose right healing abutment?
Diameter(D): Select according to the tooth position
Gingival Height(G/H): Gum thickness
Height(H): Submerge thickness into bone, Gingival height, Exposed height above gum horizontal
Suppose: the implant is generally implanted under the bone 0.5-1mm, the gum thickness is generally 3-4mm, the abutment expose 1-2mm above gum horizontal, so generally the height 5 healing abutment is the most commonly used, in other cases, if the implant implantation depth is relatively deep, the height 7 healing abutment is selected. The abutment diameter is selected according to the tooth position.
link:http://www.chirimentech.com/implant-parts/healing-abutment/osstem-healing-abutment.html