What truly accounts for biological width relative to dental implants?

When an implant is placed at or below the crest of bone and is then covered with a soft tissue barrier to prevent any ingress of bacteria, the bone level will remain in a virtual steady state. We do see some instance of cupping or bone loss around covered implants, but this is less common and may be due to aggressive countersinking, early exposure of the implant cover screw or damaging of the bone at the time of insertion. It might also be due to altered healing responses in patients with poor healing factors such as smoking.

When an implant is exposed to the outside world, there is a connection of some sort of abutment or prosthetic to the implant. This connection will always have a gap which will harbor bacteria and the body reacts to this bacteria by attempting to establish a zone of biological width. Bone and soft tissues will recede from the bacterial laden gap usually to about the two millimeter mark which usually coincides with the first thread of a threaded implant. Once this biological width has been reestablished, the system returns to a steady state.

Implants that are placed in a one stage procedure such that the top of the implant is at least 2mm above the crest of bone should not show any significant bone loss at restoration attachment and during ensuing function. The biological steady state is established in these situations right from the initial surgery and should be completely maintainable unless there is a significant loss of the attached gingiva. In this sense, any implant may be used as a one stage implant and may be used to prevent additional bone loss at restoration hookup and subsequent functional loading.

If the same implant is placed so that the top of the implant is approximately 2mm above the crest of the bone, there will be no remodeling when that implant is ultimately attached to the prosthetics.