What is the minimum extension into freshly prepared bone for immediate implant placement?

The minimum extension into freshly prepared bone for immediate implant placement is typically considered to be 4 mm. This measurement is critical because it ensures sufficient primary stability for the implant, which is essential for osseointegration—the process by which the implant integrates with the surrounding bone.

When placing an implant immediately after tooth extraction, achieving adequate bone contact is essential for the long-term success of the implant. A minimum extension of 4 mm allows for a sufficient amount of bone to engage the implant threads, providing the necessary mechanical support while the surrounding bone undergoes healing and remodeling.

Extensions shorter than 4 mm may not provide adequate stability and can lead to implant failure due to factors such as micro-movements during the healing phase, inadequate stress distribution, and potentially inadequate blood supply which is critical for healing. While extensions longer than 4 mm can contribute positively to stability, 4 mm is generally regarded as the minimum to achieve the desired mechanical properties for immediate loading scenarios.