Which guide type is least likely to offer stability during implant placement?

A soft tissue supported guide is considered the least stable option during implant placement because it relies solely on the soft tissues (such as the gums) for support. Soft tissues can be mobile or compressible, which means the guide may shift or move during the implant procedure, reducing its effectiveness in maintaining the desired position and angulation of the implant.

In contrast, a tooth supported guide utilizes adjacent teeth to provide a stable framework for implant placement, ensuring that the guide remains in a fixed position. This type generally offers superior stability, as it benefits from the rigidity and alignment of the existing teeth. Similarly, a bone supported guide is anchored directly to the underlying bone structure, providing even greater stability compared to a soft tissue supported guide. Bone support minimizes movement during the procedure, which is critical for achieving precise implant positioning.

Thus, the reliance on soft tissue alone makes a soft tissue supported guide the least stable choice among the different types available for implant placement.