American Board of Orthodontics (ABO) Practice Exam

The selection of a higher diameter discrepancy during implant placement can significantly impact the amount of ischemia and tissue necrosis experienced by the surrounding biological tissues. When there is a substantial discrepancy between the drill size and the implant diameter, it can lead to excessive removal of bone. This excessive bone removal compromises the vascular supply to the remaining bone and surrounding soft tissues, which is critical for their survival.

Ischemia occurs when there is insufficient blood supply to the tissues, and if this condition persists, it can ultimately lead to tissue necrosis, where the cells die due to a lack of oxygen and nutrients. The larger the gap between the sizes of the drill and the implant, the more trauma may be induced on the tissues, making it harder for them to maintain an adequate blood supply.

In contrast, uniform drill diameters are beneficial as they create a more appropriate fit with the implant, promoting the preservation of surrounding bone and soft tissue. Incorrect angling of the drill could lead to misalignment of the implant but does not inherently affect tissue vitality as significantly as diameter discrepancies. Excessive cooling during the drilling procedure might have its own complications, but it does not directly relate to ischemia and tissue necrosis in the same manner as significant diameter discrepancies do.