What Does a Surgical Guide Do in Implant Surgery? It Supports a Pre-planned Angle and Position, Not the Removal of Risk｜證據鏈

A surgical guide is a device designed from your imaging data and worn in the mouth during surgery. Its task is straightforward: to transfer the implant angle and position that the dentist planned beforehand on the computer into the actual operation as faithfully as possible. Research quantifies this as "deviation" — how many degrees and how many millimetres separate the planned position from the actual one. A systematic review of 55 articles reported a mean angular deviation of 7.46 degrees for freehand placement, an entry-point deviation of 1.56 mm and an apical deviation of 2.22 mm; for fully guided static guidance the corresponding figures were 2.57 degrees, 0.72 mm and 0.88 mm. The same review also reported pilot-drill guidance at 5.94 degrees, 1.13 mm and 1.43 mm and dynamic navigation at 3.67 degrees, 1.01 mm and 1.36 mm — so "wearing a guide" is not the same as fully guided: the angular deviation of pilot-drill guidance sits closer to freehand (7.46 degrees) than to fully guided (2.57 degrees). The gap is real. But the same review says plainly that guided surgery still shows apical deviations of 1 to 2 mm, and therefore recommends keeping a safety margin of 2 mm to reduce surgical risk.