Precision and trueness of implant placement with and without static surgical guides: An in vitro study

Statement of problem: Malpositioning of implants is one of the main factors leading to hard- and soft-tissue deficiencies. Whether static computer-guided implant placement increases accuracy and prevents malpositioning is unclear. Purpose: The purpose of this in vitro study was to determine accuracy defined by trueness and precision (according to International Organization for Standardization 5725) of computer-assisted implant surgery (fully guided and partially guided) in comparison with freehand single implant placement. Material and methods: Implants (n=20) were placed fully guided (sleeve-bone distance of 2, 4, or 6 mm), partially guided (guide used for pilot drill), or free hand in identical replicas produced from a cone beam computed tomography (CBCT) scan of a partially edentulous patient. The achieved implant position was digitized by using a laboratory scanner and compared with the planned position. Trueness (planned versus actual position) and precision (difference among implants) were determined. The 3D-offset at the crest of the implant (root mean square between virtual preoperative planning and postoperative standard tessellation language file) was defined as the primary outcome parameter. The means, standard deviation, and 95% confidence intervals were analyzed statistically with 1-way ANOVA and the Scheffé procedure. Results: Fully guided implant surgery achieved significantly lower 3D deviations between the planned and actual implant position with 0.22 ±0.07 mm (2-mm sleeve-bone distance) than partially guided 0.69 ±0.15 mm and freehand placement 0.80 ±0.35 mm at the crest (P<.001). The distance among the implants in each group was again lowest in the fully guided group and highest in the freehand group. Conclusions: The static computer-assisted implant surgery showed high trueness and precision. The closer the sleeve to the bone, the more accurate and precise the method. Freehand implant placement was less accurate and precise than computer-assisted implant surgery (partially or fully).