Are Sleeves Necessary in Static Computer-Assisted Implant Surgery? A Comparative In Vitro Analysis

This study aims to examine differences in trueness and precision between surgical guides with (S) and without sleeves (SL). A secondary aim was to assess the impact of the sleeve-to-bone distance.

Mandible replicas (n = 120) were printed from an STL file obtained from a clinical CBCT. The mandibles were divided into sleeved (S, n = 60) and sleeveless (SL, n = 60) groups, each further divided into three categories (n = 20 each) with different heights from the guide to the implant platform: 2 mm (H2), 4 mm (H4), or 6 mm (H6). Digital planning and surgical guide design were done for a 4.1 × 10 mm implant for site #30. Post-op positions were captured using a scan body and lab scanner. Angular deviation was the primary outcome, with 3D and 2D deviations as secondary parameters. Statistical analysis included two-sample t-tests, and one-way and two-way ANOVA.

Group S (2.41 ± 1.41°) had significantly greater angular deviation than Group SL (1.65 ± 0.93°; p = 0.0001). Angular deviation increased with sleeve-to-bone distance. H2 deviations were 1.48 ± 0.80° (S) vs. 1.02 ± 0.45° (SL; p < 0.05), H4: 2.36 ± 1.04° (S) vs. 1.48 ± 0.79° (SL; p < 0.05), H6: 3.37 ± 0.67° (S) vs. 2.46 ± 0.89° (SL; p < 0.05). 3D deviation at the implant platform was 0.36 ± 0.17 mm (S) vs. 0.30 ± 0.15 mm (SL; p < 0.05) and at the apex 0.74 ± 0.34 mm (S) vs. 0.53 ± 0.31 mm (SL; p < 0.01). Group SL at H2 had the smallest inter-implant distance (0.53 ± 0.37°), while Group S at H4 had the largest (1.20 ± 0.84°; p < 0.05).

Sleeveless guides are more accurate than sleeved guides, and angular deviation is influenced by the distance from the guide to the implant platform.