A Novel Eccentric Surgical Guide Strategy for Immediate Implant Placement: An In Vitro Study

Objectives: This study aims to evaluate the implantation accuracy of a novel eccentric surgical guide strategy for immediate implant placement (IIP). Materials and Methods: Two hundred CBCTs were used to measure anatomical parameters, and the obtained data were  used to create an anatomical extra-oral model for IIP. Eccentric guides are specialized guides that position the drills or implant eccentrically toward the high-density side. Thirty implants were placed into fifteen anatomical models utilizing three different computer-assisted static implant surgery (sCAIS) protocols: the conventional, the one-step, and the step-by-step methods. Postoperative CBCTs were superimposed on the preoperative virtual placement plan to assess 3D and 2D deviations at the implant entry and apex point. Results: The average angle between the model’s inclined plane and the implant’s central axis was 18.3°, ranging from 10° to 39°. The one-step eccentric method (Group B) had the smallest 3D deviation at the entry point (mean = 0.41 ± 0.14 mm), apex (mean = 0.68 ± 0.20 mm), and angular deviation (mean = 1.74 ± 0.68°). The 2D deviation analysis showed Group B had the lowest labial deviations at the entry (mean = 0.37 ± 0.16 mm) and apex (mean = 0.36 ± 0.29 mm). The step-by-step eccentric method (Group C) resulted in a considerable reduction in labial deviation at the apex (mean = 0.35 ± 0.39 mm). Conclusion: The novel eccentric surgical guide strategy increased implantation accuracy in IIP, particularly by lowering labio-palatal discrepancies. Clinical Relevance: Implant position can be affected by the anatomical structure of the tooth extraction socket. Therefore, it is critical to find a novel eccentric surgical guide strategy to address labial deflection during implant site preparation for IIP.