Background <p>This study aimed to evaluate the trueness of implant placement with fully guided (FG) implant placement protocol versus partial-guided (PG) protocol.</p> Methods <p>The study recruited 16 fully edentulous patients with adequate maxillary bone volume. Each patient received six implants; three were planned for each side of the maxilla to support a full-arch implant-supported fixed prosthesis 3 (FP3). Patients were randomly assigned to one of two intervention groups: Group 1 (PG group), drilling was done using a surgical guide, but implant placement was done without the guide. In group 2 (FG group), both drilling and implant placement were done through the surgical guide. The spatial relationship (entry, apex, and angle deviation) between planned and placed implants was evaluated using pre- and postoperative CBCT data.</p> Results <p>The FG approach resulted in statistically significantly higher overall trueness in entry, apex, and angle deviation across multiple implant sites, with a statistically significant difference of 0.030, 0.013, and 0.036, respectively, though differences at individual implant sites were not consistently significant.</p> Conclusion <p>This trial supported the fully guided implant placement protocol for enhancing the trueness of implant positioning in the rehabilitation of edentulous maxillary arches. Clinicians should weigh the benefits of this increased trueness against practical considerations.</p> Trial registration <p>The current study was registered at ClinicalTrials.gov (NCT06542562) on August 5, 2024.</p>