###### Abstract  
The aim of this pilot study was to evaluate the accuracy of a newly developed dynamic navigation system and to compare the accuracy between Hapless and open-flap surgery, and between surgeons. The subjects were patients who were scheduled to receive implants of the same size using the newly developed dynamic navigation system. The study's procedures included cone beam computed tomography (CBCT) filming with fiducials, virtual planning of implant placement and the use of motion tracking technology for calibration and practical implant placement. The accuracy was evaluated using preoperative (virtual implant) and postoperative (actual implant) CBCT images based on angular, apical, coronal and vertical deviations. The differences of deviations between Hapless and open-flap surgery, and between two surgeons, were statistically compared. In total, 66 implants were placed in 39 patients. The median and interquartile range of angular, apical, coronal and vertical deviations were 3.0\({}^{\circ}\) (2.52-3.54\({}^{\circ}\)), 0.96 mm (0.75-1.42 mm), 0.76 mm (0.57-1.37 mm) and 0.71 mm (0.61-0.88 mm), respectively. These deviations were similar to those found in previous studies. Hapless surgery resulted in a more accurate placement with respect to apical and coronal deviations, and the differences between the two surgeons were limited. The newly developed dynamic navigation system is considered to be eligible for clinical use.  
ynamic navigation; infrared optical camera; accuracy assessment; Hapless surgery; surgeon experience +
Footnote †: and/or lateral deviation and/or depth deviation. The results of these studies concluded that dynamic navigation surgery could achieve a more accurate implant placement as compared to freehand implant surgery, and a similar accuracy to static guided surgery. The important point is to recognize the procedures required for accurate placement. According to previous studies that validated static guided surgery, the type of guide (full-guided or half-guided) [14], digital workflow [15; 16], surgical and patient's conditions [17; 18; 19] and the type of guide support [20] can all affect the accuracy. In dynamic navigation surgery, the steps that can cause deviations are considered to be similar. Even in such a situation, the vertical position of the implant platform (the depth of the implant position) in open-plan surgery is the only implant position we can confirm under direct vision. Flapless placement, which is a minimally invasive procedure, requires virtual visualization of the surgical site (bone morphology and mucosal thickness), optimal virtual planning and accurate surgical technique. Previous studies have suggested that computer-guided surgery, with the proper workflow, permitted the surgeon to conduct accurate flapless surgery [3; 6; 9]. Regarding surgical technique in dynamic navigation, the influence of the surgical situation on the accuracy is controversial [2; 4; 21]. A dynamic navigation system with a higher accuracy is beneficial, but demanding. This means that validation of the accuracy is essential.  
The present pilot study aims to evaluate the accuracy of implant placement using a newly developed dynamic navigation system, by comparing between preoperative and postoperative CBCT images, in addition, the deviations of implant positions were statistically compared between flapless and open-plan surgery, and between surgeons.