In this study, the accuracy of a dynamic navigation system with X-clips fixed to an oral appliance and a surgical guide was measured and compared in patients with missing anterior teeth. Significant differences were observed in entry point, apex point, angular deviation, and all measurement sites, indicating the effectiveness of the dynamic navigation system using the oral appliance method for the anterior teeth.

The accuracy of dynamic navigation systems and surgical guides has been compared in several reports. A systematic review of 17 clinical studies by Yu et al. analyzed a total of 2,025 implants (dynamic navigation group: 1,526 implants and surgical guide group: 279 implants). The entry point, apex point, and angular deviation measurements were 1.07 mm, 1.27 mm, and 3.43°, respectively, in the dynamic navigation group. Compared to the surgical guide group, they reported an average difference of 0.02 mm for the entry point and − 0.07 mm for the apex point, which was not statistically significant [13]. Thus, the accuracy of the dynamic navigation system and the surgical guide has proven to be almost identical. Reports on the accuracy of implant placement for anterior teeth are scarce. Wu et al. compared the accuracy of 38 implants placed using a dynamic navigation system (Dental Implant Navigation System) with that of 57 implants placed using a surgical guide. The entry point, apex point, and angular deviation measurements were 1.36 ± 0.65 mm, 1.48 ± 0.65 mm, and 3.71 ± 1.32° in the dynamic navigation group and 1.22 ± 0.70 mm, 1.33 ± 0.73 mm, and 4.34 ± 2.22° in the surgical guide group, respectively. No statistically significant difference was observed between the two groups. Furthermore, the precision of placement of the anterior teeth for the entry point, apex point, and angular deviation in the dynamic navigation and surgical guide groups was 1.3 mm and 0.9 mm, 1.4 mm, and 1.1 mm, and 2.5° and 3.3°, respectively [14]. Younis et al. validated the accuracy of 94 implants in 65 patients. In the dynamic navigation group, the mean values across the 34 implants were 0.99 ± 0.52 mm for entry point, 1.14 ± 0.56 mm for apex point, and 3.66° ± 1.64° for angular deviation. They reported that the angular deviation of the molar implants was 4.12° ± 1.77° compared to 2.69° ± 0.67° for the anterior teeth, showing a significant difference [15]. Considering the above results, the accuracy of the dynamic navigation system and the surgical guide is comparable regardless of the site, and the dynamic navigation system can provide good angular deviation, especially in the anterior teeth. The accuracy of the surgical guide group in our study was similar to that in this report; however, the dynamic navigation group showed improved accuracy. This may be because fixing the X-clip in an oral appliance and attaching it to the dentition improved its stability in the oral cavity and prevented movement of the X-clip during surgery.

Several factors are involved in the accuracy of implant placement, including the planning software and the dynamic navigation system used [16]. Al-Ekrish measured the dimensional accuracy of implants using the planning software Blue Sky Plan, coDiagnostiX, and RadiAnt and reported no significant difference in error values between the software [17]. Wei et al. measured the implant-placement accuracy of ImplaNav, IRIS, X-Guide, NaviDent, and AqNavi based on 10 articles and reported no difference among the five dynamic navigation systems [18]. Yu et al. also compared the accuracy of IRIS-100, DCarer, ImplaNav, X-Guide, AqNavi, and Navident and reported that the six dynamic navigation systems showed a significant difference (P = 0.03) in entry point, but not for apex point and angular deviation [13]. Based on these reports, any of the planning software and dynamic navigation systems used are almost equally accurate. Ma et al. defined the accuracy of the dynamic navigation system depending on the size and length of the implant, although three implant systems were used in their study. The accuracy of implants of 3.5, 4.3, and 5 mm in diameter (P = 0.32 for entry point, P = 0.76 for apex point, and P = 0.4 for angular deviation) were compared and no significant difference was found. They also compared the accuracy of implants with lengths of 8.5, 10, 11.5, and 13 mm and reported no significant differences (P = 0.55 for entry point, P = 0.5 for apex point, and P = 0.59 for angular deviation) [19]. Therefore, the implant system does not interfere with the accuracy of dynamic navigation. Based on these studies, the most important factor regarding accuracy may be the measurement method. Examples of planning software that can measure the accuracy of implants after placement include coDiagnostiX and DentiqGuide. coDiagnostiX can measure accuracy by superimposing intraoral STL data equipped with a scan body on the planning data [20]. DentiqGuide superimposes postoperative DICOM data on the planning data, allowing for measurement of accuracy [21]. However, accuracy measurement tools do not exist in many planning software programs. Therefore, preoperative DICOM data, planning data, and postoperative DICOM data are often exported and imported into an editing software to measure accuracy [18]. However, these processes are complex and errors due to the process and artifacts can adversely affect accuracy [22]. To our knowledge, no studies have reported accuracy measurements using DTX Studio™ other than our previous study and the present report. The efficacy of these methods of measuring accuracy needs to be assessed.

Regarding the accuracy of the surgical guide, Kholy et al. reported that the extent of the surgical guide affects the accuracy of the implant placement. For a single anterior tooth defect, on using the entire remaining dentition as the fixation source, the entry point, exit point, and angular deviation were of 0.28 mm, 0.68 mm, and 4.36°, respectively, and on using two teeth on either side of the defect as the fixation source for the surgical guide, the entry point, exit point, and angular deviation were of 0.289 mm, 0.62 mm, and 4.73°, respectively, with no significant difference [10]. However, considering the limited reports on the extent of the surgical guide and the lack of evidence, this study was designed to cover the entire remaining dentition. Chen et al. compared the accuracy of a full guide, which uses a surgical guide up to the placement of the implant, and a half guide, which uses a surgical guide only for surgical site preparation, with the placement of the implant performed freehand. For the full guide, the entry point, exit point, and angular deviation were of 0.53 ± 0.29 mm, 1.10 ± 0.42 mm, and 2.09 ± 1.07°, respectively. For the half guide, the entry point, exit point, and angular deviation were of 0.94 ± 0.43 mm, 1.51 ± 0.55 mm, and 3.06 ± 1.92°, respectively, reporting significant differences in apex point and angular deviation [23]. Their half-guide method was the method of placing Nobel Biocare AG implant bodies using a drill system from another company. This method was similar to our surgical guide group’s method of placing Straumann AG implants using the Nobel guide. The inability to adjust the depth at the time of placement in the half guide is considered to be the reason for its lower accuracy than the full guide. In the present study, we used three different implant systems in the surgical guide group, and for the Straumann AG implants, we used a half guide because of the difference in the form of the surgical guide sleeve. This may have affected the accuracy of the surgical guide group. However, the dynamic navigation system with X-clips fixed to the oral appliance led to improved accuracy in the anterior teeth.

A limitation of this study is that identical implant systems could not be used. The accuracy of the surgical guide group would be improved if identical implant systems could be used. In the future, an identical implant system should be used to compare accuracy.