## 4 Discussion  
To the best of our knowledge, this was the first study to use the optical-scan-based measurement method to investigate the influence of operator experience on the accuracy of static guided implant surgery. The results of this study revealed that for mandibular partial edentulism of molars, inexperienced dentists could place dental implants as accurately as experienced operators under a well-controlled environment. However, even with the help of the surgical guide, large deviations can still occur for both experienced and inexperienced operators, suggesting the operator's skill and attention during surgery was crucial for accurately executing static guided implant surgery. In the literature, there is little consensus regarding the influence of operator experience on the accuracy of static guided implant surgery. [PERSON] et al. [17] reported a significant difference between experienced and inexperienced operators for both angular and horizontal errors at the implant apex and platform using the SLA surgical template on edentulous mandibular models. They concluded that more experienced operators place implants more accurately. [PERSON] et al. [18] reported significantly less angulation error in the buccal-lingual direction for experienced operators utilizing tooth-supported surgical guides, yet no significant difference in positional errors was found between experienced and inexperienced operators. A similar result was reported by [PERSON] et al. in a model study using a tooth-supported guide [8]. [PERSON] et al. [19] used mandibular models with bilateral second premolars missing and carried out tests with the tooth-supported guide. No significant angular nor linear deviation was found between the experienced and inexperienced groups. Nevertheless,  
Figure 11: Box plots of the lateral deviation at the implant: (**a**) platform and (**b**) apex of the three operator age groups. Figure 12: Box plots of the (**a**) depth deviation and (**b**) angular deviation of the three operator age groups. they reported the depth of guided implant placement was most influenced by the operator's level of experience. Although the studies mentioned above reported a better accuracy for experienced operators in static guided surgery, the results did not coincide with each other with regard to the influence of operator experience on the dimension of the errors. On the other hand, [PERSON] et al. [20], in their model experiment using tooth-supported guides found the operator's experience level had no significant influence on the accuracy in guided implant surgery. In addition, [PERSON] et al. [21], in a clinical report on fully edentulous jaws, concluded that inexperience of the surgeon did not influence the accuracy when they were under the supervision by experienced surgeons. Another clinical study by [PERSON] et al. [22] also demonstrated the limited influence of experience on the accuracy of guided implant placement on edentulous patients. All of the abovementioned studies exploring the relationship between operator experience and accuracy used the CT matching method to measure the errors, except for one study by [PERSON] et al. [18], which used a coordinate measuring machine to record the implant coordinates. However, they found only minimum effect of the operator experience on the accuracy of implant placement, and the magnitude of error was not large enough to be clinically significant. To avoid potential errors from estimating the vague implant outline of the CT data, the present study used the optical scan to identify the postoperative implant position. Most of the accuracy studies of guided implant surgery used cone beam computed tomography (CBCT) images for CT matching. [PERSON] and [PERSON] [23] investigated the CBCT images of human skulls and found a mean error of 0.49 mm between CBCT and direct measurements. Considering the limitations of measurement by CT matching, the present study provided additional evidence to clarify the effect of operator experience on the accuracy of static guided implant surgery.