# Digital Evaluation of the Accuracy of Computer-Guided Dental Implant Placement: An In Vitro Study
## 1 Introduction  
Digital dentistry has evolved from cone-beam computed tomography (CBCT), intra-oral scanners, computer-aided design (CAD) software, and computer-aided manufacturing (CAM), which has had a profound impact on dental implantology [1; 2; 3]. In particular, additive manufacturing (AM) technology, known as 3D printing, has contributed to the successful implementation of computer-guided implant surgery [1; 3]. Traditional implant surgical guides with modified radiographic templates requirecomplex laboratory procedures which can be inaccurate, making it somewhat difficult to accurately position implants in their planned locations [4; 5; 6; 7; 8; 9]. On the other hand, computer-assisted implant surgical guides can consider important anatomical structures, save time, and aid implant placement by drawing the pre-planned final prosthesis design [10; 11; 12].  
Accurate computer-assisted implant surgical guides are designed with implant planning CAD software to process the information obtained from CBCT, intra-oral scanners, and diagnostic casts [13]. Several studies have previously measured the accuracy of computer-assisted implant surgical guides designed using various implant planning CAD software [14]. According to a systemic review of the accuracy of the implant surgical guides, the mean apical deviation between the planned position and placed position was 1.4 mm, and the angle deviation was 3.5\({}^{\circ}\)[15]. However, the deviations may vary in different studies [16].  
[PERSON]'s study shows that the positioning accuracy of computer-guided implants can vary depending on experimental conditions, and that the accuracy of a cone beam computed tomogram (CBCT) or intraoral scanning of the patient, and the accuracy of 3D printing or milling, have been reported to have a significant effect on the positioning of implants [17]. If the positioning accuracy of computer-guided implants is inaccurate, it can lead to an unintended position, which may be the biggest cause of implant failure.  
The positioning accuracy of the placed implants is measured by superimposing the pre- and post-operative CBCT images. However, CBCT can be inaccurate due to resolution and distortion, and errors may occur during the superposition of the CBCT images. In addition, the presence of metal artifacts in the oral cavity may lower the resolution of the CBCT images [18; 19]. A non-radiographic method has been recently introduced to obtain the implant position and measure the placed implant position, by using an intraoral scanner and superimposing it on the previously obtained implant fixture scan data [20]. This allows for evaluation of the accuracy of the placed implant without post-operative CBCT imaging.  
In the 1980s, [PERSON] developed an early 3D printing device called the stereolithography apparatus (SLA) that could create 3D models from digital data [21]. Since the important patents of AM technology have recently expired, the 3D-printer market is further developing [22]. As a result, smaller 3D printers are being introduced into dental clinics quicker and with lower costs [23; 24]. These 3D printers are called in-office or personal 3D printers [25; 26]. Computer-assisted implant surgical guides can be easily produced with personal 3D printers after being designed with implant planning CAD software [27].  
Although the accuracy of computer-assisted implant surgical guides produced by personal 3D printers is an important factor in their clinical use, there is still a lack of research examining their accuracy. Therefore, this study evaluated the accuracy of computer-assisted implant surgical guides, which were designed using implant planning CAD software (Deltanine and R2 gate software) and fabricated with personal 3D printers using a non-radiographic method. The null hypothesis of this study is that there is no difference in the accuracy of surgical guides fabricated by both types of software.