# Accuracy and Wear Evaluation of the Customized Zirconia Guided Sleeves
## 1 Introduction  
Modern advancements in implant dentistry have revolutionized computer-assisted digital workflows [1]. Computer-guided implant surgery has been demonstrated to be more precise and accurate than conventional surgical guides or free-hand implant placement [2, 3, 4, 5, 6, 7, 8]. Cone-beam computed tomography (CBCT) produces 3-dimensional (3D) images that can be stored as digital imaging and communications in medicine (DICOM) files, and intraoral scan and conventional models can generate images as stereolithography (STL) files. Software can merge DICOM and STL files, virtual planning software can be used to determine the ideal implant position for the surgical guided stent. These guides are produced using CAD/CAM technology (e.g., stereolithography models) or manually produced in a dental laboratory using computer-aided implantology (CAI) [9, 10, 11]. [PERSON] et al. [7] demonstrated that an implant deviation of 1.22 \(\pm\) 0.63 mm at the entrance point and 1.91 \(\pm\) 1.17 mm at the apical point and an angulation of 7.93\({}^{\circ}\)\(\pm\) 5.56\({}^{\circ}\) were achieved through free-hand placement. The application of a CAI surgical template during surgery could enhance the accuracy of implant placement. [PERSON] et al. [12] examined implant installation by using 3D-printed guides and reported a deviation of 0.02 \(\pm\) 0.13 mm mesially and 0.07 \(\pm\) 0.14 mm distally and a mesiodistal angulation of 1.69\({}^{\circ}\)\(\pm\) 1.02\({}^{\circ}\) and a labiopalatal angulation of 1.56\({}^{\circ}\)\(\pm\) 0.92\({}^{\circ}\). However, in their systematic review, [PERSON] et al. [8] reported that the mean errors of implant placement were approximately 1.2 and 1.4 mm at the coronal and apical points, respectively, with a deviation of 3.5\({}^{\circ}\). The reported accuracy of CAI varied among multiple studies [13]. Various factors can affect the accuracy of implant placement including CBCT data acquisition, intraoral condition transfer (conventional impression or intraoral scan), surgical guided stent manufacturing, improper guided stent fixation and positioning, and the design of a surgical template. Surgical guided stent designs are mainly of two types: multiple [14] and single [15]. In multiple-type stents, the metal-guiding sleeve attached to the surgical stent and coordinating-drilling keys are inserted into the sleeve for guidance purposes during implant preparation. The tolerance of the drilling key to the sleeve and the drills to the drilling key cause deviations of the accuracy in multiple-type stents. [PERSON] et al. [15] identified an intrinsic error between the master and inner tubes in single-type stereolithographic-surgical stents. The present study examined a new and modified single-type surgical stent with individual single zirconia sleeves that were incorporated into the surgical stent to fit individual drills by using CAD software. Accuracy is substantially affected by the tolerance of the gap-drill distance of the sleeve [15], guide sleeve height, drilling distance, drilling key length [16], and surgical sites of the jaw [17]. [PERSON] et al. [16] demonstrated that reducing the drilling distance or increasing the sleeve height (3 mm) could significantly increase the accuracy of static CAI surgeries. Furthermore, [PERSON] et al. [18] reported that a greater sleeve height reduced the lateral movement of implant placement and improved overall accuracy. Most relevant studies have reported that imposing more limitations on the guided stent improved the accuracy of implant placement. Surgeries performed using a CAI template are more accurate than those performed using conventional surgical guides [19]. However, drill sleeve tolerance may directly affect deviation errors during surgery [15; 20]. The present study investigated the accuracy of varying drill sleeve distances in multiple positions and the wear conditions between the drill and sleeves.