# A Prospective Study on Accuracy of Computer-Based Fully Guided Versus Pilot-Guided Implant Surgery
## 2 Materials and Methods  
20 patients with a total of 74 implants were divided into two groups, one is pilot-guided implant surgery group and the other is fully guided implant surgery group. Pilot-guided implant surgery was performed in ten patients with 33 implants as follows. CT scan data set of patients in DICOM format registered with the surface scan data in STL format of the impression model, and data transmission was done to BlueSkyPlan (BlueSkyBio, Chicago, IL, USA). First, prosthetic crowns were aligned at the site of missing teeth. Then the positioning of the implant was placed according to the crown position. According to the virtual planning and manufacturer's recommendations, guiding sleeves of 5-mm height, 5.5-mm diameter, and 10-mm offset were incorporated into the surgical templates. Surgical guide was designed by creating patches and finally, designed surgical guide's STL file was obtained. Zenith Slicer software (Dentis, Daegu, South Korea) was used to prepare the STL files to design the surgical guide. SLA Zenith-C (Dentis, Daegu, South Korea) 3-D printer was used. The material for 3D printing was urethane acrylate oligomer-based photopolymer resin (ZMD-1000B Clear SG, Dentis, Daegu, South Korea). It uses resin fill system with a layer thickness of 50 microns and accuracy of 0.1 mm variation. After printing the guide, pour isopropyl alcohol (IPA) or alcohol (more than 75% of purity) into the cleaning container for post-processing of the surgical template, immerse the printout, clean it with a soft brush, remove the support, and cure with 385 and 405 nm wavelength for 10 min under room temperature in the curing machine (Zenith cure, Dentis, Daegu, South Korea). The correct position of each sleeve was inserted manually into the template hole (Figure 1). Initial drill and 2.0 mm drill were used for accurate planned position and then 2.8 mm drill was used for the enlargement of the drilling site, and surgical guide was removed. And then the intermediate and final drills were used for free hand sequential drilling. The implant was installed with fixture mount driver and inserted manually in the preparation site. When manual tightening met resistance, further tightening using a ratchet was continued until reaching the required depth with Dentis SLA implant (Dentis, Daegu, South Korea). For the flapless surgery, vertical depth was determined by mucosal thickness on preoperative CT data (Figures 2 and 3). Figure 1: 3D printed surgical guide for pilot-guided implant surgery. Figure 2: Surgical guide for pilot-guide implant surgery; tooth-supported. After the operation, data of actual implants were obtained from the CT scan, and this 3D image were superimposed with the pre-planned images (Figure 6). The difference between the planned implant position and the actual implanted position was measured on the superimposed 3D image. Additional measurements were made by dividing the deviations by three axes of dx(mesio-distal), dy(bucco-lingual), and dz(vertical). Deviations in the top (shoulder area) and bottom (apical area) positions of the implant fixture were evaluated. In addition, the angular difference of the implants was measured and statistically verified by dividing each measurement into two groups, tooth-supported and bone-supported, and anterior and posterior parts [10]. One year after prosthesis, CT was obtained and the marginal bone loss was measured on mesial and distal side in reconstructed CT image. The lower edge of the implant neck was used as a reference point for the marginal bone level measurements. A bone level apical or shoulder to the reference point was given a negative or positive value, respectively. Figure 5: Surgical guide for full-guide implant surgery; bone-supported. Figure 6: Deviations of the preoperatively planned implant position and the postoperative implant position: (**a**) 3D superimposed image; (**b**) measurements the distance and angulation difference. Statistical analysis was performed using IBM SPSS Statistics V20.