# A Prospective Study on Accuracy of Computer-Based Fully Guided Versus Pilot-Guided Implant Surgery
## 4 Discussion  
Guided surgery using computer has the advantage of shortening the operation time while safely placing the implant in a more accurate position. However, it requires CT image, additional software for surgical planning, additional surgical instruments for guided surgery, and 3D printer for patient specific surgical template. As computer-guided surgery has become popular, many manufacturers have introduced drilling kits for computer-guided implant surgery, and various studies have been conducted on the accuracy of computer-guided implant surgery [11; 12; 13; 14; 15]. In most studies, computer-guided implant surgery showed higher accuracy than conventional free hand implant surgery or implant surgery using conventional surgical templates [16; 17]. In the results of this study, the mean distance deviation of pilot-guided implant surgery was similar or slightly higher than that of fully guided implant surgery. However, differences of the distance and angular deviations were not statistically significant. In the shoulder area, only dy(bucco-lingual) of horizontal deviations showed a statistically significant difference between fully guided and pilot-guided. In the apical area, vertical deviations showed a statistically significant difference. But the mean deviations, not the analysis of each direction, did not show a statistically significant difference. The statistically significant difference in vertical deviation is considered to be an error caused by the \begin{table}
\begin{tabular}{c c c c} \hline  & **Harterior (\({}^{\circ}\), mm)** & **Posterior (\({}^{\circ}\), mm)** & \(p\)**-value** \\ \hline Angulation & 2.39 \(\pm\) 2.50 & 3.82 \(\pm\) 2.81 & 0.047 \({}^{*}\) \\ Shoulder area & & & \\ dx & 0.39 \(\pm\) 0.25 & 0.53 \(\pm\) 0.50 & 0.750 \\ dy & 0.71 \(\pm\) 0.55 & 0.42 \(\pm\) 0.44 & 0.031 \({}^{*}\) \\ dz & 0.92 \(\pm\) 0.61 & 0.72 \(\pm\) 0.66 & 0.129 \\ Mean & 1.36 \(\pm\) 0.61 & 1.14 \(\pm\) 0.73 & 0.154 \\ Apical area & & & \\ dx & 0.65 \(\pm\) 0.43 & 0.88 \(\pm\) 0.85 & 0.865 \\ dy & 0.78 \(\pm\) 0.59 & 0.47 \(\pm\) 0.36 & 0.140 \\ dz & 0.88 \(\pm\) 0.49 & 0.82 \(\pm\) 0.74 & 0.339 \\ Mean & 1.48 \(\pm\) 0.59 & 1.31 \(\pm\) 0.51 & 0.202 \\ \hline \end{tabular} \({}^{*}\) There is a statistically significant difference (\(p<0.05\)) (Mann-Whitney U test).  
\end{table} 
Table 7: Anterior vs. posterior (mean \(\pm\) S.D.). \begin{table}
\begin{tabular}{c c c c} \hline  & **Flap (\({}^{\circ}\), mm)** & **Flapless (\({}^{\circ}\), mm)** & \(p\)**-value** \\ \hline Angulation & 3.48 \(\pm\) 2.89 & 3.58 \(\pm\) 1.94 & 0.519 \\ Shoulder area & & & \\ dx & 0.50 \(\pm\) 0.47 & 0.49 \(\pm\) 0.40 & 0.880 \\ dy & 0.48 \(\pm\) 0.50 & 0.50 \(\pm\) 0.22 & 0.187 \\ dz & 0.73 \(\pm\) 0.64 & 0.98 \(\pm\) 0  
operator setting the vertical reference point of the alveolar bone in the non-flat alveolar bone area. However, there is no statistically significant difference in the shoulder area. In the measurement of the angular deviation, the value of fully guided was higher. However, this difference was not statistically significant. The measured errors were slightly higher in the vertical than in the horizontal in both groups. This is because both groups underwent surgery using a surgical template. The errors in the bucco-lingual and meso-distal directions are less likely to occur. However, vertical error is common in guided surgery because the superior border of alveolar bone determined by CT may be different from the superior border determined by the actual surgery. This error was also measured to an acceptable level in both groups. The measured errors were slightly higher in the apical area than in the shoulder area in both groups. This is considered to be due to the error in the drilling direction added to the positional error in shoulder area. In case of using tooth-supported guide in dentate state and bone-supported guide in edentulous state, tooth-supported guide was expected to show higher accuracy.