## 4 Discussion  
The present study reviewed the scientific literature dealing with the accuracy of guided implant placement surgery. In addition, the review recorded the deviation parameters measured, and the methods used to quantify these deviations. The study only analyzed in vivo clinical studies, excluding in vitro and ex vivo studies due to their non-representation of real clinical situations. The authors of ex vivo studies [16; 17; 45] have commented that the conservation and handling of specimens (frozen and thawed) cause modifications to the properties of tissues. This can interfere with the adjustment of radiographic and surgical guides and the positioning of the implants, probably increasing deviations during implant installation [3]. In vitro studies show that there is greater accuracy in the placement of implants in preclinical models. This is because there is no interference from oral anatomy (tongue, oral mucosa, and other factors), which contributes to a greater stability of the surgical guide. In the systematic reviews and meta-analysis published by [PERSON] et al. [46] and [PERSON] et al. [47] the accuracy of guided surgery was evaluated, comparing in vivo, ex vivo, and in vitro models. Both authors agreed that implants placed directly in the mouth (in vivo) presented average deviations greater than those placed in cadavers (ex vivo) and models (in vitro), where greater accuracy was achieved. The quality of the studies included in the present review suffered some limitations. Of the twenty-three studies, only five were RCTs. There is a clear need to perform more RCTs to reduce risks of bias and improve the quality of evidence. This limitation has also been described in the systematic review and meta-analysis by [PERSON] et al. [21]. Regarding the risk of bias in the RCTs reviewed, important criteria (such as concealment of allocation and blinding of participants, personnel, and outcome assessment) were not reported, so the risk of bias was unclear. Of the eighteen observational studies included, ten were categorized as high quality, whereas the other eight were of medium quality. No study, except one [40], reported sample size calculation, so the number of patients included in each study, selected consecutively, could affect the reliability of the results depending on the particularities of the study \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Authors (Year)** & **No. of Implants** & **Type of Support** & **Angular Deviation** & **Coronal Deviation** & **Apical Deviation** \\  & **Evaluated** & **(\({}^{\circ}\), Mean \(\pm\) SD)** & **(mm, Mean \(\pm\) SD)** & **(mm, Mean \(\pm\) SD)** \\ \hline [PERSON] et al. (2017) [37] & 72 & Mucosa & \(5.018\pm 0.197\) & \(2.052\pm 0.074\) & \(1.595\pm 0.074\) \\ \hline [PERSON] et al. (2018) [44] & 122 & Tooth & \(4.8\pm 3.1\) & \(1.2\) mm \(\pm\) 0.7 & \(1.8\) mm \(\pm\) 0.9 \\ \hline [PERSON] et al. (2018) [25] & 30 & Tooth & \(3.1\pm 2.3\) & \(1.0\pm 0.6\) & \(1.3\pm 0.6\) \\ \hline [PERSON] et al. (2018) [26] & 21 & Tooth & \(2.30\) & \(0.73\) & \(0.97\) \\ \hline [PERSON] et al. (2019) [43] & 54 & Mucosa & \(3.16\pm 1.79\) & \(1.12\pm 0.52\) & \(1.36\pm 0.68\) \\ \hline [PERSON] et al. (2019) [38] & 145 & Tooth & \(2.72\pm 1.42\) & \(0.75\pm 0.34\) & \(1.06\pm 0.44\) \\ \hline [PERSON] et al. (2021) [27] & 30 & Tooth & \(2.05\pm 0.45\) & \(0.39\pm 0.12\) & \(0.28\pm 0.09\) \\ \hline [PERSON]\(\rightarrow\)[PERSON] et al. (2021) [39] & 60 & Tooth & \(5.62\) & \(1.19\) & \(1.77\) \\ \hline [PERSON] et al. (2022) [40] & 50 & Mucosa & \(4.58\pm 2.85\) & \(0.87\pm\) 0.49 & \(1.37\pm 0.69\) \\ \hline \hline \end{tabular}  
*: These studies evaluated two different groups in the same study; SD: Standard deviation.  
\end{table} 
Table 2: _Cont._hypothesis. Future studies must follow CONSORT guidelines (Consolidated Standards of Reporting Trials) in order to improve the methodological and scientific quality of trials. Although the accuracy of guided surgery continues to improve, linear and angular deviations persist.