## 3 Results
### Main Characteristics of the Studies  
The main characteristics of the included studies are listed in Table 1. Most of the included studies followed a low level of scientific evidence since they were based on case reports (thirty papers) and in vitro studies (nineteen papers). Of the thirteen controlled clinical studies, eight presented a reduced sample size (six to fifteen patients), and just one of these included studies showed randomization. From the clinical studies with sample size between twenty and twenty-nine patients, only three included a fit accuracy assessment of the RPD frameworks (Table 1). Figure 2: Flow chart of the procedures used for the article search. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Study** & **Study** & **Sample** & **Level of** & **Information** & **Analysis** & **Intermediate** & **Framework** & **Type of** & **Production** \\
**Study** & **Design** & **Size** & **Evidence** & **(Equipmen0)** & **(Software)** & **(Technique)** & **Fabrication** & **(Brand)** & **Protocol** \\ \hline Batisse & & & & & IntraS & CAD & & AM (SLM: & & \\ \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & \multirow{2}{*}{Case report} & \multirow{2}{*}{1} & \multirow{2}{*}{4} & \begin{tabular}{} \end{tabular} & (3 Shape & - & ProX DMP & Co-Cr & \\  & & & & Trios) & DS & & 200) & (Nd) & \\ \hline [PERSON], [PERSON]\& & & & IntraS & CAD & & & & \\ \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & \multirow{2}{*}{Case report} & \multirow{2}{*}{1} & \multirow{2}{*}{4} & \begin{tabular}{} \end{tabular} & (3 Shape & - & AM (SLM: & \\ \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & (3 Shape & - & AM (SLM: & \\ \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & (3 Nissin) & 11 & \\  & & & Trios) & DS & & & & \\ \hline [PERSON] et al., 2017[51] & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & \multirow{2}{*}{10} & \multirow{2}{*}{2} & \begin{tabular}{} \end{tabular} & (3 Shape & - & AM (SLM: & \\ \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & (3 Shape & - & AM (SLM: & \\ \multirow{2}{*}{\
\begin{tabular}{} \end{tabular} } & (3 Shape & - & AM (SLM: & \\ \multirow{2}{*}{
\begin{tabular}{} \end{tabular} } & (3 Nissin) & 11 & \\  & & & & D850 & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Study** & **Study** & **Sample** & **Level of** & **Information** & **Analysis** & **Intermediate** & **Framework** & **Type of** & **Production** \\  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
The information acquisition was mainly performed using conventional impressions (thirty-nine papers) followed by the digitization of the master stone cast by an extra-oral scanning procedure using extra-oral or intra-oral scanners. In ten in vitro studies, the information of simulation models of dental arches was directly obtained by extra-oral scanning without any impression. In turn, intra-oral scanning was performed in thirteen included papers. The 3 Shape equipment was the most requested for both extra-oral (sixteen papers) and intra-oral (ten papers) scanning (Table 1). Digital techniques were executed to analyze the information and design the framework in almost all the included papers (sixty-one papers), highlighting the use of the 3 Shape Dental System software (twenty-five papers). Conversely, the conventional technique using a physical cast was applied in just two papers (Table 1). The additive manufacturing technique was used in the twenty-six studies that used the digital production of an intermediate structure made of a burnable material (resin with nineteen reports and wax with three reports), except for one study that used a milling technique. Stereolithography (SLA) was the additive manufacturing technique most described (nine studies), but material jetting technology (MJ) and digital light processing (DLP) were used in eight reports each. In turn, the milling technology was reported in four reports.