## 4 Discussion  
In this systematic review, the objective was to offer a comprehensive understanding of the manufacturing process of space maintainers in pediatric dentistry, ranging from traditional methods to the utilization of 3D printing technology. A total of nine articles were examined, which focused on the 3D printing of various types of space maintainers. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Author, Year**} & \multirow{2}{*}{**Type of Study**} & \multirow{2}{*}{**Type of Intraoral**} & \multirow{2}{*}{**CAD Software**} & \multirow{2}{*}{**CAM Soft-Manufacturing Method**} & \multirow{2}{*}{**Type/Material of Space Maintainer**} & \multirow{2}{*}{**Cementation**} \\  & & & **Truoraal** & & & & & \\  & & **Scanner** & & & & & & \\ \hline \multirow{5}{*}{5} & \multirow{5}{*}{[PERSON], et al., 2020 [16]} & \multirow{5}{*}{Research article} & \multirow{5}{*}{D800 3D} & Dental & & & & \\  & & & & & 3 Shape, & & 5-axis & & \\  & & & & & & & numerical-control & & \\  & & & & & & & milling machine & Removable & \\  & & & & & & (Organical Multi, R + & space maintainers/PEEK & - \\  & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline \multirow{5}{*}{6} & \multirow{5}{*}{[PERSON], et al., 2017 [33]} & \multirow{5}{*}{Pilot study} & D810 & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline \multirow{5}{*}{7} & \multirow{5}{*}{[PERSON], et al., 2017 [25]} & \multirow{5}{*}{Case report & **-** & N/A & N/A & BruxZir zirconia & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline \multirow{5}{*}{8} & \multirow{5}{*}{[PERSON], et al., 2022 [41]} & \multirow{5}{*}{Clinical article} & TRIOS Color & \multirow{5}{*}{DentalSystem; 3 Shape, Copenhagen, Copenhagen, Denmark} & 5-axis milling machine (Zenoetceselect hybrid; Wieland Dental, Pforzheim, German) & Zirconia block (1100 Enamel; Denmark, Seoul, Republic of Korea) & adhesive resin cement (Panavia F 2.0; Kuraray Noritake Dental) \\  & & & & & & & & \\ \hline \multirow{5}{*}{9} & \multirow{5}{*}{[PERSON], et al., 2020 [42]} & \multirow{5}{*}{Research article} & D800, 3 Shape & Dental & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & & \\  & & & & & & & \\  & & & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._The results indicate that 3D-printed space maintainers exhibit promising potential as an alternative to conventionally processed ones, effectively addressing their limitations. The advancement of additive manufacturing technologies has prompted rapid progress within the healthcare sector, encompassing various fields of dentistry [43]. The applications of 3D-printing span across education, research, patient awareness, and digital treatment planning by utilizing 3D models, as well as clinical utilization [35; 44; 45]. While there is a wealth of literature exploring the implementation of this technology in prosthodonics, reconstructive and restorative dentistry [46; 47], implantology, oral surgery [48], and orthodontics [49; 50], research in the field of pediatric dentistry remains relatively limited. The clinical implementation of 3D printing in pediatric dentistry includes the development of a 3D-printed fluoride adhesive film, enabling the creation of a slow-release delivery system. This is particularly relevant due to the challenges posed by the continuous flow of saliva and the act of chewing, which make it difficult to maintain an optimal fluoride concentration within the oral cavity [4; 27; 40; 51; 52; 53; 54]. In prosthetic procedures within the realm of pediatric dentistry, the utilization of 3D-printed crowns has demonstrated superior marginal integrity and retention, resulting in fewer instances of cementation failure compared to crowns fabricated through CAD/CAM techniques. Moreover, 3D-printed partial or complete dentures have proven to be beneficial for patients presenting with diverse teeth abnormalities [51; 55; 56].