## 4 Discussion
However, it should be noted that PEEK space maintainers have certain limitations, particularly in the anterior tooth region, such as the higher fabrication cost and limited color options [16]. In the aforementioned study, removable space maintainers were produced using two different methods. The first method involved conventional manufacturing using a Type 2 Class I deture base polymer powder (self-curing denture powder, 1R, biomimetic color, NISSINTM, Osaka, Japan). The second method utilized a 5-axis numerical-control milling machine to fabricate space maintainers out of PEEK material. The objective of this study was to assess the suitability of the digital technique and computer-aided manufacturing in space maintainer production [16]. Following a series of qualitative and quantitative evaluations, the researchers reported that the CAD/CAM-fabricated removable space maintainers demonstrated a favorable fit and were deemed suitable for clinical applications. In addition, the group that received PEEK-based space maintainers exhibited significantly smaller maximum and mean distances compared to the conventional group, as indicated by statistical analysis (\(p\)-value \(<\) 0.05) [16]. In another study, the manufacturing process of three prototypes, namely lingual arch (1.3 mm thick), band and loop, and removable plate, was described. These prototypes were fabricated using PEEK material through a digital workflow employing the Roland DWX-50 5-axis milling machine [33]. According to patient feedback, the PEEK space maintainers were found to be comfortable and satisfactory, offering ease of polishing and cleaning. Notably, no instances of fracturing or decementation were reported, indicating the durability and reliability of the PEEK prototypes [33]. * _Stereolithography_  
Stereolithography (SLA) is the oldest and most widely employed 3D-printing technique in dentistry. It involves the creation of a layered structure using UV-sensitive material that undergoes polymerization [55; 64; 68; 73]. Another type of space maintainer made from clear photopolymer resin material has been reported, although no specific results were provided for this particular space maintainer, as only the cementation of the 3D-printed metal-based space maintainer was discussed [27]. * _Other technologies_  
The first utilization of CAD/CAM technology to fabricate a zirconia-based space maintainer was reported in 2017 [25]. This innovative approach demonstrated notable characteristics, including high flexural strength, exceptional resistance to thermal shock, low thermal expansion, and availability in various shades [25; 74]. In the study conducted by [PERSON] et al. [25], the zirconia-based space maintainer exhibited positive outcomes. There were no indications of tissue irritation or gingival inflammation during the 6-month follow-up period, and patients did not report any difficulties with mastication. These findings highlight that ceramic space maintainers offer a viable alternative to conventional band and loop designs, by providing advantages such as improved aesthetics and strength [25]. In a study conducted by [PERSON] et al. in 2022, further advantages of employing CAD/CAM technology for the production of zirconia-based space maintainers were reported [41]. These benefits encompassed improved retention of the space maintainer, reduced risk of cement loss, enhanced mechanical and biological properties, and increased satisfaction among patients and parents [41]. In summarizing Table 3, multiple studies have identified several advantages of CAD/CAM technology, including:  
- improved patient cooperation and comfort  
- decreased chair-side and laboratory time  
- enhanced precision  
- enhanced efficacy and effectiveness