## 4 Discussion
Survival rates were 100% for SSCs and 82.1% for PRCs (\(p=0.047\)), with cracks and discoloration reported in PRCs. Despite their esthetic appeal and ease of repair, PRCs need further durability and clinical performance improvements to rival SSCs. In another study, [PERSON] et al. [30] evaluated the feasibility of PRCs and CAD/CAM milled resin crowns (CRCs) as alternatives to SSCs for pediatric dental restorations. Sixty crowns were fabricated across PRC, CRC, and SSC groups, each with 10 crowns for incisors and molars. PRCs and CRCs demonstrated better esthetics and surface characteristics than SSCs, with significantly smaller marginal gaps (\(p<0.05\)). All groups showed good stability. These findings indicate that PRCs and CRCs could be effective alternatives to SSCs for pediatric crown applications. Although digital production technologies provide appropriate adaptation, the properties of these restorations can differ depending on the production technique [27]. A recent systematic review and meta-analysis conducted by [PERSON] et al. [31] compared the AM and SM techniques in various aspects. The review attributed the heterogeneity of the mechanical properties of AM restorations to the variability in mechanical tests and material compositions. However, the study concluded that AM and SM techniques yielded restorations with comparable mechanical properties [23]. [PERSON] et al. [32] evaluated the fracture resistance and failure types of three types of esthetic crowns for primary molars, namely CAD-CAM-milled polymethylmethacrylate (PMMA), 3D printed glycolyl carbamate resin crowns, and direct composite celluloid crowns. The results showed significant differences in fracture resistance between the groups, with CAD-CAM and 3D printed crowns demonstrating higher fracture resistance than direct composite crowns. However, all crown types exceeded children's mean maximum bite force, indicating good clinical performance. The direct composite crowns, while less resistant, offer ease of repair, making them a viable option for pediatric dentistry. [PERSON] et al. [33] investigated the fracture resistance, biaxial flexural strength, and dynamic mechanical properties of two 3D printing resins, Graphy (GP) and NextDent (NXT), in comparison to prefabricated zirconia crowns (NuSmile, NS) for esthetic restoration of primary molars. Results showed no significant difference in fracture resistance among the groups, while GP exhibited a higher BFS than NXT. The findings suggest that GP and NXT resins possess sufficient strength for pediatric restorations, making 3D printed resin crowns a viable option for primary teeth prosthetics. [PERSON] et al. [34] evaluated the mechanical properties of two types of 3D printed resin crowns for primary teeth, focusing on strength and surface characteristics. The 3D printed resin crowns were considered capable of withstanding children's bite forces, though material improvements are needed for their use as a pediatric dental treatment option. Despite the reported appropriate mechanical properties of CAD-CAM-produced restorations, the choice of restorative material may be challenging in treating pediatric patients. Resin-based crowns that can be fabricated using both manufacturing systems have some advantages in primary teeth. Resin-containing blocks for milling techniques offer advantages for primary teeth, such as preventing wear on opposing dentition due to their low hardness and absorbing functional stresses thanks to their low modulus of elasticity [18]. [PERSON] et al. [35] tested the wear of primary teeth opposing four different restorative materials, which were composite resin (CR), stainless steel (SS), monolithic zirconia (MZ), and fiberglass (FG). The results indicated that monolithic zirconia crowns caused more wear on opposing teeth, while composite resin caused less wear on teeth. [16]. Recently, resins and hybrid ceramic resins have been approved by the Food and Drug Administration (FDA) for long-term use, allowing for the production of long-term interim resin crowns using AM [36].