Evaluation of Wear on Primary Tooth Enamel and Fracture Resistance of Esthetic Pediatric Crowns Manufactured from Different Materials

<i>Background and Objectives:</i> Advances in dental materials and CAD-CAM technology have expanded crown options in primary teeth due to their improved appearance and mechanical properties. Thus, this study aimed to assess the enamel wear and fracture resistance of prefabricated, milled, and 3D-printed esthetic pediatric crowns. <i>Materials and Methods:</i> The study involved 60 extracted maxillary second primary molars and 60 3D-printed resin dies, divided into six groups based on different crown materials (n = 10): prefabricated zirconia, prefabricated composite, milled composite, milled resin matrix ceramic, milled PEEK, and 3D-printed resin. Prefabricated crowns were selected after the preparation of the typodont mandibular second primary molar tooth, while milled and 3D-printed crowns were custom produced. The specimens underwent mechanical loading of 50 N at 1.6 Hz for 250,000 cycles with simultaneous thermal cycling. The 3D and 2D wear amounts were evaluated by scanning the specimens before and after aging. Then, the fracture resistance and failure types of the restorations were recorded. <i>Results:</i> The results showed that the milled PEEK group had superior fracture resistance compared to the other groups, while prefabricated zirconia crown group had the lowest value. Milled resin matrix ceramic crown group displayed the lowest 3D wear volume, while 3D-printed crown group showed the highest 2D wear. <i>Conclusions:</i> The restorative material type did not have a significant effect on the wear of primary tooth enamel. The fracture resistance of the tested materials differed according to the material type. Although the milled PEEK group showed the highest fracture resistance, all tested materials can withstand chewing forces in children.