This study evaluated the fracture resistance, biaxial flexural strength (BFS), and dynamic mechanical analysis (DMA) of three-dimensional (3D) printing resins for the esthetic restoration of primary molars. Two 3D printing resins, Graphy (GP) and NextDent (NXT), and a prefabricated zirconia crown, NuSmile (NS), were tested. GP and NXT samples were 3D printed using the workflow recommended by each manufacturer. Data were collected and statistically analyzed. As a result of the fracture resistance test of 0.7-mm-thick 3D printed resin crowns with a thickness similar to that of the NS crown, there was no statistically significant difference among GP (1491.6 ± 394.6 N), NXT (1634.4 ± 289.3 N), and NS (1622.8 ± 323.9 N). The BFS of GP was higher for all thicknesses than that of NXT. Both resins showed high survival probabilities (more than 90%) when subjected to 50 and 150 MPa. Through DMA, the glass transition temperatures of GP and NXT were above 120 °C and the rheological behavior of GP and NXT according to temperature and frequency were analyzed. In conclusion, GP and NXT showed optimum strength to withstand bite forces in children, and 3D printed resin crowns could be an acceptable option for fixed prostheses of primary teeth.

This study aimed to investigate parents’ and dentists’ perceptions of the national oral health screening for infants and children (OHS), and evaluate the dentists’ accuracy of analyzing the results of OHS. A questionnaire survey was conducted, face-to-face or online, for 90 parents of children who received OHS in the Department of Pediatric Dentistry at Yonsei University Dental Hospital and 100 dentists working at local clinic or university dental hospital from May to October 2021. Most parents and dentists were aware of the importance of OHS, and approximately 96.7% of parents were satisfied with OHS. The requirements of parents and dentists about OHS were different. The reasons for having difficulties in explaining parents after OHS and the opinions on appropriate period and number of OHS were disagreed between pediatric dentists and general dentists. Regardless of dentists’ major, work experience, elapsed period after taking online education program, the accuracy of the examination result was low. In this study, various opinions of parents and dentists on OHS were collected. Efforts should be made to enhance the oral health of infants and children by considering the requirements of parents and dentists and improving the accuracy of examination results.