Assessment of Internal Fitness on Resin Crown Fabricated by Digital Light Processing 3D Printer / 치위생과학회지

BACKGROUND: Recently, three-dimensional (3D) printing has been hailed as a disruptive technology in dentistry. Among 3D printers, a digital light processing (DLP) 3D printer has certain advantages, such as high precision and relatively low cost. Therefore, the latest trend in resin crown manufacturing is the use of DLP 3D printers. However, studies on the internal fitness of such resin crowns are insufficient. The recently introduced 3D evaluation method makes it possible to visually evaluate the error of the desired area. The purpose of this study is to evaluate the internal fitness of resin crowns fabricated a by DLP 3D printer using the 3D evaluation method.METHODS: The working model was chosen as the maxillary molar implant model. A total of 20 resin crowns were manufactured by dividing these into two groups. One group was manufactured by subtractive manufacturing system (PMMA), while the other group was manufactured by additive manufacturing system, which uses a DLP 3D printer. Resin crowns data were measured using a 3D evaluation program. Internal fitness was calculated by root mean square (RMS). The RMS was calculated using the Geomagic Verify software, and the mean and standard deviation (SD) were measured. For statistical analysis, IBM SPSS Statistics for Windows ver. 22.0 (IBM Corp., USA) was used. Then, independent t-test was performed between the two groups.RESULTS: The mean±SD of the RMS were 41.51±1.51 and 43.09±2.32 for PMMA and DLP, respectively. There was no statistically significant difference between PMMA and DLP.CONCLUSION: Evaluation of internal fitness of the resin crown made using a DLP 3D printer and subtractive manufacturing system showed no statistically significant differences, and clinically acceptable results were obtained.

Relationship among Maternal Sociodemographics, Oral Health Behavior, and the Prevalence of Early Childhood Caries / 치위생과학회지

The purpose of this study was to examine the influence of maternal socioeconomic status, maternal oral health behaviors, and oral health behaviors of children, on the prevalence of early childhood caries in children aged 5 years. The Korean National Health and Nutrition Examination Survey data collected between 2007 and 2014 were applied to this study, and the study sample included 824 children who received oral examinations and participated in the health behavior survey. The factor that affected the prevalence of early childhood caries were confirmed by maternal and child factors. The data were analyzed using multiple linear regression. The mothers' age, income level, and job status affected the prevalence of early childhood caries. There was a significant difference in the analysis considering the factors of motherhood and children in the prevalence of early childhood caries according to mother's age, education level, income level, and the child's oral examination. The prevalence of early childhood caries was higher in children who received oral examinations than in those who did not. When the mother's educational level was higher than college education, it was found that the index of child, i.e., there was a difference in the prevalence of early childhood caries according to the mother's educational and income levels. These results indicate that maternal socioeconomic characteristics are correlated with the oral health of children. Therefore, oral health education programs that include mothers for the prevention of early dental caries in children may improve the dental health of children. In addition, specific oral health policies are necessary to address the differences in the oral health between the income groups.