Earticle

Purpose: This study evaluated the influence of build orientation on the dimensional accuracy of three-dimensional (3D)-printed implant surgical guides. Methods: Implant surgical guides for the maxillary premolar region were designed using computer-aided design software, and identical stereolithography files were printed at three build angles (0°, 45°, and 90°) with 10 samples per group. Following postcuring, all specimens were scanned with a dental 3D scanner, and their fit was assessed by superimposing the scanned data onto the original design using 3D analysis software. Root mean square (RMS) deviation was calculated, and one-way ANOVA and Tukey’s HSD post hoc test were performed for statistical analysis (α=0.05). Results: RMS values showed significant differences among groups (p<0.001). The 45° group exhibited the lowest mean RMS value, indicating the highest accuracy, whereas the 90° group had the largest deviation. Conclusion: Build orientation significantly affected the dimensional accuracy of 3D-printed implant surgical guides. A 45° orientation produced the most accurate results and may provide a practical guideline for optimizing clinical precision and standardizing printing conditions.

Purpose: This in vitro study evaluated changes in the fit accuracy and surface roughness of selective laser melting (SLM)-fabricated substructures following three postprocessing protocols: no treatment (NT), heat treatment (HT), and heat+pressure treatment (HPT). Methods: For all specimens, an identical abutment model of the maxillary right first molar was used. Thirty single copings and flat plate specimens were fabricated using the SLM technique with a Co–Cr alloy and divided into three groups (n=10 each) according to postprocessing: NT, HT, and HPT. Marginal and internal fit were assessed using the silicone replica technique with two-dimensional analysis, and surface roughness was measured under ×200 magnification with a microscope. One-way ANOVA was performed, followed by Tukey’s HSD and Scheffé’s post hoc tests (α=0.05). Results: Marginal and internal fit differed significantly between the NT group and the postprocessed groups (HT and HPT), demonstrating the effect of postprocessing. No significant difference was observed between the HT and HPT groups. Regarding surface roughness, the HPT group exhibited the lowest values, although the HT and HPT groups were statistically similar. Conclusion: Postprocessing enhances the fit and surface characteristics of SLM-fabricated Co–Cr restorations. Therefore, postprocessing is recommended as an essential step to ensure the long-term clinical performance of SLM-based prostheses.

Purpose: This study aimed to evaluate the translucency and masking ability of colored zirconia cores at different thicknesses and investigate the optical effects on these factors. Methods: Three zirconia brands were used for the experimental groups: Everest; Kavo, LAVA; 3M ESPE, Zirkonzahn Prettau Zirkon; and Zirkonzahn, and e.max Press (Ivoclar Vivadent AG) was used as control. Everest has five, LAVA has seven, and Zirkonzahn has five shading systems. Two types of colored e.max Press ingots were used. After pre-sintered zirconia specimens were colored using appropriate colorants, they were sintered according to manufacturers’ instructions. Overall, 285 specimens were fabricated in three thicknesses: 0.3, 0.5, and 0.7 mm. Color measurements were performed for all specimens on white, black, and C4 shade backgrounds using a spectroradiometer. The translucency parameter (TP) and masking ability were calculated for statistical analysis, and the Predictive Analytics Software program was used. Results: Overall, Zirconia cores exhibited lower TP values than e.max Press; however, Zirkonzahn showed higher TP values at certain thicknesses. Lightness decreased with darker shades; however, TP values were not significantly different. Masking ability improved with increased core thickness and darker shades. Changes in scattering and absorption coefficients also affected translucency. Conclusion: The TP value of colored zirconia cores did not consistently decrease with darker shades; however, masking ability was enhanced with increased shade darkness and core thickness. These findings indicate that the clinical use of darker shades may improve masking performance. However, further studies under clinical conditions are warranted.

Purpose: This study explores the associations between chewing function, quality of life, and stress perception among older adults in South Korea. Methods: Data from the 9th National Health and Nutrition Examination Survey, 2nd year (2023), of 1,308 elderly individuals aged 65 and over were analyzed, 575 of them female (44.0%) and 733 male (56.0%). By age group, there were 480 participants (36.7%) aged 65~69, 626 (47.9%) aged 70~79, and 202 (15.4%) aged 80 years or older. The data were analyzed with chi-square tests and logistic regression using SPSS (version 29.0, IBM). Results: The prevalence of chewing function discomfort significantly increased with age (p<0.001). Individuals who reported poor oral health also experienced significantly higher levels of chewing discomfort (p<0.001), among whom those who had difficulty working, felt depressed, had memory issues, or did not experience happiness showed significantly higher rates of discomfort (p<0.001). Conclusion: We found that chewing function discomfort significantly affects the quality of life and stress perception among the elderly, highlighting the need for integrated health interventions for improved chewing function to enhance their overall well-being.