Comparison of the Surface Properties of 3D-printed Permanent Restorative Resins and Resin-based CAD/CAM Blocks

OBJECTIVE

This study aimed to investigate the surface roughness, microhardness, and color changes of resin-based computer-aided design/computer-aided manufacturing (CAD/CAM) blocks and 3D-printed permanent resins in different beverages.

METHODS AND MATERIALS

Resin-based CAD/CAM blocks (Cerasmart 270 and Grandio Blocs) and 3D-printed permanent restorative resins (Crowntec and Permanent Crown) were used in this study. A total of 96 specimens were prepared from CAD/CAM blocks and 3D-printed permanent resins. The initial surface roughness, microhardness, and shade value of the specimens were measured. Then, the specimens prepared from each material were divided into three subgroups (n=8) and immersed in tea, coffee, and distilled water for 30 days. After the specimens were immersed in the beverages, the surface roughness, microhardness, and tone values were measured again. The data were statistically analyzed using a two-way analysis of variance test (p<0.05).

RESULTS

No statistically significant difference was found in the surface roughness values of the resin-based CAD/CAM blocks and 3D-printed resins (p<0.05). Resin-based CAD/CAM blocks showed statistically significantly higher microhardness than 3D-printed permanent resins (p<0.05). Although the color changes in 3D-printed resins in tea and coffee were similar to those in resin-based CAD/CAM blocks on the first and seventh days, more color changes appeared in the 3D-printed resins after 30 days. The surface roughness and microhardness values of the specimens submerged in tea, coffee, and distilled water showed no statistically significant changes (p<0.05).

CONCLUSIONS

Although the surface roughness of 3D-printed permanent resins was similar to that of resin-based CAD/CAM blocks, they had a lower microhardness value. Moreover, 3D-printed permanent resins showed more color changes in tea and coffee.

COVID-19: booster(s) vs. hospitalization and Intensive Care Unit admission

OBJECTIVE

As the pandemic continues, different vaccine protocols have been implemented to maintain the protection of vaccines and to provide protection against new variants. The aim of this study was to assess hospitalized patients' vaccination status and document the efficacy of boosters.

PATIENTS AND METHODS

The patients that were hospitalized due to COVID-19 were enrolled from 28 hospitals in Turkey for five months from September 2021. 5,331 confirmed COVID-19 patients from collaborating centers were randomly enrolled to understand/estimate the distribution of vaccination status in hospitalized patients and to compare the efficacy of vaccination/booster protocols.

RESULTS

2,779 men and 2,552 women of which 2,408 (45.2%) were admitted to Intensive Care Units participated in this study. It was found that the highest risk reduction for all age groups was found in groups that received 4 doses. Four doses of vaccination for every 3.7 people under 50 years of age, for every 5.7 people in the 50-64 age group, and for every 4.3 people over 65 years of age will prevent 1 patient from being admitted to intensive care. Regardless of the type of vaccine, it was found that the risk of ICU hospitalization decreased in those who were vaccinated compared to those who were not vaccinated. Regardless of the type of vaccine, the ICU risk was found to decrease 1.25-fold in those who received 1 or 2 doses of vaccine, 1.18-fold in those who received 3 doses, and 3.26-fold in those who received 4 doses.

CONCLUSIONS

The results suggested that the addition of a fourth dose is more effective in preventing intensive unit care even in disadvantaged groups.

Resistance of Single-shade Composites to Discoloration

The aim of this study was to examine the color change of single-shade resin composites, which can be used for all tooth shades. In this study, samples were prepared using resin composites with single-shade (Omnichroma, Vitra Unique) and multishade composite systems (G-aenial A'Chord, Clearfil Majesty ES-2 Premium). The initial color values were measured with a spectrophotometer. Then, samples were kept in wine, coffee, black tea, and distilled water and color measurements were made after days 1, 7, and 30. Color change (ΔE00) and whiteness index (WID) values were statistically analyzed using a one-way analysis of variance (ANOVA) test (α=0.05). Single-shade resin composites showed more color change from wine, coffee, and black tea than multishade resin composites (p<0.001). Single-shade composites have a greater discoloration potential. Single-shade resin composites may show more color change from beverages than multishade resin composites, which may negatively affect clinical success.