The effect of printing angles on the color stability, solubility and water sorption properties of provisional crown

In contemporary dental practices, modern manufacturing techniques have been increasingly employed in the production of provisional fixed restorations in line with technological advancements and rising aesthetic expectations. Among these methods, additive manufacturing technology has been developed as an alternative to subtractive techniques to reduce material waste, and its use in the dental field is becoming increasingly widespread. In our study, disc-shaped provisional crown materials were fabricated using the stereolithography (SLA) method, a type of additive manufacturing technology, at three different printing angles: 0°, 45°, and 90°. The water sorption, solubility, and potential color changes over time when immersed in various solutions were investigated. Cola, red wine, orange juice, and coffee were used as staining solutions, while distilled water served as the control group. Data were analyzed using IBM SPSS V23, Jamovi, and R software. The Shapiro-Wilk test was employed to assess the normality of distribution. The Kruskal-Wallis H test was used for comparisons of non-normally distributed variables among three or more groups, and Dunn's test was applied for post-hoc multiple comparisons. Quantitative variables were presented as mean ± standard deviation and median (minimum–maximum). The significance level was set at p<0.05. According to the results, a significant difference was observed in water sorption levels among provisional crown materials printed at different angles (p=0.003); the highest water sorption was found in the 0° group, whereas the lowest was recorded in the 45° group. In terms of solubility, no significant differences were found between the groups, indicating that solubility was not affected by the printing angle (p=0.751). Regarding color stability, staining varied depending on the printing angle when specimens were immersed in different solutions (p<0.001). Analysis of the ΔE₀₀ mean values showed that the least color change occurred in the 90° group, while the most pronounced color change was observed in the 45° group. The type of staining solution also significantly influenced color change (p=0.001); the most severe staining occurred in red wine, whereas the least was noted in distilled water. It was also observed that discoloration increased gradually over time during immersion in the staining solutions (p<0.001). Keywords: 3D printing, printing angle, color stability, water sorption, solubility