Effect of post-processing alcohol washing time on the hardness and flexural strength of 3D-printed permanent dental resins

Year 2026, Volume: 8 Issue: 2, 358 - 363, 10.03.2026

Büşra Tosun , Zeynep Şen Yılmaz , Nur Uysal

https://izlik.org/JA96UR96ZX

Abstract

Aims: This study aimed to evaluate the influence of different alcohol washing durations on the hardness and flexural strength of a 3D-printed permanent dental resin, considering their critical role in clinical longevity.
Methods: Fifty bar-shaped specimens (25×2×2 mm) were fabricated using VarseoSmile TriniQ (BEGO, Bremen, Germany) permanent dental resin. The specimens were divided into five groups (n=10) according to alcohol washing times: 3, 5, 10, 15, and 20 minutes. Following washing in 99.5% ethanol, all specimens underwent standardized light postcuring. Hardness was measured using a Shimadzu microhardness tester, and flexural strength was assessed using an Instron universal testing machine through a three-point bending test. Data were analyzed using one-way ANOVA, with the significance level set at p<0.05.
Results: Alcohol washing time had a statistically significant effect on both hardness and flexural strength (p<0.001). Specimens washed for 3 minutes (21.64±3.69) and 5 minutes (18.27±2.51) exhibited significantly higher hardness values compared to those washed for 10, 15, and 20 minutes. Flexural strength showed a similar trend, with the highest strength recorded in the 3-minute group (23.19±1.02) and a progressive decrease observed with longer washing times, reaching the lowest values in the 20-minute group (17.71±1.16).
Conclusion: Prolonged alcohol washing times negatively affected the mechanical properties of the 3D printed permanent dental resin. Shorter washing durations (3-5 minutes) better preserved surface hardness and flexural strength, indicating that excessive alcohol exposure may compromise material integrity. These results emphasize the necessity of optimizing post-processing protocols to ensure the long-term mechanical performance and clinical durability of 3D-printed permanent restorations.

Keywords

3D printing , dental resin , alcohol washing time , hardness , flexural strength

Ethical Statement

This article does not require ethics committee approval as it does not involve human or animal studies

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