Influence of postwashing process on the elution of residual monomers, degree of conversion, and mechanical properties of a 3D printed crown and bridge materials. Issue 11 (November 2022)

• Record Type: Journal Article
• Authors: Jin, Gan; Gu, Hanna; Jang, Minhee; Bayarsaikhan, Enkhjargal; Lim, Jung-Hwa; Shim, June-Sung; Lee, Keun-Woo; Kim, Jong-Eun
• Is Part Of: Dental materials. Volume 38:Issue 11(2022)
• Page Start: 1812
• Page End: 1825
• Publication Date: 2022-11
• Subjects: Postwashing -- Ultrasonic -- 3D printing -- Photopolymer resin -- Degree of conversion -- Mechanical properties; Dentistry -- Periodicals; Dental materials -- Periodicals; 617.695
• DOI: 10.1016/j.dental.2022.09.017
• Languages: English
• ISSNs: 0109-5641

Abstract

Abstract: Objectives: This study aimed to determine the effects of the postwashing method and time on the mechanical properties and biocompatibility of three-dimensional (3D) printed crown and bridge resin. Methods: DLP (digital light processing)-printed specimens produced from Nextdent crown & bridge (C&B) resins were washed separately using an ultrasonic bath and rotary washer with TPM (tripropylene glycol monomethyl ether) for 3 min, 6 min, 10 min, 20 min, and 1 h. Postcuring was applied for 30 min to each specimen after the washing process. The flexural strength, Vickers hardness, water sorption and solubility, degree of conversion (DC), elution of residual monomers, and biocompatibility of the specimens were evaluated. Results: The ultrasonic bath showed greater washing efficacy by reducing the residual HEMA (2-hydroxyethyl methacrylate) from 2.0634 ppm to 0.1456 ppm and reducing the residual TEGDMA (triethylene glycol dimethacrylate) from 1.4862 ppm to 0.1484 ppm. With prolonged washing, the flexural strength significantly decreased from 129.67 ± 6.66 MPa (mean±standard deviation) to 103.17 ± 7.20 MPa, while the Vickers hardness increased slightly for the first 6 min and then decreased thereafter significantly. The DC was 87.78 ± 1.34% after 3 min and then gradually decreased with extended washing time. The cytotoxicity significantly decreases with the increment of the washing time. Significance: The washing effect on the elution of residual monomers was better for an ultrasonic bath than for a rotary washer. Extending the washing time reduces the mechanical properties and cytotoxicity of the Nextdent C&B resin. Highlight: The ultrasonic bath can reduce the residual acrylic monomers on the 3D printed objects in a short time compared to rotary washer. The mechanical properties, extent of polymerization, and biocompatibility of the Nextdent C&B resin can be optimized by 6 min of washing by both washing methods. The sufficient washing using both washing methods by TPM will lead to the reduction of the mechanical properties.