Abstract
Objective: To assess the mechanical and adhesive properties of additively manufactured (AM) materials with variable sustainability and recyclability as alternatives to traditional light-cured acrylic resin for dental custom trays.
Materials and method: Four different AM materials; a photopolymer resin tray material printed with DLP and three FDM printed polylactic acid (PLA), recycled PLA and Polyethylene Terephthalate Glycol (PETG) and a conventional light-cure acrylic resin (LC PMMA) as a control were used to construct dumbbell (tensile testing), rectangular (flexural testing) to verify suitability for custom trays (n=10/group). To evaluate bond strength, specimens were manufactured at 0, 45 and 90° printing orientation (n=10/group). Surface roughness was evaluated with confocal scanning microscopy. The three mechanical tests were completed in a universal testing machine (Instron) according to ISO 527-2 and ISO 20795-1. Results were statistically analysed with PRISM (Version 10) Software using one-way ANOVA and Kruskal-Wallis tests, with statistical significance set at p < 0.05. Confocal analysis and SEM analysis were conducted for quantitative and qualitative surface analysis.
Results: For tensile and flexural strength, PLA (Recycled) and PETG showed no statistically significant difference (p > 0.05) from LC PMMA. AM materials yielded a higher bond strength than the LC PMMA material. Print orientation was found to affect the bond strength of some materials with varying surface roughness as contributing factors.
Conclusion: LC PMMA, PLA (Recycled), and PETG have the greatest flexural and tensile strengths. PLA (Recycled) and PETG were the highest performing AM options with regard to flexural and tensile strength for custom trays. All AM materials showed a significantly higher bond strength compared to LC PMMA. To maximise the bond strength, PLA (Recycled) should be printed at an angle of 0°, and PETG at 0 or 90°. Dental practitioners should consider the varying degrees of recyclability of materials, in addition to their mechanical properties.