Comparing the physical and mechanical properties of different biocompatible three-dimensional resin materials in possible use of dental appliances: An in vitro study

Objective: This study aimed to assess the colour stability, water sorption, microhardness and water contact angle of two different 3D printing systems (SLA and DLP) in a possible use of producing paediatric and orthodontic dental appliances. Materials and Methods: SLA and DLP printer systems produced a total of 160 disk samples with a diameter of 15.00 mm and a height of 2.00 mm. Colour changes of 64 samples were assessed in distilled water, coffee, coke and cherry juice and Vicker's microhardness tests were also conducted. Solubility and water sorption were held following the water contact angle assessment. Statistical analyses were performed using the SPSS software. Mann-Whitney-U test, Friedman test and Bonferroni post hoc Multiple Comparison Test were performed. Results: In DLP and SLA groups, coffee had a statistically significant colouring effect regarding the assessment periods (P = .001, 20.09 +/- 2.96, 22.09 +/- 3.51, respectively), and the discolouration effect of coffee was higher in the SLA group at all endpoints (P <.05). At the same time, DLP was more affected by coke solution in T0-T1 and T0-T7 (P < .05). The values of water sorption showed statistically significant differences in the group of DLP compared to the SLA (P = .01, 121.11 +/- 10.54, 92.78 +/- 8.70, respectively). No statistical significance was detected between the solubility values and water contact angle of SLA and DLP groups. The SLA printer's microhardness values revealed statistically significantly higher values than the DLP group (P = .001) and a decrease was detected following the immersion period in the microhardness values of the SLA group (P = .022). Conclusion: The compared groups exposed to staining solutions revealed colour changes above the clinically acceptable values at all periods (Delta E-00 = 2.25).