Surface roughness and marginal adaptation of stereolithography versus digital light processing three-dimensional printed resins: An in-vitro study.

Abstract

The aim of this study was to assess surface roughness and marginal adaptation of Stereolithographic versus Digital Light Processed three-dimensional (3D) printed provisional resins. A 3-unit fixed partial denture (FPD) preparation was done on ideal model irrespective to 44-46. The Model was scanned and a 3-unit FPD was designed using 3-shape software. The STL file was transferred to two different 3D printers - Sprintray digital light processing (DLP) and Formlabs stereolithography (SLA). Eight samples were printed per group (total of 16 samples) using C and B temporary tooth-colored resin and cured according to the manufacturer's instructions. Marginal adaptation was checked for six surfaces per tooth for all the samples using a stereomicroscope. Surface roughness was also calculated for four samples from each group before and after polishing (pumice slurry + rouge and cotton buff) using a contact profilometer. The mean maximum marginal gap overall, was seen for the DLP group on the mesiobuccal surface of the first premolar, i.e., 178.8 ± 8.35 μm, while the minimal marginal gap was seen for the SLA group on the mesiolingual surface of first molar - 32.5 ± 7.07 μm. Furthermore, all the DLP samples showed a statistically significant higher mean marginal gap as compared to SLA samples (P < 0.005). All the samples showed surface roughness within the acceptable range. There was a statistically significant difference noted in Rz (roughness depth) before and after polishing (P < 0.05). 3D printed temporary resin FPD via SLA showed a much better marginal adaptation (49.6 μm mean marginal gap for 46 and 106.8 μm for 44) as compared to those printed via DLP (101.8 μm mean marginal gap for 46 and 157.5 μm for 44). All the samples showed an acceptable surface roughness. 3D printed temporaries have shown good marginal fit and adaptation and are a viable choice in patients where temporaries has to be given for long term before a final prosthesis can be fabricated (especially for full mouth rehabilitations).