Accuracy of polymeric dental bridges manufactured by stereolythography

Abstract

Purpose: Purpose of this paper is to investigate the accuracy of dental bridges produced via digital light projection stereolithography process. Design/methodology/approach: 3D printer Rapidshape D30 was used for manufacturing of two groups of samples – temporary four-part bridges and cast patterns for permanent bridges. The temporary bridges were made of NextDent C+B polymer, while the cast patterns - of NextDent Cast. The samples were manufactured with different layer’s thickness (0.035 mm and 0.050 mm). The geometrical and adjusting accuracy were investigated by measuring of the samples’ dimensions and silicone probe, while the surface roughness was studied out by profile meter and optical microscopy. Findings: It was established that the dimensions of the temporary bridges and the cast patterns, printed with layer thickness 50 µm, are larger than that of the virtual 3D model with 0.1-0.3 mm. Decreasing the layer thickness to 35 µm leads to 0.29%-1.10% smaller sizes of dental bridges and cast patterns in comparison to that of the virtual 3D model. The average roughness deviation Ra of the 3D printed temporary bridges and cast patterns is larger than that of the initial model. As the surface roughness depends on the layer’s thickness, the samples with 0.035 mm layer characterize with lower Ra values. The silicone probe shows that the temporary bridges as well as the cast patterns need additional adjusting in the dental office or corrections during design of the virtual 3D model and 3D printing process in the dental laboratory. Practical implications: The stereolithography as part of CAD/CAM manufacturing process characterizes with high accuracy as a whole. But present study reveals that additional adjusting or preliminary corrections of the design of 3D printing process are needed for dental constructions produced by SLA. Originality/value: The geometrical and fitting accuracy as well as the surface roughness of dental bridges, produced by stereolithography were evaluated. The data, shown in the present study, will help dentists and dental technicians to precise the manufacturing regimes for production of dental constructions with high accuracy.