Giordano II, RussellAlkandary, Abdulrahman R A A Y2025-07-212025-07-212025https://hdl.handle.net/2144/507592025OBJECTIVES: Evaluate the accuracy (Trueness and Precision) of 3D-printed full-arch fixed dental prostheses by examining the effects of different printing angulations, layer thicknesses, and the inclusion of a horizontal cross-arch bar. MATERIALS AND METHODS: Two 3D-printed dental resin materials for full-arch fixed dental prostheses were used in this study; Lucitone Digital IPN™ and OnX Tough 2. A standardized CAD design generated in Dental CAD 3.1 Rijeka software was exported as an STL file and served as the reference model. A total of 104 specimens were printed with Carbon M2 printer at varying angulations (0°, 40°, and 70°), layer thicknesses (25 µm and 50 µm), with or without a horizontal cross-arch bar, and were post-processed following the manufacture recommendations. Specimens were analyzed using Geomagic Control X software, where they were superimposed onto the reference STL via best-fit alignment for 3D inspection analysis at a tolerance level of 50 µm. Trueness was assessed by calculating root mean square (RMS) and standard deviation (SD) values, while precision was determined by measuring absolute linear deviations (mm) in pairwise comparisons within each group to evaluate reproducibility. RMS, SD and linear deviation data were analyzed using multivariate least square mean linear regression in JMP Pro 18 software to identify statistically significant effects (⍺ = 0.05). Microstructural analysis was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to examine surface morphology and elemental composition. Moreover, ash burnout testing was employed to quantify the inorganic filler content and evaluate the residual mass of each material. RESULTS: The RMS and SD values varied among resin materials, with OnX Tough 2consistently showing lowest deviation values, and the highest accuracy in term of trueness across all tested variables. Overall, for both materials printing at a lower angulation (0°) resulted in superior trueness compared to 40° and 70° angulations. OnX Tough 2, exhibited improved trueness when printed at 50 µm layer thickness and without a cross-arch bar. In contrast, for Lucitone Digital IPN™ the most accurate outcomes were achieved at 25 µm layer thickness and with the addition of a horizontal cross-arch bar. No statistically significant differences in precision were evident across study variables: angulation, layer thickness and the presence of a cross-arch bar. IPN is an unfilled resin, primarily composed of an organic polymer matrix, whereas OnX is a filled resin with a complex composite formulation of silica and ytterbium-based inorganic reinforcements. CONCLUSION: OnX Tough 2 resin demonstrated superior trueness and precision compared to Lucitone Digital IPN™, as evidenced by lower RMS, SD, and absolute linear deviation values across all study groups. Printing at 0° angulation resulted in the highest levels of both trueness and precision. The effects of layer thickness and the presence of a horizontal cross-arch bar were found to be material-dependent, with filled resins such as OnX Tough 2 being more sensitive to these parameters. The most favorable combination for achieving optimal accuracy with OnX was identified as 0° angulation, 50 µm layer thickness, and without a cross-arch bar.en-USDentistryBiomechanics3D printingAccuracy in dentistryDental printingThesis/Dissertation2025-07-02