Influence of Different Build Directions on the Fracture Load and Surface Roughness of Additively Manufactured Three-unit Provisional Restoration and Comparison with Conventional Methods of Provisional Fabrication.

Purpose: To compare the influence of 0, 45 and 90 degrees build direction on fracture load and surface roughness of additively manufactured three-unit fixed provisional restoration, and to compare with provisionals fabricated using conventional materials.

Material and methods: Mandibular typodont right second molar and premolar were prepared for missing mandibular first molar to receive three-unit fixed partial denture. Six groups of 10 samples each, 3-unit provisionals were fabricated using additional manufacturing at 0,45 and 90 degrees, heat polymerized polymethyl methacrylate, auto polymerizing resin and bis-acryl composites resins and tested for fracture load and surface roughness. One way ANOVA and Tukey tests were used to analyze the data.

Results: For fracture load, lowest mean value was obtained for auto polymerizing bis-acrylic resin (464.9N) and highest value for 0 degree (596 N), while surface roughness values were lowest for heat polymerized polymethyl methacrylate (0.132μm), and the highest for auto polymerizing polymethyl methacrylate (0.836 μm). Significant differences were obtained between three build directions for fracture load and surface roughness (p=0.001); in all pairwise comparisons except between 0 and 90 degrees (p=0.502) for fracture load; and between all three build directions for surface roughness (p=0.01). On comparing with other provisional materials, significant difference (p=0.001) was observed between all groups. Conclusion- Build direction affected the mechanical properties of additively manufactured three-unit provisionals with 0 degree printed provisionals showing highest fracture load and lowest surface roughness. On comparing with other provisional materials, 0 degree showed highest fracture load, with surface roughness similar to heat polymerized provisionals.