Effect of layer thickness, inner structure, and implant angulation on the accuracy of 3D printed models with implant analogs

Objective: This study evaluated the effect of layer thickness, model inner structure, and implantangulation on the accuracy of 3D printed models with repositional analogs. Materials andmethods: 126 models designed to receive all-on-4 implant retained fixed dental prosthesiswere 3D printed. Models were divided into 2 groups (n=63) according to posterior implantangulation (Group 1; 30 ᵒ and group 2;45 ᵒ). The models were then divided into three subgroups(n=21) according to the printing layer thickness (Group a; 50 µm, group b; 100 µm, and group c;150 µm). Each subgroup was later subdivided into 3 divisions (n=7) according to the modelinner structure (Group I; solid, group II; hollow, and group III; honeycomb). Trueness wasanalyzed using Geomagic controlX analysis software by comparing the model scans to thereference model STL file. Results: Both inner structure and layer thickness had a significanteffect on the final accuracy. Implant angulation had no effect on the finalaccuracy of the printed model. Regarding layer thickness, tukeys post-hoc testrevealed that both 100 µm (24.9± 2.4) and 150 µm (24.5 ± 1.1) layer thickness showed higheraccuracy than the 50 µm (27.9 ± 2.4). As for model form, tukeys post hoc testrevealed that the solid (24.9 ± 1.4) and honeycomb (25 ± 1.5) models were more accurate thanthe hollow models (27.5±3.3). Conclusion: Implant angulation had no effect on the finalaccuracy of the model. Both 50 µm print layer thickness and hollow model inner structureshowed the least accuracy.