Effect of geometry on deformation of anterior implant-supported zirconia frameworks: An in vitro study using digital image correlation

Purpose: To evaluate the effect of geometry on the displacement and the strain distribution of anterior implant-supported zirconia frameworks under static load using the 3D digital image correlation method. Methods: Two groups (n=5) of 4-unit zirconia frameworks were produced by CAD/CAM for the implant-abutment assembly. Group 1 comprised five straight configuration frameworks and group 2 consisted of five curved configuration frameworks. Specimens were cemented and submitted to static load up to 200N. Displacements were captured with two high-speed photographic cameras and analyzed with video correlation system in three spacial axes U, V, W. Statistical analysis was made using the nonparametric Mann-Whitney test. Results: Up to 150N loads, the vertical displacements (V axis) were statistically higher for curved frameworks (-267.83 +/- 23.76 mu m), when compared to the straight frameworks (-120.73 +/- 36.17 mu m) (p=0.008), as well as anterior displacements in the W transformed axis (589.55 +/- 64.51 pan us 224.29 +/- 50.38 mu m for the curved and straight frameworks), respectively (p =0.008). The mean von Mises strains over the surface frameworks were statistically higher for the curved frameworks under any load. Conclusion: Within the limitations of this in vitro study, it is possible to conclude that the geometric configuration influences the deformation of 4-unit anterior frameworks under static load. The higher strain distribution and micro-movements of the curved frameworks reflect less rigidity and increased risk of fractures associated to FPDs. (C) 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.