A digital image correlation analysis and non-linear 3D-FEM on the strain distribution of screwed and cemented fixed partial dentures fabricated by a CAD/CAM system in titanium and zirconia

Abstract

It is still unclear as to what the best fixation method for CAD/CAM manufactured prosthesis, as well as to what prosthesis material and the most effective prosthetic design in order to minimize the strains transferred to the bone-implant interface. Three-dimensional finite element (3D-FE) studies have been used to analyze bone strains, but an accurate in vitro method for strain calculation is still needed to validate the results found in the mathematical model. The three-dimensional digital image correlation (3D-DIC) method allows for a complete mapping of the strains found in a bone or model surface. This study aims to evaluate the influence of the material used to fabricate 12-elements, splinted and non-splinted frameworks, and their fixation method using 3D-FE and 3D-DIC methods for strain analysis. This study will be divided in two phases: (1) in vitro analysis: 24 fixed partial dentures (FPDs) will be fabricated with the CAD/CAM system and supported by 6 implants placed in a model simulating an edentulous maxilla. The FPDs will be divided in 8 groups (n=3), according to the framework material (zirconia or titanium), fixation method (cemented or screwed) and splinted or non-splinted. An opposing 250 N occlusal load will be applied to the FPDs at 0,1 mm/sec approximation speed while two CCD (charged-coupled device) cameras are used to record deformation of the loading model. The images will be later analyzed with the 3D-DIC specialist software. (2) computer analysis: four standard 3D-FE models, identical with the experimental models, will be fabricated, allowing the simulation of every group from the first phase of the study. Data from the in vitro analysis will be statistically compared and data from the non-linear 3D-FE method will be quantitatively and qualitatively compared with the aid of strain values and maps. (AU)