Validating FE Models For Dental Prostheses Using Digital Image Correlation

Objectives: A validated numerical model for stress/strain predictions is essential to understand the biomechanical behavior of implant-supported dental prostheses. This study compared the predictions from finite element analysis (FEA) in assessing the bone strain induced by the implants with in vitro measurements given by the digital image correlation (DIC) method.

Methods: An epoxy resin model simulating the mandibular jaw bone was made for the experimental test with a combination of acrylic resin replicas of the first premolar and second molar and threaded implants replacing the second premolar and first molar. Splinted (G1 and G3) and non-splinted (G2 and G4) metal-ceramic screw-retained crowns were fabricated and loaded with (G1 and G2) or without (G3 and G4) the presence of a second molar that provided proximal contact. A single-camera, 2-dimensional DIC system was used to record deformation of the resin model surface at a frequency of 1.0 Hz until the load reached 250 N. Corresponding 3-dimensional FE models were constructed using computer-aided design (CAD) software for both splinted and non-splinted crowns.

Results: Surface strains were used for comparison between the two methods, while internal strains at the implant/resin block interface were calculated using FEA. Both methods found similar regions of compression and tension, and both found insignificant differences in surface strains between the splinted and non-splinted groups (P>0.05). However, FEA gave higher strain values (P<0.05), possibly due to an underestimated elastic modulus for the epoxy resin. The internal strains predicted by FEA at the implant-resin interface were at least 12 times higher than those on the surface of the models, but differences between the groups were again insignificant (P>0.05).

Conclusions: Within the limitations of this study design, it can be concluded that DIC is a useful tool for validating finite element models, and FEA is effective in qualifying the bone strain induced by implants.