Evaluation of the Effects of Hybrid Prostheses Prepared from Different Materials on Pterygoid and Cancellous Bone- Anchored Posterior Maxillary Implants of Varying Lengths Using 3D Finite Element Analysis.

PURPOSE: To investigate the stresses generated in the bone, implant, substructure materials, and esthetic materials of hybrid prostheses prepared from three different substructure materials placed at different lengths in the pterygomaxillary region of completely edentulous maxillae using 3D finite element analysis (FEA).

MATERIALS AND METHODS: Implants of two different lengths, 11.5 mm (Group 1) and 18.0 mm (Group 2), were placed in the pterygomaxillary region. The 18-mm-long implant had bicortical anchorage. Hybrid prostheses were prepared using three different substructure materials: polyetheretherketone (PEEK), titanium (Ti), and zirconia (Zr). A force of 150 N was applied unilaterally at an angle of 30 degrees from the palatal direction to the buccal side.

RESULTS: Models with PEEK substructures exhibited greater displacement and shear stress values compared to those with Ti and Zr substructures. An increase in von Mises stresses was observed in the apical region of the 18-mm-long dental implants where cortical anchorage was achieved. In cortical bone, higher maximum principal stress (Pmax) and minimum principal stress (Pmin) values were noted in certain areas of the models with PEEK substructures.

CONCLUSIONS: Different substructure materials have varying effects on the prosthesis, bone, and implant. It is suggested that the use of substructure materials with high elastic modulus would be more appropriate to reduce potential prosthetic complications in hybrid prostheses and achieve predictable stress distribution in the bone. The use of maxilla-restricted dental implants should be considered when sufficient cortical bone anchorage is present around the neck region of the implants. However, in cases where cortical bone support in the neck region is insufficient, the use of implants providing bicortical anchorage may be more beneficial.