Comparative assessment of various implant configurations for atrophic maxilla: A three-dimensional finite element...

This study aimed to evaluate stress distributions in zygomatic, trans-sinus, and pterygoid implants and the surrounding atrophic maxillary alveolar bone using finite element analysis (FEA).

Three-dimensional (3D) FEA models with 10-mm conventional implants in the lateral incisor regions were designed. For posterior anchorage, 30° trans-sinus or 45° zygomatic implants (placed using the extrasinus technique) were positioned in the second premolar region, with or without 45° pterygoid implants in the second molar region. Accordingly, four models were created: (1) zygomatic, (2) zygomatic and pterygoid, (3) trans-sinus, and (4) trans-sinus and pterygoid implant. A titanium bar-supported polymethyl methacrylate prosthesis was designed for occlusal restoration. A force of 300 N was applied vertically and obliquely (at 20°) to each model.

Oblique forces caused higher stress than vertical forces. Compared with trans-sinus implant models, zygomatic implant models exhibited lower stress under vertical loading (except in the premolar implants and cancellous bone) and oblique loading (except in the cancellous bone around the anterior implant). Adding pterygoid implants to those in the All-on-4 protocol (All-on-6 protocol) significantly reduced stresses on the bone and restoration, and the von Mises stress in the premolar implants decreasing by >50 % in the pterygoid models.

The most ideal configuration for rehabilitation of the atrophic maxilla was Model 2 with zygomatic and pterygoid implants, but the stress values in Model 4, which used trans-sinus and pterygoid implants, were close to those in Model 2. Pterygoid implants can be considered a useful addition to All-on-4 or zygomatic implants.