A three-dimensional finite element analysis of short dental implants in the posterior maxilla

Purpose: This study evaluated the biomechanical behavior of short dental implants with different heights of residual bone and compared it with that of standard dental implants in 13 mm or less of residual bone by means of finite element analysis. Materials and Methods: It was assumed that the maxillary first and second molars had been replaced with splinted cast gold crowns supported by two implants. A total of five posterior edentulous maxilla models were fabricated with various residual bone heights (13 mm, 7 mm, 6 mm, 5 mm, and 4 mm). Residual bone height was 13 mm in the group 1 model (control) and 7, 6, 5, and 4 mm in group 2-1, group 2-2, group 2-3, and group 2-4 models, respectively. In the group 1 model, two identical implants (4.5 × 11 mm) and abutments (6 × 2.5 mm) were placed. In the group 2 models, two identical wide/short implants (6 × 5.7 mm) and abutments (6 × 5 mm) were placed. Off-axis (30 degrees) loading of 187 N was applied to the central fossae of the two implant-supported crowns. Results: Maximum von Mises stresses in crestal cortical bone were lower in group 2 models than in the group 1 model. Conclusion: This numeric simulation confirmed that, without maxillary sinus bone graft, more effective stress distribution could be obtained in 4, 5, 6, or 7 mm of residual bone with short dental implants than in 13 mm of residual bone with standard dental implants.