Comparison of stresses in monoblock tilted implants and conventional angled multiunit abutment-implant connection systems in the all-on-four procedure

Özge Özdal Zincir,Ateş Parlar

doi:10.1186/s12903-021-02023-y

Abstract

BackgroundThe All-on-four dental implant method is an implantology method designed to provide a comfortable prosthetic treatment option by avoiding advanced surgical procedures. This research aims to compare and evaluate the stress and tension values in conventional angled multiunit abutment-implant connection systems and monoblock dental implants used in the all-on-four procedure with finite element analysis.MethodsTwo master models were created by placing four implants connected to multiunit abutments (group A) in the interforaminal region of a completely edentulous mandible and four monoblock implants (group B) in the same region of another completely edentulous mandible. Group A implants were classified according to their diameter as follows: 3.5 mm (M1A), 4.0 mm (M2A), and 4.5 mm (M3A). Similarly, group B implants were classified as M1B, M2B, and M3B. In the six models rehabilitated with acrylic fixed prostheses, a 100 N force was applied to the anterior implant region, and a 250 N force was applied to the posterior cantilever in both axial and 30° oblique directions. Von Mises stresses were analyzed in the bone and implant regions of all models.ResultsM1A and M1B, M2A and M2B, and M3A and M3B were compared with each other under axial and oblique forces. The maximum Von Mises stresses in the bone around implants and the prosthesis screws, and the maximum and minimum principal stresses in the cortical and trabecular bone in group A models were significantly higher than those in group B models.ConclusionsIn monoblock implant systems under axial and oblique forces, higher stress is accumulated in the bone, prosthesis screw and implant compared to multiunit abutment-implant connection systems.

Highlights

The All-on-four dental implant method is an implantology method designed to provide a comfortable prosthetic treatment option by avoiding advanced surgical procedures
The maximum von Mises stress (VMS) (MPa) values in the implants and prosthesis screws and the minimum– maximum principal stress (PS) (MPa) values in the cortical and trabecular bone are shown in Tables 3, 4, 5 and 6, and their distribution is shown in Figs. 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16
Assessment of the models Assessment of VMS in implants The highest VMS values under axial and oblique loading in both anterior and posterior implants were observed in the M1B model

Summary

Introduction

The All-on-four dental implant method is an implantology method designed to provide a comfortable prosthetic treatment option by avoiding advanced surgical procedures. Dental implant-supported restorations are preferred over complete dentures as they provide edentulous patients with a more comfortable treatment option. Eliasson et al [5] suggested that four implants can be distributed between the mental foramina to receive fixed restorations in edentulous patients. A limited bone volume between the mental foramina necessitates the fabrication of prostheses with long-span cantilevered segments distal to posterior implants. The presence of cantilevers in fixed restorations can augment the load on implants up to two or three times due to bending moments. Some alternatives have been proposed to overcome these limitations, such as placing a short implant distal to the mental foramina and combining the cantilever segment with these implants [6]

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