Optimizing all-on-4 full-arch restorations: Can mandibular monolithic zirconia prosthesis enhance implant biomechanics? An FEA study
Dr. Mary Delia Bondoc1, Mi-El Kim2, Zhiyan Jin1, Prof. Ho-Beom Kwon1
1 Dental Research Institute and Department of Prosthodontics, School of Dentistry, Seoul National University, Seoul, Republic of Korea,
2 Dental Research Institute and Department of Oral Anatomy, School of Dentistry, Seoul National University, Seoul, Republic of Korea
Objectives
This study aimed to investigate the stress distribution and displacement of a mandibular full-arch all-on-4 implant-supported monolithic zirconia prosthesis, as well as its influence on peri-implant bone, in order to determine an effective treatment option for patients with full mandibular edentulism.
Materials and Methods
3D finite element models of the mandible, mucosa, zirconia prosthesis, and implant components [BlueDiamond® (BD), MegaGen, Daegu, Korea] were created using CT, DICOM, and STL data. Models were developed with a mesh generating tool (Visual-Mesh; ESI Group). Four simulations were completed, each with a corresponding load direction [vertical and oblique (45°)] and static load (160 N and 300 N, respectively). Loads were distributed to the posterior teeth, specifically on buccal slope of the buccal cusp, lingual slope of the buccal cusp, and buccal slope of the lingual cusp. Finite element analysis was performed using simulation software (Visual-Crash for PAM; ESI Group). The highest von Mises stress (MPa) and displacement (µm) were then compared and assessed.
Results
Under a 300N load, cancellous bone exhibited the lowest von Mises stress (4.2 MPa), followed by cortical bone (72.18 MPa). Left premolar fixture, particularly at the distal area of the collar, exhibited the highest stresses under a 300 N oblique loading (481.59 MPa). The left premolar abutment screws yielded 287.13 MPa. The amount of stress received, from highest to lowest, was as follows: fixture, abutment screw, abutment, prosthetic screw, ZrGen Link, zirconia prosthesis, cortical bone, and cancellous bone. Our findings demonstrate that the highly stressed parts of each component were frequently located at the connection. For displacement, the zirconia prosthesis had a maximum displacement of 154.02 µm (300N oblique).
Conclusions
Although oblique loading resulted in higher stresses on the components and bone, and an increased prosthesis displacement, it did not exceed beyond the physiological limits. Given its satisfactory biomechanical performance, mandibular full-arch all-on-4 implant-supported monolithic zirconia can be a suitable definitive prosthesis for patients.