Four Regular-Diameter Implants Provide Superior Biomechanical Performance for Maxillary Overdentures in Bruxism: Study

A new study published in The Journal of Prosthetic Dentistry showed that the best biomechanical behavior was shown by overdentures supported by four regular-diameter implants. On the other hand, under conditions of repeated loading, overdentures made of both polymethyl methacrylate (PMMA) and polyether ether ketone (PEEK) showed inadequate fatigue endurance.

Severe teeth grinding concentrates excessive stress on the implants and surrounding bone, changing the usual distribution of occlusal force. It is essential to comprehend how bruxism affects these stresses in order to optimize prosthetic design and avoid long-term mechanical problems. This study used polymethyl methacrylate and polyether ether ketone denture base materials to assess the biomechanical impact of bruxism on maxillary IODs with various implant designs.

In this study, with different implant numbers, sizes, and locations, four 3-dimensional finite element models of maxillary IODs were created. The implant configuration was used to designate the models: R4 had four regular-diameter implants in the regions of the lateral incisor and first premolar; N4 had four narrow-diameter implants in the same locations; R2N1 had two regular-diameter posterior implants and one narrow-diameter midline implant; and R2 had two regular-diameter implants in the canine regions. PMMA and PEEK overdentures were used to examine each model under three occlusal relationships and simulated bruxism loads (1350 N). Fatigue behavior, von Mises stress, and total deformation were assessed.

Implant distribution had a bigger influence on biomechanical behavior than overdenture material. While N4 and R2N1 produced greater cortical bone stresses (about 80 to 85 MPa), nearing fatigue limits, R4 displayed the lowest cortical bone (roughly 48 to 55 MPa) and implant stresses (approximately 135 to 160 MPa).

The largest mucosal deformation (up to around 98 µm) was seen in R2. While PEEK overdentures showed more deformation (up to about 270 µm) with lower stress magnitudes (about 90 to 135 MPa), PMMA overdentures showed less deformation (<100 µm) but higher stress values (up to about 300 MPa). Under simulated bruxism loads, both materials surpassed stated fatigue limits.

Overall, maxillary overdentures supported by four regular-diameter implants showed the best biomechanical performance under simulated bruxism circumstances. Overdentures made of PEEK and PMMA both have poor fatigue resistance. These results highlight the need for frequent maintenance and ideal implant distribution for bruxism patients receiving maxillary overdenture therapy. Using four regular-diameter implants may boost biomechanical stability and perhaps improve long-term clinical results.

Reference:

Aldowah, O., Zarbah, M., Okshah, A., Alyami, M. H., Almobti, M. N., & Mosaddad, S. A. (2026). Influence of bruxism on occlusal force distribution in maxillary implant-supported overdentures: A finite element analysis study. The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2026.05.057