Biomechanics in Removable Partial Dentures: A Literature Review of FEA-Based Studies

Abstract

The present study was aimed at reviewing the studies that used finite element analysis (FEA) to estimate the biomechanical stress arising in removable partial dentures (RPDs) and how to optimize it. A literature survey was conducted for the English full-text articles, which used only FEA to estimate the stress developed in RPDs from Jan 2000 to May 2021. In RPDs, the retaining and supporting structures are subjected to dynamic loads during insertion and removal of the prosthesis as well as during function. The majority of stresses in free-end saddle (FES) RPDs are concentrated in the shoulder of the clasp, the horizontal curvature of the gingival approaching clasp, and the part of the major connector next to terminal abutments. Clasps fabricated from flexible materials were beneficial to eliminate the stress in the abutment, while rigid materials were preferred for major connectors to eliminate the displacement of the prosthesis. In implant-assisted RPD, the implant receive the majority of the load, thereby reducing the stress on the abutment and reducing the displacement of the prosthesis. The amount of stress in the implant decreases with zero or minimal angulation, using long and wide implants, and when the implants are placed in the first molar area.

Performance of Graphene-Based and Polyether-Ether-Ketone Polymers as Removable Partial Denture Esthetic Clasp Materials after Cyclic Fatigue

“…In the same context, the retentive terminal and the reciprocal arm are subjected to friction, which is magnified as the retentive terminal crosses the survey line to the undercut areas. These findings coincide with previous studies showing bands of stress concentration at the junction of the clasp arm with the minor connector [ 1 , 13 , 17 , 29 , 33 ]. It is also in harmony with the deformation pattern seen mostly in the arm terminals as a response to the arm fatigue [ 11 , 33 ].…”

“…This could be seen clearly in Figure 2 , where the graph shows a higher level for PEEK material than GBP in all measured cycles [ 34 ]. It was believed that the thickness, width, length, and depth of the undercut could play a major role in the stress generated [ 1 , 13 ]. The optimization process may encompass increasing the clasp dimensions and may limit its use to certain clinical conditions [ 13 , 15 , 35 ].…”

“…The reciprocal arm also has more rigidity than the retentive arm, as it has a less taper and length. Therefore, the retentive arm exerts more displacement than the reciprocal arm and is more flexible, so it is expected to have more deformation [ 1 , 33 , 41 ]. By the end of 10,000 cycles, the clasp arms showed deformation at the clasp tips, expressing the arms’ fatigue ( Figure 3 ).…”

“…The removable partial denture (RPD) has been used as a successful treatment for many decades. It is indicated in several clinical conditions that tooth-supported or implant-supported fixed partial dentures might not be suitable [ 1 , 2 ]. The removable partial denture is the preferred treatment option for patients having few remaining teeth, poor periodontal condition, inadequate residual bone for implant placement, and those who underwent bone grafting as a temporary prosthesis.…”

“…The major shortcomings of the alloys such as cobalt-chromium (Co-Cr) are the unesthetic color of the material, corrosion tendency, and harmful effect on the periodontal ligaments because of high rigidity [ 11 ]. Recently, many esthetic materials, such as acetal resin, aryl ketone, ceria-stabilized zirconia/alumina nanocomposite, polyester, polyamide, polyaryl-ether-ketone, and polyether-ether-ketone have been used to replace the framework alloys [ 1 , 6 , 8 , 11 , 12 , 13 , 14 , 15 ]. These esthetic materials were not only able to exchange the metal display of the RPD alloys but also minimize the forces on the abutment teeth because of their flexibility [ 5 , 10 ].…”