Evaluation of Tension and Deformation in a Mandibular Toronto Bridge Anchored on Three Fixtures Using Different Framework Materials, Abutment Systems, and Loading Conditions: A FEM Analysis

Abstract

Objective The aim of this study was to investigate by finite element method analysis the behaviour of a three-implant mandible Toronto framework made by three different materials, with two abutment systems and two loading conditions. Materials and Methods Three implants were virtually inserted in a mandible model in positions 3.6, 4.1, and 4.6. Three prosthetic framework bars with the same design and dimension (4.8 × 5.5 mm) were projected. The variables introduced in the computer model were the framework materials (glass fiber reinforced resin, Co-Cr, TiAl6V4), the abutment systems (Multi-Unit-Abutment [MUA]/OT-Bridge), and the loading conditions (500 N vertical load on all the framework area and 400 N on a 7-mm distal cantilever). The computer was programmed with physical properties of the materials as derived from the literature. Maximum tension and deformation values for each variable were registered at framework, screws, and abutment level and then compared. Results Metal frameworks Cr-Co and TiAl6V4 resulted in lower deformation than glass fiber-reinforced resin frameworks while presenting higher tension values. The OT-Bridge exhibited lower maximum tension and deformation values than the MUA system. The first loading condition reached higher tension and deformation values than the second and it resulted in more uniformly distributed load on all the framework area, especially with the OT-Bridge system. Conclusion More rigid materials and OT-Bridge system decrease the deformation on the prosthetic components. Tension stresses are more uniformly distributed with glass fiber-reinforced resin, in the OT-Bridge system and avoiding cantilever loading.

Long-Term Clinical Outcomes of Single Crowns or Short Fixed Partial Dentures Supported by Short (≤6 mm) Dental Implants: A Systematic Review

“…51 More follow-up studies can be helpful in order to improve trustworthiness, as the force distribution is a crucial factor to avoid tension and deformation of oral appliances. 52,53 For example, it is better to check the presence of bruxism in cases of success. In addition, there is a need for uniform standard definitions for prosthesis side effects between studies.…”

Rehabilitation with implant‐supported overdentures in preteens patients with ectodermal dysplasia: A cohort study

“…The Seeger rings positioned between the bar walls and the subequatorial portion of the OT Equators allows to center the bar on the attachments before screwing, passivating the framework and compensating at the same time the small misfit originating from the prosthetic fabrication processes 27 . Moreover, the Seeger rings reduce the stress on the screws during the masticatory cycles, reducing the possibility of screw loosening/fracture 28–30 . In our study, we used a low‐profile attachment (OT Equator) that has a smaller volume than a conventional MUA and is coated with titanium nitride for an improved biocompatibility with soft tissues 31,32 …”

“…27 Moreover, the Seeger rings reduce the stress on the screws during the masticatory cycles, reducing the possibility of screw loosening/fracture. [28][29][30] In our study, we used a low-profile attachment (OT Equator) that has a smaller volume than a conventional MUA and is coated with titanium nitride for an improved biocompatibility with soft tissues. 31,32 Another factor that is worth of consideration in terms of implant prosthetic success was the sliding bar, able to anchor the overdenture and to follow the mandibular transverse growth or bone deformation during chewing or mouth opening and closure.…”