Validation of finite-element simulations with synchrotron radiography – A descriptive study of micromechanics in two-piece dental implants

Abstract

State-of-the art, two-piece dental implants made from titanium alloys exhibit a complex micromechanical behavior under dynamical load. Its understanding, especially the formation of microgaps, is of crucial importance in order to predict and improve the long-term performance of such implants. Microgap formation in a loaded dental implant with a conical implant-abutment connection can be studied and quantified by synchrotron radiography with micrometer accuracy. Due to the high costs and limited access to synchrotron radiation sources, alternative approaches are needed in order to depict the microgap formation. Therefore, synchrotron radiography is used in this article to validate a simple finite element model of an experimental conical implant design. Once validated, the model is in turn employed to systematically study the microgap formation developed in a variety of static load scenarios and the influence of the preload of abutment screw on the microgap formation. The size of the microgap in finite element analysis (FEA) simulations is consistent with that found in in-vitro experiments. Furthermore, the FE approach gives access to more information such as the von-Mises stresses. It is found that the influence of the abutment screw preload has only a minor effect on the microgap formation and local stress distribution. The congruence between FE simulations and in-vitro measurements at the micrometer scale underlines the validity and relevance of the simple FE method applied to study the micromovement of the abutment and the abutment screw preload in conical implant-abutment connections under load.

Contact analysis of gap formation at dental implant‐abutment interface under oblique loading: A numerical‐experimental study

“…To simulate the load in the in vitro test, we employed a concentrated point load as used in other FE analyses. 16,17 As the results showed, there was a significant difference between centric and eccentric loading in the predicted "bridging" load and interfacial area in contact ( Figures 5 and 6).…”

“…16,17 As the results showed, there was a significant difference between centric and eccentric loading in the predicted "bridging" load and interfacial area in contact ( Figures 5 and 6). 16,17 As the results showed, there was a significant difference between centric and eccentric loading in the predicted "bridging" load and interfacial area in contact ( Figures 5 and 6).…”

“…However, the Morse taper connection has been shown to better prevent microleakage with smaller micro-gaps compared to the butt-joint and external connection. 17 F I G U R E 1 Photos of the components, three-dimensional finite-element models with structured meshes of the conical connection (A) and the external hexagonal connection (B). 16 Good agreement between FE simulation and in vitro measurements of the size of micro-gaps has been reported.…”

“…16 Good agreement between FE simulation and in vitro measurements of the size of micro-gaps has been reported. 17 F I G U R E 1 Photos of the components, three-dimensional finite-element models with structured meshes of the conical connection (A) and the external hexagonal connection (B). Top views of the load adaptor showing the positions and directions (arrows) of the concentrated force applied for centric and eccentric loading (C) F I G U R E 2 In vitro test set up However, the reported micro-gap size varies considerably (from 0 to 135 μm), depending on the technique used.…”

Principles of biomechanics in oral implantology

“…ISO 14801 (Dynamic loading test for endosseous dental implants) is currently the accepted standard for these tests, although it has severe limitations [6]. More and more authors suggest using Fine Element Analysis (FEA) as a substitute or in conjunction with the classical means of testing, as it can provide supplemental information and reduce testing time and costs [7,8]. Even the best results in laboratory testing and FEA cannot guarantee clinical success, if the basic biomechanical principles are not taken into consideration during insertion and loading.…”