A New Model to Study Fatigue in Dental Implants Based on Probabilistic Finite Elements and Cumulative Damage Model

Abstract

The aim of this study was to predict the fatigue life of two different connections of a dental implant as in load transfer to bone. Two three-dimensional models were created and assembled. All models were subjected to a natural masticatory force of 118 N in the angle of 75° to the occlusal plane. All degrees of freedom in the inferior border of the cortical bone were restrained, and the mesial and distal borders of the end of the bone section were constrained. Fatigue material data and loads were assumed as random variables. Maximum principal stresses on bone were evaluated. Then, the probability of failure was obtained by the probabilistic approach. The maximum principal stress distribution predicted in the cortical and trabecular bone is 32 MPa for external connection and 39 MPa for internal connection. A mean life of 103 and 210 million cycles were obtained for external and internal connection, respectively. Probability cumulative function was also evaluated for both connection types. This stochastic model employs a cumulative damage model and probabilistic finite element method. This methodology allows the possibility of measured uncertainties and has a good precision on the results.

Figure 1

Geometry of the dental implants analyzed in this study (L: implant total length; D: diameter). (a) External connection; (b) internal connection.

Figure 2

(a) Regions modelled in the finite element model of dental implants and bone. (b) Bone dimensions.

Figure 3

Applied loads and boundary conditions.

Figure 4

Scheme of the probabilistic model.

Figure 5

Stress distribution in dental implants. (a) Model number 1. (b) Cross section of model number 1. (c) Model number 2. (d) Cross section of model number 2.

Figure 6

Probability of failure function for external dental implant.

Figure 7

Failure probability function for internal dental implant.