Finite Element Analysis of a TMJ Implant

Abstract

To determine the causes of failure of an artificial temporomandibular joint implant, one must study the magnitude and location of the maximum stresses under physiological loading. In this study, we analyzed the stresses in a commercially available TMJ implant, the bone (i.e., mandible), and the bone-implant interface using a finite element software package. Both titanium and Co-Cr-Mo/Vitallium metals as well as bones with various degrees of osteoporosis were studied. The results of the analysis showed that the maximum stresses occurred at the location of the first screw hole (closest to the condyle) of the implant. In addition, the highest microstrains were observed in the bone adjacent to the first screw hole. The results of our study have potential clinical benefit in terms of improved implant design and hence better performance.

Finite element analysis of a condylar support prosthesis to replace the temporomandibular joint

“…It is referred to as "ANAT". As with previous studies, [9][10][11] there was no contact between the prosthesis and the resected condylar surface. Each prosthesis was made from cobalt chrome alloy (Young's modulus 200 GPa) and was attached to the mandible with 6 screws.…”

“…However, this was for a much lower level of loading with only the masseter active, so the strain levels would have been considerably higher for the magnitude of muscle forces used in our study. Kashi et al 10 reported a maximum stress of 140 MPa on the prosthesis, which is about 55% of the maximum level in our study, but it was for a larger (13-hole) Christensen mandible component that used 10, 3 mm diameter screws. Ramos et al 7 found that an anatomically-shaped prosthesis with a thinner section could cause overstrain on the bone; its lower rigidity caused more load to be transferred to the bone proximally than would be the case for the thicker Christensen-type prosthesis.…”

“…We compared it with 2 variations of a Christensen-type prosthesis, versions of which have been used in previous studies. [9][10][11][12] The version in Fig. 1b in which the flat surface was in contact with the unmodified ramus of the mandible (3 mm thick) is referred to subsequently as "FLAT".…”

“…1,2 The biomechanical performance of the TMJ is well understood, 3-6 but detailed biomechanical studies using finite element analysis computer modelling have only recently investigated how different features of the mandibular component affect the stresses and strains on the implant, fixation screws, and the ramus of the mandible. Features have included the effects of the number and position of the screws, 7-9 a comparison between titanium and cobalt chrome, 10 the thickness of the component where it is fixed to the bone, 11 the effect of stress on bone of different quality (density), 10 and comparisons between standard prostheses and those that are customised to fit the ramus. 7,11 All these studies focused on designs based on current prostheses and not on new ones.…”

A comparison of stress distributions for different surgical procedures, screw dimensions and orientations for a Temporomandibular joint implant

“…The material properties of cancellous and cortical bone were calculated from bone density of each element measured by CT (Park et al, 2008). We have previously described the boundary conditions, implant dimensions, instrumentation and software used and thus they will not be repeated here (Kashi et al, 2010). Implant with a maximum of 10 screws was utilized for the analysis (Fig.…”