Impact de deux orthèses d'avancée mandibulaire sur l'articulation temporomandibulaire

Objectives

Understand mechanical forces applied on the temporo-mandibular joint by two different designs of mandibular advancement devices.

Methods and measurements

Rigid elements model of the temporo-mandibular joint, taking into account six muscles, was developed. A study is designed to compare traction based vs. compression based devices, with mandible in a 10 mm protrusion position. Static equilibrium can be written as hyperstatic equations and resolution is obtained through numeric optimization of different criteria under constraints.

Results

For compression based device, equation results show that important strength is applied in the masseter and posterior temporal. As both muscles lift the mandible up, this implies mouth opening happens when these muscles are at rest. However, the traction based device enables 10 mm protrusion with minimal effort on these muscles. Additionally, joint contact strength is consistently less (10%) with traction based device than with compression based device.

Conclusion

This simple mechanical model enables comparison of mandibular advancement devices with different modes of action. The results found are consistent with the ones from literature. Findings on studied parameters (mouth opening, joint contact strength) may imply an improved side-effect and a compliance profile in clinical practice for traction-based over compression-based mechanisms.