Stress in the Mandible with Splinted Dental Implants caused by Limited Flexure on Mouth Opening: An in vitro Study

Aim: The aim of this study was to evaluate the stress developed in the bar connecting implants and in the mandible as a result of the elastic deformation of the mandible during mouth opening when using a finite element method (FEM). Materials and methods: A three-dimensional model of an edentulous mandible was generated based on the computer tomography (CT) data of a patient. Two cylindrical implants (diameter 4.3 mm, length13 mm) were inserted in the area of the mandibular canine, premolar and molar in the mandibular model. Implants were connected with a rigid bar (width 2 mm, height 3 mm), and mouth opening was simulated on the threedimensional (3D) model. The location and magnitude of maximum von Misess stress that occurred in the mandible and in the bar were estimated. Results: The highest stress level in the mandible (4.5 GPa) and in the splint (32 GPa) was measured in the longest fixed partial denture with the implants in the mandibular left canine and left second molar position. The maximum stress in the bone was measured distal to the splinted implants. Conclusion: Since, great distance between splinted implants caused high stress during mouth opening, due to mandibular deformation, the use of a short span fixed partial denture supported by implants in the molar region of the edentulous mandible is probably more advantageous.