Ti-15Mo Alloy Decreases the Stress Concentration in Mandibular Angle Fracture Internal Fixation Hardware

Comparison of the mechanical stability of 2.0 plates made of commercially pure titanium (cpTi) and a titanium-molybdenum (Ti-15Mo) alloy and two methods of internal fixation employed mandibular angle fractures, using 3D finite element analysis.

Four groups were evaluated. For the cpTi: group Eng 1P, one 4-hole plate and 4 screws 6 mm long, in the tension zone of the mandible; group Eng 2P, two 4-hole plates, one in the tension zone of the mandible and the other in the compression zone, both were fixed with 8 screws 6 mm long. The same groups were created for the Ti-15Mo alloy. A 100 N compressive load was applied to the occlusal surface of the mandibular first molar on the plated side.

When considering the von Mises equivalent stress (σ _vM) values for the comparison between both groups with one plate, a decrease of 10.5% in the plate and a decrease of 29.0% in the screws for the Ti-15Mo group was observed. Comparing the same groups with two plates, a decrease of 28.5% in the screws was shown for the Ti-15Mo alloy group. No significant differences were observed when considering maximum and minimum principal stresses (σ _max, σ _min), and maximum principal strain (ε _max) to the mandibular bone. The Ti-15Mo alloy plates substantially decreased the stress concentration in the screws for both internal fixation techniques and in the plate for the Ti-15Mo 1 plate group.

From a clinical standpoint, the use of Ti-Mo alloy with reduced stiffness will decrease the stress shielding between the hardware and bone, influencing the outcome of the treatment.