Influence of bone quality on the mechanical interaction between implant and bone: A finite element analysis

Objectives: To evaluate the influence of bone type in terms of bone density and cortical bone thickness, on the stresses induced by two implants under compressive and oblique loads.

Methods: A numerical simulation technique based on the finite element method was applied. Two implant types (M-12 and Astra Tech) were introduced in a model matrix whose geometry was extracted from a real CBCT radiograph of the posterior mandibular region. The Young's module and Poisson's coefficient of the bone qualities described by Misch were calculated. Loads with amplitude of 400 N were exerted in two directions: compressive and 15° oblique to 5 mm above the uppermost part of the implant.

Results: The von Misses variant was analysed. Both implant types presented greater tension in the ​​cortical bone area than in the ​​trabecular bone region under compressive loading. For the oblique load condition, the stresses obtained in the cortical zone were significantly higher than those registered as a consequence of compressive loads in both implant types.

Conclusions: Regardless of bone type, the M-12 implants presented lower tensions in the cortical bone than did the Astra implants. The tensions recorded for D3 and D4 bone types in the trabecular zone surrounding the M-12 implants were greater than those recorded for the Astra implants.

Clinical significance: For both compressive and oblique loads, good mechanical behaviour was observed. The decrease in bone quality determines a worse stress distribution, and the cortical bone is overloaded. An efficient distribution of the forces may increase the implants' longevity.