The effect of shot blasting and heat treatment on the fatigue behavior of titanium for dental implant applications.

OBJECTIVES The effect of shot blasting treatment on the cyclic deformation and fracture behavior of a commercial pure titanium with two different microstructures; equiaxed (alpha-phase) and acicular (martensitic alpha'-phase) was investigated. METHODS Fatigue tests were carried out in artificial saliva at 37 degrees C. Cyclic deformation tests were carried out up to fracture and fatigue crack nucleation and propagation were analysed. Residual stresses were determined by means of X-ray diffraction. RESULTS The results show that shot blasting treatment improves fatigue life in the different microstructures studied. The equiaxed phase has improved mechanical properties compared to the acicular one. Despite the fact that control of the variables of shot blasting is not precise because of the nature of the treatment, it improves the fatigue life by the fact that the initiation site of the fatigue crack changes from the surface of the specimen to the interior of the shot blasted specimen. This is a consequence of the layer of compressive residual stresses that the treatment generates on titanium surfaces. The acicular morphology of the martensite favors crack propagation along the interface of the alpha' plates. SIGNIFICANCE Shot blasting, which is widely used on titanium dental implants in order to favour their osseointegration, can also improve their fatigue resistance.