Relationship between surface properties (roughness, wettability and morphology) of titanium and dental implant removal torque.

The biological properties of titanium depend on its surface oxide film. Several mechanical and chemical treatments have been used to modify the surface morphology and properties of titanium dental implants. One possible method of improving dental implant biocompatibility is to increase surface roughness and decrease the contact angle. In the present work, the biological properties of dental implants were investigated through in vivo and in vitro tests. The effects of surface roughness, contact angle and surface morphology on titanium dental implant removal torque were investigated. Machined dental implants and discs made with commercially pure titanium ASTM grade 4 were submitted to sandblasting treatments, acid etching and anodizing. The sample surface morphologies were characterized by SEM, the surface roughness parameters were quantified using a laser non-contact profilometer, and a contact angle measurement was taken. Dental implants were placed in the tibia of rabbits and removed 12 weeks after the surgery. It was found that: (i) acid etching homogenized the surface roughness parameters; (ii) the anodized surface presented the smallest contact angle; (iii) the in vivo test suggested that, in similar conditions, the surface treatment had a beneficial effect on the implant biocompatibility measured through removal torque; and (iv) the anodized dental implant presented the highest removal torque.