Ti Alloy Surface Modifications and Coatings: An Update

Since 1952 when Branemark first reported osseointegration of titanium (Ti) with bone, many academic and industrial research activities have endeavored to improve the efficacy of Ti or Ti alloy (Ti6Al4V) by modifying the chemistry, topography and design of the implant surface. Strong bonding between implant and host tissue minimize the micromovements that promote fibrous tissue formation at the implant interface that may lead to implant failure. Surface design include lateral holes perpendicular to the implant axis, grooves, variations of spacings between ridges, etc. Physico-mechanical means of surface modification is by grit-blasting with various abrasives (alumina, silica, apatitic abrasive), laser ablation, spark discharge, etc. Chemical modifications include: acid etching, treatment with alkali, treatment with fluoride, coating with titanium or with calcium phosphate (by plasma spray, electromagnetic sputtering, electrochemical deposition). A review of studies on Ti or Ti alloy implants with different surfaces showed the following methods to enhance osseointegration and greater bone formation: (1) grit-blasting with apatitic abrasive; (2) acid-etching with mixed acids; (3) adjusting plasma-spray parameter to get a higher HA/ACP ratio in the coating; (4) employing electrochemical deposition (with pulse modulation) or precipitation to obtain thin coating with homogeneous composition; and/or (5) Ftreatment.