Cleaning and heat-treatment effects on unalloyed titanium implant surfaces

This study tested the following hypotheses: (1) acid-cleaned and passivated unalloyed titanium implants have higher surface energies (which are consid ered desirable for hone implants) than ethanol-cleaned titanium; (2) higher temperatures of heat treatment of unalloyed titanium result in higher surf ace energies; and (3) these changes can be related to changes in surface co mposition and roughness. Thus, unalloyed titanium specimens were either aci d-cleaned and passivated (CP) or ethanol-cleaned (Et). Each set was then di vided into 3 groups and heat-treated for 1 hour at 316 degrees C (600 degre es F), 427 degrees C (800 degrees F), and 538 degrees C (1,000 degrees F), respectively. Surface roughness values for each of these groups were determ ined using atomic force microscopy, while surface compositions were determi ned using Auger electron, x-ray photoelectron, and Raman spectroscopic tech niques. Surface energies were estimated using a 2-liquid geometric mean tec hnique and correlated with surface roughness, elemental composition, and el emental thickness. The CP surfaces were slightly rougher than the Et specim ens, which had greater oxide thickness and hydrocarbon presence. The surfac e oxides were composed of TiO2, Ti2O3, and possibly titanium peroxide; thos e heat-treated at 427 degrees C or above were crystalline. The CP specimens had carbonaceous coverage that was of a different composition from that on Et specimens. The CP specimens had significantly higher surface energies, which showed statistically significant correlations with oxide thickness an d carbonaceous presence. In conclusion, ethanol cleaning of unalloyed titan ium dental implants may not provide optimal surface properties when compare d to cleaning with phosphoric acid followed by nitric acid passivation.