Osseointegration enhanced by chemical etching of the titanium surface. A torque removal study in the rabbit.

Abstract

Roughened implant surfaces are thought to enhance osseointegration. Torque removal forces have been used as a biomechanical measure of anchorage or osseointegration in which the greater forces required to remove implants may be interpreted as an increase in the strength of osseointegration. The purpose of this study was to compare the torque resistance to removal of screw shaped titanium implants having an acid etched (HC1/H2SO4) surface (Osseotite) with implants having a machined surface. Two custom screw shaped implants, 1 acid etched and the other machined, were placed into the distal femurs of 10 adult New Zealand White rabbits. These implants were 3.25 mm in diameter x 4.00 mm in length without holes, grooves or slots to resist rotation. Following a 2 month healing period, the implants were removed under reverse torque rotation with a digital torque measuring device. Two implants with the machined surface preparation failed to achieve osseointegration. All other implants were found to be anchored to bone. Resistance to torque removal was found to be 4 x greater for the implants with the acid etched surface as compared to the implants with the machined surface. The mean torque values were 20.50 +/- 6.59 N cm and 4.95 +/- 1.61 N cm for the acid etched and machined surfaces respectively. The results of this study suggest that chemical etching of the titanium implant surface significantly increases the strength of osseointegration as determined by resistance to reverse torque rotation.

Effect of implant design and bone density in primary stability

“…So, our results contradict studies that found a higher primary stability at treated implants 8,[19][20] . However, our results can be explained by Cunha et al 21 , who concluded that the design is more important than the surface for primary stability, when verified that the stability of machined implants was the highest of those treated.…”

“…Statistically, the Master Porous and Master Screw implants were equals in the insertion torque of all densities and shows that the presence of surface treatment did not influence the results, despite having selected the use of machined implants (Master Screw and Conect Cônico) as negative control, due to better biomechanical characteristics of the treated implants, which its surface roughness, theoretically promotes a larger area of bone-implant contact [18][19] . So, our results contradict studies that found a higher primary stability at treated implants 8,[19][20] .…”

Microcosm Biofilm Formation on Titanium Surfaces

“…Initial biofilm formation may be influenced by the implant surface and the adhesion of microorganisms seems to be directly proportional to surface roughness 35,43,[45][46][47][48][49][50][51] . Other studies also confirm the relationship between surface roughness and the efficiency for osseointegration [52][53][54][55] . Thus, the rougher the surface, the larger the accumulation of biofilm 46,48 , and the greater the chances for clinical failure due to the interplay between these factors.…”

“…The relationship between surface treatment with nitric acid etching (E) and the lower amount of microorganisms in the first two assessment periods (12 and 24 hours) may be associated with a decrease in roughness, compared to groups where sand-blasted was used, due to the acid etching process, or to a possible antimicrobial property of the nitric acid. Some studies aimed to maximize the quantity and quality of the bone-implant interface, reported that several changes in the implant surface have been proposed, most of them based on the assumption that a better and quicker osseointegration may be achieved by changing the topography or roughness of the implant 52,53,59 . Since the R a values found in the present study were different between the groups, biological results may not have been influenced by roughness according to the experimental periods assessed (48 to 168 hours) but rather by factors such as irregular surface topography, surface contamination by aluminum (Al) particles or possible changes in the surface energy of the metal by the surface treatments used.…”

Titanium dental implant surfaces

“…Studies have shown that Ti implants with adequate roughness may enhance bone-to-implant contact [6] and increase the removal torque force [7][8][9]. Elias et al [10] analyzed different methods for increasing surface roughness and improving dental implant osseointegration.…”