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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.

The maximum implant insertion torque depends on the implant geometry, thread form, and implant surface morphology. The placement of conical implants with treated surfaces required the highest insertion torque. There was no correlation between RFA and insertion torque implant.

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The physical characteristics of an implant surface can determine and/or facilitate osseointegration processes. In this sense, a new implant surface with microgrooves associated with plus double acid treatment to generate roughness was evaluated and compared in vitro and in vivo with a non-treated (smooth) and double acid surface treatment. Thirty disks and thirty-six conical implants manufactured from commercially pure titanium (grade IV) were prepared for this study. Three groups were determined, as described below: Group 1 (G1), where the samples were only machined; group 2 (G2), where the samples were machined and had their surface treated to generate roughness; and test group 3 (G3), where the samples were machined with microgrooves and the surface was treated to generate the roughness. For the in vitro analysis, the samples were submitted to scanning microscopy (SEM), surface profilometry, the atomic force microscope (MFA) and the surface energy test. For the in vivo analyses, thirty-six implants were placed in the tibia of 9 New Zealand rabbits in a randomized manner, after histological and histomorphometric analysis, to determine the level of contact between the bone and implant (BIC%) and the bone area fraction occupancy (BAFO%) inside of the threads. The data collected were statistically analyzed between groups (p < 0.05). The in vitro evaluations showed different roughness patterns between the groups, and the G3 group had the highest values. In vivo evaluations of the BIC% showed 50.45 ± 9.57% for the G1 group, 55.32 ± 10.31% for the G2 group and 68.65 ± 9.98% for the G3 group, with significant statistical difference between the groups (p < 0.0001). In the BAFO% values, the G1 group presented 54.97 ± 9.56%, the G2 group 59.09 ± 10.13% and the G3 group 70.12 ± 11.07%, with statistical difference between the groups (p < 0.001). The results obtained in the evaluations show that the surface with microgrooves stimulates the process of osseointegration, accelerating the healing process, increasing the contact between the bone and the implant and the area of new bone formation.