Biomechanical Analysis of Dual Acid-Etched and Chemically Modified Implant Surfaces

Introduction: Rough and chemically modified surfaces of dental implants may lead to an improvement in maintenance of secondary stability, favoring the process of remodeling and bone formation and allowing the installation of immediate function or early loading. However, there is a question how is the ideal condition of primary stability required in the initial period of osseointegration. Objectives: The objective of this preclinical in vivo study was to compare the biomechanical fixation throughout the removal torque values and its intrinsic properties, such as energy and stiffness, between two types of surfaces of dental implants: in the control group were used implants with surfaces that received blasting and dual-acid etching (E - Etched n = 12); the experimental group received dual-acid etching with concentrations of 50% of hydrochloric acid and 50% of sulfuric acid, followed by treatment with microwaves for 10 minutes at an average frequency of 2.45 GHz and the insertion in an isotonic saline of 0, 9% in order to increase the degree of hydrophilicity (H - Hydrophilic n = 12). Materials and Method: Two pairs of implants were installed bilaterally in the proximal tibia of six beagle dogs, remaining for 2 and 4 weeks in vivo. After euthanasia, the specimens were fixed for 24 hours and used for the biomechanical test (removal torque - 1.96 mm / min). The values of strength (N.cm) and the rotation angle applied to the implants were used to calculate the energy (J) and stiffness (Ncm / rad). The Tukey tests for multiple comparisons and ANOVA with 95% significance level were used for statistical analysis. Results: The test for the significance of the removal torque was statistically similar between the experimental and control groups at 2 and 4 weeks (p = 0.05), although noting a rise in values over time. The experimental group showed higher values of energy required to remove the torque, while the stiffness values were revealed very similar between the groups tested. Conclusion: The biomechanical results suggest that the initial phase of bone healing can be positively affected by the chemically modified surface; however, upcoming studies are needed to confirm these effects. Keywords: Biomechanical Evaluation, Dental Implants, Osseointegration, Dogs