Abstract

Background/Objectives: One-piece (monoblock) dental implants are increasingly used, particularly in patients with limited bone availability. Prosthetic alignment is often achieved via plastic deformation of the titanium implant. This study aimed to evaluate the impact of such deformation-induced residual stress on the corrosion resistance of these implants. Methods: Two types of monoblock dental implants (spherical “S” and Mag-Conical “M”) were subjected to controlled plastic deformation. Residual stress was quantified by X-ray diffraction using the Bragg–Brentano method. Electrochemical behavior was evaluated by measuring the open-circuit potential (EOCP) and performing potentiodynamic polarization tests in phosphate-buffered saline (PBS) at 37 °C. Metal ion release (Ti, V, Al) was quantified by inductively coupled plasma mass spectrometry (ICP-MS) at specific immersion time points. Surface morphology and corrosion features were examined by scanning electron microscopy (SEM). Results: Residual stress values increased significantly after plastic deformation. The open-circuit potential (EOCP) shifted towards more electronegative values in both implant designs as deformation-induced residual stresses increased. The EOCP values shifted from −0.099 V to −0.227 V in the S design and from −0.115 V to −0.141 V in the M design, comparing the as-received condition with the deformed state, respectively. Potentiodynamic tests showed an increase in corrosion rate from 0.0021 mm/year for the original implants to 0.0156 mm/year for the deformed ones. Surfaces in the stressed regions exhibited a high density of corrosion pits, indicating localized electrochemical degradation. Deformed dental implants also exhibited higher ion release, particularly of titanium and vanadium, with higher levels observed in implants with greater residual stress and lower corrosion resistance. In the deformed regions, the release of titanium and vanadium ions into the surrounding medium was nearly five-fold higher. Conclusions: Plastic deformation of monoblock dental implants is associated with reduced corrosion resistance. Increased residual stress correlates with enhanced electrochemical degradation and ion release, which may have relevant implications for implant selection and clinical placement.

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