Stability of cp‐Ti and Ti‐6Al‐4V alloy for dental implants as a function of saliva pH – an electrochemical study

Abstract

Objectives To investigate the role of different levels of pH of artificial saliva under simulated oral environment on the corrosion behavior of commercially pure titanium (cp‐Ti) and Ti‐6Al‐4V alloy. Special attention is given to understand the changes in corrosion kinetics and surface characterization of Ti by using electrochemical impedance spectroscopy (EIS). Materials and methods Fifty‐four Ti disks (15‐mm diameter, 2‐mm thickness) were divided into six groups (n = 9) as a function of saliva pH (3, 6.5, and 9) and Ti type. Samples were mechanically polished using standard metallographic procedures. Standard electrochemical tests, such as open circuit potential, EIS, and potentiodynamic tests were conducted in a controlled environment. Data were evaluated by two‐way ANOVA, Tukey multiple comparison test, and independent t‐test (α = 0.05). Ti surfaces were examined using white‐light‐interferometry microscopy and scanning electron microscopy (SEM). Results Saliva pH level significantly affected the corrosion behavior of both Ti types. At low pH, acceleration of ions exchange between Ti and saliva, and reduction of resistance of Ti surface against corrosion were observed (P < 0.05). Corrosion rate was also significantly increased in acidic medium (P < 0.05). Similar corrosion behavior was observed for both Ti types. The white‐light‐interferometry images of Ti surfaces show higher surface changes at low pH level. SEM images do not show detectable changes. No pitting corrosion was observed for any group. Conclusions The pH level of artificial saliva influences the corrosion behavior of cp‐Ti and Ti‐6Al‐4V alloy in that lower pH accelerates the corrosion rate and kinetics. The corrosion products may mitigate the survival rate of dental implants.

The role of nicotine, cotinine and caffeine on the electrochemical behavior and bacterial colonization to cp-Ti

“…Additionally, although attention has been closely paid to the adverse result of nicotine on the bone healing [26,27]; and the effect of saliva, fluoride, human plasma, osteoclast, biofilm and lipopolysaccharide on the corrosion behavior of titanium [13,14,[28][29][30], to the best of the authors' knowledge, there have been no study to date that have evaluated the influence of smoking compounds and caffeine on the electrochemical stability of titanium.…”

“…Nevertheless, the complex oral environment can potentially damage the longevity of dental implants due to the presence of chemical, microbial and physical agents such as saliva, acid, fluoride, bacteria and mastication load [13,17,18]. Such conditions can impair the electrochemical stability of titanium which may be a factor contributing to the failure of the implant-bone interface [19].…”

“…Titanium and its alloy have been used for dental implant due to their good strength, corrosion resistance, and biocompatibility [13][14][15][16]. Nevertheless, the complex oral environment can potentially damage the longevity of dental implants due to the presence of chemical, microbial and physical agents such as saliva, acid, fluoride, bacteria and mastication load [13,17,18].…”

Fundamentals of Linking Tribology and Corrosion (Tribocorrosion) for Medical Applications: Bio-tribocorrosion

“…Numerous studies have attempted to investigate the chemical corrosion of titanium surfaces [33,34,[51][52][53][56][57][58][59][60][61][62][63][64]; however, very few have reported on the effect of combined chemical and mechanical actions, which resemble the clinical oral environment [3]. Vieira et al (2006) [30] investigated the tribocorrosion behavior of commercially pure titanium in contact of artificial saliva with different levels of pH (3.8, presence of citric acid, and 5.5) and the presence of inhibitors included in the content of tooth-cleaning agents or medicines (sodium nitrite, anodic inhibitor; calcium carbonate, cathodic inhibitor; and benzotriazole, organic inhibitor).…”

“…It provides an integrated protocol to study the material degradation mechanisms as mechanical movements combined with environmental effects. For example, a dental implant is exposed to a constantly changing oral environment, which due to the patient's diet can have sudden changes in pH levels [33,34]. Additionally, mechanical movements of the mouth play a role during the mastication process (2,000 mastication cycles/day) [3].…”