Effect of Enterococcus faecalis Biofilm on Corrosion Kinetics in Titanium Grade 4 Alloys with Different Surface Treatments

Abstract

E. faecalis has been associated with bacteremia, sepsis, and bacterial endocarditis and peri-implantitis. This microorganism can remain in the alveolus even after extraction of the root remnant. This study aimed to evaluate the corrosion on different surfaces of commercially pure titanium (Ti) grade 4 (Ticp-G4) as a function of the bacterial biofilm effect of Enterococcus faecalis. A total of 57 discs were randomly divided according to their surface finish (n = 19). For microbiological analysis (n = 9), the discs were placed in 12-well plates containing E. faecalis culture and incubated at 37 °C for 7 days. The results show that for the intergroup analysis, considering the "electrolyte" factor, there was a difference between the groups. There was greater biofilm formation for the D.A.Zir group, with greater electrochemical exchange for Biofilm, and the presence of biofilm favored greater electrochemical exchange with the medium.

Keywords: biofilms; bone-integrated endo-osseous dental implantation; corrosion; titanium.

Figure 1

Flowchart.

Figure 2

Comparative graph between D.A., D.A.Zir, and Universal Scanning Interferometry (USI) groups considering the average of CFU/mL × 10⁵, according to ANOVA and Tukey tests (p < 0.05; different lowercase letters indicate the statistical difference).

Figure 3

Diagram of the Nyquist values of the surfaces tested are as follows: USI (BHI and Biofilm), D.A. (BHI and Biofilm), and D.A.Zir (BHI and Biofilm).

Figure 4

Graphical representation of the means and standard deviations of the Rp values for the USI, D.A. and D.A.Zir groups in Biofilm and BHI. Equal capital letters show statistical similarity between the surfaces. Equal lowercase letters show statistical similarity with respect to the electrolytes (BHI and Biofilm) between the groups.

Figure 5

Potentiodynamic curves of the USI, D.A. and D.A.Zir groups as a function of electrolytes (BHI and Biofilm).

Figure 6

Graphical representation of the means and standard deviations of the Icorr values for the groups of surfaces (USI, D.A. and D.A.Zir as a function of electrolytes (BHI and Biofilm)). A single asterisk on the indication of the specimens corresponds to the electrolyte factor. Asterisks over the specimen indication correspond to the surface factor.

Figure 7

Images obtained by MFA in an area of 50 µm by 50 µm on the surface of the Machined (USI), Double Acid Etch (D.A.) and Double Acid Etch and Zirconia Blasting (D.A.Zir) discs. Representing [USI, D.A. and D.A.Zir (Standard)] (disc received by the manufacturer for testing); [USI, D.A. and D.A.Zir (BHI)] (disk that underwent the electrochemical test without biofilm growth for 7 days) and; [USI, D.A. and D.A.Zir (Biofilm)] (disk that underwent the microbiological test for biofilm growth for 7 days followed by the electrochemical test).