Antibacterial Effects of Modified Orthodontic Mini-implants to S. Mutans

Objectives: Objectives: The widespread use of mini-implants in orthodontics has enhanced treatment capabilities; yet, failure rates are higher than endosseous dental implants, often accompanied by soft tissue inflammation, possibly from insufficient osseous contact and an inadequate soft tissue barrier failing to thwart bacterial challenges. Streptococcus mutans as an early biofilm colonizer has been linked to failed endosseous implants. Literature suggests that enhancing the native TiO2 on titanium surfaces improves osseointegration, increases antibacterial effects, and increases soft tissue adhesion. The goal of this study was to enhance the TiO2 surface of mini-implants and evaluate the resultant anti-adherent, antibacterial, and topographical changes in the presence of S. Mutans.

Methods: Methods: 30 mini-implants from Aarhus (American Orthodontics, Sheboygan, Wisc) compromised of Ti6I4V, (Wrought Titanium-6 Aluminium 4 Vanadium ELI) were oxidized in 30% H2O2 at 80° C then aged in H2O at 80° C. These samples and 20 unmodified implants were placed in 2ml of BHI broth and 30μl Streptococcus mutans were added and incubated at 37° C. Initial contact was evaluated after 4 hours using resazurin dye that was measured on a fluorescence plate reader. Bacterial growth was evaluated at 4, 8, and 24 hours using a spectrometer to assess turbidity. Three samples were also plated to evaluate growth. SEM images were taken prior to and after treatment to assess topographical changes. ANOVA and pair-wise post-hoc tests were used to analyze the data.

Results: Results: Overall, bacterial adherence and growth differed significantly between groups. ANOVA and pair-wise comparisons between the treated and untreated groups indicated that treated mini-implants had significantly fewer viable adherent bacteria after 4 hours (p< 0.001). Growth over 24 hours on the treated mini-implants was also significantly decreased (p< 0.001).

Conclusions: Conclusion: Preliminary results show that modifying the titanium alloy surface of orthodontic mini-implants potentially increases antiadherent and antibacterial properties against Streptococcus mutans.