Initial in vitro bacterial adhesion on dental restorative materials.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory experiment on biomaterials (bench research)
PubMed 23065885 · doi:10.5301/ijao.5000153
What was done
Researchers evaluated initial bacterial adhesion across 60 cylindrical slabs made from four dental restorative materials: zirconia (Zr), alumina-toughened zirconia (Al-Zr), type III gold alloy (Au), and commercially pure titanium (Ti). All specimens were polished to a mirror-like finish, and surface roughness was verified using atomic force microscopy. Surface free energy was determined by contact angle measurements. Following salivary pellicle formation, specimens were incubated for 4 hours with Streptococcus sanguinis, Streptococcus gordonii, or Streptococcus oralis. Adherent bacteria were quantified using crystal violet staining and resazurin reduction assays, analyzed via one-way ANOVA and Tukey's post hoc tests.
What was found
Surface roughness (Ra) values were below 5 nm for all polished specimens. Surface free energy increased in the order of Al-Zr, Zr, Ti, and Au. Significant differences were observed among materials for both crystal violet absorbance and fluorescence intensities, with gold alloy demonstrating significantly higher adhesion for all three bacterial strains compared to the other materials (p < 0.05). Specific numerical values for absorbance and fluorescence were not reported in the abstract.
Why it matters
Initial bacterial adhesion is a critical factor in biofilm accumulation and subsequent peri-implant disease. These results suggest that zirconia, alumina-toughened zirconia, and titanium may be preferable to gold alloy for restorative abutments to minimize early streptococcal colonization.
Limits
This was an in vitro bench study that cannot replicate the dynamic oral environment, including salivary flow, shear forces, host immune defenses, and complex polymicrobial interactions. The evaluation was limited to a 4-hour incubation window and single-strain inoculations of three oral streptococci.
Cited by
- contradicts Gold dental restorations are antibacterial and support a healthy oral microbiome.