Nano Bioactive Glass. A High Potential Material for Root Canal Infection Treatment

Bioactive glasses are potentially interesting materials in dentistry not only because of their ability to mineralize dentine [1] but also due to their antimicrobial effect in closed systems [2]. We investigated nanometric bioactive glasses because of their higher surface area and their faster mode of action. Furthermore, we tested the hypothesis whether nano-sized bioactive glasses also kill microbiota via mineralization or the release of ions other than sodium. Flame-spray synthesis was applied to produce nanometric glasses (Figure) with different sodium content. Calcium hydroxide was used as a control. Standardized bovine dentine disks with adherent E. faecalis. cells were exposed to test and control suspensions.

Sodium containing glasses induced pH levels above 12, compared to less than pH 9 with sodium-free glasses. Calcium hydroxide and the sodium containing glasses killed all bacteria after 1 d. The study revealed that bioactive glasses have both, a not and a directly pH-related antibacterial effect. The former is due to ion release rather than mineralization [4].

Our study shows that nanoparticulate biomaterial can have a strong combined antimicrobial action. This opens wide applications in clinical settings.

Figure: Transmission electron microscopy image of bioactive glass nanoparticles (left). Scannning electron microscopy image of a dentine surface after treatment for 1 week with ultrafine bioactive glass showing no viable bacteria (right).

References

[1] M. Vollenweider, T.J. Brunner, S. Knecht, R.N. Grass, M. Zehnder, T. Imfeld, W.J. Stark, Acta Biomater., 2007, 3(6), 936-43.

[2] P. Stoor, E. Soderling and J.I. Salonen, Acta Odontol. Scand., 1998, 56(3), 161-5.

[3] T.J. Brunner, R.N. Grass and W.J. Stark, Chem. Commun., 2006, 13, 1384-86.

[4] M. Gubler, T.J. Brunner, M. Zehnder, T. Waltimo, B. Sener and W.J. Stark, Int. Endod. J., 2008, in press.