Comparative analyses of ion release, pH and multispecies biofilm formation between conventional and bioactive gutta-percha

Aim: To analyse the effect of commercial and experimental gutta-percha with the addition of niobium phosphate glass on biofilm formation by oral bacteria from human dental plaque. Additional pH and elemental release of the materials were analysed.

Methodology: The multispecies biofilm was grown anaerobically from plaque bacteria on standardized discs of each material: hydroxyapatite (HA), gutta-percha pellets (OBT) (Obtura pellets, Shoreline, CT, USA), ProTaper gutta-percha (PTP) (ProTaper Universal Gutta-Percha Points, Dentsply Maillefer, Ballaigues, Switzerland), EndoSequence BC gutta-percha (GBC) (Brasseler USA, Savannah, GA, USA), experimental gutta-percha associated with niobium phosphate glass (GNB) and niobium phosphate glass (NPG). Specimens (n = 5 per group and per incubation period) were incubated in brain-heart infusion broth for 3, 14 and 30 days, at 37 °C, and stained using live/dead viability assay. Images were analysed by confocal laser scanning microscopy (CLSM) and the total biovolume (mm³ ), viable bacteria biovolume (mm³ ), and live percentage (%) were quantified. For pH measurement, specimens of each material (n = 3) were immersed in phosphate-buffered saline at 37 °C, and pH was monitored in multiple intervals, up to 30 days. For elemental analysis, additional specimens (n = 3) were immersed in deionized water and elemental release was analysed by ICP-OES (inductively coupled plasma - optical emission spectrometry) at time intervals of 3, 14 and 30 days. Differences between groups were evaluated by the two-way analysis of variation (anova) with Tukey's post hoc test (P < 0.05).

Results: The lowest total biovolume at 30 days was found in GNB, GBC and NPG. GNB had the lowest viable bacteria biovolume (mean value) at 30 days (P < 0.05), and the lowest live percentage of bacteria at 3 and 30 days (P < 0.05), whilst NPG had the lowest live percentage at 14 days (P < 0.05). GNB had the highest pH (8.45) after 30 days (P < 0.05), and the greatest Zn and Na release at all time intervals (P < 0.05). Both GBC and GNB had significantly higher Ca release at 14 and 30 days.

Conclusion: GNB and GBC reduced biofilm formation, GNB had the lowest amount of viable bacteria in biofilms with the highest pH, and high Zn and Na release values after 30 days.