Niobium pentoxide as a new filler for methacrylate-based root canal sealers

To evaluate the influence of several niobium pentoxide (Nb(2) O(5) ) concentrations on the radio-opacity, flow, film thickness, microhardness and degree of conversion of an experimental root canal sealer.

An experimental dual-cured root canal sealer was produced with a methacrylate-based comonomer blend. Nb(2) O(5) was added at four different concentrations: 0, 80, 100 and 120 wt%. Radio-opacity was evaluated according to ISO 6876 using a digital system (n = 5). Flow and film thickness were determined in accordance with ISO 6876 (n = 3). Microhardness was evaluated with 50 g for 15 s (n = 5). Degree of conversion was evaluated with FTIR immediately after photocuring and after 1, 7 and 14 days. The data were analysed using anova and Tukey's test. The degree of conversion over time was evaluated using RM-anova (α = 0.05).

The groups with 80 wt% and 100 wt% of filler showed no significant difference in radio-opacity from that of equivalent 2 mmAl (P > 0.05). The addition of 120 wt% resulted in radio-opacity values higher than 2 mmAl (P < 0.05). The flow was not significantly different amongst the different groups (P > 0.05). All groups had a film thickness of <50 μm (ISO 6876). All groups with Nb(2) O(5) were associated with higher values of microhardness than the control group. The group with 0 wt% was associated with a higher degree of conversion at all times. All groups except those with 80 wt% had higher values for degree of conversion after 14 days than immediately after photocuring.

The addition of Nb(2) O(5) increases radio-opacity and microhardness; this material may be a promising filler for the production of a new endodontic sealer.