Biocompatibility and bioactive potential of the NeoMTA Plus endodontic bioceramic-based sealer

Abstract

Objectives: This study evaluated the biocompatibility and bioactive potential of NeoMTA Plus mixed as a root canal sealer in comparison with MTA Fillapex.

Materials and methods: Polyethylene tubes filled with NeoMTA Plus (n = 20), MTA Fillapex (n = 20), or nothing (control group, CG; n = 20) were inserted into the connective tissue in the dorsal subcutaneous layer of rats. After 7, 15, 30 and 60 days, the specimens were processed for paraffin embedding. The capsule thickness, collagen content, and number of inflammatory cells (ICs) and interleukin-6 (IL-6) immunolabeled cells were measured. von Kossa-positive structures were evaluated and unstained sections were analyzed under polarized light. Two-way analysis of variance was performed, followed by the post hoc Tukey test (p ≤ 0.05).

Results: At 7 days, the capsules around NeoMTA Plus and MTA Fillapex had more ICs and IL-6-immunostained cells than the CG. However, at 60 days, there was no significant difference in the IC number between NeoMTA Plus and the CG (p = 0.1137) or the MTA Fillapex group (p = 0.4062), although a greater number of IL-6-immunostained cells was observed in the MTA Fillapex group (p = 0.0353). From 7 to 60 days, the capsule thickness of the NeoMTA Plus and MTA Fillapex specimens significantly decreased, concomitantly with an increase in the collagen content. The capsules around root canal sealers showed positivity to the von Kossa stain and birefringent structures.

Conclusions: The NeoMTA Plus root canal sealer is biocompatible and exhibits bioactive potential.

Keywords: Bioactive potential; Biocompatibility; Immunohistochemistry; Inflammatory reaction; Interleukin-6.

Figure 1. Light micrographs of sections of capsules at 7 days (A-F) and 15 days (G-L). (A-C and G-I) Photomicrographs at a low magnification show well-defined capsules around the implants (bars = 500 µm). (D-F and J-L) Higher magnification of (A-C and G-I), showing inflammatory cells (arrows) and Fb (bars = 20 µm). In MTA Fillapex (K), several material particles are seen.

BV, blood vessel; C, capsules; Fb, fibroblasts; GC, multinucleated giant cell; I, space of polyethylene tubes; MTA, mineral trioxide aggregate.

Figure 2. Light micrographs of sections of capsules at 30 days (A-F) and 60 days (G-L). (A-C and G-I) Photomicrographs show a general view of the capsules juxtaposed to the opening of the tubes. All groups exhibited thinner capsules at 60 days than at 30 days (bars = 500 µm). (D-F and J-L) Inflammatory cells (arrows) and Fb (bars = 20 µm). Note that in the control group (F and L), the capsules exhibited Fb dispersed among CF and few inflammatory cells (arrows). In MTA Fillapex (K), material particles were observed throughout the capsule. Graphs show data on the numerical density of inflammatory cells (M) and the capsule thickness (N) of the NeoMTA Plus, MTA Fillapex, and control groups at 7, 15, 30 and 60 days. Superscript letters indicate comparisons among the groups; different letters denote significant differences. Superscript numbers indicate the analysis of each group over time; different numbers denote significant differences. Tukey's test (p ≤ 0.05).

BV, blood vessel; C, capsules; CF, collagen fibers; Fb, fibroblasts; GC, multinucleated giant cell; I, space of polyethylene tubes; M, muscle tissue; MTA, mineral trioxide aggregate.

Figure 3. Light micrographs show portions of capsules juxtaposed with the implant tubes. (A-L) Immunohistochemistry was used to detect IL-6 with hematoxylin counterstaining. The immunostaining (brown-yellow color) is seen in inflammatory cells (arrows) and Fb in the capsules at all periods (bars = 20 µm). (M) Graph showing the numerical density of IL-6-immunostained cells in the NeoMTA Plus, MTA Fillapex, and control groups at 7, 15, 30, and 60 days. Superscript letters indicate comparisons among the groups; different letters denote significant differences. Superscript numbers indicate the analysis of each group over time; different numbers denote significant differences. Tukey's test (p ≤ 0.05).

BV, blood vessel; Fb, fibroblasts; GC, multinucleated giant cell; I, space of polyethylene tubes; IL, interleukin; MTA, mineral trioxide aggregate.

Figure 4. Light micrographs of portions of capsules juxtaposed with the implant tubes. The sections were stained with picrosirius red and photographed with a polarization microscope. At 7 (A-C) and 15 (D-F) days, the capsules contained few birefringent fibers (orange/red colors). At 30 (G-I) and 60 (J-L) days, the capsules contained thick bundles of collagen exhibiting strong birefringence (bars = 20 µm). (M) Graph illustrating the birefringent collagen content (in percentage) in NeoMTA Plus, MTA Fillapex, and control groups at 7, 15, 30, and 60 days. Superscript asterisks denote significant between-group differences. Superscript numbers indicate the analysis of each group over time; different numbers denote significant differences. Tukey's test (p ≤ 0.05).

Figure 5. Light micrographs of portions of capsules juxtaposed with the implant tubes. (A-F) von Kossa histochemical reaction (black) and counterstaining with picrosirius red (red). The capsules in the NeoMTA Plus and MTA Fillapex groups exhibited reactivity to the von Kossa method (structures shown in black). In the control group (E and F), von Kossa-positive structures are absent. (G-J) Unstained sections analyzed under polarized light. Fine granular material exhibiting birefringence is observed in the capsules of NeoMTA Plus and MTA Fillapex (bars = 20 µm).