Linlin Han

Uptake of calcium and silicon released from calcium silicate-based endodontic materials into root canal dentine

AIM To compare Biodentine and White ProRoot mineral trioxide aggregate (MTA) with regard to Ca and Si uptake by adjacent root canal dentine in the presence of phosphate-buffered saline (PBS). METHODOLOGY Root canals of bovine incisor root segments were instrumented, filled with either Biodentine or MTA (n = 20 each) and then immersed in Ca-and Mg-free PBS for 1, 7, 30 or 90 days (n = 5 each). Unfilled, unimmersed dentine specimens (n = 5) served as controls. The specimens were sectioned longitudinally, and the ultrastructure of the dentine-material interface and the elemental composition/distribution in the material-adjacent dentine were analysed using a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with image observation function. Data were statistically analyzed using one-way anova and Tukeys honestly significant difference test or the Mann-Whitney U-test. RESULTS Along the material-dentine interface, both materials formed a tag-like structure that was composed of either Ca- and P-rich crystalline deposits or the material itself. The width of a Ca- and Si-rich layer detected along the dentine layer of the material-dentine interface showed increases over time. The Ca- and Si-rich layer width was significantly larger (P < 0.05) in Biodentine than MTA at 30 and 90 days. CONCLUSIONS Both Biodentine and MTA caused the uptake of Ca and Si in the adjacent root canal dentine in the presence of PBS. The dentine element uptake was more prominent for Biodentine than MTA.

Evaluation of calcium-releasing and apatite-forming abilities of fast-setting calcium silicate-based endodontic materials

AIM To evaluate two fast-setting calcium silicate-based endodontic materials (Endocem mineral trioxide aggregate (MTA) and Endocem Zr) with regard to their ability to release calcium ions (Ca(2+)) and produce apatite-like precipitates after immersion in phosphate-buffered saline (PBS). METHODOLOGY Endocem MTA, Endocem Zr and white ProRoot MTA (WMTA) were used. Chemical composition of the powder of each material was analysed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with image observation function (SEM-EPMA). The amount of Ca(2+) released from water-immersed set cements was measured with an EDTA titration method. Morphology and chemical composition of surface precipitates formed on the surface of PBS-immersed cements were analysed with the SEM-EPMA. Data obtained were analysed using one-way analysis of variance and Tukeys honestly significant difference test with a significance level of 5%. RESULTS Endocem MTA and WMTA contained calcium (Ca), silicon (Si) and bismuth as the major elemental constituents, whereas Endocem Zr contained zirconium as the most abundant element, followed by Ca and Si. The amount of Ca(2+) release was WMTA >Endocem MTA ≥Endocem Zr. After immersion in PBS for 14 days, the three materials produced Ca- and phosphorus (P)-containing apatite-like surface precipitates. WMTA showed higher Ca/P ratio of the precipitates compared with the other cements, with statistical significance between WMTA and Endocem Zr (P < 0.05). CONCLUSION Compared with WMTA, Endocem MTA and Endocem Zr were associated with significantly less Ca ions release and, when immersed in PBS, produced apatite-like crystalline precipitates of significantly lower Ca/P ratios.

Evaluation of the ions release / incorporation of the prototype S-PRG filler-containing endodontic sealer

OBJECTIVE This study aimed to evaluate a prototype surface reaction-type pre-reacted glass-ionomer (S-PRG) filler-containing endodontic sealer (S-PRG sealer) in terms of its ion-releasing ability and the incorporation of the released ions by root canal dentin. MATERIALS AND METHODS The concentration of ions in the set S-PRG sealer was measured by ICPS and with a fluoride ion electrode. Element mapping and chemical component bulk analysis of the outermost dentin of the S-PRG sealer-dentin interface were performed by SEM-EPMA. The incorporation depth of the elements in dentin was measured by element line scanning. RESULTS AND DISCUSSION Ions released from the S-PRG sealer (Al, B, F, Na, Si, Sr, and Zn) were detected over time. The incorporation of fluoride (F), strontium (Sr), silicon (Si), and boron (B) was observed along the outermost dentin of the S-PRG sealer-dentin interface by EPMA analysis, and the incorporation depth increased with prolonged immersion. CONCLUSION The continuous release of ions from the S-PRG sealer and their subsequent incorporation by root canal dentin were confirmed.