Distrontium Cerate as a Radiopaque Component of Hydraulic Endodontic Cement

Synthesis of a Calcium Silicate Cement Containing a Calcinated Strontium Silicate Phase

Objectives

The positive effects of strontium on dental and skeletal remineralization have been confirmed in the literature. This study aimed to assess the properties of a calcium silicate cement (CSC) containing a sintered strontium silicate phase.

Materials and Methods

The calcium silicate and strontium silicate phases were synthesized by the sol-gel technique. Strontium silicate powder in 0 (CSC), 10 (CSC/10Sr), 20 (CSC/20Sr), and 30 (CSC/30Sr) weight percentages was mixed with calcium silicate powder. Calcium chloride was used in the liquid phase. X-ray diffraction (XRD) of specimens was conducted before and after hydration. The setting time and compressive strength were assessed at 1 and 7 days after setting. The set discs of the aforementioned groups were immersed in the simulated body fluid (SBF) for 1 and 7 days. The ion release profile was evaluated by inductively coupled plasma-optical emission spectrometry (ICP-OES). Biomineralization on the specimen surface was evaluated by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Data were analyzed by the Kolmogorov-Smirnov test, one-way and mixed ANOVA, Levene's test, and LSD post hoc test (P  < 0.05).

Results

Except for an increasement in the peak intensity of hydrated specimens, XRD revealed no other difference in the crystalline phases of hydrated and nonhydrated specimens. The compressive strength was not significantly different at 1 and 7 days in any group (P  > 0.05). The setting time significantly decreased by an increase in percentage of strontium (P  < 0.05). Release of Ca and Si ions significantly decreased by an increase in percentage of strontium (P  < 0.05). SEM/EDS showed the formation of calcium phosphate deposits at 1 and 7 days.

Conclusion

Incorporation of 10-30 wt% sintered strontium silicate phase as premixed in CSC can significantly decrease the setting time without compromising the compressive strength or biomineralization process of the cement.

Preparation and properties of the fine ground strontium-based endodontic cements

In this study, fine powders of tristrontium aluminate (S3A) and distrontium cerate (S2Ce) cement were prepared using a dry grinding process, and their mechanical and ion dissolution properties were estimated. Fine cements showed the particles about 10 μm in diameter or smaller with sharp particle size distribution curves. The setting reaction of the fine cements was rapid; therefore, a 0.1% w/v of citric acid solution was used as the retarder. The compressive strengths of the fine cements were improved compared to those of the coarse cements at both 1 and 28 days after mixing at a water/powder ratio (W/P) of 0.4. The dissolution of Sr and Al ions from fine S3A cement was enhanced. However, the relative flowability decreases with fine grinding. Further studies on flowability, handling property are required. Additionally, the biological effects of endodontic cement should be studied both in vitro and in vivo.