A Strontium And Amorphous Calcium Phosphate Dipped Premixed Injectable Calcium Silicate-based Ceramic For Dental Root Canal Sealing

Objectives:We aimed to synthesize a type of a strontium and amorphous calcium phosphate(ACP)dipped premixed injectable calcium silicate-based sealer with good dental root canal sealing property,mineralizing activity,and biocompatibility.Methods:A powder mixture containing tricalcium silicate,strontium carbonate(6,8,10,and 12 wt%),zirconia(20 wt%),calcium chloride(6 wt%),and ACP(5 wt%)was mixed with liquid polyethylene glycol 400(PEG 400)at a liquid-to-powder ratio of 0.5 mL/g and mechanically ground using a planetary ball to obtain the premixed injectable calcium silicate-based sealer.The sealers containing ACP were named as Bio-G group,otherwise as G group.The sub-group was divided in different group according to the strontium carbonate content,labeled as Bio-G6,Bio-G8,Bio-G10 Bio-G12,and G6,G8,G10,G12.The sealer’s structure,flowability,setting time,radiopacity,root canal sealing property,pH,mineralizing activity,and cytocompatibility were evaluated in vitro.Results:All the sealer groups had suitable flowability,setting time,and X-ray opacity.The pH value generally stabilized between 10-12 when the sealer was immersed into deionized water or phosphate buffered solution.Bio-G6 groups had the best root canal sealing property among all the groups,bonded together to the dental root canal wall,penetrated the dentinal tubule,and occluded the dentinal tubules.The setting Bio-G6 formed calcium-silicate-hydrate(C-S-H)network structure,but distinctively forming a layer of calcium carbonate on its surface.In comparison with the G6 sealer,the Bio-G6 sealer could induce a layer of nano hydroxyapatite crystal grown on its surface in simulated body fluid(SBF),showing good biomineralization activity.Bio-G6 sealer had good cytocompatibility and had superior osteogenic differentiation activity.Conclusion:A novel premixed injectable calcium silicate-based sealer containing 6%strontium carbonate and 5%ACP was developed.It exhibited suitable operative property,good dental root canal sealing property,high mineralizing activity,and good cytocompatibility.Lastly,it induced osteogenic differentiation activity.This sealer provided a new filling material for root canal therapy and has promising application prospects.