Chemical interaction of calcium-silicate cements with demineralized dentin

To characterize the chemical interactions induced by calcium-silicate cements when applied on caries-like demineralized dentin.

Method:

Two standard Class-I mid-coronal dentin cavities (3 x 1.5 x 0.5 mm) were prepared in 36 sound human third molars. One cavity was demineralized with 10% formic acid for 5 hours, the other remained untreated as control. Teeth were divided into 3 groups on the basis of the three calcium-silicate cements investigated (ProRoot MTA, Dentsply; Biodentine, Septodont; TheraCal LC, BISCO). After 1-week, 1-, 3-, and 6-month storage in simulated body fluid, specimens were cross-sectioned and polished using an argon-ion beam cross section polisher (IB-09010CP, JEOL). The interfacial interaction was characterized using micro-Raman (Senterra, Bruker) and Electron Probe Micro Analysis (EPMA, JXA-8530F, JEOL).

Result:

Formic acid treatment resulted in a fully demineralized layer of about 10±5 μm and underneath a partially demineralized layer of approximately 30±10 μm. Both Micro-Raman and EPMA revealed that the partially demineralized layer can be remineralized. Calcium phosphate depositions were detected by EPMA, and the thickness of this interaction layer increased gradually with storage time. Micro-Raman analysis of these deposited crystals revealed a similar structure as that of the unaffected dentin. The non-resin cements, Biodentine and ProRoot MTA, were more effective, as calcium phosphate crystals deposited at a higher rate. In fully demineralized dentin, no changes induced by the cements could be detected. This may be attributed to a lack of apatite nucleation sites and/or collapse of the collagen-fibril network. 

Conclusion:

Calcium-silicate cements can induce remineralization of carious-like partially demineralized dentin. Fully demineralized dentin cannot be remineralized using solely these cements. Further studies are needed to analyze the remineralization potential of calcium-silicate cements in combination with biomimetic analogs when applied on fully demineralized dentin.