Chemical, Microstructural and Morphological Characterisation of Dentine Caries Simulation by pH-Cycling

In vitro simulation of natural caries is of great importance in dental research for the development of more effective clinical treatments. The pH-cycling (pHc) procedure consists of a dynamic caries process with alternating de-remineralisation periods. The current research aims to evaluate the effects of the pHc procedure on mineral dentine properties in comparison with sound dentine and natural residual caries. For this purpose, dentine slices from human third molars were submitted to cycling periods of 14 and 28 days. The chemical composition, morphological and microstructural properties of the dentine samples were examined by infrared and Raman spectroscopies, X-ray diffraction, and scanning electron microscopy techniques. In addition, the depth of the demineralisation front was evaluated by Masson’s trichrome (MT) staining. The results showed that the pHc procedure led to notable changes in the mineral composition and the crystalline characteristics with respect to sound dentine and some extent to natural caries. The MT results revealed that pHc 28 yields a deeper lesion than pHc 14, simulating potential progression of natural caries. The results of this study provide a better understanding of the mechanisms of demineralisation that could occur in an in vivo environment and provide a standardised substrate similar to natural residual caries.