Assessment of the remineralisation induced by contemporary ion-releasing materials in mineral-depleted dentine

Objectives Evaluate the ability of current ion-releasing materials to remineralise bacteria-driven artificial caries lesions. Materials and methods Standardised class I cavities were obtained in 60 extracted human molars. Specimens underwent a microbiological cariogenic protocol (28 days) to generate artificial caries lesions and then were randomly divided into four restorative groups: adhesive + composite (negative control); glass ionomer cement (GIC); calcium silicate cement (MTA); and resin-modified calcium silicate cement (RMTA). Microhardness analysis (Delta KHN) was performed on 40 specimens (10/group, t = 30 days, 45 days, 60 days in artificial saliva, AS). Micro-CT scans were acquired (3/group, t = 0 days, 30 days, and 90 days in AS). Confocal microscopy was employed for interfacial ultra-morphology analysis (2/group, t = 0 days and 60 days in AS). Additional specimens were prepared and processed for scanning electron microscopy (SEM) and FTIR (n = 3/group + control) to analyse the ability of the tested materials to induce apatite formation on totally demineralised dentine discs (60 days in AS). Statistical analyses were performed with a significance level of 5%. Results Adhesive + composite specimens showed the lowest Delta KHN values and the presence of gaps at the interface when assessed through micro-CT even after storage in AS. Conversely, all the tested ion-releasing materials presented an increase in Delta KHN after storage (p < 0.05), while MTA best reduced the demineralised artificial carious lesions gap at the interface. MTA and RMTA also showed apatite deposition on totally demineralised dentine surfaces (SEM and FTIR). Conclusions All tested ion-releasing materials expressed mineral precipitation in demineralised dentine. Additionally, calcium silicate-based materials induced apatite precipitation and hardness recovery of artificial carious dentine lesions over time.