In vitro Caries-affected Dentine Remineralisation Using Modern Ion-releasing Materials

Objectives: This study aimed at evaluating the ability of modern ion-releasing materials to remineralise simulated bacterially-mediated caries-affected dentine.
Methods: Class I cavities were created in extracted human molars (4mm x 3mm x 4mm). The specimens were submitted to a cariogenic protocol (24 days at 37°C) to create bacteria-induced simulated caries lesions. The specimens were divided into groups (10/group) based on the materials used for restoration: GIC (Fuji IX, GC); BIO (ACTIVA, Pulpdent); MTA (ENDOPASS, DEI-Italia); RMTA (Theracal, BISCO); Control (adhesive/composite, SDI). The specimens were submitted to KHN assessment (weekly measurements; 25gf; DT 30s) and confocal microscopy after 24h and 28 days storage in artificial saliva (AS). The first indentation was performed 50 um away from the material-dentine interface (load]. The results were statistically analysed (α < 0.05). Further three dentine discs (1 mm thick) for each group were demineralised in EDTA 37% for 5 days and covered on the occlusal side with a layer (3 mm) of each tested material. The specimens were assessed through FTIR at different intervals (0, to 28 days in AS) and finally analysed using FEG-SEM.
Results: All the tested ion-releasing materials were all able to induce mineral precipitation in dentine. However, the highest (p < 0.05) KHN values were obtained with the MTA and RMTA ; MTA induced deeper remineralisation. Conversely, GIC and BIO, showed lower KHN (p < 0.05) than MTA and RMTA. MTA and RMTA showed clear apatite precipitation after 3 days, while GIC and BIO showed CaPO precipitation only after 28 days in AS.
Conclusions: CaSi-based materials can provide effective “quick” apatite precipitation and microhardness recovery in deep carious lesions during atraumatic restorative treatments (ART). Whereas, GIC and BIO can induce a “slower” dentine remineralisation compared to CaSi-based materials; these latter might be more indicated for conventional or post-ART/step-wise restorative procedures.