Bioactive resin composite with the potential of ion exchange following selective carious lesion removal -A laboratory-based study.

Objectives: This laboratory-based study aimed to assess the possible ion exchange within residual leathery dentine using a bioactive UDMA-based resin composite.

Materials and methods: A total of 45 extracted teeth with deep carious lesions were assessed using the International Caries Risk and Assessment System (ICDAS). After radiographical evaluation, six teeth (ICDAS 4-5) were subsequently selected. After randomisation of the samples into three groups, the carious lesion was removed, leaving a layer of leathery dentine. The samples in the test group were restored with UDMA-based resin composite (Cention Forte, Ivoclar Vivadent, Liechtenstein), whilst the sculptable resin composite (Tetric Prime, Ivoclar Vivadent, Liechtenstein) was used for the positive control group. In contrast, the negative control group received no treatment. Each sample was stored in simulated body fluid (SBF). The 3D non-destructive X-ray microtomography (XMT) subtraction methodology, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were employed at different stages to assess the samples. XMT scans were carried out immediately following the placement of restorations, and after three weeks and three months. At the end of the study, the surface topography and composition were analysed with SEM/EDX.

Results: The quantitative analyses at these time points revealed an increase in Linear Attenuation Coefficient (LAC) (related to mineral density) following the placement of restoration in one test tooth. However, the other samples failed to show any evidence of ion exchange within the residual dentine. The SEM and EDX analyses showed that the UDMA-based resin composite released ions and formed an apatite-like phase after three months in the same test tooth.

Conclusion: After a three-month laboratory-based study, the bioactive resin composite demonstrated evidence of slight exchange of mineral ions within remaining carious lesions following the selective carious lesion removal in only one test tooth. Notably, an 'apatite-like' phase was formed after immersion in SBF in the same tooth.

Clinical significance: The integration of bioactive glass represents a significant innovation in dental restorative materials. The use of bioactive resin composites not only restores the tooth structure but also potentially inhibits further demineralisation and promotes remineralisation following the selective carious lesion removal.