| dc.description.abstract | Aim: This study aimed to determine ion release properties and apatite formation ability of three composites. Methods: The three composites investigated were an experimental Bioactive-glass composite (BGC), Cention-Forte (CF), which contains alkasite filler and Tetric Powerfill (TP) which contains an inert glass. Composite discs (126) were prepared and immersed in artificial saliva at pH7 (AS7) and pH4 (AS4), and TRIS-buffer (TB, pH 7.3) for seven time points (6h-12wks). These discs were characterised using Fourier-transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD) for apatite formation. The solution was analysed after immersion for fluoride using an ion selective electrode (ISE) and inductively coupled plasma-optical emission spectrometry (ICP-OES) for all other elements. For the mineralisation study, a standardised cavity was prepared in three premolar teeth using Forces Recorded Exhibited from a Dental Drill (FREDD). They were demineralised using acetate buffer solution and the teeth were restored with the composites- BGC, CF and TP. These teeth were scanned using X-ray microtomography (XMT) post restoration at 0wk, 2wk, 4wk, and 12 weeks. Results: The pH analysis showed maximum rise in pH for BGC in AS4. BGC in AS7 released less fluoride ions in solution then CF indicating fluoride was consumed for fluorapatite formation as seen in FTIR and XRD. There was a rise in fluoride concentration in solution and Calcium (Ca2+) ion release was also observed for both CF and BGC in AS4. In AS7, there was less Ca2+ release and the phosphorus level reduced consistent with it being consumed to form apatite for both BGC and CF. TP did not show significant ion release apart from small amount of Barium (Ba) in AS4. FTIR analysis of BGC in AS7, AS4 and TRIS and CF in AS7 showed the presence of apatite formation which was confirmed by the XRD scan. TP showed no evidence of apatite formation by FTIR or XRD. On XMT, the linear attenuation coefficient (LAC) and subtraction images for BGC and CF showed some evidence of remineralisation. In BGC the degradation of the surface layer of the restoration was clearly evident. There was stronger evidence for prevention of demineralisation than remineralisation in teeth restored with BGC and CF. Due to the teeth being immersed in acidic pH solution (AS4), there was lot of erosion to the teeth and demineralisation of enamel and cementum at the crown and root surface respectively was visible. Conclusion: The results indicated that BGC and CF composites raised the pH, released ions and formed apatite. BGC and CF have potential to occlude marginal gaps and inhibit secondary caries. | en_US |
