Development and Characterisation of a Novel Tin Bioactive Glass Dental Composite

Objectives: To develop and characterise novel tin containing bio glasses (BAG) for use in dental composites.
Methods: A novel Tin containing bioactive glass and a Sn Free BAG were prepared using the melt quench technique. Both BAG powders were immersed in AS4 (demineralizing artificial saliva at pH 4) and AS7 (remineralising artificial saliva at pH7) at several time points. An ion release study was performed using ICP-OES and ISE, pH studies were also performed on these solutions. BAG powders were evaluated using XRD, FTIR and NMR spectroscopy for the detection of any apatite formation. The BAG powder was incorporated into a prepared resin matrix (ratio of 63:37) and a light cured paste was obtained. 120 bar shaped samples with height and thickness approximately 2mm and length of 20mm were fabricated. These were kept under the AS4 and AS7 solutions for specific time points, a 3-point bend test was used to measure the flexural strength of these samples.
Results: An increase in pH was observed in both types of BAG composites immersed in the two solutions. ICP studies showed an increase of Ca, Na and Si ions over time, phosphate however showed a decrease of ions over time. Sn ions were not detected. Fluoride ions showed an increase up to 6 hours followed by a decrease for up to one week. XRD studies showed the formation of CaF₂ and a slight formation of apatite at one week. Sn BAG composite sample was observed to have greater flexural strength compared to a Sn Free BAG composite.
Conclusions:
The introduction of a novel tin bioactive glass dental composite may have several advantages (such an increase of ions over time leading to apatite formation and greater flexural strength) over a tin free bioactive glass dental composite as a restorative material.