LAUSR

OBJECTIVE To investigate the remineralizing effect of a strontium-doped bioactive glass (HX-BGC) and fluoride on demineralized enamel and dentine. MATERIALS Sixty demineralized human tooth specimens were allocated to four groups. Group 1 received 5% HX-BGC, Group 2 received 5% HX-BGC and 1,450 ppm fluoride, Group 3 received 1,450 ppm fluoride, and Group 4 received deionized water as negative control. The specimens were subjected to pH cycling for 14 days. The surface morphology, lesion depths, crystal characteristics and collagen matrix degradation of the specimens were assessed by scanning electron microscopy (SEM), micro-computed tomography (mico-CT), X-ray diffraction (XRD), and spectrophotometry with a hydroxyproline (HYP) assay, respectively. RESULTS SEM images showed the enamel surface was smooth with regularly arranged enamel rods in Groups 1 to 3. Granular grains were observed in both inter-tubular and intra-tubular dentine in Groups 1 to 3. The mean lesion depths in enamel were 80.8 μm, 50.6 μm, 72.7 μm and 130.7 μm in Groups 1 to 4, respectively (p < 0.001), and those in dentine were 152.6 μm, 140.9 μm, 165.4 μm and 214.1 μm, respectively (p < 0.001). The differences in mean mineral loss in enamel and in dentine between the four study groups follow the same pattern as that of the differences in lesion depth. XRD illustrated apatite formation in each group. There were no significant differences in the HYP concentrations among the four groups (p = 0.261). CONCLUSION Combined use of HX-BGC and fluoride can reduce mineral loss and promote remineralization of demineralized enamel and dentine through the precipitation of newly formed apatite. CLINICAL SIGNIFICANCE Adjunctive use of HX-BGC may enhance the remineralization effect of fluoride in the management of early dental caries lesions.