Study on a new strontium-doped bioactive glass-ceramic for caries management

Abstract

Bioactive glasses have been introduced for dental use for a long period. This study aimed to investigate the inhibitory effect of a strontium-doped bioactive glass-ceramic (HX-BGC) on the growth of cariogenic bacteria and the effect of this HX-BGC on hydroxyapatite formation, and to evaluate the effect of the HX-BGC in remineralizing demineralized lesions on enamel and dentine surfaces and the preventive effect of the HX-BGC on dental caries. A narrative review was first conducted to investigate the mechanism of bioactive glass on dental caries management. The review explained the two mechanisms of different types of bioactive glass on caries management and concluded that pH elevation and the presence of antibacterial ions in bioactive glass mainly influences the preventive and remineralizing effect of bioactive glass. This thesis consists of five laboratory studies. The first study evaluated the antibacterial effect of the new HX-BGC on multi-species cariogenic bacteria and found it had better antibacterial effect on cariogenic bacteria than a traditional bioactive glass (3MTM Specialty Glass 19933, SG) without addition of strontium. The second experiment investigated the effect of this new bioactive glass on hydroxyapatite crystallization. The reaction occurred in a water bath at 37℃ between HX-BGC and Tris-buffered saline with calcium and phosphate. This study concluded that combined use of HX-BGC and fluoride has synergistic effects on hydroxyapatite crystallization by producing strontium-substituted-fluorohydroxyapatite with enhanced bioactivity and chemical stability. The third and fourth studies used the same chemical pH-cycling model to investigate the remineralizing and caries preventive effect of HX-BGC on enamel and dentine. Results show that HX-BGC can reduce mineral loss and promote remineralization of demineralized enamel and dentine through the deposition of newly formed apatite. In addition, the fourth study found the new HX-BGC had a preventive effect on caries formation on sound enamel and dentine surface. Furthermore, enamel lesions were only detected in the control group (water) while there was no lesion formation in the groups treated with HX-BGC. Results of the laboratory study show that HX-BGC containing toothpaste can prevent the formation of artificial dentine caries. These findings suggest that this new strontium-doped bioactive glass can be used for dental caries remineralization and prevention, and daily use of HX-BGC containing toothpaste can be beneficial to dental health.