Novel bioactive zinc phosphate dental cement with low irritation and enhanced microhardness

Abstract

Wide range of cements used in dentistry for cementation of dental restorations to tooth structure. The properties of dental cements should be carefully considered during their selection for achievement of long-term clinical performance of cemented dental restorations. Conventional zinc phosphate cement and other types of dental cements except polycarboxylate and glass-ionomer depend on their retention to tooth structure upon mechanical bonding. Bioactive glasses have shown a talented result in minerals regeneration. Therefore, the aim of this article is to create bioactivate zinc phosphate dental cement by incorporation of nano-sized bioglass. A total of 20 specimens; 10 specimens per type of cement were prepared. The control group was made by mixing the conventional zinc phosphate dental cement. The other group was made by addition of 5 wt% nano-sized bioactive glass powders (45S5) to the conventional zinc phosphate dental cement. The fresh mix packed into cylindrical Teflon molds and then stored in deionized water for 7 days. The pH variations were measured immediately after immersion and after 7 days storage using pH meter. Calcium and phosphorus ion release were measured using inductively coupled plasma optical emission spectroscopy. It also evaluated the surface microhardness of the experimental cements using digital Vickers hardness tester. Regarding pH changes mean values, the bioglass contained zinc phosphate cement group showed significantly higher mean pH values than control group. As regards the bioglass contained zinc phosphate cement group; there was a significant increase in mean pH values after setting as well as after 7 days storage. While in control group, there was a significant decrease in mean pH values after setting followed by a significant increase in mean pH values after 7 days storage. Regarding calcium and phosphorus ions release mean values, the bioglass contained zinc phosphate cement group showed significantly higher mean values than the other control group. Regarding surface microhardness, the bioglass contained zinc phosphate cement group showed significantly higher mean surface microhardness values than control group. In conclusion, bioactivation of conventional zinc phosphate cement by addition of nano-sized bioglass filler leads to calcium and phosphorus ions release which may be beneficial for chemical bonding to tooth structure with enhanced surface microhardness and minimal irritating effect. [DOI: 10.1380/ejssnt.2018.431]