Fluoride release conventional glass-ionomer cement

Resin-modified glass-ionomers, like their conventional counterparts, are capable of releasing fluoride [224,264,265], and in greater amounts under acid conditions than neutral ones [265], Release rates and release profiles have been shown to be comparable with those from conventional glass-ionomer cements [264,265], Other ions have also been shown to be released by these materials and, as for fluoride, these ions show a greater release under low pH conditions [265], However, the level of phosphorus released has been shown to be much lower from resin-modified glass-ionomers than from conventional ones [263], This suggests that there is little or no possibility of association of fluoride as monofluorophosphate, but rather that almost all of the fluoride is released either as the free fluoride ion or as alumino-fluoride complex ions. 

In this section, three aspects of the interaction of resin-modified glass-ionomers with water are dealt with, namely water uptake, fluoride release and other ion release and its associated buffering effect. Like conventional glass-ionomer cements, resin-modified glass-ionomers are deployed in an essentially wet environment and their behaviour in terms of each of these features differs more or less from that of conventional glass-ionomers, due to the presence of the polyHEMA phase. These are considered in turn. 

M.F. Costa Cabral, R.L. de Menezes Martinho, M.V. Guedes-Neto, M.A.B. Rebelo, D.G. Pontes, F. Cohen-Cameiro, Do conventional glass ionomer cements release more fluoride than resin-modified glass ionomer cements Restor. Dent. Endod. 40 (2015) 209-215. 

J.A. Williams, R.W. Billington, G.J. Pearson, A long term study of fluoride release from metal containing conventional and resin modified glass ionomer cements, J. Oral Rehabil. 28 (2001) 41 7. 

De Moor R, Verbeeck R, Martens L. [Evaluation of long-term release of fluoride by type II glass ionomer cements with a conventional hardening reaction]. Rev Beige Med Dent 1996 51(3) 22-35. 

Polyacid-modified composite resins were developed in an attempt to make a composite resin with the sort of ion-release capability of glass-ionomer cements, especially of fluoride [38]. They are similar to conventional composites in that they are mainly based on the hydrophobic monomers bis-GMA or urethane dimethaaylate, and their setting is typically initiated by light. In addition, they contain inert fillers of appropriate particle size. 

The alternative tooth-coloured material, the glass-ionomer cement, has also been widely studied, especially in terms of its bioactivity. This arises from its ability to exchange ions with its surroundings when placed in the mouth. Typical conventional glass-ionomers have been shown to release sodium, silicon and phosphorus under neutral conditions, and also calcium and aluminium under acidic conditions [48]. The non-metals are assumed to be released as sihcate, Si03 ", and phosphate, PO/, respectively. In addition, they release fluoride [49], a process that is capable of continuing for several years [50]. 

Resin-modified glass-ionomer cements have been used for both Class II and Class III restorations in primary teeth [97,98]. Their lower brittleness compared with conventional glass-ionomers make them appropriate for these applications, though composite resin again appears preferred for these types of cavity in permanent teeth [94], Various clinical studies have shown resin-modified glass-ionomers to perform well in these restorations [99,100], and in addition they have been shown to have useful caries inhibition properties as a result of their fluoride release [101]. 

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