Structure of fluoride-containing bioactive glasses

Abstract

SummaryFluoride prevents dental cavities, stimulates bone mineralisation and decreases the melting temperature of glasses and is therefore an interesting component of bioactive glasses for use as dental or orthopaedic biomaterials. However, when designing new glass compositions, the structural role of fluoride in the glass needs to be better understood. We have characterised a glass series in the system SiO 2 -P 2 O 5 -CaO-Na 2 O with increasing concentrations of CaF 2 . Network connectivity was fixed at 2.13 by adding CaF 2 while the ratio of all other components was kept constant. 19

Bioactive glass engineered coatings for Ti6Al4V alloys: Influence of strontium substitution for calcium on sintering behaviour

“…They have also looked at the structural role of phosphate and found evidence for glasses with greater than 5 mol% P 2 O 5 exhibiting amorphous phase separation into a silica rich and phosphate rich phase [15]. This was confirmed by solid-state 31 P nuclear magnetic resonance (NMR) experiments, which showed an orthophosphate phase for all phosphate contents when NC<2.5 [10,11,16].…”

“…The network connectivity may be calculated according to Hill [7], but it is now recognised that phosphate in bioactive glasses does not form part of the silicate network [10,11] and is thought to exist as a distinct orthophosphate droplet phase [12], and due allowance must be made for this in the calculation of NC as well as in the calculation of the TEC. We assume that by analogy with sodium borosilicate glasses of low borate content, such as Pyrex™, the TEC of the glass is determined solely by the matrix silicate phase.…”

Bactericidal strontium-releasing injectable bone cements based on bioactive glasses

“…two bridging oxygen atoms, BO, per silicon atom, corresponding to a silicate chain structure) with smaller amounts of Q 3 silicate units (i.e. three BO per silicon, corresponding to branching silicate units), which is typical for BG [14][15][16][17]. Strontium for calcium substitution did not significantly alter the structure of the silicate network.…”

Fluoride-containing bioactive glasses: Effect of glass design and structure on degradation, pH and apatite formation in simulated body fluid

“…Network connectivity (NC) [11] was fixed at 2.13 by adding CaF 2 while the ratio of all other components was kept constant, assuming that fluoride stays associated with calcium, i.e. no Si-F bonds are formed [10,12]. Our hypothesis was that by keeping NC fixed we would not affect the degradability of the glasses and their ability to form apatite in SBF in vitro.…”

“…We recently characterised the structure of a series of glasses in the system SiO 2 -P 2 O 5 -CaO-Na 2 O with increasing concentrations of CaF 2 [10]. Network connectivity (NC) [11] was fixed at 2.13 by adding CaF 2 while the ratio of all other components was kept constant, assuming that fluoride stays associated with calcium, i.e.…”