Biomedical Engineering Reference
In-Depth Information
to the continuous liberation of alkaline species during application
[33, 34]. The release of Na
+
and Ca
2+
ions from, and the incorporation
of H
3
O
+
protons into, the corroding glass result in a high-pH
environment in closed systems, which is not well-tolerated by
microbiota [2, 31]. In addition, the release of silica has been linked to
the antibacterial bioactive glass effect [34]. In contrast to commonly
used disinfectants in dentistry, silica-containing bioactive glasses
induce dentin mineralization, and thus are potentially interesting
materials for the treatment of demineralized and infected dentin
found in deep caries lesions and necrotic root canals [6].
Most recent advances in nanomaterials fabrication have given
access to complex materials such as SiO
2
-Na
2
O-CaO-P
2
O
5
bioactive
glasses in the form of amorphous nanoparticles of 20 to 60 nm size
[22, 33]. This substantially increases ionic release in suspension,
and may thus result in enhanced antimicrobial eficacy [31]. As
observed by scanning electron microscopy, the nanoparticulate
bioglass was spherically shaped and highly agglomerated, while
the conventional melt-derived glass was in the form of sharp-edged
shards (Fig. 11.1). According to laser ablation inductively coupled
plasma mass spectrometry, the composition of the nanometric
bioactive glass was 44.7 wt% SiO
2
, 4.9 wt% P
2
O
5
, 27.6 wt% CaO, and
22.8% Na
2
O. Transmission electron microscopy conirmed particle
size of the nanometric materials to be 30 ± 7.8 nm for bioactive glass
(
N
= 200).
Figure 11
.
1
Scanning electron microscopic images of lame-derived,
nanometric bioactive glass (left) and the micron-sized com-
mercially available 45S5 glass (PerioglassTM, right) [33].
