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Kolan, et al.
polymer scaffolds with 100 – 300 µm pores having material (e.g. silicate glass, borate glass, or HA),
an accelerated effect during the first 4 weeks which pore size, porosity, and architecture play a more
quickly fell off after 8 weeks of implantation . If important role than strength and modulus in a
[27]
that was the case, grid-like borate glass scaffolds calvarial defect model. Moreover, there was no
with 150 – 300 µm pores should have higher bone significant difference in compressive strength
formation within 6 weeks in comparison to SLS and modulus of cubic (4.3 MPa and 0.7 GPa) and
scaffolds with 1 mm pore size used in this study. diamond (3.5 MPa and 0.6 GPa) scaffolds used
Since this was not observed, nonlinear effects for in vivo assessment in this study. Therefore, the
of pore sizes on bone regeneration might not be difference in bone and fibrous tissue formation is
the case for bioresorbable material scaffolds. The more likely due to architecture.
qualitative comparison of H&E stains reported in This study demonstrated the fabrication of
other in vivo studies (Table 4) showed that bone biomimetic borate glass scaffolds using the SLS
formation was mainly through the infiltration of process. The faster degradation of borate glass
fibrous tissue and initiated from the dura mater side scaffolds was likely because of the increased
of the scaffold. This is in strong agreement with surface area associated with the SLS part surface
our study. In addition, the quantification of bone roughness. After immersion in SBF for 1 week,
growth as 6% in our study compared to 15% in SLS borate glass scaffolds showed a 60% –
other studies could be subject to a large deviation. 90% reduction in strength, depending on the
In our previous study, diamond and gyroid architecture. This data provide an opportunity to
architecture scaffolds made with silicate glass design an implant to repair defect sites based on
showed significant cell proliferation in vitro in the strength requirements of the skeletal region.
comparison to cubic scaffolds . Nevertheless, This shows the potential of the laser powder
[34]
a significant difference in in vivo bone growth bed fusion process for bone repair by utilizing a
for diamond scaffolds versus cubic scaffolds combination of architecture, porosity, and choice
was not observed in the current study. However, of bioactive glass for scaffold fabrication. For
qualitative analysis indicated a more mature example, diamond architecture could be the
fibrous tissue in defects treated with diamond choice for an implant fabricated with a bioactive
scaffolds. While the fibrous tissue in the diamond glass having a slower degradation rate (such as
scaffold appears to have osteocytes, indicating silicate glass) as diamond scaffolds degrade faster
that it has almost transformed into new bone, and have the potential to provide more bone
while the fibrous tissue from the central region of regeneration in vivo. In a similar fashion, if high
the cubic scaffold appears to be soft tissue. This structural integrity is needed for tissue repair in a
indicates that it would take longer to form new load-bearing bone, a lower porosity design using
bone within the cubic scaffold in comparison to a cubic or spherical architecture could be the best
the diamond scaffold. Faster maturation of fibrous option to slow down degradation. The laser powder
tissue in the diamond scaffold could be attributed bed fusion process can be used to manufacture
to the curvature that drives the fibrous tissue, and bioactive glass scaffolds for bone repair with
thereby osteoblasts and osteocytes, to orient and controlled degradation by selecting the appropriate
adapt to the pore geometry. A scaffold’s mechanical geometric design and material combinations.
properties are known to influence cell proliferation,
differentiation, and bone regeneration . 4 Conclusions
[62]
However, the mechanical properties could not
be a major factor in a calvarial defect model Borate-based bioactive glass scaffolds with
because it is not for load-bearing application, and different porosities and pore sizes were fabricated
studies showed no apparent correlation between using the SLS process, with scaffold porosities
scaffold compressive modulus, strength, and varying from 30% to 60% and pore sizes varying
bone formation (Table 4). It is likely that scaffold from 0.5 to 1.2 mm. Scaffold strength and

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