In these studies, E-glass-fibre-reinforced composite (FRC) implants with
photopolymerisable resin systems and bioactive glass granules (BAG) were evaluated as a
reconstructive material in the critical size bone defects made to rabbits’ calvarial bones. In the first
study, a new experimental resin system, DD1/MMA/BDDMA, was used to impregnate the doubleveil
FRC-implants, while in the second study, a commercial resin system composed of
BisGMA/MMA/PMMA was used in impregnation. These double-veil FRC-implants were coated
with bioactive glass granules (BAG, 315-500 0m). In the second study, an experimental FRC
consisting of two laminates of woven fibres, was also tested as an implant material. These implants
were filled with BAG-granules and pure fused quartz fibers (Quartzel wool). In the first study,
implantation time was 4 or 12 weeks, while in the second study, it was 12 weeks for both the
implant types. Results: In the first study, the healing of the defects had started in the form of new
bone growth from the defect margins, as well as small islands of woven bone in the middle of the
defect, at 4 weeks postoperatively. Ingrowth of dense connective tissue into the pores of the implant
was widely seen. At 12 weeks postoperatively, more bony islands were seen as compared to the
animals studied at 4 weeks. Part of the newly formed bone had an appearance of lamellar structure.
The porous structures of the implant were deeply filled with fibroconnective tissue. Ingrowth of
maturing bone to the implant structures was occasionally seen. The inflammatory reaction was
moderate, and was mostly found inside the upper part of the implant. In the second study,
inflammatory reactions caused by both types of the FRC implants were very slight. Small amount
of new bone had started to grow from the defect margins in doulble-veil implanted defects. No
ingrowth of connective tissues or new bone formation was seen inside these implants. Instead, both
the connective tissues and newly formed, mineralizing bone were seen inside the experimental
double-laminate implants. SiO2-fibres seemed to cause moderate inflammatory reaction inside the
implants, while BAG granules did not. In both the study groups, the brain tissue was oedemic, but
no obvious serious damage was found. Conclusions: The structural properties of the FRC-implants
had an influence on the healing process of the bone defect. BAG, as a constituent of the FRCimplants,
enhanced the bone formation process. After some modifications to the properties of the
FRC, this type of implant has possibilities to become one material alternative in clinical bone defect
reconstruction at the craniofacial area in the future.
RNA interfering molecule delivery from in situ forming biodegradable hydrogels for enhancement of bone formation in rat calvarial bone defects