Repairing of rabbit calvarial defects by rapid prototyping BisGMA and hydroxy-appatite incorporated BisGMA

Abstract

The in vivo bone regenerative capacity and biocompatibility of bisphenol A glycidylmethacrylate (BisGMA)
implants fabricated by Stereolithography Rapid Prototyping machine (SLA) was investigated in rabbit’s calvarial defect
model. The study focused on two different materials: BisGMA alone and hydroxyapatite (HA) incorporated BisGMA,
of which were formulated especially for SLA fabrication. Each rabbit’s skull implant was fabricated with size 1x1 cm2
according to the rabbit skull’s contour based on its Computed Tomographic data and replaced at the full thickness
cavarial defects in 6 rabbits. Computed Tomography (CT) scan and blood tests were performed at certain time points
during 6 months after surgical operation to evaluate the bone regenerative capacity and biocompatibility. CT images
revealed that the newly formed bone was gradually increased according to the implantation periods and all rabbit
skulls showed good healing response without adverse tissue reactions. There was no remarkable difference in bone
regeneration compared between BisGMA and HA incorporated BisGMA. After 24 weeks, the implants with
surrounding skull tissues were removed and observed for cellular response of bone to implants. Scanning electron
microscope revealed more callus formation surrounding the BisGMA (3.870.05 mm) compared to HA incorporated
BisGMA (3.210.22 mm, P = 0.023). From histological studies, BisGMA implants were encapsulated with thicker fibrous
tissue compared to HA incorporated BisGMA, suggesting that HA incorporated BisGMA induced less tissue reaction.
Based on the present study in a rabbit calvarial defect model, it is concluded that SLA provides a well fitting implant.
Furthermore, incorporation of HA to BisGMA improves biological compatibility with less fibrous tissue encapsulation.