Biomedical Engineering Reference
In-Depth Information
antibiotic prophylaxis (gentamycine, 4 mg/kg). The animals were
placedinaventralpositionfortheinsertionoftheimplants.Thedor-
sumoftheskullwasshaved,washed,anddisinfectedwithpovidone-
iodine. A midsagittal incision was made through the skin. The skin
and subcutaneous tissue were separated from the periosteum by
using blunt dissection. A second, longitudinal incision was made
through the periosteum, which was the elevated and carefully dis-
sected from the underlying skull bone. After exposure of the pari-
etal calvaria, four full-thickness skull defects were made by using
an 8 mm trephine hand instrument (Leibinger, Germany). Subse-
quently,thescaffoldsections(diameter8mm;thickness2mm;aver-
age pore sizes
∼
88,
∼
200,
∼
310, and
∼
405
μ
m) without cells were
inserted into the defects randomly. After inserting the scaffold sec-
tions, the periosteum was closed over the implant by using a 5-0
chromic catgut suture, and the skin was closed with use of a 5-0
nylon suture. At 4, 8, and 16 weeks postimplantation, euthanasia
was performed with an overdose of pentobarbital sodium. A total
of nine rabbits (three rabbits per period) were used for the implan-
tation of scaffold sections. For histological study, the implants with
surrounding cranial tissue were removed, fixed with 4% formalde-
hyde in phosphate buffered saline (PBS), and then decalcified in
10% formic acid. After dehydration in a graded series of ethanol,
the specimens were embedded in para
n wax and cut into 5
μ
m
transverse sections in the center of the bony defects. These sec-
tions were stained with hematoxyline and eosin for the observation
by light microscopy (Model BX50F4, Olympus, Japan). Throughout
theobservationperiods,nosignificantdifferenceswereobservedin
tissue reaction within the defects. In all specimens, some inflamma-
tory cells were observed inside the pores; however, the inflamma-
toryresponsewaslimitedanddecreasedfortheimplantsat8and16
weeks compared with 4 weeks of implantation. Analysis of the scaf-
foldsectionsvialightmicroscopyrevealedvariouslevelsofbonefor-
mationat4,8,and16weekspostimplantation.At4weeks'implanta-
tion,itwasobservedthatthescaffoldsectionhaving
∼
310
μ
mpore
size showed faster new bone formation than other group sections
(Fig.30.12).Thesefeaturesweremoreobviousafter8and16weeks'
implantation.Inthescaffoldsectionhaving
∼
310
μ
mporesize,new
boneformationwasmoreextensiveinsidetheporesandprogressed
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