Biomedical Engineering Reference
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be effective in creating thick cementum on denuded root surfaces.
63
Another study also demonstrated that three-layered human peri-
odontal ligament cell sheets cultured in an osteoinductive medium
regenerated thick cementum, including Sharpey's fibers, in a rat
back model.
61
In a canine model, we demonstrated periodontal regeneration
using a monolayered canine periodontal ligament cell sheet rein-
forced with hyaluronan, although such periodontal tissue formation
was not observed, except in one defect in the control group.
60
His-
tometric analysis revealed that the formation of new cementum in
the experimental group was significantly higher than that in the
control group. Its success rate was 60% (3 out of 5), and bone
regeneration was limited. In order to improve the success rate, we
transplanted three-layered PDL cell sheets supported with woven
poly(glycolic acid) to dental root surfaces with three-wall periodon-
tal defects in an autologous manner, and bone defects were filled
with porous
-tricalcium phosphate.
62
The cell sheet transplanta-
tion regenerated both new bone and cementum connecting with
well-oriented collagen fibers, whereas only limited bone regenera-
tion was observed in the control group where cell sheet transplan-
tation was eliminated. In detail, two-dimensional (2D) images of
a micro-computer tomography (micro-CT) analysis demonstrated
that almost 50% of the bone filling was observed after treatment
with a poly(glycolic acid) sheet without periodontal ligament cells
as a control group (Fig. 44.7a). In contrast, complete bone filling
with an appropriate space of periodontal ligament was observed
in the group treated with a poly(glycolic acid) sheet and a peri-
odontal ligament cell sheet (Fig. 44.7b). Periodontal defects were
still observed in a three-dimensional (3D) virtual model after a six-
week healing period in the control group (Fig. 44.7c). In contrast,
completely bone-filled alveolar ridges were seen in the experimen-
tal group (Fig. 44.7d). Based on the histometric analysis, there was
no significant difference in the apical extension of the junctional
epithelium between the experimental group and the control group.
Ankylosis was not observed in any samples. Complete periodontal
regeneration with both newly formed bone and cementum connect-
ing with well-oriented collagen fibers was observed in all cases of
the experimental group, whereas limited bone regeneration with
poorly oriented periodontal fibers was seen in the control group.
β
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