
What are Orthodontic Forces?
Orthodontic forces are usually small
forces used to move crowded or unerupted teeth into place
Orthodontic
forces on teeth
crowns
Force
transmit to
Bone & PDL
Bone
resorption in
direction of
force & bone
apposition on
the other side

What is periodontal ligament (PDL) ?

It is a soft ligamentous tissue enclosed between 2 hard tissues
(alveolar bone and tooth cementum). PDL acts as a shock absorbent
in response to orthodontic forces.
Periodontal ligament
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

The molecular mechanism that underlies this
phenomenon(bone resorption and formation) is not
fully understood.
Current in vitro models fall short of simulating the
tooth attachment apparatus (periodontium) with
both of its components : hard tissue (bone) and soft
tissue (PDL).
Hence there is a demand for a multilayered tissue
engineered model to simulate tooth periodontium
under orthodontic forces
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


Characterizing 2 scaffolds to be used in our proposed
multilayered model :one representing the hard tissue
component of periodontium: Sol-Gel scaffolds.
In addition a membrane representing the soft tissue
component of periodontium: Geistlich Bio-Gide®
Biological Characterization: investigating the following: cells’
viability, adhesion, proliferation, and matrix formation
(Confocal and SEM imaging).
Mechanical Characterization: properties were evaluated
before and after cell seeding.
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

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Biologically:
scaffolds tested in this study were all biocompatible with human periodontal ligament
cells individually and in combined culture
Gene expression studies qRT PCR:
Gen expression for the BGC and SGC were different in most of the genes studied
Gene expression profile was in accordance with the previous literature which is an
indication of a suitable model for studying OTM
Sol-Gel Scaffold SEM
SolGel Scaffold Live/Dead
imaging
Bio-Gide membrane SEM
Bio-Gide Live/Dead imaging
Bio-Gide
membrane
Sol-Gel
Scaffold
SEM showing cells grown at the
interface
SEM image
Sol-Gel
Bio-Gide
*
1
0.1
ephrin B2
10
1
0.1
7.
7. 2g
2g 6
h
24 S
h GC
SG
12
C
.
2
12 g
.2 6
g h
24 S
h GC
SG
C
7.
7. 2g
2g 6
h
24 B
h GC
B
G
12
C
12 .2g
.
2g 6h
7.
24 B
12 2g
h GC
. 2 24
B
g h
G
24 +
C
h 2h
+2 re
7.
h st
re S
12 2g
st G
. 2 24
SGC
g h
24 +
C
2
h h
+2 r e
h st
re B
st G
B C
G
C
*
*
7.
2
7. g
2g 6h
2 4 SG
h C
SG
C
12
.
12 2g
.2 6
g h
2 4 SG
h C
SG
C
7.
2
g
7.
2g 6h
2 4 BG
h C
B
G
C
12
12 .2g
.2 6
g h
7.
24 BG
2g
h C
12
2
B
.2 4
G
g h
C
24 +2
h h
r
+2 e
h st
7.
re SG
2
st C
g
12
SG
. 2 24
g h
C
24 +2
h h
+2 re
h st
re B
st GC
B
G
C
Relative change in the expression
of EB4 to un-loaded control
7.
7. 2g
2g 6
h
24 S
h GC
S
G
12
C
.
12 2g
.2 6
g h
24 S
h GC
S
G
C
7.
7. 2g
2g 6
h
24 B
h GC
B
G
12
C
12 .2g
.
2
6
7.
g h
24 B
12 2g
h GC
2
.2 4
B
g h
G
24 +
C
h 2h
+2 re
7.
h st
re S
12 2g
st G
. 2 24
S C
g h
G
24 +
C
h 2h
+2 re
h st
re B
st G
B C
G
C
10
Relative change in the expression
of COL1A1 to un-loaded control
7
7. .2g
2g 6
2 4h S
h GC
SG
12
C
.
12 2g
.2 6
g h
24 S
h GC
SG
7.
C
2
7. g
2g 6
2 4h B
h GC
B
G
12
C
12 . 2
g
.
2g 6
7.
12 2g
24h B
. 2 24
h GC
g h
B
G
24 +
C
h 2h
+2 re
7.
h
s
12 2g
re t S
st G
. 2 24
g h
SGC
24 +
C
h 2h
+2 re
h st
re B
st G
B C
G
C
Relative change in the expression
of ephrinB2 to un-loaded control
Relative change in the expression
of PGE2 to un-loaded control
PGE2
EB4
10
*
*
*
1
0.1
COL1A1
10
1
0.1
 SolGel
was considered to be suitable
in representative for the hard tissue
component.
 Bio-Gide® membrane was considered
more suitable to represent the soft
tissue component.
 A bi-layered construct with the above
materials can be considered a
suitable model for studying OTM
In-Vivo implantation of the bi-layered
construct in mice
 Cell-cell interaction studies
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El-Gendy R, Raif E Leeds Uni UK
Goudouri OM, Boccaccini A , Erlangen Uni Germany
Refaat W, Ramadan A, SCU Egypt