الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Stabilizing teeth in their new acceptable post-treatment positions after orthodontic corrections
is often the most difficult part of the orthodontic plan. Orthodontic relapse is defined as the
return of teeth to pre-treatment conditions. The etiology of orthodontic relapse is varied, ranging
from muscle disorders, harmful oral habits, changes in the shape of the dental arch, and unfavorable
pattern of growth, to the extension of transeptal fibers. It is possible that pharmacological agents
can inhibit bone resorption and enhance bone formation. This may have clinical relevant effects on
the regulation of orthodontic tooth movement and relapse. Therefore, many pharmacological factors
have been used to reduce orthodontic relapse. Coenzyme Q10 is one of the substances that has
proven to affect bone remodeling. However, it has not been studied to show its effect in orthodontics.
Therefore, this study was computed to assess the effect of systemic administration of coenzyme
Q10 on orthodontic relapse, and to assess the histological changes of bone synchronized with
administration of this substance in rabbits.
Thirty white New Zealand rabbits were randomly categorized into an experimental group of
15 rabbits receiving a daily dosage of 25 mg / kg / day CoQ10 dissolved in olive oil and control
group of another 15 rabbits receiving only olive oil. Orthodontic movement was performed using a
NiTi coil spring for 21 days for both groups, then the orthodontic appliance was removed and teeth
were allowed to relapse for another 21 days. Amounts and percentages of relapse were measured on
three-dimensional models of experimental and control teeth at two time points (T2: one week of
relapse) and (T3: three weeks of relapse). Animals were sacrificed after the relapse period, then the
sections were prepared for histological and histomorphometric analysis.
The amount of relapse after 1 week in the control and experimental groups were 0.86 ± 0.30
and 0.72 ± 0.10 respectively and after 3 weeks were 1.24 ± 0.39 and 1.06 ± 0.29 respectively. Re-
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garding the relapse percentage, it was 43.94 ± 14.94 % and 59.11 ± 9.17% in the control group after
1 week and 3 weeks of relapse respectively and 38.27 ± 7.53% and 54.71 ± 10.14% after 1 week
and 3 weeks of relapse respectively in the experimental group. There were no statistically significant
differences in the amounts and percentages of relapse between both groups. However, the histological
analysis showed that Co-enzyme Q10 resulted in significant reduction in osteoclast count
with significant increase in the area of new bone formation along the distal surface of the root of the
lower first premolar. Signs of bone resorption were more evident in the control group.
The following could be concluded from this study :
1. The systemic administration of Co-enzyme Q10 had no effect on neither the amounts nor the
percentages of post-orthodontic relapse in rabbit models.
2. Histologically, the systemic administration of Co-enzyme Q10 enhanced bone formation and
reduced bone resorption as evidenced by the increase in the area of newly formed bone and the
decrease in the osteoclasts count.
3. Although the results of the present study showed the ineffectiveness of CoQ10 in minimizing
relapse clinically, histomorphometric analysis proved that it is still a potent bio-modulator
which can be used in the future with different parameters to reveal its action.
The limitations in the current study could be solved by the following recommendations
:
1. A prolonged follow up period of relapse phase is highly recommended to test the effect of
the systemic administration of Co-enzyme Q10 on post treatment relapse more than 3 weeks
of relapse.
2. More histological analysis is needed at multiple time points of orthodontic tooth movement
and relapse.
3. Changing the dosage of Co-enzyme Q10 which may result in different findings.
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4. The use of other formulation of Co-enzyme Q10 which are more readily soluble than the
used formulation in the present study.
5. Being safe and having positive effect on bone formation as found from previous studies, Coenzyme
Q10 should be tested in human clinical trials in the future.