الفهرس 
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Abstract
Aim: The aim of the study was to evaluate the effect of posterior teeth extraction on type of
intrinsic muscles’ fibers of the tongue via histological, histomorphometric, gene expression
analysis, and ultrastructure via transmission electron microscope.
Methodology: The study was carried out on 28 healthy male albino rats weight range 150 to
200 gm, fed with standard diet pellets and tap water ad libitum. 14 rats had bilateral mandibular
molars extraction and 14 rats were used as control. Animals were randomly divided as following,
group I: included 7 healthy male rats, that were not subjected to extraction and euthanized after 4
weeks, group II: included 7 healthy male rats, that were not subjected to extraction and euthanized
after 8 weeks, group III: included 7 healthy male rats, that were subjected to bilateral mandibular
molars extraction and euthanized after 4 weeks and group IV: included 7 healthy male rats, that were
subjected to bilateral mandibular molars extraction and euthanized after 8 weeks.
All 28 rats were euthanized either at 4 weeks (group I &group III) or at 8 weeks (group III
&group IV) by decapitation. Tongues from 28 rats were dissected for histological, histomorphometic,
gene expression analysis, and ultrastructure examination via transmission electron microscope.
Results: The histological examination of group III showed significant deterioration in tongue
muscles as compared to other groups where, areas of spacing between muscle bundles,
increased perimysium connective tissue, together with dilated and congested blood vessels were
detected. Upon long duration adaptation, group IV showed improvement in histological features
of muscles together with signs of hypertrophy in comparison to the other groups. Morphometric
analysis revealed a significant increase in (mean total area percent of muscle fibers, area of
single muscle fiber, perimeter of single muscle fiber and minimum Feret’s diameter) in group IV
in addition to significant decrease in number of inflammatory cells as compared to group III.
Additionally, transmission electron microscopic imaging revealed mitochondrial degeneration
together with a statistically significant increase in length of sarcomere and length of I-band in
group III (4 weeks extraction). Further a statistically significant increase in (length of
sarcomere, width of sarcomere, length of I-band and width of Z-line) in addition to Cox IV
gene and PGC-1 alpha gene expression was observed in group IV (8 weeks extraction group)
as compared to the other groups.
Conclusions: The current study revealed that bilateral mandibular molar extraction had a great
impact on intrinsic tongue muscles. We observed that 4 weeks following bilateral extraction of
mandibular molars in albino rats was associated with altered mechanical loading on the tongue
muscles inducing inflammatory response and muscle atrophy. While 8 weeks post extraction muscle
adaptation with hypertrophy took place as evident by histological findings additionally, shift in
muscle fiber type to slow more fatigue resistant type was clearly evident by elevation of Cox IV
gene and PGC-1 alpha gene expression in intrinsic muscles of the tongue.
Key words: Tongue Intrinsic Muscles ,Extraction ,PGC-1 alpha ,Cox IV , Transmission electron
microscope , PCR.