Summary:
Nowadays, there is an increasing prevalence of degenerative diseases, such as
osteoporosis. This bone disease is characterized by decreased bone mass and
bone remodeling and has a significant impact on the health of postmenopausal
women and elderly people. It is worth noting that, while the effects of
osteoporosis on the long bones and the vertebrae have been widely studied, its
impact on the jaw bones is less known. Ιt has been proved that replacement
therapy with estrogens prevents bone loss in postmenopausal women. A
particularly interesting question is whether estrogens and phytoestrogens could
prevent the bone density loss of the mandible during menopause.
The aim of this Master’s thesis was to examine the ability of phytoestrogens to
restore ovariectomy-induced reduction in bone density. For this purpose, 57
female mice C57, aged 6 months, were used. in 50 of those ovariectomy was
performed, while in the remaining 7 surgery was performed without removal of
the ovaries (SHAM). Afterwards, the mice were separated into 9 groups (SHAM,
OVX, EE, RAL, OLEAMED, SESAME, ONOBRYCHIS, OLEUROPEIN, OH-TYROSOL), of which
the first two were the control groups. The administration of the estrogenic
compounds ethinyl estradiol (EE), raloxifene (RAL), OLEAMED, SESAME,
ONOBRYCHIS, OLEUROPEIN and OH-TYROSOL started the next day of the surgery,
daily, for 4 weeks. The results were evaluated radiographically and
histologically. Radiographic evaluation of the animals’ mandible included
radiographs and digital mammograph images while, for the histological analysis,
hematoxylin-eosin and TRAP staining were performed in thin paraffin sections.
The results revealed that bone density of the cortical bone of the mandible did
not change after ovariectomy or administration of estrogenic compounds. On the
contrary, in radiographs, the area of cortical bone increased, compared to OVX
group, in EE, SESAME, ONOBRYCHIS and OLEUROPEIN groups, while in mammograms
only in ONOBRYCHIS group. Moreover, ovariectomy reduced significantly bone
mineral density of alveolar bone of the mandible compared to SHAM group,
increased the area of bone marrow cavities and indicated a possible increase of
TRAP-positive osteoclasts. The administration of EE or RAL reversed the
ovariectomy-induced decrease in bone density and area of the bone marrow
cavities, indicating a possible reduction of TRAP-positive osteoclasts. The
phytoestrogens used did not show similar effects. The area of mandibular ramus
was not affected by ovariectomy, but appeared increased only in SESAME group.
Finally, thickness of periodontal ligament showed no statistically significant
difference between groups.
In conclusion, the present study demonstrated that ovariectomy affected the
mandible, within four weeks. Specifically, ovariectomy or/and administration of
estrogenic compounds affected the area of cortical bone and mandibular ramus,
the bone mineral density of alveolar bone, the area of bone marrow cavities and
possibly the number of TRAP-positive osteoclasts. Phytoestrogens appear to
mimic the action of estrogens, but they presented limited activity in the
mandible, indicating the need for further studies.
