Histological and histomorphometrical changes in rat alveolar bone following antagonistic tooth extraction and/or ovariectomy.
OBJECTIVE
To examine changes appearing in the alveolar bone following the removal of the mechanical stress of occlusal loading, as well as the added influence of estrogen deficiency on such changes.


METHODS
The right mandibular molars of female rats were extracted. After 8 weeks, 12 animals were ovariectomized (OVX), and the other 12 were subjected to sham surgery (sham). Four weeks after surgery, all rats were sacrificed. The left-half and right-half maxillas of the sham group (the sham-occluded side and the sham-extruded side, respectively) and right-half maxilla of OVX group (the OVX-extruded side) were examined by histological observation and bone histomorphometry.


RESULTS
The vertical height of alveolar bone in the sham-extruded and the OVX-extruded sides increased as compared with that of the sham-occluded side. In both extruded sides, active bone formation occurred on the surface of the alveolar bone facing the periodontal ligament, but the bone marrow was expanded and the bone volume had decreased in the internal area of the alveolar bone. In the OVX-extruded side, the bone marrow expanded more remarkably than that of the sham-extruded side, and the highest percentage of osteoclast surface was detected.


CONCLUSIONS
Around the extruded teeth, there were regional differences in bone dynamics between the internal area of the alveolar bone and the bone surface facing the periodontal ligament, and estrogen deficiency seems to have caused further loss of bone volume in the interior of the alveolar bone supporting the extruded tooth.
Ejiri
Sadakazu
S
Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Section for Oral Life Science, Niigata University Graduate School of Medical and Dental Science, Niigata, Japan. ejiri@dent.niigata-u.ac.jp
Toyooka
Eiichi
E
Tanaka
Mikako
M
Anwar
Rezwana Binte
RB
Kohno
Shoji
S
D000135:Acid Phosphatase / Q000032:analysis; D000539:Alveolar Process / Q000201:enzymology / Q000473:pathology*; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001853:Bone Marrow / Q000201:enzymology / Q000473:pathology; D001862:Bone Resorption / Q000473:pathology; D004967:Estrogens / Q000172:deficiency*; D005260:Female; D007527:Isoenzymes / Q000032:analysis; D008334:Mandible / Q000201:enzymology / Q000473:pathology*; D018613:Microscopy, Confocal / Q000379:methods; D008963:Molar / Q000601:surgery; D010010:Osteoclasts / Q000473:pathology; D010052:Ovariectomy / Q000379:methods; D010513:Periodontal Ligament / Q000201:enzymology / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D000071681:Tartrate-Resistant Acid Phosphatase; D014081:Tooth Extraction
D015415:Biomarkers; D004967:Estrogens; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase