Effect of ovariectomy on tissue-level changes in rat maxilla.

ABSTRACT

PURPOSE: It remains unclear whether estrogen deficiency affects the ultrastructure and tissue-level mechanical properties of the maxilla. The hypothesis of this study was that the ovariectomized rat could induce tissue-level changes of the maxilla. MATERIALS AND METHODS: Twelve 3-month-old female Sprague Dawley rats were acquired and randomly divided into two groups ovariectomized and SHAM (control) (n = 6 for each group). Three months after the ovariectomy, implants were placed; the animals were sacrificed at day 28, and then samples were collected and prepared according to the previously established protocols. Advanced analytical equipment including scanning electron microscope with energy-dispersive spectrometry, transmission electron microscope, and nanoindentation were used to analyze bone quality. RESULTS: The results showed that the mature bone areas in the ovariectomized group were significantly affected in the mineral crystal and the microstructure. The micro-mechanical properties of the mature bone were also affected, showing significantly increased hardness (H) and reduced modulus (Er) in ovariectomized rats compared with the normal rats (P < .05). Differences in H and Er in new bone areas between the normal and ovariectomized rats were less significant. CONCLUSION: Ovariectomy affected maxilla bone tissue-level quality; however, the effects mainly existed in the mature bone areas, which were characterized by higher crystalline mineralization, hardness, and modulus.