The effect of ovariectomy on bone changes in the mandible of adult female rats
Bibliographic record
Abstract
Concerns have been raised about the outcome of therapeutic oral rehabilitation procedures in elderly patients with osteoporosis. A review of the literature, however, reveals that the effects of postmenopausal osteoporosis on the mandible are not clearly understood. The aim of this project is to investigate the effect of estrogen depletion on bone changes in the edentulous and dentate mandibles in the ovariectomized adult female rat model. To establish the time required for healing after extraction, the mandibular molars and the incisor on one side of the mandible were extracted and animals sacrificed at 0-, 2, 4-, 8- and 16-weeks post-extraction. Using bone mineral density and histomorphometric measurements, we established that healing was completed 16 weeks post-extraction. Furthermore, we found that the edentulous mandible undergoes significant reduction in size, height and width up to 16 weeks post-extraction. In the next series of experiments, mandibular teeth were extracted and animals were ovariectomized at 16 weeks post-extraction. 12–14 animals were sacrificed at 6 weeks, 6- and 9-months post-ovariectomy. Bone changes in the edentulous and dentate mandibles as well as the tibia and femur were evaluated using bone mineral density measurements and histomorphometry using backscattered electron microscopy, light and fluorescent microscopy. Ovariectomy induced bone loss in the edentulous mandible, tibia and femur and had no effect on the dentate mandible. The bone loss observed in the edentulous mandible was due to reduction in cancellous bone volume, while the cortical bone volume was not affected. Ovariectomy had no effect on the size, height and width of the mandible. Measuring static and dynamic parameters of bone histomorphometry showed that bone loss in the cancellous bone of the edentulous mandible and in the tibia was accompanied by an increase in bone turnover rate where both bone formation and resorption indices were increased. On the other hand, ovariectomy had no significant effect on histomorphometric bone formation and resorption parameters in the dentate mandible. Our results suggest that while normal function did not prevent bone loss in the tibia and femur of ovariectomized animals, functional stresses due to masticatory force prevented post-ovariectomy bone loss in the dentate mandible.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".