An experimental model of disuse in the alveolar rat bone: A histomorphometrical study

Lack of mechanical stimulation is known to cause disuse osteopenia in bones. However, experimental models for disuse osteopenia on bones other than jawbones are not applicable to jawbones. The little available information in this field has been applied to the study of overeruption of teeth lacking antagonists. However, the absence of an antagonist in the opposite jaw means that there is no stimulation by occlusion. Our hypothesis is that the lack of stimulation due to the absence of teeth causes disuse osteopenia in the interradicular bone of the antagonist teeth. Our aim was to develop a model of disuse osteopenia due to the absence of occlusal forces. We used male Wistar rats with 215-230 g body weight, divided into 2 groups: one absolute control group (C) and one experimental group in which the three right lower molars were extracted (E). The left side of the jaw in the experimental group was used as a paired control (PC). The animals were euthanized 7 days after extraction. The jaws were placed in occlusion, fastened and fixed in 10% formalin. The heads were cut in half and radiographs made of both jaws. The upper jaws were processed histologically. After decalcification, bucco-palatine oriented sections were cut at the level of the mesial root and distal roots of the first upper molars. On the radiographs, the distance from the tip of the cusp on the first upper molar to the antagonist edentulous ridge (DA) was measured. On the microphotographs, the following parameters were measured: passive eruption degree (PED), height of periodontal ligament at the level of the furcation (HPL) and interradicular bone volume (BVI). The data were compared statistically using ANOVA and Bonferroni's post-hoc test, considering p