A basic assumption of comparative morphology is that the skeletal elements reflect, to some degree, their loading environment. The alteration of the consistency of the food is a well-known model of altering the functional capacity of the masticatory muscles in the rat. This model was used in the series of investigations presented here in order to develop animals with masticatory hypofunction. The aim was to investigate the relationship between masticatory functional changes and the morphology, bone mass and bone micro-architecture of the mandible and its alveolar process. We have investigated this relationship in both growing and adult rats, under both normal and pathological bone metabolic conditions. In this thesis, it was shown that there is a significant effect of masticatory functional loading changes on the mandible and the mandibular alveolar bone, which is the site that directly receives the forces exerted on the teeth during mastication. The alteration of masticatory function during growth leads to significant changes of the morphology of the mandible. The quantity and the quality of the alveolar bone were influenced by masticatory function loading in both growing and adult animals. We were, moreover, able to demonstrate that normal masticatory function protects, at least partially, the alveolar bone, from the well-known negative effects of ovariectomy on other skeletal sites. This finding is probably due to the particular characteristics of the loading of the alveolar process during mastication, although morphological and embryological differences between the alveolar bone and the trabecular bone of the axial and appendicular skeleton might play a role. The findings of this series of experiments help understanding the observed morphological differences of the mandible between people with low and people with high masticatory functional demands. Although further investigation is needed, it seems that the efficiency of functional orthodontic appliances and the rate of orthodontic tooth movement may depend more than previously suspected on the characteristics of the individual masticatory apparatus (bite force, masticatory muscle capacity, etc.). Finally, based on the results of these studies, it seems that maintenance of normal masticatory function may be a critical element for the prevention of oral bone loss due to osteoporosis.