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Objectives: The effects of reduced chewing loads on load bearing integrity of interradicular bone (IB) within dentoalveolar joints (DAJ) in rats were investigated., Methods: Four-week-old Sprague Dawley rats (N = 60) were divided into two groups; rats were either fed normal food, which is hard-pellet food (HF) (N = 30), or soft-powdered chow (SF) (N = 30). Biomechanical testing of intact DAJs and mapping of the resulting mechanical strains within IBs from 8- through 24-week-old rats fed HF or SF were performed. Tension- and compression-based mechanical strain profiles were mapped by correlating digital volumes of IBs at no load with the same IBs under load. Heterogeneity within IB was identified by mapping cement lines and TRAP-positive multinucleated cells using histology, and mechanical properties using nanoindentation technique., Results: Significantly decreased interradicular functional space, IB volume fraction, and elastic modulus of IB in the SF group compared with the HF group were observed, and these trends varied with an increase in age. The elastic modulus values illustrated significant heterogeneity within IB from HF or SF groups. Both compression- and tension-based strains were localized at the coronal portion of the IB and the variation in strain profiles complemented the observed material heterogeneity using histology and nanoindentation., Significance: Interradicular space and IB material-related mechanoadaptations in a DAJ are optimized to meet soft food related chewing demands. Results provided insights into age-specific regulation of chewing loads as a plausible "therapeutic dose" to reverse adaptations within the periodontal complex as an attempt to regain functional competence of a dynamic DAJ., Competing Interests: Declaration of Competing Interest The authors report no declarations of interest., (Copyright © 2020 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Morphological investigations of rats after extended period of drinking water with varying amounts of conventionally pathogenic microflora revealed changes in the cellular composition of different morphological/functional sections of lymphoid plaques in the small intestine which depended on concentrations of microorganisms. Comparing with the control, sites of lymphoid node reproduction were significantly richer in the relative number of plaques and large lymphocytes when water contained 1,000 microbial bodies in 1 cm3. Concentrations of microorganisms higher, the parameters tended down to referential levels. Rise in water concentrations of microorganisms was associated with a decrease in the relative number of small lymphocytes, i.e. main members of the cell in lymphoid nodule mantle with the reproduction site, and an increase in the number of plasmatic cells and macrophages in the diffuse lymphoid tissue. Lymphoid nodes lacking the reproduction sites were observed in the control and in the group of animals who drank minimum microbes (100 cells in 1 cm3). These nodules were viewed again in the rats who had drunk maximum antigens (1 000,000 cells in 1 cm3). These changes point to proliferation and differentiation of lymphoid cells driven by water microorganisms, and inhibition of these processes by water concentrations of conventionally pathogenic microflora above 1,000 microbial bodies in 1 cm3.

In the experiment, performed in 3-months-old albino Wistar rats, the response of small intestine lymphoid patches to continuous action of drinking water with different content of opportunistic microorganisms was studied histologically and morphometrically. Changes of lymphoid nodule number and diameter and of correlation of the organ cross section areas occupied by lymphoid nodules and diffuse internodular lymphoid tissue which is dependent on microbe concentration in drinking water was demonstrated.