成長期における液状飼料摂取がラット歯根膜およびセメント質に与える影響

liquid diet

北海道歯学会

北海道歯学雑誌

Because modern people, especially children, tend to prefer soft food, the effects of soft food on the growth of oral tissues have been attracting clinical interest. This st udy was performed to clarify, both histologically and immunohistochemically, the effects of liquid-diet feeding on growth of the rat periodontal ligament and cementum, which are important for supporting the teeth against occlusal forces. Male Wistar rats were weaned at 21 days after birth (week 0). They were then divided into two groups: a control group fed a pellet diet and an experimental group fed a liquid diet for up to 8 weeks. The rats were then perfused with a fixative solution under general anesthesia following an injection of 5-bromo-2’-deoxyuridine (BrdU), and their maxillae were removed. Sagittal sections of the mesial root of the first molar were stained with hematoxylin and eosin (HE) and Azan. The width and area of the periodontal ligament as well as the thickness, length and area of the cellular cementum, were measured. The sections were immunostained with BrdU, and the number of BrdU-positive cells in the periodontal ligament were counted under a light microscope. In both the HE- and Azan-sections, abundant fibers were regularly arranged in the periodontal ligament at each period in both groups. Histometrically, there were no significant differences in the width and area of the periodontal ligament between two groups at any time point. The cellular cementum increased o ver time in both groups. However, the thickness and area of the cellular cementum in the experimental group were significantly less than those in the control group at some time points. Immunohistochemical examination showed that the nu mber of BrdU-positive cells in the periodontal ligament decreased over time in both groups. In some areas of t he periodontal ligament, the number of BrdU-positive cells per unit area was significantly lower in the experimental group than in the control up to 2 weeks. These observations indicate that liquid-diet intake during the growing period has the unfavorable effects on the growth of the periodontal ligament and cellular cementum in rats.