The progress of the periodontal syndrome in the rice rat

Several morphometric and cellular parameters were studied in the rice rat ( Oryzomys palustris ). When fed a soft, high carbohydrate diet, a severe periodontal disease occurred, with significant alterations in the morphometric and cellular endpoints observed. Weaned animals were placed on a high carbohydrate diet for periods of 6, 12 or 18 weeks. There was a linear, rapid loss of bone by 18 weeks, approaching a 75 % loss of original bone. Vascular spaces decreased as the remaining connective tissue became fibrotic in character. The percentage of the interdental test site which was destroyed by periodontal disease increased dramatically over the time of the experiment. The numbers of fibroblasts per mm of bone surface increased slightly at the 18 week period; osteoblasts were unchanged at any period. The numbers of osteoclast nuclei rose dramatically by 12 weeks, and these cell nuclei remained at increased levels at 18 weeks. Also, the numbers of inflammatory cells residing at the bone surface increased greatly by 18 weeks time. Finally, the numbers of ³H-TdR labeled periodontal ligament (PDL) fibroblasts increased significantly at both 12 and 18 weeks time. These cellular changes and their relation to the bone loss due to periodontal disease are discussed.     

Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat

The periodontal syndrome in the rice rat was studied in animals fed a high sucrose diet. Progressive degenerative and inflammatory changes within the coronal aspects of the rice rat psriodontium (viz. sulcus, epithelium and lamina propria) were noted. PMN's were seen to migrate from blood vessels within the lamina propria, through the basal lamina, and to either the cemental surface or to the bacterial plaque, where a minimal degree of PMN phagocytosis and degranulation was observed. The degree of PMN phagocytosis appeared to be inversely related to the density of bacterial plaque as viewed on the electron microscopic level.
Progressive degenerative changes (viz. vacuolization, lipid accumulation, mitochondrial swelling, etc.) were seen in gingivai epithelial cells subjacent to the bacterial plaque, as well as at the basal layer. Similar changes were noted in fibroblasts in the underlying lamina propria. At later stages of observation (8–14 weeks post-weaning) a prominent population of macrophages and mononuclear cells was seen within the lamina propria. "Clumping" of these cell types with degenerating fibroblasts was a common finding.     

Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat

In this paper on the periodontal syndrome in the rice rat, the effects of dietary penicillin and tetracycline on the progressive inflammatory and degenerative changes (as seen in rice rats fed diet 700 alone) were noted at the light and electron microscopic level. Throughout the observation period (0–14 weeks postweaning), animals fed diet 700 with penicillin or diet 700 with tetracycline showed no evidence of bacterial colonization, a minimal PMN infiltrate restricted to the gingival epithelium and subjacent lamina propria, and no marked degenerative changes within cells that normally inhabited the periodontium (viz. epithelial cells, fibroblasts, osteoblasts). Marked osteoblastic or osteoclastic activity was rarely noted along the alveolar crest in this group of animals.
These results give added support to the concept of a single microbial agent or group of microbial agents, as the primary etiology of this disease.     

Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat

In this study on the periodontal syndrome in the rice rat, the progressive inflammatory and degenerative changes were noted in the transseptal fiber area and alveolar crest.
The predominant inflammatory cell types within the transseptal fiber area were PMN's, monocytes and macrophages. Progressive degenerative changes were noted in fibroblasts and collagen fibers with replacement of these elements by the inflammatory infiltrate.
At the alveolar crest, extensive osteoclastic activity was observed. Expressions of this activity included the presence of prominent osteoclast ruffled borders and osteoclastic phagocytosis of osteocytic cells. Degenerative changes within osteoblasts were noted at later stages.
From these observations, the accelerated rate of destruction seen in this animal model can be explained in part by the increase in resorptive elements (macrophages, osteoclasts) with the simultaneous decrease in formative elements (epithelial cells, fibroblasts, osteoblasts).     

Histological and ultrastructural characteristics of the periodontal syndrome in the rice rat

In this study on the periodontal syndrome in the rice rat, observations were made on rice rats fed stock diet and followed from six days to fifteen weeks after birth, and on rice rats fed a high sucrose diet (Diet 700) from weaning (3 weeks after birth) and followed to seventeen weeks after birth.
In rats fed stock diet, early massive accumulations of bacterial plaque were seen on erupting posterior teeth with an underlying PMN exudate and a PMN infiltrate within the gingival epithelium and lamina propria. Inflammatory and resorptive changes were rarely seen in the transeptal fiber area and alveolar crest in this group of animals.
In rats fed diet 700, similar patterns of bacterial plaque accumulations and PMN infiltrations were seen. At later time periods, this PMN infiltrate was commonly seen to extend through the transseptal fiber area to the alveolar crest where marked osteoclastic activity was noted. Such apical extension of the inflammatory infiltrate was associated with ulceration of the overlying gingival epithelium.     

The lack of pulpal pathosis in rice rats with the periodontal syndrome.

The purpose of this study was to determine in the rice rat model whether a relationship exists between the severity of periodontal disease and the presence of severity of pulpal lesions. The results indicated that, even in the presence of severe loss of alveolar bone, extending close to the root apices, there were no detectable changes in the pulpal tissues as compared to the pulps of teeth in which there was no loss of alveolar bone. The scarcity of accessory pulp canals in the rice rat may be related to our findings.     

牙周膜干细胞的研究进展

牙周膜干细胞可分化为成骨细胞或成牙骨质细胞、脂肪细胞和胶原形成细胞,是牙周组织工程中新的种子细胞。笔者就牙周膜干细胞的生物学特性、牙周膜干细胞的多向分化潜能、牙周膜干细胞的移植及其潜在的临床应用价值作一综述。     

牙周病与糖尿病关系的研究进展

牙周病主要包括牙龈炎和牙周炎,是人类最常见的感染病之一,严重的牙周炎有可能增加心血管病、糖尿病、早产及肺部感染等系统性疾病的易感性。近年来,牙周病与全身性疾病的关系不仅引起国内外口腔医学界学者的关注,同时也受到其他医学界的重视。其中牙周病与糖尿病关系的研究更是倍受瞩目。目前,牙周病与糖尿病之间的关系虽已基本确立,但两者相互作用的内在机制尚未完全明确。本文总结有关牙周病与糖尿病关系方面的资料,对牙周病感染增加糖尿病易感性作综合阐述。     

Vector系统用于牙周病治疗的研究进展

Vector系统是一种新型超声治疗设备,其工作尖平行于牙体表面的振动方式使其在有效去除菌斑、牙石的同时,不会产生医源性带菌气溶胶及损伤牙体表面结构,同传统超声治疗方法相比,能明显减轻疼痛,提高病人的依从性.     

The effects of inanition on the periodontal tissues of the rat

The changes in the periodontal tissues of the rat, when submitted to inanition, were studied at body weight losses of 4, 8, 12, 20, 24, 28, 32, 36, and 40 per cent. Histological and histochemical methods were used to investigate the effects.
It was possible to establish that the tissue changes started in the middle portion of the periodontal membrane, migrating in the beginning towards the alveolar bone and only in a later stage towards the cementum. There were no structural changes in the gingival mucosa. The results obtained are discussed in the light of the varying known metabolic rates of the various zones.