An autoradiographic study of experimental odontogenic cyst formation in the mouse

Proliferative populations of cells within the epithelial lining of developing experimental odontogenic cysts were identified by labeling with ³H-thymidine. Mouse molar teeth extracted from 10-day-old mice were transplanted subcutaneously and host animals were injected with 3H-thymidine 1 h prior to sacrifice. The cysts which developed around the crown of the transplanted teeth were prepared for autoradiographical examination. Labeling indices were high initially but decreased rapidly as the cysts enlarged. The pattern of labeling, however, bore no resemblance to the labeling of the reduced enamel epithelium from which the cysts developed. It was concluded that labeling activity reflects only the state of development and activity of the cyst and not the origin of the cyst.     

An autoradiographic study of experimental odontogenic cyst formation in the mouse.

Proliferative populations of cells within the epithelial lining of developing experimental odontogenic cysts were identified by labeling with 3H-thymidine. Mouse molar teeth extracted from 10-day-old mice were transplanted subcutaneously and host animals were injected with 3H-thymidine 1 h prior to sacrifice. The cysts which developed around the crown of the transplanted teeth were prepared for autoradiographical examination. Labeling indices were high initially but decreased rapidly as the cysts enlarged. The pattern of labeling, however, bore no resemblance to the labeling of the reduced enamel epithelium from which the cysts developed. It was concluded that labeling activity reflects only the state of development and activity of the cyst and not the origin of the cyst.     

An autoradiographic investigation of the developing rat periodontal membrane

Sprague-Dawley rats were killed at 2, 3 and 4 weeks after birth. One hour prior to death, they were injected intraperitoneally with [³H]-proline. Autoradiographs of the mandibles, sectioned in a mesiodistal plane, were analysed to ascertain the pattern of proline incorporation in four locations of the developing periodontal membrane of the mandibular first molar. At 2, 3 and 4 weeks after birth, the periodontal membrane in the extreme apical area was evenly labelled with [³H]-proline, while the membrane in the apical area was more intensely labelled in the root aspect than on the alveolar side. At 3 weeks, the periodontal membrane in the middle area displayed a uniform labelling reaction, but at 4 weeks the labelling was more intense in the alveolar aspect of the membrane. At 2 weeks, the periodontal membrane in the cervical area showed uniform labelling. However, at 3 and 4 weeks the labelling appeared more intense on the alveolar side of the membrane. These observations indicated that the pattern of proline incorporation in the developing periodontal membrane varied with the location in the membrane and changed concurrently with the growth and eruption of the tooth.     

An autoradiographic study on the effect of epidermal growth factor on cell proliferation in erupting mouse incisors

Epidermal growth factor (EGF) is a small polypeptide that induces precocious eyelid opening and incisor eruption in newborn mice; it stimulates cell proliferation in various cell types in vitro and in vivo. EGF was injected twice daily into newborn mice (0.4 μg/g) and tritiated thymidine was injected subcutaneously 6 h before killing the mice. Longitudinal sections of the lower incisors showed significantly more thymidine-labelled mitoses in the pre-odontoblast and pre-ameloblast layers at the basal ends of incisors in EGF-treated mice than in control mice. Although these results indicate that the EGF-induced precocious tooth emergence is associated with a stimulation of cell proliferation in the root sheath, this tissue may not be the target for the actions of EGF. Earlier studies have shown that root growth is not a factor in the generation of the eruptive force and, as neither the pre-ameloblasts nor pre-odontoblasts express EGF-receptors, the stimulation of cell proliferation in the root-sheath region appears to be a result and not a cause of accelerated tooth eruption, i.e. the increase in root growth may meet the need to maintain the tooth positionally during the accelerated eruptive process.     

The autoradiographic uptake and turnover of [1-3H]-galactose in mouse periodontal tissues

In 5-week-old Brookhaven National Laboratory short-lived mice, [³H]-galactose was utilized in all the oral tissues studied. Uptake and turnover of the tracer assessed by autoradiography revealed three uptake peaks. Synchronous fluctuation of total grain counts was repeatedly observed in different periodontal tissues. Acid glycosaminoglycans were strongly labelled and the neutral glycosaminoglycan fraction of the tissues was labelled to a lesser degree. The radiotracer became incorporated during their synthesis. The complex plots derived may represent several metabolic events occurring simultaneously. The uptake of radiotracer in fibrogenic, osteogenic and cementogenic cells was low. Accumulation of matrical output, however, was significant. The matrical output of the cementogenic cells and the osteogenic layer mesial to the alveolar bone was the highest of all the oral tissues studied throughout the 30-day period.     

Tritiated thymidine autoradiographic study on the influence of sensory and sympathetic innervation on periodontal wound healing in the rat

Understanding of wound healing mechanisms is important in designing preventive and therapeutic approaches to inflammatory periodontal diseases, which are a major cause of dental morbidity. In this study, cell proliferation was assessed after an experimental gingival wound; this was preceded by either resection of 3 mm of the inferior alveolar nerve, total extirpation of the superior cervical ganglion, trauma to those structures or sham operations. At different times, animals were pulsed with 0.5 microCi/g body weight of tritiated thymidine; histological sections were processed for quantitative autoradiography of different compartments of the periodontium. Wounding led to a significant increase in cell proliferation in the epithelial layer, the fibroblast compartment and the periodontal ligament, but not in the alveolar crest compartment. Sympathetic denervation significantly enhanced this response in the epithelial layer, the fibroblast compartment and the alveolar crest, whereas sensory denervation only modified the response in the fibroblast layer. Thus it appears that sympathetic innervation plays an important role in the regulation of cell proliferation in the periodontium and that pharmacological modulation of sympathetic activity should be further studied as a therapeutic approach in periodontal disease.     

An autoradiographic study of calcium movement in the enamel organ of rat molar tooth germs

The distribution and movement of calcium through the enamel organ and into the forming enamel was studied in 6-day-old rats, intravenously injected with 45Ca. To prevent dislocation of radiocalcium in the specimens, the tooth germs were rapidly frozen/freeze-substituted and processed for 45Ca autoradiography under dry conditions. At 30 s after the 45Ca injection, there was a decrease in labelling intensity progressing from the overlying connective tissue to the enamel organ and, in the secretory ameloblasts, from the proximal to distal cytoplasm. The most intense labelling was in the enamel matrix, where it was restricted to the superficial layer extending approx. 15 microns below the surface. At later times the density of silver grains over the connective tissue decreased considerably, whereas secretory ameloblasts showed an increasing intensity in the distal portions. Enamel had the heaviest labelling: the width of the labelled enamel increased gradually to only 40 microns from the surface 60 min after the injection. The use of wet emulsion over similarly prepared sections caused a severe dislocation of radiocalcium in the specimens. These findings confirm the rapid penetration of systemically administered calcium to newly formed enamel, probably due to isotopic exchange. A relatively slow diffusion through the enamel organ and into the surface layer of enamel suggests that net transport of calcium through the enamel organ is transcellular.     

基于AGEs的糖尿病在牙周病发展过程的影响机制研究

目的:考察糖尿病(T2DM)与牙周病(CP)发病之间的相关性,并探讨其可能的作用机制.方法:60只SD大鼠随机分为4组,每组15只,分别构建T2DM、CP、T2DM合并CP大鼠模型和一组正常对照,4周、8周后,测量大鼠实验区牙周探诊深度和菌斑指数,并用ELISA检测血清中IL-6,TNF-α及AGEs表达水平情况.结果...     

西藏驻军牙周健康状况流行病学抽样调查

目的：调查我国西藏驻军人员的牙周健康状况，并分析相关因素。方法：采用世界卫生组织1997年版口腔健康调查基本方法和标准器材，以分层、整群抽样方法选择拉萨驻军某部队为调查样本，对其进行问卷调查和临床检查。结果：共调查驻军人员730名，其中201人（27，53％）至少有1个区段牙龈探诊出血，505人（69．18％）检出牙结石，34人（4．66％）患有轻度牙周炎，1人（0.14％）患有重度牙周炎，牙周非健康状态的检出率为80．8％，总区段数为4380，其中牙周非健康的区段数为1941，牙周非健康状态的平均区段数为2．66。统计学表明牙结石的检出率、牙周非健康状态的检出率和年龄、军龄、军衔呈正相关，而与兵源、文化程度不相关。结论：牙周疾病已成为西藏驻军人员的常见病、多发病之一，有必要一方面加强口腔卫生教育，以促进其保持口腔卫生，另一方面需要加强配备口腔医疗设备和医疗人员，及时地为其预防和控制牙周病的病情。     

An autoradiographic study of the sensory innervation of teeth. I. Dentin.

Autoradiography of axoplasmically transported proteins revealed that the coronal dentin of rat molar teeth receives sensory innervation from the trigeminal ganglion. The labeled processes appear to run in dentinal tubules and sometimes reach the peripheral dentinal region near the enamel.     

Cell rests in the periodontal ligament of mouse molars

Recent reports have indicated that Hertwig's epithelial root sheath in rats and mice becomes trapped between dentin and cementum or within cementum during molar root development. Evidence is presented that well defined cell rests persist nevertheless in the periodontal ligament of mouse molars. These rests are located in close proximity to the cementum surface. They are composed of clumped epithelial cells with typical ultrastructural features. The latter include intracytoplasmic tonofibrils, intercellular desmosomal connections and a limiting basal lamina showing frequent interruptions in its continuity. Hemidesmosomes and occasional anchoring fibrils are associated in the usual manner with the basal lamina.