Retzius Lines Research Articles

水銀中毒の歯科学的研究 : 第 I 編水銀連続投与の歯牙並びに歯周組織に及ぼす影響に関する病理組織学的研究(後半)

The author administered intramusclarly the various concentration of mercuric chloride solution to albino rats and caused experimentally mercury poisoning. The patho-histological findings of the teeth and the peridental tissues were clarified and the author obtained his opinion concerning the patho-histological nature and appearing mechanism. 1) Patho-histologically the soft tissues such as tooth germs, dental pulps, peridental membranes and dental gums showed as a rule the symptoms of atrophy, proliferation, hydropic cyst formation that were chronic type as well as the symptoms of degeneration, necrosis and circulatory disturbance that appeared highly in acute type. The patho-histological nature of the hard tissues such as enamel, dentine, cement and alveolus was calcification impediment, forming decrease of the ground substances and its formation anomaly in incisors, while in molars proliferation, abortion and fusion that are cardinal phases, and proliferation is recognized remarkably in chronic type. 2) Patho-histological changes of the enamel system. In enamel-forming anlages, turbidity and swelling of cells, hydropic degeneration proteinic degeneration, atrophy, necrobiosis and necrotic aspects were found, and the abnormal proliferation of the outer enamel cells, hydropic cyst formation of the intra-mediary layers and enamel pulps were recognized. In the calcifying layers of the enamel of incisors were often found out diffuse calcifying impediment, forming decrease of the ground substances, formation anomaly of prisms, wave form figure in the younger layer, enamel drop-forming, pile of abnormal substance, appearance of Retzius line. While in molars the frequent occurrence of dental caries was recognized. 3) Changes of the dentine In incisors the following findings were recognized, namely the forming decrease of the ground substances, cloud like dentine that was deemed diffuse calcification impediment, anomaly of dentinal tubules and fibres. While in molars there were observed disappearance of calcareous globes as decalcifying phenomenon, derangement of Andresens lines. caries-like change, crevice-forming, appearance of the fusing aspect starting from the pulp cavity wall, absorption, dentikel formation of the secondary dentine, hindrance or suspension of globe-shaped calcification in the praedentine both of incisors and of molars, increase or decrease of width, degeneration of proteinic line deposition and Tomes fibres. 4) Patho-histological changes of the dental pulp system. As the fundamental changes of the pulps of iucisors and dental papillae, the author found the degeneration and atrophy of odontoblasts, cells proper and Korffs fibres, hydropic degeneration of the ground substance, in the fatty degenration transformation into necrosis from hydropic cyst formation. While in molars atrophy, degeneration, partial necrosis and corruption of odontoblasts and cells proper, calcification of the ground substance, in the circulatory system hyperaemic dilatation of fine vessels, vessel leakage, collapse haemorrhage, erythro-thrombus formation. 5) Changes of the cement. As the main patho-histological changes of the incisors cementum, the forming decrease of the ground substance calcification impediment, hydropic cyst formation of cementblasts were recognized. While in molars proliferation, absorption, fusion, dentikel, occurrence of caries were recognized and cementblasts fell in atrophy, degeneration and necrosis. 6) Changes of the periodontal tissues. There were found commonly atrophy, hydropic degeneration, mucous degeneration necrosis, hydropic cyst formation and hyperaemic dilatation, anaemia, leakage collapse haemorrhage anb thrombus formation in the blood vessel system as the changes of the periodontium and dental capsule. 7) Changes of the alveolar bone. There were found the absorption of the ground substance, fusion, decalcification, proliferation in case of the

Histopathology of Enamel Caries

Miller (1) was the first to investigate carious enamel microscopically. It appeared to him that the interprismatic substance was dissolved, bacteria forcing their way between the loosened prisms. The loosening of the prisms he considered caused by acid, the action of the microorganisms on the enamel being indirect through the acid which they produce. Williams (2) described the beginning of the carious process as a dissolution of the interrod substance, this material being less resistant to the acid of decay. This substance is not the sheath for the sheath, as well as Nasmyth membrane, is more resistant to acid than the prisms. G. V. Black (3) described the process in a similar way. Caries of the enamel, he believed, was caused by acid formed by microorganisms, which lie upon the outside of the enamel and never enter the tissue until the enamel rods are loosened and fall out. C. F. Bodecker (4) stated that the first action of the acid of decay on the enamel is to attack the cementing substance by robbing it of inorganic salts. The bacteria tunnel into the core of the rod, the sheaths and the cementing substance appearing to be more resistant to acid. Appelbaum (5) showed that the Retzius (incremental) lines become more visible in incipient caries. The calcium salts disappear by acid action and the organic framework shows up more clearly. Beust (6) was the first to call attention to the fact that carious enamel resists acid action and therefore caries cannot consist purely of acid action. Gottlieb (7) described undermining enamel caries, explaining it by the known fact that the deeper layers of the enamel are less calcified than the superficial ones.

Age-Incidence of Lines of Retzius in the Enamel of Human Permanent Teeth

Age-Incidence of Lines of Retzius in the Enamel of Human Permanent Teeth