The study investigated the remineralization effect of calcified seaweed with large amounts of calcium (Ca), magnesium (Mg), sodium (Na), fluorine (F) and phosphorus (P). Human third molars were used in the experiment with the approval of the Ethics Committee of Tokyo Dental College. Cementum was removed from the cervical area around the teeth exposing the dentin. Small dentin blocks were prepared and immersed in acetic acid-sodium acetate buffer for 24 hours. Samples were immersed in remineralized liquid or saliva solution with or without calcified seaweed for 2 weeks. Structural changes in remineralization, depth of demineralization and loss in mineral volume were evaluated by contact microradiogram (CMR). Qualitative analysis was carried out with electron probe microanalyzer (EPMA). Morphology of crystal was observed using high-resolution transmission electron microscopy (HR-TEM). CMR image analysis revealed that part of the samples immersed in the solutions underwent remineralization. However, there was no significant difference in the degree of remineralization. EPMA observation of dentin partly detected Ca and P but not Mg or F. HR-TEM analysis revealed changes in crystal structure caused by Mg and F, which influenced remineralization in a small amount.

Calcified seaweed contains abundant quantities of calcium, magnesium, phosphate, sodium and fluorine ions. The objective of this study was to investigate the effect of chewing gum containing calcified seaweed on the remineralization and aciduric properties of enamel. For intraoral experiments, enamel blocks prepared from third molars were attached to an appliance. Each block was covered with acid-resistant nail varnish, except for a window measuring 6 x 4 mm. A caries-like lesion was artificially prepared in the window. Participants attached the appliance and chewed gum for 20 min, 4 times a day. The intraoral experiment period was 2 weeks. Half of each window was re-covered with nail varnish. In the aciduric experiment, these blocks were immersed in demineralizing solution. After demineralization, the blocks were embedded in polyester resin and prepared in ground sections. Contact microradiograms of these ground sections were obtained. A high degree of remineralization occurred at the surface and at a deep layer in the remineralized enamel area. In the aciduric experiment area, further demineralization was observed beneath the original demineralized layer, and overall depth of demineralization increased. A thin, highly mineralized layer was observed between the two demineralized layers. The degree of remineralization and aciduric rate with calcified seaweed treatment was higher than that with non-calcified seaweed treatment (p<0.05). These results suggest that chewing calcified seaweed-containing gum significantly enhances the remineralization and acid resistance of enamel by exposure to fluorine ions.

Kyushu Dental Sooiety 会 報 一 723 一 development with age of gingivitis ， inducing a periodontal pocket formation． Alveolar bone loss becomes apparent beyond 8 months ． In this study ， we found that young STR ／N mice secreted the same volume of saliva by pilocarpine stimulation as that in ICR while aged STR ／ N mice less secreted than aged ICR mice did ． This suggests that dysfunction of salivary secretion develops with age and its development may be related to the development of periodontitis ．

The three-dimensional structure of the odontoblastic organelle and the alignment of collagen fibers in predentin and dentin were observed by scanning electron microscopy (SEM) using pultaceous treatment (AODO method). The structure of the nuclear membrane and transitional images from granular endoplasmic reticulum (rER) to transport vesicles and clear surface of Golgi apparatus unobtainable with transmission electron microscopy (TEM) were observed. Cross-sections of the rER system and tubular mitochondria revealed configurations similar to those usually described in TEM studies. There were a large number of ribosomes on the surface of the rER. A fibrous structure which maintained an appropriate distance between the various elements of the rER was also observed. The alignment of the dentin collagen fibers accorded with TEM images, but the alignment of the collagen fibers in predentin did not, with many fibers arranged horizontally.