The purpose of this study was to evaluate F, Zn and Sr release and uptake by dentin from a new type of glass ionomer cement (GIC) containing a tannin-fluoride preparation (HY agent). Four cements were prepared containing 0wt% (HY0), 1.5wt% (HY1.5), 5.0wt% (HY5) and 10.0wt% (HY10) of the preparation.
1. The quantity and duration of F release was greater than the release of the other two elements. A strong initial booster effect was obvious for both Zn and Sr.
2. The amount of F, Zn and Sr release increased in direct proportion to the amount of HY agent and was the greatest for HY10.
3. The greatest amount of penetration and the deepest penetration was for F, while Sr had the smallest and was limited to the surface region. An increase in the HY agent resulted in an increase in the initial uptake of the three elements.
4. An increase in the HY agent resulted in a corresponding increase in F penetration, and the amount of penetration increased over time. A similar tendency occurred with F release in distilled water.
5. The amount of Zn released into the dentin for the HY1.5 formulation increased over time. Although the amount of Zn in the surface layer decreased for HY5 and HY10 over time, there was an increase in its depth of penetration.
6. The amount of penetration of Sr in the outer surface layer increased over time for the HY1.5 and HY5 formulation. In contrast, there was very little penetration of Sr for the HY10 formulation.
These results indicated that, compared with the other two elements, F was released more easily from GIC and it was taken up more readily in the dentin. An increase in the HY agent resulted in a corresponding increase in the penetration of F and Zn, although the greatest amount of penetration of Sr was for the HY5 formulation.

View full abstract

In pedodontics, where growth and the development must be taken into consideration, average profile values are very important in diagnosing growth changes, and ideal profile values are essential for establishing treatment goals. We attempted to ascertain the average and the ideal values for profiles of Japanese children using the Powell analysis.
The average values for each of the measurements of this analysis were investigated from photographs of the profiles of 1,518 Japanese children between the ages of 6 and 17 years. Ideal values were investigated in 276 selected profiles of adolescents between the ages of 16 and 17 years.
The results were as follows :
1. Average values were obtained for the Powell analysis in Japanese children between the ages of 6 and 17.
2. There were no chronological changes in the nasofrontal angle, nasofacial angle, nasomental angle, mentocervical angle, nasolabial angle and subnasale-stomion/stomion-menton ratio. However, there were significant chronological changes in the base to dorsum ratio and nasion-subnasale/subnasale-menton ratio.
3. Ideal values were obtained from the esthetic evaluation of profiles for adolescents between the ages of 16 and 17 years.
These values may be useful in developing treatment goals for profiles during interceptive and corrective orthodontics.

View full abstract

I studied biochemically and immunohistochemically the kinetics of collagen and tenascin during progression of a human gingival carcinoma xenograft line, GK-1, in nude mice.
Tumors showed logarithmic growth from five to seven weeks after transplantation. Total collagen content increased during progression of the tumor, and positively correlated with the tumor growth. Although the ratio of composition of type I collagen did not change after transplantation, from five weeks after transplantation, type IV and type V collagen increased gradually, and type III collagen decreased. Type IV collagen localized in the capillary wall and in patchs in the basement membrane of the tumor nest. Tenascin localized in all the stroma of the tumor mass and partially in the basement membrane of the tumor nest. In human gingiva it localized in the prickle cell layer, underlying connective tissue and partially in the basement membrane. GK-1 tenascin had two subunits of 220 kDa and 130 kDa, and was different from human gingiva tenascin which had two subunits of 220 kDa and 200 kDa. Although tenascin content increased at five weeks after transplantation, it decreased gradually after this tlme.
These findings indicate that collagen functions as a scaffold and a host response to tumor cell proliferation, and tenascin functions to maintain a suitable environment for the progressing tumor tissue.

View full abstract

The present study was undertaken to assess whether nociceptive neurons in the intralaminar nuclei of the cat thalamus could be inhibited by electrical stimulation of either the ventromedial periaqueductal gray (PAG) or the nucleus raphe dorsalis (NRD).
Experiments were carried out on cats anesthetized with urethane and chloralose. Single unit activities were recorded from the thalamus using glass capillary microelectrodes filled with 2% pontamine sky blue in 0.5 M sodium acetate. Bilateral maxillary and mandibular canine dental pulps, the greater splanchnic nerve (SPL), the greater occipital nerve (C2) and the mesencephalic reticular formation (MRF) were prepared for electrical stimulation.
Nociceptive neurons were recorded from the nucleus centralis lateralis (CL) and the nucleus parafascicularis (Pf). The effects of stimulating either PAG or NRD on responses obtained from these neurons were investigated. Conditioning electrical stimulation of either PAG or NRD inhibited responses to electrical stimulation of the dental pulp, SPL and/or C2 in some of the CL and Pf neurons. The same conditioning stimulation also inhibited short latency responses to electrical stimulation of MRF. The stimulation had no effects on the majority of intralaminar nociceptive neurons.
These data suggest that PAG or NRD stimulation-produced inhibition of these neurons may be partially mediated by an ascending pathway, in addition to the well-known descending pathways. We found that electrical stimulation of either PAG or NRD was not effective in inhibiting the majority of the intralaminar nociceptive neurons. However, the same stimulation always inhibited resposes to electrical stimulation of SPL of nociceptive reurons in the nucleus ventralis posterolateralis.

View full abstract

The purpose of this study was to investigate morphometrical and histological changes in craniofacial growth after maxillary expansion. A total of 135 four-week old male Wistar rats were used in this experiment. Lateral expansion was applied to the maxillary incisors by a stainless helical loop that was activated for one week and then removed. The experimental animals were killed at 5, 8, 11 and 14 weeks of age and the skulls were resected. Morphological measurements and microscopic as well as microradiographic observation were carried out.
The results were as follows :
1. Lateral maxillary expansion extended the midpalatal suture.
2. Maxillary expansion affected not only the midpalatal suture, but also the sutures of the craniofacial complex.
3. Skull width after removal of the appliance was greater in the experimental animals than in the controls.
4. However, the skull height and length after removal of the appliance were smaller in the experimental group.
These results indicate that maxillary expansion creates changes in the direction of craniofacial growth.

View full abstract

We investigated age related changes in the arrangement of the collagen fibrillar network of palatal mucosa using female Sprague-Dawley rats between 3 and 90 weeks of age. A cell-maceration/scanning electron microscope method was employed to demonstrate the three-dimensional architecture of the collagen fibrils. Numerous microridges made up of interwoven collagen fibrils were observed on the connective tissue surface. Differences in the number and shape of the microridges by location were observed in rats of the same age. The microridges increased in number and extended towards the epidermis with age until 10 weeks. The collagen fibrillar network on the connective tissue surface became tighter with age until 32 weeks, but loosened at 90 weeks.

View full abstract

I investigated the surface characterization of synthetic hydroxyapatite (HAp) treated with four types of fluorosurfactant (FSA) and its sequent effect on the adsorption of protein to HAp. The surface tension, zeta potential, chemical composition of the topmost surface and contact angle were measured for the HAp and dental enamel treated with FSA. The adsorption of protein on the surface of HAp treated with FSA was analyzed from the zeta potential as a function of protein concentration. The surface characterization of HAp changed with the coverage of FSA. Adsorption of FSA on the HAp surface prevented adsorption of protein.

View full abstract

I devised and evaluated a method for determining sweet preference using a sweet preference point corresponding to the lowest concentration of surface solution among those the subject felt too sweet and unpleasant. This method showed better reliability and validity than evaluations based on conventional sweet threshold values or the most preferred solution. Althouth no sex differences were observed in sweet preference, age differences did exist. Those subjects who reported liking sweet foods often had high sweet preference points, although they did not always show greater caries experience.

View full abstract

Human pulp tibroblasts (HPF-C) were isolated from deciduous teeth and cultured in vitro. With continued culture in normal tissue culture medium, six pulp fibroblast strains formed mineralized nodules. HPF-C showed high levels of alkaline phosphatase activity that could be increased more than seven fold by the addition of 1,25 (OH)_2D_3 at 5-50×10^<-9>. In addition to the production of type I collagen, these cells also synthesized fibronectin and osteonectin, and expressed mRNA of transforming growth factortype B and liver / bone / kidney alkaline phosphatase. The responses of HPF-C to parathyroid hormone, cAMP and calcitonin were similar to that of odontoblasts. Also, HPF-C in contact with hydroxyapatite served as a mediator of cell-to-cell interaction and was related to the functional differentiation of cells for tissue repair, including pulpal calcification.

View full abstract

The constituents of microbial flora from both saliva and tongue dorsum were compared for 11 subjects with recurrent aphtha and six healthy controls. The isolated bacteria from the two sites were predominantly facultative, Gram-positive cocci. The proportional distribution of facultative, Gram-positive, catalase-positive cocci in the recurrent aphtha cases (19.7% in saliva and 28.3% in the tongue dorsum) were distinctly different (p<0.001) from the controls (3.3% in saliva and 8.9% in the tongue dorsum). Using DNA-DNA hybridization, 22.4% of the strains tested were identified as Stomatococcus mucilaginosus, although the other strains were not identified. These results suggest that unknown Gram-positive, catalase-positive cocci may exert an important influence on the incidence of recurrent aphtha.

View full abstract

I studied the therapeutic effects of low energy lasers on the mechanical expansion of the sagittal suture of rats using both the Ga-Al-As semiconductor and He-Ne lasers. Histological examination and quantitative analysis showed that active tissue remodelling was prominent in the laser irradiation groups. However, collagen degeneration resulted from the irradiation. Image analysis indicated that new bone formation was more evident in the laser irradiated group than in the non-irradiated group. It was also found that although laser irradiation promoted bone remodelling, neither the duration nor the type of irradiation produced significant differences.

View full abstract

[in Japanese]

View full abstract